Sample records for air flow regimes

  1. Boolean logic analysis for flow regime recognition of gas-liquid horizontal flow

    NASA Astrophysics Data System (ADS)

    Ramskill, Nicholas P.; Wang, Mi

    2011-10-01

    In order to develop a flowmeter for the accurate measurement of multiphase flows, it is of the utmost importance to correctly identify the flow regime present to enable the selection of the optimal method for metering. In this study, the horizontal flow of air and water in a pipeline was studied under a multitude of conditions using electrical resistance tomography but the flow regimes that are presented in this paper have been limited to plug and bubble air-water flows. This study proposes a novel method for recognition of the prevalent flow regime using only a fraction of the data, thus rendering the analysis more efficient. By considering the average conductivity of five zones along the central axis of the tomogram, key features can be identified, thus enabling the recognition of the prevalent flow regime. Boolean logic and frequency spectrum analysis has been applied for flow regime recognition. Visualization of the flow using the reconstructed images provides a qualitative comparison between different flow regimes. Application of the Boolean logic scheme enables a quantitative comparison of the flow patterns, thus reducing the subjectivity in the identification of the prevalent flow regime.

  2. Air filtration in the free molecular flow regime: a review of high-efficiency particulate air filters based on carbon nanotubes.

    PubMed

    Li, Peng; Wang, Chunya; Zhang, Yingying; Wei, Fei

    2014-11-01

    Air filtration in the free molecular flow (FMF) regime is important and challenging because a higher filtration efficiency and lower pressure drop are obtained when the fiber diameter is smaller than the gas mean free path in the FMF regime. In previous studies, FMF conditions have been obtained by increasing the gas mean free path through reducing the pressure and increasing the temperature. In the case of carbon nanotubes (CNTs) with nanoscale diameters, it is possible to filtrate in the FMF regime under normal conditions. This paper reviews recent progress in theoretical and experimental studies of air filtration in the FMF regime. Typical structure models of high-efficiency particulate (HEPA) air filters based on CNTs are introduced. The pressure drop in air filters operated in the FMF regime is less than that predicted by the conventional air filtration theory. The thinnest HEPA filters fabricated from single-walled CNT films have an extremely low pressure drop. CNT air filters with a gradient nanostructure are shown to give a much better filtration performance in dynamic filtration. CNT air filters with a hierarchical structure and an agglomerated CNT fluidized bed air filter are also introduced. Finally, the challenges and opportunities for the application of CNTs in air filtration are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Early regimes of water capillary flow in slit silica nanochannels.

    PubMed

    Oyarzua, Elton; Walther, Jens H; Mejía, Andrés; Zambrano, Harvey A

    2015-06-14

    Molecular dynamics simulations are conducted to investigate the initial stages of spontaneous imbibition of water in slit silica nanochannels surrounded by air. An analysis is performed for the effects of nanoscopic confinement, initial conditions of liquid uptake and air pressurization on the dynamics of capillary filling. The results indicate that the nanoscale imbibition process is divided into three main flow regimes: an initial regime where the capillary force is balanced only by the inertial drag and characterized by a constant velocity and a plug flow profile. In this regime, the meniscus formation process plays a central role in the imbibition rate. Thereafter, a transitional regime takes place, in which, the force balance has significant contributions from both inertia and viscous friction. Subsequently, a regime wherein viscous forces dominate the capillary force balance is attained. Flow velocity profiles identify the passage from an inviscid flow to a developing Poiseuille flow. Gas density profiles ahead of the capillary front indicate a transient accumulation of air on the advancing meniscus. Furthermore, slower capillary filling rates computed for higher air pressures reveal a significant retarding effect of the gas displaced by the advancing meniscus.

  4. Experimental Study on the Flow Regimes and Pressure Gradients of Air-Oil-Water Three-Phase Flow in Horizontal Pipes

    PubMed Central

    Al-Hadhrami, Luai M.; Shaahid, S. M.; Tunde, Lukman O.; Al-Sarkhi, A.

    2014-01-01

    An experimental investigation has been carried out to study the flow regimes and pressure gradients of air-oil-water three-phase flows in 2.25 ID horizontal pipe at different flow conditions. The effects of water cuts, liquid and gas velocities on flow patterns and pressure gradients have been studied. The experiments have been conducted at 20°C using low viscosity Safrasol D80 oil, tap water and air. Superficial water and oil velocities were varied from 0.3 m/s to 3 m/s and air velocity varied from 0.29 m/s to 52.5 m/s to cover wide range of flow patterns. The experiments were performed for 10% to 90% water cuts. The flow patterns were observed and recorded using high speed video camera while the pressure drops were measured using pressure transducers and U-tube manometers. The flow patterns show strong dependence on water fraction, gas velocities, and liquid velocities. The observed flow patterns are stratified (smooth and wavy), elongated bubble, slug, dispersed bubble, and annular flow patterns. The pressure gradients have been found to increase with the increase in gas flow rates. Also, for a given superficial gas velocity, the pressure gradients increased with the increase in the superficial liquid velocity. The pressure gradient first increases and then decreases with increasing water cut. In general, phase inversion was observed with increase in the water cut. The experimental results have been compared with the existing unified Model and a good agreement has been noticed. PMID:24523645

  5. Experimental study on the flow regimes and pressure gradients of air-oil-water three-phase flow in horizontal pipes.

    PubMed

    Al-Hadhrami, Luai M; Shaahid, S M; Tunde, Lukman O; Al-Sarkhi, A

    2014-01-01

    An experimental investigation has been carried out to study the flow regimes and pressure gradients of air-oil-water three-phase flows in 2.25 ID horizontal pipe at different flow conditions. The effects of water cuts, liquid and gas velocities on flow patterns and pressure gradients have been studied. The experiments have been conducted at 20 °C using low viscosity Safrasol D80 oil, tap water and air. Superficial water and oil velocities were varied from 0.3 m/s to 3 m/s and air velocity varied from 0.29 m/s to 52.5 m/s to cover wide range of flow patterns. The experiments were performed for 10% to 90% water cuts. The flow patterns were observed and recorded using high speed video camera while the pressure drops were measured using pressure transducers and U-tube manometers. The flow patterns show strong dependence on water fraction, gas velocities, and liquid velocities. The observed flow patterns are stratified (smooth and wavy), elongated bubble, slug, dispersed bubble, and annular flow patterns. The pressure gradients have been found to increase with the increase in gas flow rates. Also, for a given superficial gas velocity, the pressure gradients increased with the increase in the superficial liquid velocity. The pressure gradient first increases and then decreases with increasing water cut. In general, phase inversion was observed with increase in the water cut. The experimental results have been compared with the existing unified Model and a good agreement has been noticed.

  6. Zero-G experiments in two-phase fluids flow regimes

    NASA Technical Reports Server (NTRS)

    Heppner, D. B.; King, C. D.; Littles, J. W.

    1975-01-01

    The two-phase flows studied were liquid and gas mixtures in a straight flow channel of circular cross-section. Boundaries between flow regimes have been defined for normogravity on coordinates of gas quality and total mass velocity; and, when combined with boundary expressions having a Froude number term, an analytical model was derived predicting boundary shifts with changes in gravity level. Experiments with air and water were performed, first in the normogravity environment of a ground laboratory and then in 'zero gravity' aboard a KC-135 aircraft flying parabolic trajectories. Data reduction confirmed regime boundary shifts in the direction predicted, although the magnitude was a little less than predicted. Pressure drop measurements showed significant increases for the low gravity condition.

  7. Vertical two-phase flow regimes and pressure gradients under the influence of SDS surfactant

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Duangprasert, Tanabordee; Sirivat, Anuvat; Siemanond, Kitipat

    2008-01-15

    Two-phase gas/liquid flows in vertical pipes have been systematically investigated. Water and SDS surfactant solutions at various concentrations were used as the working fluids. In particular, we focus our work on the influence of surfactant addition on the flow regimes, the corresponding pressure gradients, and the bubble sizes and velocity. Adding the surfactant lowers the air critical Reynolds numbers for the bubble-slug flow and the slug flow transitions. The pressure gradients of SDS solutions are lower than those of pure water especially in the slug flow and the slug-churn flow regimes, implying turbulent drag reduction. At low Re{sub air}, themore » bubble sizes of the surfactant solution are lower than those of pure water due to the increase in viscosity. With increasing and at high Re{sub air}, the bubble sizes of the SDS solution become greater than those of pure water which is attributed to the effect of surface tension. (author)« less

  8. Modelling of air flow supply in a room at variable regime by using both K - E and spalart - allmaras turbulent model

    NASA Astrophysics Data System (ADS)

    Korbut, Vadim; Voznyak, Orest; Sukholova, Iryna; Myroniuk, Khrystyna

    2017-12-01

    The abstract is to The article is devoted to the decision of actual task of air distribution efficiency increasing with the help of swirl and spread air jets to provide normative parameters of air in the production apartments. The mathematical model of air supply with swirl and spread air jets in that type of apartments is improved. It is shown that for reachin of air distribution maximal efficiency it is necessary to supply air by air jets, that intensively extinct before entering into a working area. Simulation of air flow performed with the help of CFD FLUENT (Ansys FLUENT). Calculations of the equation by using one-parameter model of turbulence Spalart-Allmaras are presented. The graphical and the analytical dependences on the basis of the conducted experimental researches, which can be used in subsequent engineering calculations, are shown out. Dynamic parameters of air flow that is created due to swirl and spread air jets at their leakage at variable regime and creation of dynamic microclimate in a room has been determined. Results of experimental investigations of air supply into the room by air distribution device which creates swirl air jets for creation more intensive turbulization air flow in the room are presented. Obtained results of these investigations give possibility to realize engineer calculations of air distribution with swirl air jets. The results of theoretical researches of favourable influence of dynamic microclimate to the man are presented. When using dynamic microclimate, it's possible to decrease conditioning and ventilation system expenses. Human organism reacts favourably on short lasting deviations from the rationed parameters of air environment.

  9. Gas flow through rough microchannels in the transition flow regime.

    PubMed

    Deng, Zilong; Chen, Yongping; Shao, Chenxi

    2016-01-01

    A multiple-relaxation-time lattice Boltzmann model of Couette flow is developed to investigate the rarified gas flow through microchannels with roughness characterized by fractal geometry, especially to elucidate the coupled effects of roughness and rarefaction on microscale gas flow in the transition flow regime. The results indicate that the surface roughness effect on gas flow behavior becomes more significant in rarefied gas flow with the increase of Knudsen number. We find the gas flow behavior in the transition flow regime is more sensitive to roughness height than that in the slip flow regime. In particular, the influence of fractal dimension on rarefied gas flow behavior is less significant than roughness height.

  10. Flow regimes of adiabatic gas-liquid two-phase under rolling conditions

    NASA Astrophysics Data System (ADS)

    Yan, Chaoxing; Yan, Changqi; Sun, Licheng; Xing, Dianchuan; Wang, Yang; Tian, Daogui

    2013-07-01

    Characteristics of adiabatic air/water two-phase flow regimes under vertical and rolling motion conditions were investigated experimentally. Test sections are two rectangular ducts with the gaps of 1.41 and 10 mm, respectively, and a circular tube with 25 mm diameter. Flow regimes were recorded by a high speed CCD-camera and were identified by examining the video images. The experimental results indicate that the characteristics of flow patterns in 10 mm wide rectangular duct under vertical condition are very similar to those in circular tube, but different from the 1.41 mm wide rectangular duct. Channel size has a significant influence on flow pattern transition, boundary of which in rectangular channels tends asymptotically towards that in the circular tube with increasing the width of narrow side. Flow patterns in rolling channels are similar to each other, nevertheless, the effect of rolling motion on flow pattern transition are significantly various. Due to the remarkable influences of the friction shear stress and surface tension in the narrow gap duct, detailed flow pattern maps of which under vertical and rolling conditions are indistinguishable. While for the circular tube with 25 mm diameter, the transition from bubbly to slug flow occurs at a higher superficial liquid velocity and the churn flow covers more area on the flow regime map as the rolling period decreases.

  11. Identifying natural flow regimes using fish communities

    NASA Astrophysics Data System (ADS)

    Chang, Fi-John; Tsai, Wen-Ping; Wu, Tzu-Ching; Chen, Hung-kwai; Herricks, Edwin E.

    2011-10-01

    SummaryModern water resources management has adopted natural flow regimes as reasonable targets for river restoration and conservation. The characterization of a natural flow regime begins with the development of hydrologic statistics from flow records. However, little guidance exists for defining the period of record needed for regime determination. In Taiwan, the Taiwan Eco-hydrological Indicator System (TEIS), a group of hydrologic statistics selected for fisheries relevance, is being used to evaluate ecological flows. The TEIS consists of a group of hydrologic statistics selected to characterize the relationships between flow and the life history of indigenous species. Using the TEIS and biosurvey data for Taiwan, this paper identifies the length of hydrologic record sufficient for natural flow regime characterization. To define the ecological hydrology of fish communities, this study connected hydrologic statistics to fish communities by using methods to define antecedent conditions that influence existing community composition. A moving average method was applied to TEIS statistics to reflect the effects of antecedent flow condition and a point-biserial correlation method was used to relate fisheries collections with TEIS statistics. The resulting fish species-TEIS (FISH-TEIS) hydrologic statistics matrix takes full advantage of historical flows and fisheries data. The analysis indicates that, in the watersheds analyzed, averaging TEIS statistics for the present year and 3 years prior to the sampling date, termed MA(4), is sufficient to develop a natural flow regime. This result suggests that flow regimes based on hydrologic statistics for the period of record can be replaced by regimes developed for sampled fish communities.

  12. Dynamic Modeling Strategy for Flow Regime Transition in Gas-Liquid Two-Phase Flows

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xia Wang; Xiaodong Sun; Benjamin Doup

    In modeling gas-liquid two-phase flows, the concept of flow regimes has been widely used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are flow regime dependent. Current nuclear reactor safety analysis codes, such as RELAP5, classify flow regimes using flow regime maps or transition criteria that were developed for steady-state, fully-developed flows. As twophase flows are dynamic in nature, it is important to model the flow regime transitions dynamically to more accurately predict the two-phase flows. The present workmore » aims to develop a dynamic modeling strategy to determine flow regimes in gas-liquid two-phase flows through introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation of the interfacial area, fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation, and the destruction of the interfacial area, fluid particle coalescence and condensation. For flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shapes, namely group-1 and group-2 bubbles. A preliminary approach to dynamically identify the flow regimes is discussed, in which discriminator s are based on the predicted information, such as the void fraction and interfacial area concentration. The flow regime predicted with this method shows good agreement with the experimental observations.« less

  13. Experimental and analytical dynamic flow characteristics of an axial-flow fan from an air cushion landing system model

    NASA Technical Reports Server (NTRS)

    Thompson, W. C.; Boghani, A. B.; Leland, T. J. W.

    1977-01-01

    An investigation was conducted to compare the steady-state and dynamic flow characteristics of an axial-flow fan which had been used previously as the air supply fan for some model air cushion landing system studies. Steady-state flow characteristics were determined in the standard manner by using differential orifice pressures for the flow regime from free flow to zero flow. In this same regime, a correlative technique was established so that fan inlet and outlet pressures could be used to measure dynamic flow as created by a rotating damper. Dynamic tests at damper frequencies up to 5 Hz showed very different flow characteristics when compared with steady-state flow, particularly with respect to peak pressures and the pressure-flow relationship at fan stall and unstall. A generalized, rational mathematical fan model was developed based on physical fan parameters and a steady-state flow characteristic. The model showed good correlation with experimental tests at damper frequencies up to 5 Hz.

  14. DYNAMIC MODELING STRATEGY FOR FLOW REGIME TRANSITION IN GAS-LIQUID TWO-PHASE FLOWS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    X. Wang; X. Sun; H. Zhao

    In modeling gas-liquid two-phase flows, the concept of flow regime has been used to characterize the global interfacial structure of the flows. Nearly all constitutive relations that provide closures to the interfacial transfers in two-phase flow models, such as the two-fluid model, are often flow regime dependent. Currently, the determination of the flow regimes is primarily based on flow regime maps or transition criteria, which are developed for steady-state, fully-developed flows and widely applied in nuclear reactor system safety analysis codes, such as RELAP5. As two-phase flows are observed to be dynamic in nature (fully-developed two-phase flows generally do notmore » exist in real applications), it is of importance to model the flow regime transition dynamically for more accurate predictions of two-phase flows. The present work aims to develop a dynamic modeling strategy for determining flow regimes in gas-liquid two-phase flows through the introduction of interfacial area transport equations (IATEs) within the framework of a two-fluid model. The IATE is a transport equation that models the interfacial area concentration by considering the creation and destruction of the interfacial area, such as the fluid particle (bubble or liquid droplet) disintegration, boiling and evaporation; and fluid particle coalescence and condensation, respectively. For the flow regimes beyond bubbly flows, a two-group IATE has been proposed, in which bubbles are divided into two groups based on their size and shape (which are correlated), namely small bubbles and large bubbles. A preliminary approach to dynamically identifying the flow regimes is provided, in which discriminators are based on the predicted information, such as the void fraction and interfacial area concentration of small bubble and large bubble groups. This method is expected to be applied to computer codes to improve their predictive capabilities of gas-liquid two-phase flows, in particular for the

  15. Gas holdup and flow regime transition in spider-sparger bubble column: effect of liquid phase properties

    NASA Astrophysics Data System (ADS)

    Besagni, G.; Inzoli, F.; De Guido, G.; Pellegrini, L. A.

    2017-01-01

    This paper discusses the effects of the liquid velocity and the liquid phase properties on the gas holdup and the flow regime transition in a large-diameter and large-scale counter-current two-phase bubble column. In particular, we compared and analysed the experimental data obtained in our previous experimental studies. The bubble column is 5.3 m in height, has an inner diameter of 0.24 m, it was operated with gas superficial velocities in the range of 0.004-0.20 m/s and, in the counter-current mode, the liquid was recirculated up to a superficial velocity of -0.09 m/s. Air was used as the dispersed phase and various fluids (tap water, aqueous solutions of sodium chloride, ethanol and monoethylene glycol) were employed as liquid phases. The experimental dataset consist in gas holdup measurements and was used to investigate the global fluid dynamics and the flow regime transition between the homogeneous flow regime and the transition flow regime. We found that the liquid velocity and the liquid phase properties significantly affect the gas holdup and the flow regime transition. In this respect, a possible relationship (based on the lift force) between the flow regime transition and the gas holdup was proposed.

  16. Flow regimes during immiscible displacement

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Armstrong, Ryan T.; Mcclure, James; Berrill, Mark A.

    Fractional ow of immiscible phases occurs at the pore scale where grain surfaces and phases interfaces obstruct phase mobility. However, the larger scale behavior is described by a saturation-dependent phenomenological relationship called relative permeability. As a consequence, pore-scale parameters, such as phase topology and/ or geometry, and details of the flow regime cannot be directly related to Darcy-scale flow parameters. It is well understood that relative permeability is not a unique relationship of wetting-phase saturation and rather depends on the experimental conditions at which it is measured. Herein we use fast X-ray microcomputed tomography to image pore-scale phase arrangements duringmore » fractional flow and then forward simulate the flow regimes using the lattice-Boltzmann method to better understand the underlying pore-scale flow regimes and their influence on Darcy-scale parameters. We find that relative permeability is highly dependent on capillary number and that the Corey model fits the observed trends. At the pore scale, while phase topologies are continuously changing on the scale of individual pores, the Euler characteristic of the nonwetting phase (NWP) averaged over a sufficiently large field of view can describe the bulk topological characteristics; the Euler characteristic decreases with increasing capillary number resulting in an increase in relative permeability. Lastly, we quantify the fraction of NWP that flows through disconnected ganglion dynamics and demonstrate that this can be a significant fraction of the NWP flux for intermediate wetting-phase saturation. Furthermore, rate dependencies occur in our homogenous sample (without capillary end effect) and the underlying cause is attributed to ganglion flow that can significantly influence phase topology during the fractional flow of immiscible phases.« less

  17. Flow regimes during immiscible displacement

    DOE PAGES

    Armstrong, Ryan T.; Mcclure, James; Berrill, Mark A.; ...

    2017-02-01

    Fractional ow of immiscible phases occurs at the pore scale where grain surfaces and phases interfaces obstruct phase mobility. However, the larger scale behavior is described by a saturation-dependent phenomenological relationship called relative permeability. As a consequence, pore-scale parameters, such as phase topology and/ or geometry, and details of the flow regime cannot be directly related to Darcy-scale flow parameters. It is well understood that relative permeability is not a unique relationship of wetting-phase saturation and rather depends on the experimental conditions at which it is measured. Herein we use fast X-ray microcomputed tomography to image pore-scale phase arrangements duringmore » fractional flow and then forward simulate the flow regimes using the lattice-Boltzmann method to better understand the underlying pore-scale flow regimes and their influence on Darcy-scale parameters. We find that relative permeability is highly dependent on capillary number and that the Corey model fits the observed trends. At the pore scale, while phase topologies are continuously changing on the scale of individual pores, the Euler characteristic of the nonwetting phase (NWP) averaged over a sufficiently large field of view can describe the bulk topological characteristics; the Euler characteristic decreases with increasing capillary number resulting in an increase in relative permeability. Lastly, we quantify the fraction of NWP that flows through disconnected ganglion dynamics and demonstrate that this can be a significant fraction of the NWP flux for intermediate wetting-phase saturation. Furthermore, rate dependencies occur in our homogenous sample (without capillary end effect) and the underlying cause is attributed to ganglion flow that can significantly influence phase topology during the fractional flow of immiscible phases.« less

  18. Flow diagnostics in unseeded air

    NASA Technical Reports Server (NTRS)

    Miles, R.; Lempert, W.

    1990-01-01

    Several approaches are presented for the quantitative measurement of flowfield parameters in high-speed flows. The techniques are developed for the study of air flows in the Mach 2 to Mach 3 regime and can be extended to the hypersonic and subsonic regimes in a straightforward manner. Instantaneous two-dimensional cross-sectional images of the density using UV Rayleigh scattering and the measurement of velocity profiles using the RELIEF technique are shown. The RELIEF technique employs two high-powered lasers separated in frequency by the vibrational frequency of oxygen molecules to write lines across the flowfield by stimulated Raman scattering. The preliminary results indicate that the UV Rayleigh scattering may also be extended to the measurement of velocity and temperature fields by using an atomic or molecular absorption filter window, and that the RELIEF technique can be extended to marking shaped volumetric points or arrays of points in the flowfield for velocity and vorticity measurements.

  19. Modified unified kinetic scheme for all flow regimes.

    PubMed

    Liu, Sha; Zhong, Chengwen

    2012-06-01

    A modified unified kinetic scheme for the prediction of fluid flow behaviors in all flow regimes is described. The time evolution of macrovariables at the cell interface is calculated with the idea that both free transport and collision mechanisms should be considered. The time evolution of macrovariables is obtained through the conservation constraints. The time evolution of local Maxwellian distribution is obtained directly through the one-to-one mapping from the evolution of macrovariables. These improvements provide more physical realities in flow behaviors and more accurate numerical results in all flow regimes especially in the complex transition flow regime. In addition, the improvement steps introduce no extra computational complexity.

  20. Neutron imaging of diabatic two-phase flows relevant to air conditioning

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Geoghegan, Patrick J; Sharma, Vishaldeep

    The design of the evaporator of an air conditioning system relies heavily on heat transfer coefficients and pressure drop correlations that predominantly involve an estimate of the changing void fraction and the underlying two-phase flow regime. These correlations dictate whether the resulting heat exchanger is oversized or not and the amount of refrigerant charge necessary to operate. The latter is particularly important when dealing with flammable or high GWP refrigerants. Traditional techniques to measure the void fraction and visualize the flow are either invasive to the flow or occur downstream of the evaporator, where some of the flow distribution willmore » have changed. Neutron imaging has the potential to visualize two-phase flow in-situ where an aluminium heat exchanger structure becomes essentially transparent to the penetrating neutrons. The subatomic particles are attenuated by the passing refrigerant flow. The resulting image may be directly related to the void fraction and the overall picture provides a clear insight into the flow regime present. This work presents neutron images of the refrigerant Isopentane as it passes through the flow channels of an aluminium evaporator at flowrates relevant to air conditioning. The flow in a 4mm square macro channel is compared to that in a 250 m by 750 m rectangular microchannel in terms of void fraction and regime. All neutron imaging experiments were conducted at the High Flux Isotope Reactor, an Oak Ridge National Laboratory facility« less

  1. New results in gravity dependent two-phase flow regime mapping

    NASA Astrophysics Data System (ADS)

    Kurwitz, Cable; Best, Frederick

    2002-01-01

    Accurate prediction of thermal-hydraulic parameters, such as the spatial gas/liquid orientation or flow regime, is required for implementation of two-phase systems. Although many flow regime transition models exist, accurate determination of both annular and slug regime boundaries is not well defined especially at lower flow rates. Furthermore, models typically indicate the regime as a sharp transition where data may indicate a transition space. Texas A&M has flown in excess of 35 flights aboard the NASA KC-135 aircraft with a unique two-phase package. These flights have produced a significant database of gravity dependent two-phase data including visual observations for flow regime identification. Two-phase flow tests conducted during recent zero-g flights have added to the flow regime database and are shown in this paper with comparisons to selected transition models. .

  2. Methodology Development of a Gas-Liquid Dynamic Flow Regime Transition Model

    NASA Astrophysics Data System (ADS)

    Doup, Benjamin Casey

    Current reactor safety analysis codes, such as RELAP5, TRACE, and CATHARE, use flow regime maps or flow regime transition criteria that were developed for static fully-developed two-phase flows to choose interfacial transfer models that are necessary to solve the two-fluid model. The flow regime is therefore difficult to identify near the flow regime transitions, in developing two-phase flows, and in transient two-phase flows. Interfacial area transport equations were developed to more accurately predict the dynamic nature of two-phase flows. However, other model coefficients are still flow regime dependent. Therefore, an accurate prediction of the flow regime is still important. In the current work, the methodology for the development of a dynamic flow regime transition model that uses the void fraction and interfacial area concentration obtained by solving three-field the two-fluid model and two-group interfacial area transport equation is investigated. To develop this model, detailed local experimental data are obtained, the two-group interfacial area transport equations are revised, and a dynamic flow regime transition model is evaluated using a computational fluid dynamics model. Local experimental data is acquired for 63 different flow conditions in bubbly, cap-bubbly, slug, and churn-turbulent flow regimes. The measured parameters are the group-1 and group-2 bubble number frequency, void fraction, interfacial area concentration, and interfacial bubble velocities. The measurements are benchmarked by comparing the prediction of the superficial gas velocities, determined using the local measurements with those determined from volumetric flow rate measurements and the agreement is generally within +/-20%. The repeatability four-sensor probe construction process is within +/-10%. The repeatability of the measurement process is within +/-7%. The symmetry of the test section is examined and the average agreement is within +/-5.3% at z/D = 10 and +/-3.4% at z/D = 32

  3. Natural flow regimes of the Ozark-Ouachita Interior Highlands region

    USGS Publications Warehouse

    Leasure, D. R.; Magoulick, Daniel D.; Longing, S. D.

    2016-01-01

    Natural flow regimes represent the hydrologic conditions to which native aquatic organisms are best adapted. We completed a regional river classification and quantitative descriptions of each natural flow regime for the Ozark–Ouachita Interior Highlands region of Arkansas, Missouri and Oklahoma. On the basis of daily flow records from 64 reference streams, seven natural flow regimes were identified with mixture model cluster analysis: Groundwater Stable, Groundwater, Groundwater Flashy, Perennial Runoff, Runoff Flashy, Intermittent Runoff and Intermittent Flashy. Sets of flow metrics were selected that best quantified nine ecologically important components of these natural flow regimes. An uncertainty analysis was performed to avoid selecting metrics strongly affected by measurement uncertainty that can result from short periods of record. Measurement uncertainties (bias, precision and accuracy) were assessed for 170 commonly used flow metrics. The ranges of variability expected for select flow metrics under natural conditions were quantified for each flow regime to provide a reference for future assessments of hydrologic alteration. A random forest model was used to predict the natural flow regimes of all stream segments in the study area based on climate and catchment characteristics, and a map was produced. The geographic distribution of flow regimes suggested distinct ecohydrological regions that may be useful for conservation planning. This project provides a hydrologic foundation for future examination of flow–ecology relationships in the region. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  4. Space-Time Variability in River Flow Regimes of Northeast Turkey

    NASA Astrophysics Data System (ADS)

    Saris, F.; Hannah, D. M.; Eastwood, W. J.

    2011-12-01

    The northeast region of Turkey is characterised by relatively high annual precipitation totals and river flow. It is a mountainous region with high ecological status and also it is of prime interest to the energy sector. These characteristics make this region an important area for a hydroclimatology research in terms of future availability and management of water resources. However, there is not any previous research identifying hydroclimatological variability across the region. This study provides first comprehensive and detailed information on river flow regimes of northeast Turkey which is delimited by two major river basins namely East Black Sea (EBS) and Çoruh River (ÇRB) basins. A novel river flow classification is used that yields a large-scale perspective on hydroclimatology patterns of the region and allows interpretations regarding the controlling factors on river flow variability. River flow regimes are classified (with respect to timing and magnitude of flow) to examine spatial variability based on long-term average regimes, and also by grouping annual regimes for each station-year to identify temporal (between-year) variability. Results indicate that rivers in northeast Turkey are characterised by marked seasonal flow variation with an April-May-June maximum flow period. Spatial variability in flow regime seasonality is dependent largely on the topography of the study area. The EBS Basin, for which the North Anatolian Mountains cover the eastern part, is characterised by a May-June peak; whereas the ÇRB is defined by an April-May flow peak. The timing of river flows indicates that snowmelt is an important process and contributor of river flow maxima for both basins. The low flow season is January and February. Intermediate and low regime magnitude classes dominate in ÇRB and EBS basins, respectively, while high flow magnitude class is observed for one station only across the region. Result of regime stability analysis (year-to-year variation) shows

  5. Regimes of Two-Phase Flow in Short Rectangular Channel

    NASA Astrophysics Data System (ADS)

    Chinnov, Evgeny A.; Guzanov, Vladimir V.; Cheverda, Vyacheslav; Markovich, Dmitry M.; Kabov, Oleg A.

    2009-08-01

    Experimental study of two-phase flow in the short rectangular horizontal channel with height 440 μm has been performed. Characteristics of liquid motion inside the channel have been registered and measured by the Laser Induced Fluorescence technique. New information has allowed determining more precisely the characteristics of churn regime and boundaries between different regimes of two-phase flow. It was shown that formation of some two-phase flow regimes and transitions between them are determined by instability of the flow in the lateral parts of the channel.

  6. System-focused environmental flow regime prescription, monitoring and adaptive management

    NASA Astrophysics Data System (ADS)

    Hetherington, David; Lexartza Artza, Irantzu

    2016-04-01

    The definition of appropriate environmental flow regimes through hydropower schemes and water storage reservoirs is key part of mitigation. Insufficient (magnitude and variability) environmental flows can result in much environmental harm with negative impacts being encountered by morphological, ecological and societal systems. Conventionally, environmental flow regimes have been determined by using generic protocols and guidance such as the Tennant method of environmental flow estimation. It is generally accepted that such approaches to minimum environmental flow definition, although being a useful starting point, are not universally applicable across catchment typologies and climatic regions. Such approaches will not always produce conditions that would be associated with 'Good Ecological Status' under the Water framework Directive (or equivalent). Other similar approaches to minimum environmental flow estimation are used that are specific to geographies, yet still the associated guidance rarely thoroughly covers appropriate definition for healthy holistic systems across the flow regime. This paper draws on experience of system-focused environmental flow regime determination in the UK and the Georgian Caucasus Mountains, which allowed for a critical analysis of more conventional methods to be undertaken. The paper describes a recommended approach for determining appropriate environmental flow regimes based on analysis of the impacted geomorphological, ecological and societal systems in a way which is sensitive to the local holistic environment and associated complexities and interactions. The paper suggests that a strong understanding of the local geomorphology in key in predicting how flows will manifest habitat differently across the flow regime, and be spatially dynamic. Additionally, an understanding of the geomorphological system allows the flow of course and fine sediment to be factored into the initial suggested environmental flow regime. It is suggested

  7. Online recognition of the multiphase flow regime and study of slug flow in pipeline

    NASA Astrophysics Data System (ADS)

    Liejin, Guo; Bofeng, Bai; Liang, Zhao; Xin, Wang; Hanyang, Gu

    2009-02-01

    Multiphase flow is the phenomenon existing widely in nature, daily life, as well as petroleum and chemical engineering industrial fields. The interface structure among multiphase and their movement are complicated, which distribute random and heterogeneously in the spatial and temporal scales and have multivalue of the flow structure and state[1]. Flow regime is defined as the macro feature about the multiphase interface structure and its distribution, which is an important feature to describe multiphase flow. The energy and mass transport mechanism differ much for each flow regimes. It is necessary to solve the flow regime recognition to get a clear understanding of the physical phenomena and their mechanism of multiphase flow. And the flow regime is one of the main factors affecting the online measurement accuracy of phase fraction, flow rate and other phase parameters. Therefore, it is of great scientific and technological importance to develop new principles and methods of multiphase flow regime online recognition, and of great industrial background. In this paper, the key reasons that the present method cannot be used to solve the industrial multiphase flow pattern recognition are clarified firstly. Then the prerequisite to realize the online recognition of multiphase flow regime is analyzed, and the recognition rules for partial flow pattern are obtained based on the massive experimental data. The standard templates for every flow regime feature are calculated with self-organization cluster algorithm. The multi-sensor data fusion method is proposed to realize the online recognition of multiphase flow regime with the pressure and differential pressure signals, which overcomes the severe influence of fluid flow velocity and the oil fraction on the recognition. The online recognition method is tested in the practice, which has less than 10 percent measurement error. The method takes advantages of high confidence, good fault tolerance and less requirement of

  8. Rheological equations in asymptotic regimes of granular flow

    USGS Publications Warehouse

    Chen, C.-L.; Ling, C.-H.

    1998-01-01

    This paper assesses the validity of the generalized viscoplastic fluid (GVF) model in light of the established constitutive relations in two asymptotic flow regimes, namely, the macroviscous and grain-inertia regimes. A comprehensive review of the literature on constitutive relations in both regimes reveals that except for some material constants, such as the coefficient of restitution, the normalized shear stress in both regimes varies only with the grain concentration, C. It is found that Krieger-Dougherty's relative viscosity, ??*(C), is sufficiently coherent among the monotonically nondecreasing functions of C used in describing the variation of the shear stress with C in both regimes. It not only accurately represents the C-dependent relative viscosity of a suspension in the macroviscous regime, but also plays a role of the radial distribution function that describes the statistics of particle collisions in the grain-inertia regime. Use of ??*(C) alone, however, cannot link the two regimes. Another parameter, the shear-rate number, N, is needed in modelling the rheology of neutrally buoyant granular flows in transition between the two asymptotic regimes. The GVF model proves compatible with most established relations in both regimes.

  9. Numerical modeling of flow focusing: Quantitative characterization of the flow regimes

    NASA Astrophysics Data System (ADS)

    Mamet, V.; Namy, P.; Dedulle, J.-M.

    2017-09-01

    Among droplet generation technologies, the flow focusing technique is a major process due to its control, stability, and reproducibility. In this process, one fluid (the continuous phase) interacts with another one (the dispersed phase) to create small droplets. Experimental assays in the literature on gas-liquid flow focusing have shown that different jet regimes can be obtained depending on the operating conditions. However, the underlying physical phenomena remain unclear, especially mechanical interactions between the fluids and the oscillation phenomenon of the liquid. In this paper, based on published studies, a numerical diphasic model has been developed to take into consideration the mechanical interaction between phases, using the Cahn-Hilliard method to monitor the interface. Depending on the liquid/gas inputs and the geometrical parameters, various regimes can be obtained, from a steady state regime to an unsteady one with liquid oscillation. In the dispersed phase, the model enables us to compute the evolution of fluid flow, both in space (size of the recirculation zone) and in time (period of oscillation). The transition between unsteady and stationary regimes is assessed in relation to liquid and gas dimensionless numbers, showing the existence of critical thresholds. This model successfully highlights, qualitatively and quantitatively, the influence of the geometry of the nozzle, in particular, its inner diameter.

  10. Propulsive jet simulation with air and helium in launcher wake flows

    NASA Astrophysics Data System (ADS)

    Stephan, Sören; Radespiel, Rolf

    2017-06-01

    The influence on the turbulent wake of a generic space launcher model due to the presence of an under-expanded jet is investigated experimentally. Wake flow phenomena represent a significant source of uncertainties in the design of a space launcher. Especially critical are dynamic loads on the structure. The wake flow is investigated at supersonic (M=2.9) and hypersonic (M=5.9) flow regimes. The jet flow is simulated using air and helium as working gas. Due to the lower molar mass of helium, higher jet velocities are realized, and therefore, velocity ratios similar to space launchers can be simulated. The degree of under-expansion of the jet is moderate for the supersonic case (p_e/p_∞ ≈ 5) and high for the hypersonic case (p_e/p_∞ ≈ 90). The flow topology is described by Schlieren visualization and mean-pressure measurements. Unsteady pressure measurements are performed to describe the dynamic wake flow. The influences of the under-expanded jet and different jet velocities are reported. On the base fluctuations at a Strouhal number, around St_D ≈ 0.25 dominate for supersonic free-stream flows. With air jet, a fluctuation-level increase on the base is observed for Strouhal numbers above St_D ≈ 0.75 in hypersonic flow regime. With helium jet, distinct peaks at higher frequencies are found. This is attributed to the interactions of wake flow and jet.

  11. Inertial flow regimes of the suspension of finite size particles

    NASA Astrophysics Data System (ADS)

    Lashgari, Iman; Picano, Francesco; Brandt, Luca

    2015-03-01

    We study inertial flow regimes of the suspensions of finite size neutrally buoyant particles. These suspensions experience three different regimes by varying the Reynolds number, Re , and particle volume fraction, Φ. At low values of Re and Φ, flow is laminar-like where viscous stress is the dominating term in the stress budget. At high Re and relatively small Φ, the flow is turbulent-like where Reynolds stress has the largest contribution to the total stress. At high Φ, the flow regime is as a form of inertial shear-thickening characterized by a significant enhancement in the wall shear stress not due to the increment of Reynolds stress but to the particle stress. We further analyze the local behavior of the suspension in the three different regimes by studying the particle dispersion and collisions. Turbulent cases shows higher level of particle dispersion and higher values of the collision kernel (the radial distribution function times the particle relative velocity as a function of the distance between the particles) than those of the inertial shear-thickening regimes providing additional evidence of two different transport mechanisms in the Bagnoldian regime. Support from the European Research Council (ERC) is acknowledged.

  12. Salix response to different flow regimes in controlled experiments: first results

    NASA Astrophysics Data System (ADS)

    Gorla, Lorenzo; Signarbieux, Constant; Buttler, Alexandre; Perona, Paolo

    2013-04-01

    Dams and water management for hydropower production, agriculture and other human activities alter the natural flow regime of rivers. The new river hydrograph components depend on the type of impoundment and the policy of regulation but such a different flow regime will likely affect the riparian environment. The main challenge in order to define sustainable flow releases is to quantify hydrological effects in terms of geomorphology and ecosystem response. A considerable lack of knowledge still affects the link hydrology-ecology and inadequate flow rules (e.g., minimal or residual flows) are consequently still widespread: further research in this direction is urgently required. We present an experiment, which aims to investigate the effects of different water stage regimes on riparian vegetation (salix Viminalis cuttings) development in a temperate region (Switzerland). This work describes the installation setup, together with the first results concerning the first of the two scheduled seasons of campaign. Sixty Salix cuttings were planted in non-cohesive sandy-gravel sediment within 1 meter tall plastic pots installed outside in the EPFL campus. After grouping them in three batteries, the water level within them has been varying following three river regimes simulated by adjusting the water level within the pots by means of an automatic hydraulic system. The three water level regimes reproduce a natural flow regime, a minimum residual flow policy, which only conserves peaks during flooding conditions, and an artificial regime conserving only low frequencies (e.g., seasonality) of the natural dynamic. The natural flow regime of the first battery has been applied for two months to the entire system; the three regimes above said started in June 2012. This triggered a plant response transitory regime, which we monitored by measuring plant growth, soil and atmospheric variables. Particularly, measures concern with branches development leaves photosynthesis and

  13. A solution algorithm for fluid–particle flows across all flow regimes

    DOE PAGES

    Kong, Bo; Fox, Rodney O.

    2017-05-12

    Many fluid–particle flows occurring in nature and in technological applications exhibit large variations in the local particle volume fraction. For example, in circulating fluidized beds there are regions where the particles are closepacked as well as very dilute regions where particle–particle collisions are rare. Thus, in order to simulate such fluid–particle systems, it is necessary to design a flow solver that can accurately treat all flow regimes occurring simultaneously in the same flow domain. In this work, a solution algorithm is proposed for this purpose. The algorithm is based on splitting the free-transport flux solver dynamically and locally in themore » flow. In close-packed to moderately dense regions, a hydrodynamic solver is employed, while in dilute to very dilute regions a kinetic-based finite-volume solver is used in conjunction with quadrature-based moment methods. To illustrate the accuracy and robustness of the proposed solution algorithm, it is implemented in OpenFOAM for particle velocity moments up to second order, and applied to simulate gravity-driven, gas–particle flows exhibiting cluster-induced turbulence. By varying the average particle volume fraction in the flow domain, it is demonstrated that the flow solver can handle seamlessly all flow regimes present in fluid–particle flows.« less

  14. A solution algorithm for fluid-particle flows across all flow regimes

    NASA Astrophysics Data System (ADS)

    Kong, Bo; Fox, Rodney O.

    2017-09-01

    Many fluid-particle flows occurring in nature and in technological applications exhibit large variations in the local particle volume fraction. For example, in circulating fluidized beds there are regions where the particles are close-packed as well as very dilute regions where particle-particle collisions are rare. Thus, in order to simulate such fluid-particle systems, it is necessary to design a flow solver that can accurately treat all flow regimes occurring simultaneously in the same flow domain. In this work, a solution algorithm is proposed for this purpose. The algorithm is based on splitting the free-transport flux solver dynamically and locally in the flow. In close-packed to moderately dense regions, a hydrodynamic solver is employed, while in dilute to very dilute regions a kinetic-based finite-volume solver is used in conjunction with quadrature-based moment methods. To illustrate the accuracy and robustness of the proposed solution algorithm, it is implemented in OpenFOAM for particle velocity moments up to second order, and applied to simulate gravity-driven, gas-particle flows exhibiting cluster-induced turbulence. By varying the average particle volume fraction in the flow domain, it is demonstrated that the flow solver can handle seamlessly all flow regimes present in fluid-particle flows.

  15. A solution algorithm for fluid–particle flows across all flow regimes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kong, Bo; Fox, Rodney O.

    Many fluid–particle flows occurring in nature and in technological applications exhibit large variations in the local particle volume fraction. For example, in circulating fluidized beds there are regions where the particles are closepacked as well as very dilute regions where particle–particle collisions are rare. Thus, in order to simulate such fluid–particle systems, it is necessary to design a flow solver that can accurately treat all flow regimes occurring simultaneously in the same flow domain. In this work, a solution algorithm is proposed for this purpose. The algorithm is based on splitting the free-transport flux solver dynamically and locally in themore » flow. In close-packed to moderately dense regions, a hydrodynamic solver is employed, while in dilute to very dilute regions a kinetic-based finite-volume solver is used in conjunction with quadrature-based moment methods. To illustrate the accuracy and robustness of the proposed solution algorithm, it is implemented in OpenFOAM for particle velocity moments up to second order, and applied to simulate gravity-driven, gas–particle flows exhibiting cluster-induced turbulence. By varying the average particle volume fraction in the flow domain, it is demonstrated that the flow solver can handle seamlessly all flow regimes present in fluid–particle flows.« less

  16. Development of an inflow controlled environmental flow regime for a Norwegian river

    NASA Astrophysics Data System (ADS)

    Alfredsen, Knut; Harby, Atle; Linnansaari, Tommi; Ugedal, Ola

    2010-05-01

    For most regulated rivers in Norway the common environmental flow regime is static and shows very little variation over the year. Recent research indicate that flow regimes that follow the natural inflow variation can meet the ecological and social demands for water in a better way. The implementation of a variable environmental flow regime provides many challenges both related to defining flow for various species and user groups in the river, but also due to practical implementation, legislation and control. A inflow controlled flow regime is developed for a Norwegian river regulated for hydro power as a pilot study. The regime should meet ecological demands from Atlantic salmon and brown trout, recreational use of water and visual impression of the river. This should be achieved preferably without altering the energy production in the hydro power system. The flow regime is developed for wet, dry and normal discharge conditions based on unregulated inflow to the catchment. The development of the seasonal flow requirements for various targets identified is done using a modification of the Building Block Method. Several options are tested regarding the integration of the flow regime into the operational strategy of the hydropower plant, both using real time prognosis of inflow and combinations with historical data. An important topic in selecting the release strategy is how it meets current Norwegian legislation and how well future documentation and environmental control can be carried out. An evaluation protocol is also proposed for the flow regime to test if the ecological targets are met.

  17. Fibrous filter efficiency and pressure drop in the viscous-inertial transition flow regime.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sanchez, Andres L.; Brockmann, John E.; Dellinger, Jennifer Gwynne

    2011-10-01

    Fibrous filter pressure drop and aerosol collection efficiency were measured at low air pressures (0.2 to 0.8 atm) and high face velocities (5 to 20 meters per second) to give fiber Reynolds numbers in the viscous-inertial transition flow regime (1 to 16). In this regime, contemporary filtration theory based on Kuwabara's viscous flow through an ensemble of fibers under-predicts single fiber impaction by several orders of magnitude. Streamline curvature increases substantially as inertial forces become dominant. Dimensionless pressure drop measurements followed the viscous-inertial theory of Robinson and Franklin rather than Darcy's linear pressure-velocity relationship (1972). Sodium chloride and iron nano-agglomeratemore » test aerosols were used to evaluate the effects of particle density and shape factor. Total filter efficiency collapsed when plotted against the particle Stokes and fiber Reynolds numbers. Efficiencies were then fitted with an impactor type equation where the cutpoint Stokes number and a steepness parameter described data well in the sharply increasing portion of the curve (20% to 80% efficiency). The cutpoint Stokes number was a linearly decreasing function of fiber Reynolds number. Single fiber efficiencies were calculated from total filter efficiencies and compared to contemporary viscous flow impaction theory (Stechkina et al. 1969), and numerical simulations from the literature. Existing theories under-predicted measured single fiber efficiencies although the assumption of uniform flow conditions for each successive layer of fibers is questionable; the common exponential relationship between single fiber efficiency and total filter efficiency may not be appropriate in this regime.« less

  18. Flow regimes and mechanistic modeling of critical heat flux under subcooled flow boiling conditions

    NASA Astrophysics Data System (ADS)

    Le Corre, Jean-Marie

    Thermal performance of heat flux controlled boiling heat exchangers are usually limited by the Critical Heat Flux (CHF) above which the heat transfer degrades quickly, possibly leading to heater overheating and destruction. In an effort to better understand the phenomena, a literature review of CHF experimental visualizations under subcooled flow boiling conditions was performed and systematically analyzed. Three major types of CHF flow regimes were identified (bubbly, vapor clot and slug flow regime) and a CHF flow regime map was developed, based on a dimensional analysis of the phenomena and available data. It was found that for similar geometric characteristics and pressure, a Weber number (We)/thermodynamic quality (x) map can be used to predict the CHF flow regime. Based on the experimental observations and the review of the available CHF mechanistic models under subcooled flow boiling conditions, hypothetical CHF mechanisms were selected for each CHF flow regime, all based on a concept of wall dry spot overheating, rewetting prevention and subsequent dry spot spreading. It is postulated that a high local wall superheat occurs locally in a dry area of the heated wall, due to a cyclical event inherent to the considered CHF two-phase flow regime, preventing rewetting (Leidenfrost effect). The selected modeling concept has the potential to span the CHF conditions from highly subcooled bubbly flow to early stage of annular flow. A numerical model using a two-dimensional transient thermal analysis of the heater undergoing nucleation was developed to mechanistically predict CHF in the case of a bubbly flow regime. In this type of CHF two-phase flow regime, the high local wall superheat occurs underneath a nucleating bubble at the time of bubble departure. The model simulates the spatial and temporal heater temperature variations during nucleation at the wall, accounting for the stochastic nature of the boiling phenomena. The model has also the potential to evaluate

  19. Theoretical flow regime diagrams for the AGCE

    NASA Technical Reports Server (NTRS)

    Fowlis, W. W.; Miller, T. L.; Roberts, G. O.; Kopecky, K. J.

    1984-01-01

    The major criterion for the design of the Atmospheric General Circulation Experiment is that it be possible to realize strong baroclinic instability in the apparatus. A spherical annulus configuration which allows only steady basic state flows was chosen for the first set of stability analyses. Baroclinic instability was found for this configuration and few results suggest a regime diagram very different from the cylindrical annulus regime diagram.

  20. Experimental setup for investigation of two-phase (water-air) flows in a tube

    NASA Astrophysics Data System (ADS)

    Kazunin, D. V.; Lashkov, V. A.; Mashek, I. Ch.; Khoronzhuk, R. S.

    2018-05-01

    A special setup was designed and built at St. Petersburg State University for providing experimental research in flow dynamics of the of air-water mixtures in a pipeline. The test section of the setup allows simulating a wide range of flow regimes of a gas-liquid mixture. The parameters of the experimental setup are given; the initial test results are discussed.

  1. Multi-metric calibration of hydrological model to capture overall flow regimes

    NASA Astrophysics Data System (ADS)

    Zhang, Yongyong; Shao, Quanxi; Zhang, Shifeng; Zhai, Xiaoyan; She, Dunxian

    2016-08-01

    Flow regimes (e.g., magnitude, frequency, variation, duration, timing and rating of change) play a critical role in water supply and flood control, environmental processes, as well as biodiversity and life history patterns in the aquatic ecosystem. The traditional flow magnitude-oriented calibration of hydrological model was usually inadequate to well capture all the characteristics of observed flow regimes. In this study, we simulated multiple flow regime metrics simultaneously by coupling a distributed hydrological model with an equally weighted multi-objective optimization algorithm. Two headwater watersheds in the arid Hexi Corridor were selected for the case study. Sixteen metrics were selected as optimization objectives, which could represent the major characteristics of flow regimes. Model performance was compared with that of the single objective calibration. Results showed that most metrics were better simulated by the multi-objective approach than those of the single objective calibration, especially the low and high flow magnitudes, frequency and variation, duration, maximum flow timing and rating. However, the model performance of middle flow magnitude was not significantly improved because this metric was usually well captured by single objective calibration. The timing of minimum flow was poorly predicted by both the multi-metric and single calibrations due to the uncertainties in model structure and input data. The sensitive parameter values of the hydrological model changed remarkably and the simulated hydrological processes by the multi-metric calibration became more reliable, because more flow characteristics were considered. The study is expected to provide more detailed flow information by hydrological simulation for the integrated water resources management, and to improve the simulation performances of overall flow regimes.

  2. Impact of Climate Change and Human Intervention on River Flow Regimes

    NASA Astrophysics Data System (ADS)

    Singh, Rajendra; Mittal, Neha; Mishra, Ashok

    2017-04-01

    Climate change and human interventions like dam construction bring freshwater ecosystem under stress by changing flow regime. It is important to analyse their impact at a regional scale along with changes in the extremes of temperature and precipitation which further modify the flow regime components such as magnitude, timing, frequency, duration, and rate of change of flow. In this study, the Kangsabati river is chosen to analyse the hydrological alterations in its flow regime caused by dam, climate change and their combined impact using Soil and Water Assessment Tool (SWAT) and the Indicators of Hydrologic Alteration (IHA) program based on the Range of Variability Approach (RVA). Results show that flow variability is significantly reduced due to dam construction with high flows getting absorbed and pre-monsoon low flows being augmented by the reservoir. Climate change alone reduces the high peaks whereas a combination of dam and climate change significantly reduces variability by affecting both high and low flows, thereby further disrupting the functioning of riverine ecosystems. Analysis shows that in the Kangsabati basin, influence of dam is greater than that of the climate change, thereby emphasising the significance of direct human intervention. Keywords: Climate change, human impact, flow regime, Kangsabati river, SWAT, IHA, RVA.

  3. Obseration of flow regime transition in CFB riser using an LDV

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yue, Paul C.; Mei, Joseph S.; Shadle, Lawrence J.

    2011-01-01

    The solids flow in a circulating fluidized bed (CFB) riser is often described to have a core-annular structure. For a given superficial gas velocity, at the initial introduction of solids into a riser a flow structure of dilute upflow regime exists. Continuing to increase the solids flow in the riser transitions the flow structure to the core-annular flow regime. However, with further increase of solids flow a condition is reached, depending on the superficial gas velocity, where all the solids across the riser cross section flow upwards, even those at the wall. When the solids flux, solids fraction and gasmore » velocity are relatively high, such a condition is described as the dense phase suspense upflow (DSU) regime. In this paper we report our observations of these flow regime transitions by using a laser Doppler velocimeter (LDV) to monitor the upward and downward particle flow velocities at and near the riser wall of the National Energy Technology Laboratory’s 30.4 centimeters diameter CFB cold flow model. The particles were high density polyethylene (PPE) spheres with a Sauter mean diameter of 861 micron and a density of 800 kg/m3. Three superficial gas velocities of 6.55 m/s, 10.67 m/s and 13.72 m/s were used in this study. For the case of superficial gas velocity 6.55 m/s, the experimental data show that the transition from dilute upflow to core-annular flow occurred when the solids flux was about 7 kg/m{sup 2}-s and the transition from core-annular flow to dense suspension upflow was about 147 kg/m{sup 2}-s. As the superficial gas velocity was increased to 10.67 m/s the corresponding flow regime transitions were at 34 kg/m{sup 2}-s and 205 kg/m{sup 2}-s, respectively. For the case of superficial gas velocity of 13.72 m/s the data showed no distinct transition of flow regimes. The particles were all upflow for the range of solids fluxes from 10 kg/m{sup 2}-s to 286 kg/m{sup 2}-s.« less

  4. Experimental investigation of the two-phase flow regimes and pressure drop in horizontal mini-size rectangular test section

    NASA Astrophysics Data System (ADS)

    Elazhary, Amr Mohamed; Soliman, Hassan M.

    2012-10-01

    An experimental study was conducted in order to investigate two-phase flow regimes and fully developed pressure drop in a mini-size, horizontal rectangular channel. The test section was machined in the form of an impacting tee junction in an acrylic block (in order to facilitate visualization) with a rectangular cross-section of 1.87-mm height on 20-mm width on the inlet and outlet sides. Pressure drop measurement and flow regime identification were performed on all three sides of the junction. Air-water mixtures at 200 kPa (abs) and room temperature were used as the test fluids. Four flow regimes were identified visually: bubbly, plug, churn, and annular over the ranges of gas and liquid superficial velocities of 0.04 ≤ JG ≤ 10 m/s and 0.02 ≤ JL ≤ 0.7 m/s, respectively, and a flow regime map was developed. Accuracy of the pressure-measurement technique was validated with single-phase, laminar and turbulent, fully developed data. Two-phase experiments were conducted for eight different inlet conditions and various mass splits at the junction. Comparisons were conducted between the present data and former correlations for the fully developed two-phase pressure drop in rectangular channels with similar sizes. Wide deviations were found among these correlations, and the correlations that agreed best with the present data were identified.

  5. Two Phase Flow Modeling: Summary of Flow Regimes and Pressure Drop Correlations in Reduced and Partial Gravity

    NASA Technical Reports Server (NTRS)

    Balasubramaniam, R.; Rame, E.; Kizito, J.; Kassemi, M.

    2006-01-01

    The purpose of this report is to provide a summary of state-of-the-art predictions for two-phase flows relevant to Advanced Life Support. We strive to pick out the most used and accepted models for pressure drop and flow regime predictions. The main focus is to identify gaps in predictive capabilities in partial gravity for Lunar and Martian applications. Following a summary of flow regimes and pressure drop correlations for terrestrial and zero gravity, we analyze the fully developed annular gas-liquid flow in a straight cylindrical tube. This flow is amenable to analytical closed form solutions for the flow field and heat transfer. These solutions, valid for partial gravity as well, may be used as baselines and guides to compare experimental measurements. The flow regimes likely to be encountered in the water recovery equipment currently under consideration for space applications are provided in an appendix.

  6. Non-invasive classification of gas-liquid two-phase horizontal flow regimes using an ultrasonic Doppler sensor and a neural network

    NASA Astrophysics Data System (ADS)

    Musa Abbagoni, Baba; Yeung, Hoi

    2016-08-01

    The identification of flow pattern is a key issue in multiphase flow which is encountered in the petrochemical industry. It is difficult to identify the gas-liquid flow regimes objectively with the gas-liquid two-phase flow. This paper presents the feasibility of a clamp-on instrument for an objective flow regime classification of two-phase flow using an ultrasonic Doppler sensor and an artificial neural network, which records and processes the ultrasonic signals reflected from the two-phase flow. Experimental data is obtained on a horizontal test rig with a total pipe length of 21 m and 5.08 cm internal diameter carrying air-water two-phase flow under slug, elongated bubble, stratified-wavy and, stratified flow regimes. Multilayer perceptron neural networks (MLPNNs) are used to develop the classification model. The classifier requires features as an input which is representative of the signals. Ultrasound signal features are extracted by applying both power spectral density (PSD) and discrete wavelet transform (DWT) methods to the flow signals. A classification scheme of ‘1-of-C coding method for classification’ was adopted to classify features extracted into one of four flow regime categories. To improve the performance of the flow regime classifier network, a second level neural network was incorporated by using the output of a first level networks feature as an input feature. The addition of the two network models provided a combined neural network model which has achieved a higher accuracy than single neural network models. Classification accuracies are evaluated in the form of both the PSD and DWT features. The success rates of the two models are: (1) using PSD features, the classifier missed 3 datasets out of 24 test datasets of the classification and scored 87.5% accuracy; (2) with the DWT features, the network misclassified only one data point and it was able to classify the flow patterns up to 95.8% accuracy. This approach has demonstrated the

  7. A Risk-Based Ecohydrological Approach to Assessing Environmental Flow Regimes

    NASA Astrophysics Data System (ADS)

    Mcgregor, Glenn B.; Marshall, Jonathan C.; Lobegeiger, Jaye S.; Holloway, Dean; Menke, Norbert; Coysh, Julie

    2018-03-01

    For several decades there has been recognition that water resource development alters river flow regimes and impacts ecosystem values. Determining strategies to protect or restore flow regimes to achieve ecological outcomes is a focus of water policy and legislation in many parts of the world. However, consideration of existing environmental flow assessment approaches for application in Queensland identified deficiencies precluding their adoption. Firstly, in managing flows and using ecosystem condition as an indicator of effectiveness, many approaches ignore the fact that river ecosystems are subjected to threatening processes other than flow regime alteration. Secondly, many focus on providing flows for responses without considering how often they are necessary to sustain ecological values in the long-term. Finally, few consider requirements at spatial-scales relevant to the desired outcomes, with frequent focus on individual places rather than the regions supporting sustainability. Consequently, we developed a risk-based ecohydrological approach that identifies ecosystem values linked to desired ecological outcomes, is sensitive to flow alteration and uses indicators of broader ecosystem requirements. Monitoring and research is undertaken to quantify flow-dependencies and ecological modelling is used to quantify flow-related ecological responses over an historical flow period. The relative risk from different flow management scenarios can be evaluated at relevant spatial-scales. This overcomes the deficiencies identified above and provides a robust and useful foundation upon which to build the information needed to support water planning decisions. Application of the risk assessment approach is illustrated here by two case studies.

  8. Environmental Flows: Evaluating Long-Term Baselines for Hydrological Regime Change in the Southern United States

    NASA Astrophysics Data System (ADS)

    Deines, A. M.; Morrison, A. M.; Menzie, C.

    2016-12-01

    The wide variety of ecosystem services associated with running fresh waters are dependent on an assortment of flow conditions including timing and duration of seasonal floods as well as intermittent flows, such as storm peaks. Modern methods of assessing environmental flows consider hydrological regime change by comparing actual or simulated baseline flow conditions against putatively altered regime flows. These calculated flow changes are used as inputs to models of ecosystem responses such as for fish populations, inundated habitat area, or nutrient supplies. However, common and recommended tools and software used to make flow comparisons between putative regimes lack robust mechanisms for evaluating the significance of hydrological regime change in the context of long-term (multiple decades, centuries, or greater) trends, such as climatic conditions, or the facility to determine the existence and causes of regime changes when no obvious discontinuity exists, such as the construction of a dam. As such, environmental flow decisions based on short (recent) baseline records or baseline records assumed to represent stable hydrological conditions may lead to inefficient water use and ecosystem services distribution. Here we examine long-term patterns in discharge, the frequency and severity of regional droughts, and the Atlantic Multidecadal Oscillation to better understand the occurrence and causes of hydrological regime change in rivers in the Southern United States. For each river we ask: 1) Has hydrological regime change occurred? 2) To what degree is observed regime change associated with regional climatic drivers? 3) How might environmental flows suggested by current methods (e.g. the USGS Hydroecological Integrity Assessment or the Indicators of Hydrologic Alteration software) compare with flows derived by additional consideration of long-term drivers of hydrological change? We discuss the different temporal scales through which climate can influence a

  9. High-temperature synthesis of silica particles by the chloride method in the regime of counter flow jet quenching

    NASA Astrophysics Data System (ADS)

    Kartaev, E. V.; Emel'kin, V. A.; Aul'chenko, S. M.

    2017-10-01

    The experimental and numerical investigations of synthesis of silica (SiO2) nanoparticles from premixed gaseous silicon tetrachloride (SiCl4) and oxygen of dry air in the high-temperature nitrogen flow of plasma-chemical reactor have been carried out. The regime of counter flow jet quenching of high-temperature heterogeneous flow has been utilized. The latter provided a rapid cooling of silica particles under nonequilibrium conditions with substantial temperature gradients. Synthesized silica particles were amorphous, with surface-average size being about 28 nm. The results of numerical calculations are found to agree qualitatively with experimental data.

  10. A contrast between nocturnal flow regimes: Observations and modeling simulations of katabatic intrusions in the Laramie Valley

    NASA Astrophysics Data System (ADS)

    Juliano, Timothy W.

    Katabatic winds commonly occur in mountainous regions under statically stable conditions when a sufficient deficit exists in the net radiation budget. Observations of these stable boundary layer (SBL) downslope flows have extended back to the 1930s. Their interactions with other SBL processes, including cold air pools (CAPs) and mountain waves, are quite complex, however, and have only more recently been deeply investigated. The University of Wyoming (UW) wind tower (WT) and flux tower (WT), situated in the Laramie Valley, were utilized in examining a dataset spanning from 14 December 2011 to 12 September 2013. A set of criteria were developed to determine katabatic intrusion events, and establish a climatology of these events, at the WT. The 21-22 December 2012 nighttime period was then studied in detail using data from the aforementioned towers in addition to weather stations throughout the Laramie Valley and the Weather Research and Forecasting (WRF) model. Both observations and modeling results indicated a competition between two strongly contrasting flow regimes: synoptic and katabatic. The synoptic regime was characterized by strong, southwesterly winds, warm temperatures, and turbulent flow, while the katabatic regime featured weaker, southeasterly winds, cooler temperatures, and intermittently turbulent flow. Sonic and propeller anemometers on the WT elucidated the chaotic transition between the regimes. At the WT, it was found that between regimes the wind speed decreased by up to 60%, wind direction often shifted over 120°, and potential temperature usually decreased more than 2°C. The katabatic wind depth was postulated to be variable in time and space, with its head sloping towards the trailing CAP. Topographically generated mountain waves and local terrain forcing are suspected to play an integral role in the development and evolution of the katabatic wind in the Laramie Valley. Results from this research yield promising insight into the intricate

  11. Lava Fountaining Discharge Regime driven by Slug-to-Churn Flow Transition. (Invited)

    NASA Astrophysics Data System (ADS)

    Ripepe, M.; Pioli, L.; Marchetti, E.; Ulivieri, G.

    2013-12-01

    Lava fountaining episodes at Etna volcano appear characterized by the transition between Strombolian and Hawaiian end-member eruptive styles. There is no evidence for this transition in the seismic (i.e. seismic tremor) signal. However, infrasonic records provide unprecedented evidence on this flow transition. Each eruptive episode is characterized by distinctive common trend in the amplitude, waveform and frequency content of the infrasonic wavefield, which evidences the shift from discrete, and transient, strombolian to sustained, and oscillatory, lava fountain dynamics. Large scale experiments on the dynamics of two-phase flow of basaltic magmas show how the transition between different regimes mainly depends on gas volume flow, which in turn controls pressure distribution within the conduit and also magma vesicularity. In particular, while regular large bubble bursting is associated with slug flow regime, large amplitude and low frequency column oscillations are associated with churn flow. In large pipes, transition from slug to churn flow regime is independent on conduit diameter and it is reached at high superficial gas velocity. Lava fountaining episodes at Etna can be thus interpreted as induced by the transition from the slug (discrete strombolian) to churn flow (sustained lava fountain) regimes that is reflecting an increase in the gas discharge rate. Based on laboratory experiments, we calculate that transition between these two end-member explosive regimes at Etna occurs when gas superficial velocity is 76 m/s for near-the-vent stagnant magma conditions.

  12. General slip regime permeability model for gas flow through porous media

    NASA Astrophysics Data System (ADS)

    Zhou, Bo; Jiang, Peixue; Xu, Ruina; Ouyang, Xiaolong

    2016-07-01

    A theoretical effective gas permeability model was developed for rarefied gas flow in porous media, which holds over the entire slip regime with the permeability derived as a function of the Knudsen number. This general slip regime model (GSR model) is derived from the pore-scale Navier-Stokes equations subject to the first-order wall slip boundary condition using the volume-averaging method. The local closure problem for the volume-averaged equations is studied analytically and numerically using a periodic sphere array geometry. The GSR model includes a rational fraction function of the Knudsen number which leads to a limit effective permeability as the Knudsen number increases. The mechanism for this behavior is the viscous fluid inner friction caused by converging-diverging flow channels in porous media. A linearization of the GSR model leads to the Klinkenberg equation for slightly rarefied gas flows. Finite element simulations show that the Klinkenberg model overestimates the effective permeability by as much as 33% when a flow approaches the transition regime. The GSR model reduces to the unified permeability model [F. Civan, "Effective correlation of apparent gas permeability in tight porous media," Transp. Porous Media 82, 375 (2010)] for the flow in the slip regime and clarifies the physical significance of the empirical parameter b in the unified model.

  13. Regulation of snow-fed rivers affects flow regimes more than climate change.

    PubMed

    Arheimer, B; Donnelly, C; Lindström, G

    2017-07-05

    River flow is mainly controlled by climate, physiography and regulations, but their relative importance over large landmasses is poorly understood. Here we show from computational modelling that hydropower regulation is a key driver of flow regime change in snow-dominated regions and is more important than future climate changes. This implies that climate adaptation needs to include regulation schemes. The natural river regime in snowy regions has low flow when snow is stored and a pronounced peak flow when snow is melting. Global warming and hydropower regulation change this temporal pattern similarly, causing less difference in river flow between seasons. We conclude that in snow-fed rivers globally, the future climate change impact on flow regime is minor compared to regulation downstream of large reservoirs, and of similar magnitude over large landmasses. Our study not only highlights the impact of hydropower production but also that river regulation could be turned into a measure for climate adaptation to maintain biodiversity on floodplains under climate change.Global warming and hydropower regulations are major threats to future fresh-water availability and biodiversity. Here, the authors show that their impact on flow regime over a large landmass result in similar changes, but hydropower is more critical locally and may have potential for climate adaptation in floodplains.

  14. The natural flow regime of Hawaíi streams

    NASA Astrophysics Data System (ADS)

    Tsang, Y. P.; Strauch, A. M.; Clilverd, H. M.

    2016-12-01

    Freshwater is a critical, but limited natural resource on tropical islands; sustaining agriculture, industry, hydropower, urban development, and domestic water supply. The hydrology of Hawaíi islands is largely influenced by the health of mountain forests, which capture and absorb rain and fog drip, recharging aquifers and sustaining stream flow. Forests in Hawaíi are being degraded through the replacement of native vegetation with introduced species or conversion to another land use. Streams in the tropics frequently experience flash flooding due to extreme rainfall-runoff events and low flows due to seasonal drought. These patterns drive habitat availability for freshwater fauna, as well as sediment and nutrient export to near-shore ecosystems. Flow regimes can be used to characterize the frequency and magnitude of extreme high and low flows and are influenced by watershed climate, geology, land cover and soil composition. We examined the effect of climate extremes on stream flow from Hawaiian forests using historical flow data to characterize the spatial and temporal patterns in surface water resources. By defining flow regimes from forests we can improve our understanding of climate extremes on water resource availability across tropical island landscapes.

  15. Flow regimes in a T-mixer operating with a binary mixture

    NASA Astrophysics Data System (ADS)

    Camarri, Simone; Siconolfi, Lorenzo; Galletti, Chiara; Salvetti, Maria Vittoria

    2015-11-01

    Efficient mixing in small volumes is a key target in many processes. Among the most common micro-devices, passive T-shaped micro-mixers are widely used. For this reason, T-mixers have been studied in the literature and its working flow regimes have been identified. However, in most of the available theoretical studies it is assumed that only one working fluid is used, i.e. that the same fluid at the same thermodynamic conditions is entering the two inlet conduits of the mixer. Conversely, the practical use of micro-devices often involves the mixing of two different fluids or of the same fluid at different thermodynamic conditions. In this case flow regimes significantly different than those observed for a single working fluid may occur. The present work aims at investigating the flow regimes in a T-mixers when water at two different temperatures, i.e. having different viscosity and density, is entering the mixer. The effect of the temperature difference on the flow regimes in a 3D T-mixer is investigated by DNS and stability analysis and the results are compared to the case in which a single working fluid is employed.

  16. Catalytic combustion of hydrogen-air mixtures in stagnation flows

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ikeda, H.; Libby, P.A.; Williams, F.A.

    1993-04-01

    The interaction between heterogeneous and homogeneous reactions arising when a mixture of hydrogen and air impinges on a platinum plate at elevated temperature is studied. A reasonably complete description of the kinetic mechanism for homogeneous reactions is employed along with a simplified model for heterogeneous reactions. Four regimes are identified depending on the temperature of the plate, on the rate of strain imposed on the flow adjacent to the plate and on the composition and temperature of the reactant stream: (1) surface reaction alone; (2) surface reaction inhibiting homogeneous reaction; (3) homogeneous reaction inhibiting surface reaction; and (4) homogeneous reactionmore » alone. These regimes are related to those found earlier for other chemical systems and form the basis of future experimental investigation of the chemical system considered in the present study.« less

  17. A Framework to Assess the Cumulative Hydrological Impacts of Dams on flow Regime

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Wang, D.

    2016-12-01

    In this study we proposed a framework to assess the cumulative impact of dams on hydrological regime, and the impacts of the Three Gorges Dam on flow regime in Yangtze River were investigated with the framework. We reconstructed the unregulated flow series to compare with the regulated flow series in the same period. Eco-surplus and eco-deficit and the Indicators of Hydrologic Alteration parameters were used to examine the hydrological regime change. Among IHA parameters, Wilcoxon signed-rank test and Principal Components Analysis identified the representative indicators of hydrological alterations. Eco-surplus and eco-deficit showed that the reservoir also changed the seasonal regime of the flows in autumn and winter. Annual extreme flows and October flows changes lead to negative ecological implications downstream from the Three Gorges Dam. Ecological operation for the Three Gorges Dam is necessary to mitigate the negative effects on the river ecosystem in the middle reach of Yangtze River. The framework proposed here could be a robust method to assess the cumulative impacts of reservoir operation.

  18. Prediction of gas-liquid two-phase flow regime in microgravity

    NASA Technical Reports Server (NTRS)

    Lee, Jinho; Platt, Jonathan A.

    1993-01-01

    An attempt is made to predict gas-liquid two-phase flow regime in a pipe in a microgravity environment through scaling analysis based on dominant physical mechanisms. Simple inlet geometry is adopted in the analysis to see the effect of inlet configuration on flow regime transitions. Comparison of the prediction with the existing experimental data shows good agreement, though more work is required to better define some physical parameters. The analysis clarifies much of the physics involved in this problem and can be applied to other configurations.

  19. Characterizing effects of hydropower plants on sub-daily flow regimes

    NASA Astrophysics Data System (ADS)

    Bejarano, María Dolores; Sordo-Ward, Álvaro; Alonso, Carlos; Nilsson, Christer

    2017-07-01

    A characterization of short-term changes in river flow is essential for understanding the ecological effects of hydropower plants, which operate by turning the turbines on or off to generate electricity following variations in the market demand (i.e., hydropeaking). The goal of our study was to develop an approach for characterizing the effects of hydropower plant operations on within-day flow regimes across multiple dams and rivers. For this aim we first defined ecologically meaningful metrics that provide a full representation of the flow regime at short time scales from free-flowing rivers and rivers exposed to hydropeaking. We then defined metrics that enable quantification of the deviation of the altered short-term flow regime variables from those of the unaltered state. The approach was successfully tested in two rivers in northern Sweden, one free-flowing and another regulated by cascades of hydropower plants, which were additionally classified based on their impact on short-term flows in sites of similar management. The largest differences between study sites corresponded to metrics describing sub-daily flow magnitudes such as amplitude (i.e., difference between the highest and the lowest hourly flows) and rates (i.e., rise and fall rates of hourly flows). They were closely followed by frequency-related metrics accounting for the numbers of within-day hourly flow patterns (i.e., rises, falls and periods of stability of hourly flows). In comparison, between-site differences for the duration-related metrics were smallest. In general, hydropeaking resulted in higher within-day flow amplitudes and rates and more but shorter periods of a similar hourly flow patterns per day. The impacted flow feature and the characteristics of the impact (i.e., intensity and whether the impact increases or decreases whatever is being described by the metric) varied with season. Our approach is useful for catchment management planning, defining environmental flow targets

  20. Numerical investigation of air flow in a supersonic wind tunnel

    NASA Astrophysics Data System (ADS)

    Drozdov, S. M.; Rtishcheva, A. S.

    2017-11-01

    In the framework of TsAGI’s supersonic wind tunnel modernization program aimed at improving flow quality and extending the range of test regimes it was required to design and numerically validate a new test section and a set of shaped nozzles: two flat nozzles with flow Mach number at nozzle exit M=4 and M=5 and two axisymmetric nozzles with M=5 and M=6. Geometric configuration of the nozzles, the test section (an Eiffel chamber) and the diffuser was chosen according to the results of preliminary calculations of two-dimensional air flow in the wind tunnel circuit. The most important part of the work are three-dimensional flow simulation results obtained using ANSYS Fluent software. The following flow properties were investigated: Mach number, total and static pressure, total and static temperature and turbulent viscosity ratio distribution, heat flux density at wind tunnel walls (for high-temperature flow regimes). It is demonstrated that flow perturbations emerging from the junction of the nozzle with the test section and spreading down the test section behind the boundaries of characteristic rhomb’s reverse wedge are nearly impossible to eliminate. Therefore, in order to perform tests under most uniform flow conditions, the model’s center of rotation and optical window axis should be placed as close to the center of the characteristic rhomb as possible. The obtained results became part of scientific and technical basis of supersonic wind tunnel design process and were applied to a generalized class of similar wind tunnels.

  1. Liquid-Vapor Flow Regime Transitions for Spacecraft Heat Transfer Loops

    DTIC Science & Technology

    1988-12-01

    effects of fluid properties on flow regime transitions. 5 A carnauba wax with no additives was used because it resists dissolution by oil. 19 4.2...importance of an annular flow entrance geometry and of waxing the tube wall to change its wetting properties (to prevent inverse annular flow) were

  2. Laminar, turbulent, and inertial shear-thickening regimes in channel flow of neutrally buoyant particle suspensions.

    PubMed

    Lashgari, Iman; Picano, Francesco; Breugem, Wim-Paul; Brandt, Luca

    2014-12-19

    The aim of this Letter is to characterize the flow regimes of suspensions of finite-size rigid particles in a viscous fluid at finite inertia. We explore the system behavior as a function of the particle volume fraction and the Reynolds number (the ratio of flow and particle inertia to viscous forces). Unlike single-phase flows, where a clear distinction exists between the laminar and the turbulent states, three different regimes can be identified in the presence of a particulate phase, with smooth transitions between them. At low volume fractions, the flow becomes turbulent when increasing the Reynolds number, transitioning from the laminar regime dominated by viscous forces to the turbulent regime characterized by enhanced momentum transport by turbulent eddies. At larger volume fractions, we identify a new regime characterized by an even larger increase of the wall friction. The wall friction increases with the Reynolds number (inertial effects) while the turbulent transport is weakly affected, as in a state of intense inertial shear thickening. This state may prevent the transition to a fully turbulent regime at arbitrary high speed of the flow.

  3. Rapid granular flows on a rough incline: phase diagram, gas transition, and effects of air drag.

    PubMed

    Börzsönyi, Tamás; Ecke, Robert E

    2006-12-01

    We report experiments on the overall phase diagram of granular flows on an incline with emphasis on high inclination angles where the mean layer velocity approaches the terminal velocity of a single particle free falling in air. The granular flow was characterized by measurements of the surface velocity, the average layer height, and the mean density of the layer as functions of the hopper opening, the plane inclination angle, and the downstream distance x of the flow. At high inclination angles the flow does not reach an x -invariant steady state over the length of the inclined plane. For low volume flow rates, a transition was detected between dense and very dilute (gas) flow regimes. We show using a vacuum flow channel that air did not qualitatively change the phase diagram and did not quantitatively modify mean flow velocities of the granular layer except for small changes in the very dilute gaslike phase.

  4. Comprehensive assessment of dam impacts on flow regimes with consideration of interannual variations

    NASA Astrophysics Data System (ADS)

    Zhang, Yongyong; Shao, Quanxi; Zhao, Tongtiegang

    2017-09-01

    Assessing the impact of human intervention on flow regimes is important in policy making and resource management. Previous impact assessments of dam regulation on flow regimes have focused on long-term average patterns, but interannual variations, which are important characteristics to be considered, have been ignored. In this study, the entire signatures of hydrograph variations of Miyun Reservoir in northern China were described by forty flow regime metrics that incorporate magnitude, variability and frequency, duration, timing, and rate of change for flow events based on a long-term synchronous observation series of inflow and outflow. Principal component analysis and cluster analysis were used to reduce the multidimensionality of the metrics and time and to determine impact patterns and their interannual shifts. Statistically significant driving factors of impact pattern variations were identified. We found that dam regulation resulted in four main impact classes on the flow regimes and that the regulated capacity was interannually attenuated from 1973 to 2010. The impact patterns alternated between the highly regulated class with extremely decreasing flow magnitude, slight variability, and extreme intermittency and the slightly regulated class with extremely increasing flow magnitude, slight variability, and extreme intermittency from 1973 to 1987 and then stabilized in the latter class from 1988 to 2001. After 2001, the pattern gradually changed from the moderately regulated class with moderately decreasing flow magnitude, extreme variability, and extreme intermittency to the slightly regulated class with slightly decreasing flow magnitude, slight variability, and no intermittency. Decreasing precipitation and increasing drought were the primary drivers for the interannual variations of the impact patterns, and inflow variability was the most significant factor affecting the patterns, followed by flow event frequency and duration, magnitude, and timing. This

  5. Optical Air Flow Measurements for Flight Tests and Flight Testing Optical Air Flow Meters

    NASA Technical Reports Server (NTRS)

    Jentink, Henk W.; Bogue, Rodney K.

    2005-01-01

    Optical air flow measurements can support the testing of aircraft and can be instrumental to in-flight investigations of the atmosphere or atmospheric phenomena. Furthermore, optical air flow meters potentially contribute as avionics systems to flight safety and as air data systems. The qualification of these instruments for the flight environment is where we encounter the systems in flight testing. An overview is presented of different optical air flow measurement techniques applied in flight and what can be achieved with the techniques for flight test purposes is reviewed. All in-flight optical airflow velocity measurements use light scattering. Light is scattered on both air molecules and aerosols entrained in the air. Basic principles of making optical measurements in flight, some basic optical concepts, electronic concepts, optoelectronic interfaces, and some atmospheric processes associated with natural aerosols are reviewed. Safety aspects in applying the technique are shortly addressed. The different applications of the technique are listed and some typical examples are presented. Recently NASA acquired new data on mountain rotors, mountain induced turbulence, with the ACLAIM system. Rotor position was identified using the lidar system and the potentially hazardous air flow profile was monitored by the ACLAIM system.

  6. CFD simulations of the flow control performance applied for inlet of low drag high-bypass turbofan engine at cross flow regimes

    NASA Astrophysics Data System (ADS)

    Kursakov, I. A.; Kazhan, E. V.; Lysenkov, A. V.; Savelyev, A. A.

    2016-10-01

    Paper describes the optimization procedure for low cruise drag inlet of high-bypass ratio turbofan engine (HBRE). The critical cross-flow velocity when the flow separation on the lee side of the inlet channel occurs is determined. The effciency of different flow control devices used to improve the flow parameters at inlet section cross flow regime is analyzed. Boundary layer suction, bypass slot and vortex generators are considered. It is shown that flow control devices enlarge the stability range of inlet performance at cross flow regimes.

  7. Anthropogenic Water Uses and River Flow Regime Alterations by Dams

    NASA Astrophysics Data System (ADS)

    Ferrazzi, M.; Botter, G.

    2017-12-01

    Dams and impoundments have been designed to reconcile the systematic conflict between patterns of anthropogenic water uses and the temporal variability of river flows. Over the past seven decades, population growth and economic development led to a marked increase in the number of these water infrastructures, so that unregulated free-flowing rivers are now rare in developed countries and alterations of the hydrologic cycle at global scale have to be properly considered and characterized. Therefore, improving our understanding of the influence of dams and reservoirs on hydrologic regimes is going to play a key role in water planning and management. In this study, a physically based analytic approach is combined to extensive hydrologic data to investigate natural flow regime alterations downstream of dams in the Central-Eastern United States. These representative case studies span a wide range of different uses, including flood control, water supply and hydropower production. Our analysis reveals that the most evident effects of flood control through dams is a decrease in the intra-seasonal variability of flows, whose extent is controlled by the ratio between the storage capacity for flood control and the average incoming streamflow. Conversely, reservoirs used for water supply lead to an increase of daily streamflow variability and an enhanced inter-catchment heterogeneity. Over the last decades, the supply of fresh water required to sustain human populations has become a major concern at global scale. Accordingly, the number of reservoirs devoted to water supply increased by 50% in the US. This pattern foreshadows a possible shift in the cumulative effect of dams on river flow regimes in terms of inter-catchment homogenization and intra-annual flow variability.

  8. Surface-slip equations for multicomponent, nonequilibrium air flow

    NASA Technical Reports Server (NTRS)

    Gupta, Roop N.; Scott, Carl D.; Moss, James N.; Goglia, Gene

    1985-01-01

    Equations are presented for the surface slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds-number, high-altitude flight regime of a space vehicle. These are obtained from closed-form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities have been obtained in a form which can readily be employed in flow-field computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate species-concentration boundary condition for a multicomponent mixture in absence of slip.

  9. Phase 2: HGM air flow tests in support of HEX vane investigation

    NASA Technical Reports Server (NTRS)

    Cox, G. B., Jr.; Steele, L. L.; Eisenhart, D. W.

    1993-01-01

    Following the start of SSME certification testing for the Pratt and Whitney Alternate Turbopump Development (ATD) High Pressure Oxidizer Turbopump (HPOTP), cracking of the leading edge of the inner HEX vane was experienced. The HEX vane, at the inlet of the oxidizer bowl in the Hot Gas Manifold (HGM), accepts the HPOTP turbine discharge flow and turns it toward the Gaseous Oxidizer Heat Exchanger (GOX HEX) coil. The cracking consistently initiated over a specific circumferential region of the hex vane, with other circumferential locations appearing with increased run time. Since cracking had not to date been seen with the baseline HPOTP, a fluid-structural interaction involving the ATD HPOTP turbine exit flowfield and the HEX inner vane was suspected. As part of NASA contract NAS8-36801, Pratt and Whitney conducted air flow tests of the ATD HPOTP turbine turnaround duct flowpath in the MSFC Phase 2 HGM air flow model. These tests included HEX vane strain gages and additional fluctuating pressure gages in the turnaround duct and HEX vane flowpath area. Three-dimensional flow probe measurements at two stations downstream of the turbine simulator exit plane were also made. Modifications to the HPOTP turbine simulator investigated the effects on turbine exit flow profile and velocity components, with the objective of reproducing flow conditions calculated for the actual ATD HPOTP hardware. Testing was done at the MSFC SSME Dynamic Fluid Air Flow (Dual-Leg) Facility, at air supply pressures between 50 and 250 psia. Combinations of turbine exit Mach number and pressure level were run to investigate the effect of flow regime. Information presented includes: (1) Descriptions of turbine simulator modifications to produce the desired flow environment; (2) Types and locations for instrumentation added to the flow model for improved diagnostic capability; (3) Evaluation of the effect of changes to the turbine simulator flowpath on the turbine exit flow environment; and (4

  10. Thermal Regime of the Downstream Shoulder of Rockfill Dams (Termicheskii Regim Nizovoy Prizm Kamennona’Rosnoy Plotin),

    DTIC Science & Technology

    1977-02-01

    conditi ons for machanical displacement . Hence a flow of air depending on the thermal regime of the dam itself is formed in the downstream should .w of a...The constant coefficients of basic finite—difference equations (33) , , — (34), (35), (38), and (40) were

  11. Implicit gas-kinetic unified algorithm based on multi-block docking grid for multi-body reentry flows covering all flow regimes

    NASA Astrophysics Data System (ADS)

    Peng, Ao-Ping; Li, Zhi-Hui; Wu, Jun-Lin; Jiang, Xin-Yu

    2016-12-01

    Based on the previous researches of the Gas-Kinetic Unified Algorithm (GKUA) for flows from highly rarefied free-molecule transition to continuum, a new implicit scheme of cell-centered finite volume method is presented for directly solving the unified Boltzmann model equation covering various flow regimes. In view of the difficulty in generating the single-block grid system with high quality for complex irregular bodies, a multi-block docking grid generation method is designed on the basis of data transmission between blocks, and the data structure is constructed for processing arbitrary connection relations between blocks with high efficiency and reliability. As a result, the gas-kinetic unified algorithm with the implicit scheme and multi-block docking grid has been firstly established and used to solve the reentry flow problems around the multi-bodies covering all flow regimes with the whole range of Knudsen numbers from 10 to 3.7E-6. The implicit and explicit schemes are applied to computing and analyzing the supersonic flows in near-continuum and continuum regimes around a circular cylinder with careful comparison each other. It is shown that the present algorithm and modelling possess much higher computational efficiency and faster converging properties. The flow problems including two and three side-by-side cylinders are simulated from highly rarefied to near-continuum flow regimes, and the present computed results are found in good agreement with the related DSMC simulation and theoretical analysis solutions, which verify the good accuracy and reliability of the present method. It is observed that the spacing of the multi-body is smaller, the cylindrical throat obstruction is greater with the flow field of single-body asymmetrical more obviously and the normal force coefficient bigger. While in the near-continuum transitional flow regime of near-space flying surroundings, the spacing of the multi-body increases to six times of the diameter of the single

  12. Detrimental effects of a novel flow regime on the functional trajectory of an aquatic invertebrate metacommunity.

    PubMed

    Ruhi, Albert; Dong, Xiaoli; McDaniel, Courtney H; Batzer, Darold P; Sabo, John L

    2018-04-17

    Novel flow regimes resulting from dam operations and overallocation of freshwater resources are an emerging consequence of global change. Yet, anticipating how freshwater biodiversity will respond to surging flow regime alteration requires overcoming two challenges in environmental flow science: shifting from local to riverscape-level understanding of biodiversity dynamics, and from static to time-varying characterizations of the flow regime. Here, we used time-series methods (wavelets and multivariate autoregressive models) to quantify flow-regime alteration and to link time-varying flow regimes to the dynamics of multiple local communities potentially connected by dispersal (i.e., a metacommunity). We studied the Chattahoochee River below Buford dam (Georgia, U.S.A.), and asked how flow regime alteration by a large hydropower dam may control the long-term functional trajectory of the downstream invertebrate metacommunity. We found that seasonal variation in hydropeaking synchronized temporal fluctuations in trait abundance among the flow-altered sites. Three biological trait states describing adaptation to fast flows benefitted from flow management for hydropower, but did not compensate for declines in 16 "loser" traits. Accordingly, metacommunity-wide functional diversity responded negatively to hydropeaking intensity, and stochastic simulations showed that the risk of functional diversity collapse within the next 4 years would decrease by 17% if hydropeaking was ameliorated, or by 9% if it was applied every other season. Finally, an analysis of 97 reference and 23 dam-affected river sites across the U.S. Southeast suggested that flow variation at extraneous, human-relevant scales (12-hr, 24-hr, 1-week) is relatively common in rivers affected by hydropower dams. This study advances the notion that novel flow regimes are widespread, and simplify the functional structure of riverine communities by filtering out taxa with nonadaptive traits and by spatially

  13. Simulation of 3-D Nonequilibrium Seeded Air Flow in the NASA-Ames MHD Channel

    NASA Technical Reports Server (NTRS)

    Gupta, Sumeet; Tannehill, John C.; Mehta, Unmeel B.

    2004-01-01

    The 3-D nonequilibrium seeded air flow in the NASA-Ames experimental MHD channel has been numerically simulated. The channel contains a nozzle section, a center section, and an accelerator section where magnetic and electric fields can be imposed on the flow. In recent tests, velocity increases of up to 40% have been achieved in the accelerator section. The flow in the channel is numerically computed us ing a 3-D parabolized Navier-Stokes (PNS) algorithm that has been developed to efficiently compute MHD flows in the low magnetic Reynolds number regime: The MHD effects are modeled by introducing source terms into the PNS equations which can then be solved in a very efficient manner. The algorithm has been extended in the present study to account for nonequilibrium seeded air flows. The electrical conductivity of the flow is determined using the program of Park. The new algorithm has been used to compute two test cases that match the experimental conditions. In both cases, magnetic and electric fields are applied to the seeded flow. The computed results are in good agreement with the experimental data.

  14. Effects of flow regime on benthic algae and macroinvertebrates - A comparison between regulated and unregulated rivers.

    PubMed

    Schneider, Susanne C; Petrin, Zlatko

    2017-02-01

    Natural fluctuations in flow are important for maintaining the ecological integrity of riverine ecosystems. However, the flow regime of many rivers has been modified. We assessed the impact of water chemistry, habitat and streamflow characteristics on macroinvertebrates and benthic algae, comparing 20 regulated with 20 unregulated sites. Flow regime, calculated from daily averaged discharge over the five years preceding sampling, was generally more stable at regulated sites, with higher relative discharges in winter, lower relative discharges in spring and smaller differences between upper and lower percentiles. However, no consistent differences in benthic algal or macroinvertebrate structural and functional traits occurred between regulated and unregulated sites. When regulated and unregulated sites were pooled, overall flow regime, calculated as principal components of discharge characteristics over the five years preceding sampling, affected macroinvertebrate species assemblages, but not indices used for ecosystem status assessment or functional feeding groups. This indicates that, while species identity shifted with changing flow regime, the exchanged taxa had similar feeding habits. In contrast to macroinvertebrates, overall flow regime did not affect benthic algae. Our results indicate that overall flow regime affected the species pool of macroinvertebrates from which recolonization after extreme events may occur, but not of benthic algae. When individual components of flow regime were analyzed separately, high June (i.e. three months before sampling) flow maxima were associated with low benthic algal taxon richness, presumably due to scouring. Macroinvertebrate taxon richness decreased with lower relative minimum discharges, presumably due to temporary drying of parts of the riverbed. However, recolonization after such extreme events presumably is fast. Generally, macroinvertebrate and benthic algal assemblages were more closely related to water physico

  15. Assessment of flow regime alterations over a spectrum of temporal scales using wavelet-based approaches

    NASA Astrophysics Data System (ADS)

    Wu, Fu-Chun; Chang, Ching-Fu; Shiau, Jenq-Tzong

    2015-05-01

    The full range of natural flow regime is essential for sustaining the riverine ecosystems and biodiversity, yet there are still limited tools available for assessment of flow regime alterations over a spectrum of temporal scales. Wavelet analysis has proven useful for detecting hydrologic alterations at multiple scales via the wavelet power spectrum (WPS) series. The existing approach based on the global WPS (GWPS) ratio tends to be dominated by the rare high-power flows so that alterations of the more frequent low-power flows are often underrepresented. We devise a new approach based on individual deviations between WPS (DWPS) that are root-mean-squared to yield the global DWPS (GDWPS). We test these two approaches on the three reaches of the Feitsui Reservoir system (Taiwan) that are subjected to different classes of anthropogenic interventions. The GDWPS reveal unique features that are not detected with the GWPS ratios. We also segregate the effects of individual subflow components on the overall flow regime alterations using the subflow GDWPS. The results show that the daily hydropeaking waves below the reservoir not only intensified the flow oscillations at daily scale but most significantly eliminated subweekly flow variability. Alterations of flow regime were most severe below the diversion weir, where the residual hydropeaking resulted in a maximum impact at daily scale while the postdiversion null flows led to large hydrologic alterations over submonthly scales. The smallest impacts below the confluence reveal that the hydrologic alterations at scales longer than 2 days were substantially mitigated with the joining of the unregulated tributary flows, whereas the daily-scale hydrologic alteration was retained because of the hydropeaking inherited from the reservoir releases. The proposed DWPS approach unravels for the first time the details of flow regime alterations at these intermediate scales that are overridden by the low-frequency high-power flows when

  16. Numerical modelling of convective heat transport by air flow in permafrost talus slopes

    NASA Astrophysics Data System (ADS)

    Wicky, Jonas; Hauck, Christian

    2017-06-01

    Talus slopes are a widespread geomorphic feature in the Alps. Due to their high porosity a gravity-driven internal air circulation can be established which is forced by the gradient between external (air) and internal (talus) temperature. The thermal regime is different from the surrounding environment, leading to the occurrence of permafrost below the typical permafrost zone. This phenomenon has mainly been analysed by field studies and only few explicit numerical modelling studies exist. Numerical simulations of permafrost sometimes use parameterisations for the effects of convection but mostly neglect the influence of convective heat transfer in air on the thermal regime. In contrast, in civil engineering many studies have been carried out to investigate the thermal behaviour of blocky layers and to improve their passive cooling effect. The present study further develops and applies these concepts to model heat transfer in air flows in a natural-scale talus slope. Modelling results show that convective heat transfer has the potential to develop a significant temperature difference between the lower and the upper parts of the talus slope. A seasonally alternating chimney-effect type of circulation develops. Modelling results also show that this convective heat transfer leads to the formation of a cold reservoir in the lower part of the talus slope, which can be crucial for maintaining the frozen ground conditions despite increasing air temperatures caused by climate change.

  17. Natural flow regimes, nonnative fishes, and native fish persistence in arid-land river systems.

    PubMed

    Propst, David L; Gido, Keith B; Stefferud, Jerome A

    2008-07-01

    Escalating demands for water have led to substantial modifications of river systems in arid regions, which coupled with the widespread invasion of nonnative organisms, have increased the vulnerability of native aquatic species to extirpation. Whereas a number of studies have evaluated the role of modified flow regimes and nonnative species on native aquatic assemblages, few have been conducted where the compounding effects of modified flow regimes and established nonnatives do not confound interpretations, particularly at spatial and temporal scales that are relevant to conservation of species at a range-wide level. By evaluating a 19-year data set across six sites in the relatively unaltered upper Gila River basin, New Mexico, USA, we tested how natural flow regimes and presence of nonnative species affected long-term stability of native fish assemblages. Overall, we found that native fish density was greatest during a wet period at the beginning of our study and declined during a dry period near the end of the study. Nonnative fishes, particularly predators, generally responded in opposite directions to these climatic cycles. Our data suggested that chronic presence of nonnative fishes, coupled with naturally low flows reduced abundance of individual species and compromised persistence of native fish assemblages. We also found that a natural flow regime alone was unlikely to ensure persistence of native fish assemblages. Rather, active management that maintains natural flow regimes while concurrently suppressing or excluding nonnative fishes from remaining native fish strongholds is critical to conservation of native fish assemblages in a system, such as the upper Gila River drainage, with comparatively little anthropogenic modification.

  18. Relationships between Atmospheric Transport Regimes and PCB Concentrations in the Air at Zeppelin, Spitsbergen.

    PubMed

    Ubl, Sandy; Scheringer, Martin; Hungerbühler, Konrad

    2017-09-05

    Polychlorinated biphenyls (PCBs) are persistent hazardous chemicals that are still detected in the atmosphere and other environmental media, although their production has been banned for several decades. At the long-term monitoring site, Zeppelin at Spitsbergen, different PCB congeners have been continuously measured for more than a decade. However, it is not clear what factors determine the seasonal and interannual variability of different (lighter versus heavier) PCB congeners. To investigate the influence of atmospheric transport patterns on PCB-28 and PCB-101 concentrations at Zeppelin, we applied the Lagrangian Particle Dispersion Model FLEXPART and calculated "footprints" that indicate the potential source regions of air arriving at Zeppelin. By means of a cluster analysis, we assigned groups of similar footprints to different transport regimes and analyzed the PCB concentrations according to the transport regimes. The concentrations of both PCB congeners are affected by the different transport regimes. For PCB-101, the origin of air masses from the European continent is primarily related to high concentrations; elevated PCB-101 concentrations in winter can be explained by the high frequency of this transport regime in winter, whereas PCB-101 concentrations are low when air is arriving from the oceans. For PCB-28, in contrast, concentrations are high during summer when air is mainly arriving from the oceans but low when air is arriving from the continents. The most likely explanation of this finding is that local emissions of PCB-28 mask the effect of long-range transport and determine the concentrations measured at Zeppelin.

  19. Calculation of air movement in ice caves by using the CalcFlow method

    NASA Astrophysics Data System (ADS)

    Meyer, Christiane; Pflitsch, Andreas; Maggi, Valter

    2017-04-01

    We present a method to determine the air flow regime within ice caves by temperature loggers. Technical capabilities of conducting airflow measurements are restricted by the availability of energy at the ice cave study sites throughout the year. Though the knowledge of the airflow regime is a prerequisite for the understanding of the cave climate. By cross-correlating different time series of air temperature measurements inside a cave, we define the travel time of the air between the loggers, which corresponds to the time shift of best correlation, and use this result to derive the airflow speed. Then we estimate the temperature biases and scale factors for the temperature variations observed by the different loggers by a least squares adjustment. As quality control for bias and scale we use the formal errors of the estimation process. For the calculated airflow speed quality criteria are developed by use of a simulation study. Furthermore we will apply the method to temperature measurements in the static ice cave Schellenberger Eishöhle (Germany). In the end we show how the method can be used as an advanced filter for the separation of different signal contents of the temperature measurements.

  20. Flow regimes in a trapped vortex cell

    NASA Astrophysics Data System (ADS)

    Lasagna, D.; Iuso, G.

    2016-03-01

    This paper presents results of an experimental investigation on the flow in a trapped vortex cell, embedded into a flat plate, and interacting with a zero-pressure-gradient boundary layer. The objective of the work is to describe the flow features and elucidate some of the governing physical mechanisms, in the light of recent investigations on flow separation control using vortex cells. Hot-wire velocity measurements of the shear layer bounding the cell and of the boundary layers upstream and downstream are reported, together with spectral and correlation analyses of wall-pressure fluctuation measurements. Smoke flow visualisations provide qualitative insight into some relevant features of the internal flow, namely a large-scale flow unsteadiness and possible mechanisms driving the rotation of the vortex core. Results are presented for two very different regimes: a low-Reynolds-number case where the incoming boundary layer is laminar and its momentum thickness is small compared to the cell opening, and a moderately high-Reynolds-number case, where the incoming boundary layer is turbulent and the ratio between the momentum thickness and the opening length is significantly larger than in the first case. Implications of the present findings to flow control applications of trapped vortex cells are also discussed.

  1. Cluster analysis of multiple planetary flow regimes

    NASA Technical Reports Server (NTRS)

    Mo, Kingtse; Ghil, Michael

    1988-01-01

    A modified cluster analysis method developed for the classification of quasi-stationary events into a few planetary flow regimes and for the examination of transitions between these regimes is described. The method was applied first to a simple deterministic model and then to a 500-mbar data set for Northern Hemisphere (NH), for which cluster analysis was carried out in the subspace of the first seven empirical orthogonal functions (EOFs). Stationary clusters were found in the low-frequency band of more than 10 days, while transient clusters were found in the band-pass frequency window between 2.5 and 6 days. In the low-frequency band, three pairs of clusters determined EOFs 1, 2, and 3, respectively; they exhibited well-known regional features, such as blocking, the Pacific/North American pattern, and wave trains. Both model and low-pass data exhibited strong bimodality.

  2. Predicting regime shifts in flow of the Colorado River

    USGS Publications Warehouse

    Gangopadhyay, Subhrendu; McCabe, Gregory J.

    2010-01-01

    The effects of continued global warming on water resources are a concern for water managers and stake holders. In the western United States, where the combined climatic demand and consumptive use of water is equal to or greater than the natural supply of water for some locations, there is growing concern regarding the sustainability of future water supplies. In addition to the adverse effects of warming on water supply, another issue for water managers is accounting for, and managing, the effects of natural climatic variability, particularly persistently dry and wet periods. Analyses of paleo-reconstructions of Upper Colorado River basin (UCRB) flow demonstrate that severe sustained droughts, and persistent pluvial periods, are a recurring characteristic of hydroclimate in the Colorado River basin. Shifts between persistently dry and wet regimes (e.g., decadal to multi-decadal variability (D2M)) have important implications for water supply and water management. In this study paleo-reconstructions of UCRB flow are used to compute the risks of shifts between persistently wet and dry regimes given the length of time in a specific regime. Results indicate that low frequency variability of hydro-climatic conditions and the statistics that describe this low frequency variability can be useful to water managers by providing information about the risk of shifting from one hydrologic regime to another. To manage water resources in the future water managers will have to understand the joint hydrologic effects of natural climate variability and global warming. These joint effects may produce future hydrologic conditions that are unprecedented in both the instrumental and paleoclimatic records.

  3. Revisiting Maxwell’s accommodation coefficient: A study of nitrogen flow in a silica microtube across all flow regimes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lei, Wenwen, E-mail: wlei@physics.usyd.edu.au; McKenzie, David R., E-mail: d.mckenzie@physics.usyd.edu.au

    2014-12-15

    Gas flows have been studied quantitatively for more than a hundred years and have relevance in modern fields such as the control of gas inputs to processes, the measurement of leak rates and the separation of gaseous species. Cha and McCoy have derived a convenient formula for the flow of an ideal gas applicable across a wide range of Knudsen numbers (Kn) that approaches the Navier–Stokes equations at small Kn and the Smoluchowski extension of the Knudsen flow equation at large Kn. Smoluchowski’s result relies on the Maxwell definition of the tangential momentum accommodation coefficient α, recently challenged by Aryamore » et al. We measure the flow rate of nitrogen gas in a smooth walled silica tube across a wide range of Knudsen numbers from 0.0048 to 12.4583. We find that the nitrogen flow obeys the Cha and McCoy equation with a large value of α, unlike carbon nanotubes which show flows consistent with a small value of α. Silica capillaries are therefore not atomically smooth. The flow at small Kn has α=0.91 and at large Kn has α close to one, consistent with the redefinition of accommodation coefficient by Arya et al., which also resolves a problem in the literature where there are many observations of α of less than one at small Kn and many equal to one at large Kn. Silica capillaries are an excellent choice for an accurate flow control system. - Highlights: • First experimental study on flow rate across all flow regimes in a well-defined microtube. • Extend Cha and McCoy theory for molecular flow regime. • Demonstrate the Maxwell accommodation coefficient is different in the slip and molecular flow regimes.« less

  4. Flow Regime Identification of Horizontal Two Phase Refrigerant R-134a Flow Using Neural Networks (Postprint)

    DTIC Science & Technology

    2013-11-01

    Flows in Microchannels ," Heat Transfer Engineering, Vol. 27, No. 9, 2006, pp. 4-19. 2Kandlikar, S. G., " Heat Transfer Mechanisms During Flow...Boiling in Microchannels ," Journal of Heat Transfer , Vol. 126, No. 1, 2004, pp. 8-16. 3Kreitzer, P. J., Byrd, L., and Willebrand, B. J., "Initial...an integral aspect of modeling two phase flows as most pressure drop and heat transfer correlations rely on a priori knowledge of the flow regime for

  5. Meteorological regimes for the classification of aerospace air quality predictions for NASA-Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Stephens, J. B.; Sloan, J. C.

    1976-01-01

    A method is described for developing a statistical air quality assessment for the launch of an aerospace vehicle from the Kennedy Space Center in terms of existing climatological data sets. The procedure can be refined as developing meteorological conditions are identified for use with the NASA-Marshall Space Flight Center Rocket Exhaust Effluent Diffusion (REED) description. Classical climatological regimes for the long range analysis can be narrowed as the synoptic and mesoscale structure is identified. Only broad synoptic regimes are identified at this stage of analysis. As the statistical data matrix is developed, synoptic regimes will be refined in terms of the resulting eigenvectors as applicable to aerospace air quality predictions.

  6. Experimental observations of pressure oscillations and flow regimes in an analogue volcanic system

    USGS Publications Warehouse

    Lane, S.J.; Chouet, B.A.; Phillips, J.C.; Dawson, P.; Ryan, G.A.; Hurst, E.

    2001-01-01

    Gas-liquid flows, designed to be analogous to those in volcanic conduits, are generated in the laboratory using organic gas-gum rosin mixtures expanding in a vertically mounted tube. The expanding fluid shows a range of both flow and pressure oscillation behaviors. Weakly supersaturated source liquids produce a low Reynolds number flow with foam expanding from the top surface of a liquid that exhibits zero fluid velocity at the tube wall; i.e., the conventional "no-slip" boundary condition. Pressure oscillations, often with strong long-period characteristics and consistent with longitudinal and radial resonant oscillation modes, are detected in these fluids. Strongly supersaturated source liquids generate more energetic flows that display a number of flow regimes. These regimes include a static liquid source, viscous flow, detached flow (comprising gas-pockets-at-wall and foam-in-gas annular flow, therefore demonstrating strong radial heterogeneity), and a fully turbulent transonic fragmented or mist flow. Each of these flow regimes displays characteristic pressure oscillations that can be related to resonance of flow features or wall impact phenomena. The pressure oscillations are produced by the degassing processes without the need of elastic coupling to the confining medium or flow restrictors and valvelike features. The oscillatory behavior of the experimental flows is compared to seismoacoustic data from a range of volcanoes where resonant oscillation of the fluid within the conduit is also often invoked as controlling the observed oscillation frequencies. On the basis of the experimental data we postulate on the nature of seismic signals that may be measured during large-scale explosive activity. Copyright 2001 by the American Geophysical Union.

  7. Ring waves as a mass transport mechanism in air-driven core-annular flows.

    PubMed

    Camassa, Roberto; Forest, M Gregory; Lee, Long; Ogrosky, H Reed; Olander, Jeffrey

    2012-12-01

    Air-driven core-annular fluid flows occur in many situations, from lung airways to engineering applications. Here we study, experimentally and theoretically, flows where a viscous liquid film lining the inside of a tube is forced upwards against gravity by turbulent airflow up the center of the tube. We present results on the thickness and mean speed of the film and properties of the interfacial waves that develop from an instability of the air-liquid interface. We derive a long-wave asymptotic model and compare properties of its solutions with those of the experiments. Traveling wave solutions of this long-wave model exhibit evidence of different mass transport regimes: Past a certain threshold, sufficiently large-amplitude waves begin to trap cores of fluid which propagate upward at wave speeds. This theoretical result is then confirmed by a second set of experiments that show evidence of ring waves of annular fluid propagating over the underlying creeping flow. By tuning the parameters of the experiments, the strength of this phenomenon can be adjusted in a way that is predicted qualitatively by the model.

  8. Time-resolved Fast Neutron Radiography of Air-water Two-phase Flows

    NASA Astrophysics Data System (ADS)

    Zboray, Robert; Dangendorf, Volker; Mor, Ilan; Tittelmeier, Kai; Bromberger, Benjamin; Prasser, Horst-Michael

    Neutron imaging, in general, is a useful technique for visualizing low-Z materials (such as water or plastics) obscured by high-Z materials. However, when significant amounts of both materials are present and full-bodied samples have to be examined, cold and thermal neutrons rapidly reach their applicability limit as the samples become opaque. In such cases one can benefit from the high penetrating power of fast neutrons. In this work we demonstrate the feasibility of time-resolved, fast neutron radiography of generic air-water two-phase flows in a 1.5 cm thick flow channel with Aluminum walls and rectangular cross section. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany. Exposure times down to 3.33 ms have been achieved at reasonable image quality and acceptable motion artifacts. Different two-phase flow regimes such as bubbly slug and churn flows have been examined. Two-phase flow parameters like the volumetric gas fraction, bubble size and bubble velocities have been measured.

  9. Linear stability analysis of laminar flow near a stagnation point in the slip flow regime

    NASA Astrophysics Data System (ADS)

    Essaghir, E.; Oubarra, A.; Lahjomri, J.

    2017-12-01

    The aim of the present contribution is to analyze the effect of slip parameter on the stability of a laminar incompressible flow near a stagnation point in the slip flow regime. The analysis is based on the traditional normal mode approach and assumes parallel flow approximation. The Orr-Sommerfeld equation that governs the infinitesimal disturbance of stream function imposed to the steady main flow, which is an exact solution of the Navier-Stokes equation satisfying slip boundary conditions, is obtained by using the powerful spectral Chebyshev collocation method. The results of the effect of slip parameter K on the hydrodynamic characteristics of the base flow, namely the velocity profile, the shear stress profile, the boundary layer, displacement and momentum thicknesses are illustrated and discussed. The numerical data for these characteristics, as well as those of the eigenvalues and the corresponding wave numbers recover the results of the special case of no-slip boundary conditions. They are found to be in good agreement with previous numerical calculations. The effects of slip parameter on the neutral curves of stability, for two-dimensional disturbances in the Reynolds-wave number plane, are then obtained for the first time in the slip flow regime for stagnation point flow. Furthermore, the evolution of the critical Reynolds number against the slip parameter is established. The results show that the critical Reynolds number for instability is significantly increased with the slip parameter and the flow turn out to be more stable when the effect of rarefaction becomes important.

  10. The path to COVIS: A review of acoustic imaging of hydrothermal flow regimes

    NASA Astrophysics Data System (ADS)

    Bemis, Karen G.; Silver, Deborah; Xu, Guangyu; Light, Russ; Jackson, Darrell; Jones, Christopher; Ozer, Sedat; Liu, Li

    2015-11-01

    Acoustic imaging of hydrothermal flow regimes started with the incidental recognition of a plume on a routine sonar scan for obstacles in the path of the human-occupied submersible ALVIN. Developments in sonar engineering, acoustic data processing and scientific visualization have been combined to develop technology which can effectively capture the behavior of focused and diffuse hydrothermal discharge. This paper traces the development of these acoustic imaging techniques for hydrothermal flow regimes from their conception through to the development of the Cabled Observatory Vent Imaging Sonar (COVIS). COVIS has monitored such flow eight times a day for several years. Successful acoustic techniques for estimating plume entrainment, bending, vertical rise, volume flux, and heat flux are presented as is the state-of-the-art in diffuse flow detection.

  11. An implicit scheme with memory reduction technique for steady state solutions of DVBE in all flow regimes

    NASA Astrophysics Data System (ADS)

    Yang, L. M.; Shu, C.; Yang, W. M.; Wu, J.

    2018-04-01

    High consumption of memory and computational effort is the major barrier to prevent the widespread use of the discrete velocity method (DVM) in the simulation of flows in all flow regimes. To overcome this drawback, an implicit DVM with a memory reduction technique for solving a steady discrete velocity Boltzmann equation (DVBE) is presented in this work. In the method, the distribution functions in the whole discrete velocity space do not need to be stored, and they are calculated from the macroscopic flow variables. As a result, its memory requirement is in the same order as the conventional Euler/Navier-Stokes solver. In the meantime, it is more efficient than the explicit DVM for the simulation of various flows. To make the method efficient for solving flow problems in all flow regimes, a prediction step is introduced to estimate the local equilibrium state of the DVBE. In the prediction step, the distribution function at the cell interface is calculated by the local solution of DVBE. For the flow simulation, when the cell size is less than the mean free path, the prediction step has almost no effect on the solution. However, when the cell size is much larger than the mean free path, the prediction step dominates the solution so as to provide reasonable results in such a flow regime. In addition, to further improve the computational efficiency of the developed scheme in the continuum flow regime, the implicit technique is also introduced into the prediction step. Numerical results showed that the proposed implicit scheme can provide reasonable results in all flow regimes and increase significantly the computational efficiency in the continuum flow regime as compared with the existing DVM solvers.

  12. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 21 2013-07-01 2013-07-01 false Air flow measurement specifications. 89.414 Section 89.414 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method...

  13. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 21 2012-07-01 2012-07-01 false Air flow measurement specifications. 89.414 Section 89.414 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method...

  14. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Air flow measurement specifications. 89.414 Section 89.414 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method...

  15. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 20 2011-07-01 2011-07-01 false Air flow measurement specifications. 89.414 Section 89.414 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method...

  16. Modeling the Evolution of Riparian Woodlands Facing Climate Change in Three European Rivers with Contrasting Flow Regimes

    PubMed Central

    Rivaes, Rui P.; Rodríguez-González, Patricia M.; Ferreira, Maria Teresa; Pinheiro, António N.; Politti, Emilio; Egger, Gregory; García-Arias, Alicia; Francés, Felix

    2014-01-01

    Global circulation models forecasts indicate a future temperature and rainfall pattern modification worldwide. Such phenomena will become particularly evident in Europe where climate modifications could be more severe than the average change at the global level. As such, river flow regimes are expected to change, with resultant impacts on aquatic and riparian ecosystems. Riparian woodlands are among the most endangered ecosystems on earth and provide vital services to interconnected ecosystems and human societies. However, they have not been the object of many studies designed to spatially and temporally quantify how these ecosystems will react to climate change-induced flow regimes. Our goal was to assess the effects of climate-changed flow regimes on the existing riparian vegetation of three different European flow regimes. Cases studies were selected in the light of the most common watershed alimentation modes occurring across European regions, with the objective of appraising expected alterations in the riparian elements of fluvial systems due to climate change. Riparian vegetation modeling was performed using the CASiMiR-vegetation model, which bases its computation on the fluvial disturbance of the riparian patch mosaic. Modeling results show that riparian woodlands may undergo not only at least moderate changes for all flow regimes, but also some dramatic adjustments in specific areas of particular vegetation development stages. There are circumstances in which complete annihilation is feasible. Pluvial flow regimes, like the ones in southern European rivers, are those likely to experience more pronounced changes. Furthermore, regardless of the flow regime, younger and more water-dependent individuals are expected to be the most affected by climate change. PMID:25330151

  17. 40 CFR 89.414 - Air flow measurement specifications.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 20 2014-07-01 2013-07-01 true Air flow measurement specifications. 89.414 Section 89.414 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS... Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method used...

  18. Sensitivity of Regulated Flow Regimes to Climate Change in the Western United States

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhou, Tian; Voisin, Nathalie; Leng, Guoyong

    Water management activities or flow regulations modify water fluxes at the land surface and affect water resources in space and time. We hypothesize that flow regulations change the sensitivity of river flow to climate change with respect to unmanaged water resources. Quantifying these changes in sensitivity could help elucidate the impacts of water management at different spatiotemporal scales and inform climate adaptation decisions. In this study, we compared the emergence of significant changes in natural and regulated river flow regimes across the Western United States from simulations driven by multiple climate models and scenarios. We find that significant climate change-inducedmore » alterations in natural flow do not cascade linearly through water management activities. At the annual time scale, 50% of the Hydrologic Unit Code 4 (HUC4) sub-basins over the Western U.S. regions tend to have regulated flow regime more sensitive to the climate change than natural flow regime. Seasonality analyses show that the sensitivity varies remarkably across the seasons. We also find that the sensitivity is related to the level of water management. For 35% of the HUC4 sub-basins with the highest level of water management, the summer and winter flows tend to show a heightened sensitivity to climate change due to the complexity of joint reservoir operations. We further demonstrate that the impacts of considering water management in models are comparable to those that arises from uncertainties across climate models and emission scenarios. This prompts further climate adaptation studies research about nonlinearity effects of climate change through water management activities.« less

  19. Role of mixed boundaries on flow in open capillary channels with curved air-water interfaces.

    PubMed

    Zheng, Wenjuan; Wang, Lian-Ping; Or, Dani; Lazouskaya, Volha; Jin, Yan

    2012-09-04

    Flow in unsaturated porous media or in engineered microfluidic systems is dominated by capillary and viscous forces. Consequently, flow regimes may differ markedly from conventional flows, reflecting strong interfacial influences on small bodies of flowing liquids. In this work, we visualized liquid transport patterns in open capillary channels with a range of opening sizes from 0.6 to 5.0 mm using laser scanning confocal microscopy combined with fluorescent latex particles (1.0 μm) as tracers at a mean velocity of ∼0.50 mm s(-1). The observed velocity profiles indicate limited mobility at the air-water interface. The application of the Stokes equation with mixed boundary conditions (i.e., no slip on the channel walls and partial slip or shear stress at the air-water interface) clearly illustrates the increasing importance of interfacial shear stress with decreasing channel size. Interfacial shear stress emerges from the velocity gradient from the adjoining no-slip walls to the center where flow is trapped in a region in which capillary forces dominate. In addition, the increased contribution of capillary forces (relative to viscous forces) to flow on the microscale leads to increased interfacial curvature, which, together with interfacial shear stress, affects the velocity distribution and flow pattern (e.g., reverse flow in the contact line region). We found that partial slip, rather than the commonly used stress-free condition, provided a more accurate description of the boundary condition at the confined air-water interface, reflecting the key role that surface/interface effects play in controlling flow behavior on the nanoscale and microscale.

  20. Analytic expression for poloidal flow velocity in the banana regime

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Taguchi, M.

    The poloidal flow velocity in the banana regime is calculated by improving the l = 1 approximation for the Fokker-Planck collision operator [M. Taguchi, Plasma Phys. Controlled Fusion 30, 1897 (1988)]. The obtained analytic expression for this flow, which can be used for general axisymmetric toroidal plasmas, agrees quite well with the recently calculated numerical results by Parker and Catto [Plasma Phys. Controlled Fusion 54, 085011 (2012)] in the full range of aspect ratio.

  1. Study of the Transition Flow Regime using Monte Carlo Methods

    NASA Technical Reports Server (NTRS)

    Hassan, H. A.

    1999-01-01

    This NASA Cooperative Agreement presents a study of the Transition Flow Regime Using Monte Carlo Methods. The topics included in this final report are: 1) New Direct Simulation Monte Carlo (DSMC) procedures; 2) The DS3W and DS2A Programs; 3) Papers presented; 4) Miscellaneous Applications and Program Modifications; 5) Solution of Transitional Wake Flows at Mach 10; and 6) Turbulence Modeling of Shock-Dominated Fows with a k-Enstrophy Formulation.

  2. Numerical analysis of flow resistance and heat transfer in the transitional regime of pipe flow with twisted-tape turbulators

    NASA Astrophysics Data System (ADS)

    Rossi, R.; Cattani, L.; Mocerino, A.; Bozzoli, F.; Rainieri, S.; Caminati, R.; Pagliarini, G.

    2017-11-01

    In this paper, we present the numerical analysis of the fully developed ow and heat transfer in pipes equipped with twisted-tape inserts in the laminar to transitional flow regime. The flow Reynolds number ranges from 210 to 3100 based on the pipe diameter, whereas the Prandtl number of the working fluid, a 40% mixture of water and ethylene glycol, is about 45 at the average film temperature. The numerical study is carried out via Scale Adaptive Simulations (SAS) where the k-ω SST model is employed for turbulence modeling. Using SAS and low-dissipation discretization schemes, the present study shows that it is possible to capture the transition from the laminar regime to the pulsating or pseudo-laminar flow regime induced by the twisted-tape at low Reynolds numbers, as well as the transition to moderate turbulent regime at the higher, yet non-turbulent for smooth pipes, range of Reynolds numbers. Numerical results, validated against experiments performed in a dedicated test rig, show very good agreement with measured data and an increase of the friction factor and Nusselt number in the range of 4 to 7 times and 6 to 15 times, respectively, of the values for an empty pipe.

  3. 40 CFR 1065.225 - Intake-air flow meter.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... flow meter. (a) Application. You may use an intake-air flow meter in combination with a chemical..., you may use an intake-air flow meter signal that does not give the actual value of raw exhaust, as... requirements. We recommend that you use an intake-air flow meter that meets the specifications in Table 1 of...

  4. Nozzle Free Jet Flows Within the Strong Curved Shock Regime

    NASA Technical Reports Server (NTRS)

    Shih, Tso-Shin

    1975-01-01

    A study based on inviscid analysis was conducted to examine the flow field produced from a convergent-divergent nozzle when a strong curved shock occurs. It was found that a certain constraint is imposed on the flow solution of the problem which is the unique feature of the flow within this flow regime, and provides the reason why the inverse method of calculation cannot be employed for these problems. An approximate method was developed to calculate the flow field, and results were obtained for two-dimensional flows. Analysis and calculations were performed for flows with axial symmetry. It is shown that under certain conditions, the vorticity generated at the jet boundary may become infinite and the viscous effect becomes important. Under other conditions, the asymptotic free jet height as well as the corresponding shock geometry were determined.

  5. Natural Flow Air Cooled Photovoltaics

    NASA Astrophysics Data System (ADS)

    Tanagnostopoulos, Y.; Themelis, P.

    2010-01-01

    Our experimental study aims to investigate the improvement in the electrical performance of a photovoltaic installation on buildings through cooling of the photovoltaic panels with natural air flow. Our experimental study aims to investigate the improvement in the electrical performance of a photovoltaic installation on buildings through cooling of the photovoltaic panels with natural air flow. We performed experiments using a prototype based on three silicon photovoltaic modules placed in series to simulate a typical sloping building roof with photovoltaic installation. In this system the air flows through a channel on the rear side of PV panels. The potential for increasing the heat exchange from the photovoltaic panel to the circulating air by the addition of a thin metal sheet (TMS) in the middle of air channel or metal fins (FIN) along the air duct was examined. The operation of the device was studied with the air duct closed tightly to avoid air circulation (CLOSED) and the air duct open (REF), with the thin metal sheet (TMS) and with metal fins (FIN). In each case the experiments were performed under sunlight and the operating parameters of the experimental device determining the electrical and thermal performance of the system were observed and recorded during a whole day and for several days. We collected the data and form PV panels from the comparative diagrams of the experimental results regarding the temperature of solar cells, the electrical efficiency of the installation, the temperature of the back wall of the air duct and the temperature difference in the entrance and exit of the air duct. The comparative results from the measurements determine the improvement in electrical performance of the photovoltaic cells because of the reduction of their temperature, which is achieved by the naturally circulating air.

  6. 40 CFR 91.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Intake air flow measurement... Procedures § 91.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure the air flow over the engine...

  7. Granular-flow rheology: Role of shear-rate number in transition regime

    USGS Publications Warehouse

    Chen, C.-L.; Ling, C.-H.

    1996-01-01

    This paper examines the rationale behind the semiempirical formulation of a generalized viscoplastic fluid (GVF) model in the light of the Reiner-Rivlin constitutive theory and the viscoplastic theory, thereby identifying the parameters that control the rheology of granular flow. The shear-rate number (N) proves to be among the most significant parameters identified from the GVF model. As N ??? 0 and N ??? ???, the GVF model can reduce asymptotically to the theoretical stress versus shear-rate relations in the macroviscous and graininertia regimes, respectively, where the grain concentration (C) also plays a major role in the rheology of granular flow. Using available data obtained from the rotating-cylinder experiments of neutrally buoyant solid spheres dispersing in an interstitial fluid, the shear stress for granular flow in transition between the two regimes proves dependent on N and C in addition to some material constants, such as the coefficient of restitution. The insufficiency of data on rotating-cylinder experiments cannot presently allow the GVF model to predict how a granular flow may behave in the entire range of N; however, the analyzed data provide an insight on the interrelation among the relevant dimensionless parameters.

  8. Effects of flow regime and pesticides on periphytic communities: evolution and role of biodiversity.

    PubMed

    Villeneuve, Aurélie; Montuelle, Bernard; Bouchez, Agnès

    2011-04-01

    The effects of chemical and physical factors on periphyton structure, diversity and functioning were investigated in an outdoor mesocosm experiment. Stream biofilms were subjected to a pesticide mix (diuron and azoxystrobin) under two different hydraulic regimes. The hydraulic regimes differed by spatial variations of flow conditions (turbulent with high variations vs. laminar with low variations). The effects of the hydraulic regime and pesticides were assessed at the level of the periphytic communities. We focused on the change in the biodiversity of these communities under the two hydraulic regimes, and on the role of these biodiversity changes in case of pesticide contamination. Changes in structural (biomass, cell density), diversity (community composition assessed by PCR-DGGE and microscopic analysis) and functional (bacterial and algal production, sensitivity to the herbicide) parameters were monitored throughout a 2-month experiment. The results showed that exposure to pesticides affected the phytobenthic community targeted by the herbicide, impacting on both its growth dynamics and its primary production. Conversely, the impact of the flow regime was greater than that of pesticides on the non-target bacterial community with higher bacterial density and production in laminar mesocosms (uniform regime). An interaction between flow and pollution effects was also observed. Communities that developed in turbulent mesocosms (heterogeneous regime) were more diversified, as a result of increased microhabitat heterogeneity due to high spatial variations. However, this higher biodiversity did not increase the ability of these biofilms to tolerate pesticides, as expected. On the contrary, the sensitivity of these communities to pesticide contamination was, in fact, increased. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Air-flow regulation system for a coal gasifier

    DOEpatents

    Fasching, George E.

    1984-01-01

    An improved air-flow regulator for a fixed-bed coal gasifier is provided which allows close air-flow regulation from a compressor source even though the pressure variations are too rapid for a single primary control loop to respond. The improved system includes a primary controller to control a valve in the main (large) air supply line to regulate large slow changes in flow. A secondary controller is used to control a smaller, faster acting valve in a secondary (small) air supply line parallel to the main line valve to regulate rapid cyclic deviations in air flow. A low-pass filter with a time constant of from 20 to 50 seconds couples the output of the secondary controller to the input of the primary controller so that the primary controller only responds to slow changes in the air-flow rate, the faster, cyclic deviations in flow rate sensed and corrected by the secondary controller loop do not reach the primary controller due to the high frequency rejection provided by the filter. This control arrangement provides at least a factor of 5 improvement in air-flow regulation for a coal gasifier in which air is supplied by a reciprocating compressor through a surge tank.

  10. Implicit unified gas-kinetic scheme for steady state solutions in all flow regimes

    NASA Astrophysics Data System (ADS)

    Zhu, Yajun; Zhong, Chengwen; Xu, Kun

    2016-06-01

    This paper presents an implicit unified gas-kinetic scheme (UGKS) for non-equilibrium steady state flow computation. The UGKS is a direct modeling method for flow simulation in all regimes with the updates of both macroscopic flow variables and microscopic gas distribution function. By solving the macroscopic equations implicitly, a predicted equilibrium state can be obtained first through iterations. With the newly predicted equilibrium state, the evolution equation of the gas distribution function and the corresponding collision term can be discretized in a fully implicit way for fast convergence through iterations as well. The lower-upper symmetric Gauss-Seidel (LU-SGS) factorization method is implemented to solve both macroscopic and microscopic equations, which improves the efficiency of the scheme. Since the UGKS is a direct modeling method and its physical solution depends on the mesh resolution and the local time step, a physical time step needs to be fixed before using an implicit iterative technique with a pseudo-time marching step. Therefore, the physical time step in the current implicit scheme is determined by the same way as that in the explicit UGKS for capturing the physical solution in all flow regimes, but the convergence to a steady state speeds up through the adoption of a numerical time step with large CFL number. Many numerical test cases in different flow regimes from low speed to hypersonic ones, such as the Couette flow, cavity flow, and the flow passing over a cylinder, are computed to validate the current implicit method. The overall efficiency of the implicit UGKS can be improved by one or two orders of magnitude in comparison with the explicit one.

  11. Changes in air flow patterns using surfactants and thickeners during air sparging: bench-scale experiments.

    PubMed

    Kim, Juyoung; Kim, Heonki; Annable, Michael D

    2015-01-01

    Air injected into an aquifer during air sparging normally flows upward according to the pressure gradients and buoyancy, and the direction of air flow depends on the natural hydrogeologic setting. In this study, a new method for controlling air flow paths in the saturated zone during air sparging processes is presented. Two hydrodynamic parameters, viscosity and surface tension of the aqueous phase in the aquifer, were altered using appropriate water-soluble reagents distributed before initiating air sparging. Increased viscosity retarded the travel velocity of the air front during air sparging by modifying the viscosity ratio. Using a one-dimensional column packed with water-saturated sand, the velocity of air intrusion into the saturated region under a constant pressure gradient was inversely proportional to the viscosity of the aqueous solution. The air flow direction, and thus the air flux distribution was measured using gaseous flux meters placed at the sand surface during air sparging experiments using both two-, and three-dimensional physical models. Air flow was found to be influenced by the presence of an aqueous patch of high viscosity or suppressed surface tension in the aquifer. Air flow was selective through the low-surface tension (46.5 dyn/cm) region, whereas an aqueous patch of high viscosity (2.77 cP) was as an effective air flow barrier. Formation of a low-surface tension region in the target contaminated zone in the aquifer, before the air sparging process is inaugurated, may induce air flow through the target zone maximizing the contaminant removal efficiency of the injected air. In contrast, a region with high viscosity in the air sparging influence zone may minimize air flow through the region prohibiting the region from de-saturating. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Air conditioning system and component therefore distributing air flow from opposite directions

    NASA Technical Reports Server (NTRS)

    Obler, H. D.; Bauer, H. B. (Inventor)

    1974-01-01

    The air conditioning system comprises a plurality of separate air conditioning units coupled to a common supply duct such that air may be introduced into the supply duct in two opposite flow directions. A plurality of outlets such as registers or auxiliary or branch ducts communicate with the supply duct and valve means are disposed in the supply duct at at least some of the outlets for automatically channelling a controllable amount of air from the supply duct to the associated outlet regardless of the direction of air flow within the supply duct. The valve means comprises an automatic air volume control apparatus for distribution within the air supply duct into which air may be introduced from two opposite directions. The apparatus incorporates a freely swinging movable vane in the supply duct to automatically channel into the associated outlet only the deflected air flow which has the higher relative pressure.

  13. Evaluation of Spatial Pattern of Altered Flow Regimes on a River Network Using a Distributed Hydrological Model

    PubMed Central

    Ryo, Masahiro; Iwasaki, Yuichi; Yoshimura, Chihiro; Saavedra V., Oliver C.

    2015-01-01

    Alteration of the spatial variability of natural flow regimes has been less studied than that of the temporal variability, despite its ecological importance for river ecosystems. Here, we aimed to quantify the spatial patterns of flow regime alterations along a river network in the Sagami River, Japan, by estimating river discharge under natural and altered flow conditions. We used a distributed hydrological model, which simulates hydrological processes spatiotemporally, to estimate 20-year daily river discharge along the river network. Then, 33 hydrologic indices (i.e., Indicators of Hydrologic Alteration) were calculated from the simulated discharge to estimate the spatial patterns of their alterations. Some hydrologic indices were relatively well estimated such as the magnitude and timing of maximum flows, monthly median flows, and the frequency of low and high flow pulses. The accuracy was evaluated with correlation analysis (r > 0.4) and the Kolmogorov–Smirnov test (α = 0.05) by comparing these indices calculated from both observed and simulated discharge. The spatial patterns of the flow regime alterations varied depending on the hydrologic indices. For example, both the median flow in August and the frequency of high flow pulses were reduced by the maximum of approximately 70%, but these strongest alterations were detected at different locations (i.e., on the mainstream and the tributary, respectively). These results are likely caused by different operational purposes of multiple water control facilities. The results imply that the evaluation only at discharge gauges is insufficient to capture the alteration of the flow regime. Our findings clearly emphasize the importance of evaluating the spatial pattern of flow regime alteration on a river network where its discharge is affected by multiple water control facilities. PMID:26207997

  14. Numerical Investigation of Flow in a Centrifugal Compressor

    NASA Astrophysics Data System (ADS)

    Grishin, Yu. A.; Bakulin, V. N.

    2015-09-01

    With the use of the domestic software suite of computational hydrodynamics Flow Vision based on application of the method of control volumes, numerical simulation of air composition and delivery by a centrifugal compressor employed for supercharging a piston engine has been carried out. The head-flow characteristics of the compressor, as well as the 3D fields of flow velocity and pressure distributions in the elements of the compressor flow passage, including the interblade channels of the impeller, have been obtained for various regimes. In the regimes of diminished air flow rate, surging phenomena are identified, characterized by a return flow. The application of the technique of numerical experiment will make it possible from here on to carry out design optimization of the compressor flow passage profile and thus to improve its basic characteristics — the degree of pressure increase, compressed air flow rate, and the efficiency — as well as to reduce the costs of the development and production of compressors.

  15. EFFECT OF FLOW REGIME ON FISH-HABITAT RELATIONSHIPS IN A MID-WESTERN RIVER

    EPA Science Inventory

    Numerous studies have shown interrelationships among stream fishes, habitat and land use, but it is unclear how flow regime affects these relationships. We hypothesized that habitat would better predict fishes in streams with stable flows. Habitat should be less predictive in u...

  16. The perfect ash-storm: large-scale Pyroclastic Density Current experiments reveal highly mobile, self-fluidising and air-cushioned flow transport regime

    NASA Astrophysics Data System (ADS)

    Lube, G.; Cronin, S. J.; Breard, E.; Valentine, G.; Bursik, M. I.; Hort, M. K.; Freundt, A.

    2013-12-01

    We report on the first systematic series of large-scale Pyroclastic Density Current (PDC) experiments using the New Zealand PDC Generator, a novel international research facility in Physical Volcanology recently commissioned at Massey University. Repeatable highly energetic and hot PDCs are synthesized by the controlled ';eruption column-collapse' of up to 3500 kg of homogenously aerated Taupo ignimbrite material from a 15 m-elevated hopper onto an instrumented inclined flume. At discharge rates between 250-1300 kg/s and low- to moderate gas injection rates (yielding initial solids concentration of 15-70 vol%) channelized gas-particle mixture flows life-scaled to dense PDCs can be generated. The flow fronts of the currents reach velocities of up to 9.5 m/s over their first 12 m of travel and rapidly develop strong vertical density stratification. The PDCs typically form a highly mobile, <60 cm-thick dense and channel-confined underflow, with an overriding dilute and turbulent ash cloud surge that also laterally escapes the flume boundaries. Depending on the PDC starting conditions underflows with 1-45 vol% solids concentration are formed, while the upper surge contains <<1 vol.% solids. A characteristic feature of the underflow is the occurrence of 'ignitive' front breakouts, producing jetted lobes that accelerate outward from the flow front, initially forming a lobe-cleft structure, followed by segregation downslope into multiple flow pulses. Depending on initial solids concentration and discharge rate, stratified, dune-bedded and inversely graded bedforms are created whose thicknesses are remarkably uniform along the medial to distal runout path characterising highly mobile flow runout. Along with high-speed video footage we present time-series data of basal arrays of load- and gas-pore pressure transducers to characterise the mobile dense underflows. Data shows that the PDCs are comprised of a turbulent coarse-grained and air-ingesting front with particle

  17. Three-dimensional investigations of the threading regime in a microfluidic flow-focusing channel

    NASA Astrophysics Data System (ADS)

    Gowda, Krishne; Brouzet, Christophe; Lefranc, Thibault; Soderberg, L. Daniel; Lundell, Fredrik

    2017-11-01

    We study the flow dynamics of the threading regime in a microfluidic flow-focusing channel through 3D numerical simulations and experiments. Making strong filaments from cellulose nano-fibrils (CNF) could potentially steer to new high-performance bio-based composites competing with conventional glass fibre composites. CNF filaments can be obtained through hydrodynamic alignment of dispersed CNF by using the concept of flow-focusing. The aligned structure is locked by diffusion of ions resulting in a dispersion-gel transition. Flow-focusing typically refers to a microfluidic channel system where the core fluid is focused by the two sheath fluids, thereby creating an extensional flow at the intersection. In this study, threading regime corresponds to an extensional flow field generated by the water sheath fluid stretching the dispersed CNF core fluid and leading to formation of long threads. The experimental measurements are performed using optical coherence tomography (OCT) and 3D numerical simulations with OpenFOAM. The prime focus is laid on the 3D characteristics of thread formation such as wetting length of core fluid, shape, aspect ratio of the thread and velocity flow-field in the microfluidic channel.

  18. CFD simulation of fluid dynamic and biokinetic processes within activated sludge reactors under intermittent aeration regime.

    PubMed

    Sánchez, F; Rey, H; Viedma, A; Nicolás-Pérez, F; Kaiser, A S; Martínez, M

    2018-08-01

    Due to the aeration system, biological reactors are the most energy-consuming facilities of convectional WWTPs. Many biological reactors work under intermittent aeration regime; the optimization of the aeration process (air diffuser layout, air flow rate per diffuser, aeration length …) is necessary to ensure an efficient performance; satisfying the effluent requirements with the minimum energy consumption. This work develops a CFD modelling of an activated sludge reactor (ASR) which works under intermittent aeration regime. The model considers the fluid dynamic and biological processes within the ASR. The biological simulation, which is transient, takes into account the intermittent aeration regime. The CFD modelling is employed for the selection of the aeration system of an ASR. Two different aeration configurations are simulated. The model evaluates the aeration power consumption necessary to satisfy the effluent requirements. An improvement of 2.8% in terms of energy consumption is achieved by modifying the air diffuser layout. An analysis of the influence of the air flow rate per diffuser on the ASR performance is carried out. The results show a reduction of 14.5% in the energy consumption of the aeration system when the air flow rate per diffuser is reduced. The model provides an insight into the aeration inefficiencies produced within ASRs. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Modeling the relations between flow regime components, species traits, and spawning success of fishes in warmwater streams

    USGS Publications Warehouse

    Craven, S.W.; Peterson, J.T.; Freeman, Mary C.; Kwak, T.J.; Irwin, E.

    2010-01-01

    Modifications to stream hydrologic regimes can have a profound influence on the dynamics of their fish populations. Using hierarchical linear models, we examined the relations between flow regime and young-of-year fish density using fish sampling and discharge data from three different warmwater streams in Illinois, Alabama, and Georgia. We used an information theoretic approach to evaluate the relative support for models describing hypothesized influences of five flow regime components representing: short-term high and low flows; short-term flow stability; and long-term mean flows and flow stability on fish reproductive success during fish spawning and rearing periods. We also evaluated the influence of ten fish species traits on fish reproductive success. Species traits included spawning duration, reproductive strategy, egg incubation rate, swimming locomotion morphology, general habitat preference, and food habits. Model selection results indicated that young-of-year fish density was positively related to short-term high flows during the spawning period and negatively related to flow variability during the rearing period. However, the effect of the flow regime components varied substantially among species, but was related to species traits. The effect of short-term high flows on the reproductive success was lower for species that broadcast their eggs during spawning. Species with cruiser swimming locomotion morphologies (e.g., Micropterus) also were more vulnerable to variable flows during the rearing period. Our models provide insight into the conditions and timing of flows that influence the reproductive success of warmwater stream fishes and may guide decisions related to stream regulation and management. ?? 2010 US Government.

  20. Quantifying alteration of river flow regime by large reservoirs in France

    NASA Astrophysics Data System (ADS)

    Cipriani, Thomas; Sauquet, Eric

    2017-04-01

    Reservoirs may highly modify river flow regime. Knowing the alterations is of importance to better understand the biological and physical patterns along the river network. However data are not necessary available to carry out an analysis of modifications at a national scale, e.g. due to industrial interests or to lack of measurements. The objective of this study is to quantify the changes in a set of hydrological indices due to large reservoirs in France combining different data sources. The analysis is based on a comparison between influenced discharges (observed discharges) and natural discharges available from: (i) gauging stations available upstream the dam, (ii) regionalization procedures (Sauquet et al., 2008; Sauquet et Catalogne, 2011; Cipriani et al., 2012), or (iii) historical data free from human influence close to the dam location. The impact of large reservoirs is assessed considering different facets of the river flow regime, including flood quantiles, low flow characteristics, quantiles from the flow duration curve and the twelve mean monthly discharges. The departures from the indice representative of natural conditions quantify the effect of the reservoir management on the river flow regime. The analysis is based on 62 study cases. Results show large spread in terms of impact depending on the purposes of the reservoirs and the season of interest. Results also point out inconsistencies in data (water balance between outflow and inflow, downstream of the dam is not warranted) due to uncertainties in mean monthly discharges and to the imperfect knowledge of inflows and outflows. Lastly, we suggest a typology of hydrological alterations based on the purposes of the reservoirs. Cipriani T., Toilliez T., Sauquet E. (2012). Estimating 10 year return period peak flows and flood durations at ungauged locations in France. La Houille Blanche, 4-5: 5-13, doi : 10.1051/lhb/2012024. Sauquet E., Catalogne C. (2011). Comparison of catchment grouping methods for

  1. Comparing observations and morphodynamic numerical modeling of upper-flow-regime bedforms in fjords and outcrop

    NASA Astrophysics Data System (ADS)

    Hubbard, Stephen; Kostic, Svetlana; Englert, Rebecca; Coutts, Daniel; Covault, Jacob

    2017-04-01

    Recent bathymetric observations of fjord prodeltas in British Columbia, Canada, reveal evidence for multi-phase channel erosion and deposition. These processes are interpreted to be related to the upstream migration of upper-flow-regime bedforms, namely cyclic steps. We integrate data from high-resolution bathymetric surveys and monitoring to inform morphodynamic numerical models of turbidity currents and associated bedforms in the Squamish prodelta. These models are applied to the interpretation of upper-flow-regime bedforms, including cyclic steps, antidunes, and/or transitional bedforms, in Late Cretaceous submarine conduit strata of the Nanaimo Group at Gabriola Island, British Columbia. In the Squamish prodelta, as bedforms migrate, >90% of the deposits are reworked, making morphology- and facies-based recognition challenging. Sedimentary bodies are 5-30 m long, 0.5-2 m thick and <30 m wide. The Nanaimo Group comprises scour fills of similar scale composed of structureless sandstone, with laminated siltstone locally overlying basal erosion surfaces. Backset stratification is locally observed; packages of 2-4 backset beds, each of which are up to 60 cm thick and up to 15 m long (along dip), commonly share composite basal erosion surfaces. Numerous scour fills are recognized over thin sections (<4 m), indicating limited aggradation and preservation of the bedforms. Preliminary morphodynamic numerical modeling indicates that Squamish and Nanaimo bedforms could be transitional upper-flow-regime bedforms between cyclic steps and antidunes. It is likely that cyclic steps and related upper-flow-regime bedforms are common in strata deposited on high gradient submarine slopes. Evidence for updip-migrating cyclic step and related deposits inform a revised interpretation of a high gradient setting dominated by supercritical flow, or alternating supercritical and subcritical flow in the Nanaimo Group. Integrating direct observations, morphodynamic numerical modeling, and

  2. Dune growth under multidirectional wind regimes

    NASA Astrophysics Data System (ADS)

    Gadal, C.; Rozier, O.; Claudin, P.; Courrech Du Pont, S.; Narteau, C.

    2017-12-01

    Under unidirectional wind regimes, flat sand beds become unstable to produce periodic linear dunes, commonly called transverse dunes because their main ridges are oriented perpendicular to the air flow. In areas of low sediment availability, the same interactions between flow, transport and topography produce barchan dunes, isolated sand-pile migrating over long distances with a characteristic crescentic shape. For the last fifteen years, barchan dunes and the instability at the origin of transverse dunes have been the subject of numerous studies that have identified a set of characteristic length and time scales with respect to the physical properties of both grains and fluid. This is not the case for dunes developing under multidirectional wind regimes. Under these conditions, dune orientation is measured with respect to the direction of the resultant sand flux. Depending on the wind regime, dunes do not always line up perpendicularly to the resultant sand flux, but can also be at an oblique angle or even parallel to it. These oblique and longitudinal dunes are ubiquitous in all deserts on Earth and planetary bodies because of the seasonal variability of wind orientation. They are however poorly constrained by observations and there is still no complete theoretical framework providing a description of their orientation and initial wavelength. Here, we extend the linear stability analysis of a flat sand of bed done in two dimensions for a unidirectional flow to three dimensions and multidirectional flow regimes. We are able to recover transitions from transverse to oblique or longitudinal dune patterns according to changes in wind regimes. We besides give a prediction for the initial dune wavelength. Our results compare well to previous theory of dune orientation and to field, experimental and numerical data.

  3. Propagation of atmospheric pressure helium plasma jet into ambient air at laminar gas flow

    NASA Astrophysics Data System (ADS)

    Pinchuk, M.; Stepanova, O.; Kurakina, N.; Spodobin, V.

    2017-05-01

    The formation of an atmospheric pressure plasma jet (APPJ) in a gas flow passing through the discharge gap depends on both gas-dynamic properties and electrophysical parameters of the plasma jet generator. The paper presents the results of experimental and numerical study of the propagation of the APPJ in a laminar flow of helium. A dielectric-barrier discharge (DBD) generated inside a quartz tube equipped with a coaxial electrode system, which provided gas passing through it, served as a plasma source. The transition of the laminar regime of gas flow into turbulent one was controlled by the photography of a formed plasma jet. The corresponding gas outlet velocity and Reynolds numbers were revealed experimentally and were used to simulate gas dynamics with OpenFOAM software. The data of the numerical simulation suggest that the length of plasma jet at the unvarying electrophysical parameters of DBD strongly depends on the mole fraction of ambient air in a helium flow, which is established along the direction of gas flow.

  4. Experimental response of Salix cuttings to different flow regimes due to human activities

    NASA Astrophysics Data System (ADS)

    Gorla, Lorenzo; Signarbieux, Constant; Turberg, Pascal; Buttler, Alexandre; Perona, Paolo

    2014-05-01

    Hydropower production and other human activities change the natural flow regime of rivers, in turn impacting the riparian environment. The main challenge in order to define eco-sustainable flows is to quantify the effects in terms of geomorphology and ecosystem adaptation. We present 2-years controlled experiments to investigate riparian vegetation (Salix Viminalis) response to forced water table changing dynamics, from one water regime to another, in a temperate region (Switzerland). Three synthetic flow regimes have been simulated and applied to three batteries of Salix cuttings growing outdoor within plastic pots, each about 1 meter tall. In 2012 one treatment simulated a minimal flow policy for small run-of-river hydropower plants, which drastically impacts the low and the medium-low components of the hydrograph, but not the extremes. In 2013 we confirmed and completed some of 2012 results, by reproducing typical hydropeaking effects due to dam management and focusing on daily water table variations and offsets. For both the seasons, after an initial period where all pots undergone the same oscillations in order to uniform the plants initial conditions, the experiment started, and the water dynamic was changed. Cuttings transitory response dynamics has been quantified by continuous sap flow and water potential measurements, and by regularly collecting growth parameters, as well as leaves photosynthesis, fluorescence, and pictures of each plant. At the end of the experiment, all cuttings were carefully removed and the both above and below ground biomass analyzed in detail. Particularly, the 3D root structure was obtained by High Resolution Computer Tomography. Our analyses revealed a clear dependence between roots distribution and water regime reflecting the need for adaptation, in agreement with field observations of Pasquale et al. (2012). In particular, an initial strong difference in terms of stress and growth performances was then followed by a later

  5. An ecological economic assessment of flow regimes in a hydropower dominated river basin: the case of the lower Zambezi River, Mozambique.

    PubMed

    Fanaian, Safa; Graas, Susan; Jiang, Yong; van der Zaag, Pieter

    2015-02-01

    The flow regime of rivers, being an integral part of aquatic ecosystems, provides many important services benefiting humans in catchments. Past water resource developments characterized by river embankments and dams, however, were often dominated by one (or few) economic use(s) of water. This results in a dramatically changed flow regime negatively affecting the provision of other ecosystem services sustained by the river flow. This study is intended to demonstrate the value of alternative flow regimes in a river that is highly modified by the presence of large hydropower dams and reservoirs, explicitly accounting for a broad range of flow-dependent ecosystem services. In this study, we propose a holistic approach for conducting an ecological economic assessment of a river's flow regime. This integrates recent advances in the conceptualization and classification of ecosystem services (UK NEA, 2011) with the flow regime evaluation technique developed by Korsgaard (2006). This integrated approach allows for a systematic comparison of the economic values of alternative flow regimes, including those that are considered beneficial for aquatic ecosystems. As an illustration, we applied this combined approach to the Lower Zambezi Basin, Mozambique. Empirical analysis shows that even though re-operating dams to create environmentally friendly flow regimes reduces hydropower benefits, the gains to goods derived from the aquatic ecosystem may offset the forgone hydropower benefits, thereby increasing the total economic value of river flow to society. The proposed integrated flow assessment approach can be a useful tool for welfare-improving decision-making in managing river basins. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Combustor air flow control method for fuel cell apparatus

    DOEpatents

    Clingerman, Bruce J.; Mowery, Kenneth D.; Ripley, Eugene V.

    2001-01-01

    A method for controlling the heat output of a combustor in a fuel cell apparatus to a fuel processor where the combustor has dual air inlet streams including atmospheric air and fuel cell cathode effluent containing oxygen depleted air. In all operating modes, an enthalpy balance is provided by regulating the quantity of the air flow stream to the combustor to support fuel cell processor heat requirements. A control provides a quick fast forward change in an air valve orifice cross section in response to a calculated predetermined air flow, the molar constituents of the air stream to the combustor, the pressure drop across the air valve, and a look up table of the orifice cross sectional area and valve steps. A feedback loop fine tunes any error between the measured air flow to the combustor and the predetermined air flow.

  7. Characteristics of coal mine ventilation air flows.

    PubMed

    Su, Shi; Chen, Hongwei; Teakle, Philip; Xue, Sheng

    2008-01-01

    Coal mine methane (CMM) is not only a greenhouse gas but also a wasted energy resource if not utilised. Underground coal mining is by far the most important source of fugitive methane emissions, and approximately 70% of all coal mining related methane is emitted to the atmosphere through mine ventilation air. Therefore, research and development on mine methane mitigation and utilisation now focuses on methane emitted from underground coal mines, in particular ventilation air methane (VAM) capture and utilisation. To date, most work has focused on the oxidation of very low concentration methane. These processes may be classified based on their combustion kinetic mechanisms into thermal oxidation and catalytic oxidation. VAM mitigation/utilisation technologies are generally divided into two basic categories: ancillary uses and principal uses. However, it is possible that the characteristics of ventilation air flows, for example the variations in methane concentration and the presence of certain compounds, which have not been reported so far, could make some potential VAM mitigation and utilisation technologies unfeasible if they cannot cope with the characteristics of mine site ventilation air flows. Therefore, it is important to understand the characteristics of mine ventilation air flows. Moreover, dust, hydrogen sulphide, sulphur dioxide, and other possible compounds emitted through mine ventilation air into the atmosphere are also pollutants. Therefore, this paper presents mine-site experimental results on the characteristics of mine ventilation air flows, including methane concentration and its variations, dust loadings, particle size, mineral matter of the dust, and other compounds in the ventilation air flows. The paper also discusses possible correlations between ventilation air characteristics and underground mining activities.

  8. Flow Regime Based Climatologies of Lightning Probabilities for Spaceports and Airports

    NASA Technical Reports Server (NTRS)

    Bauman, William H., III; Sharp, David; Spratt, Scott; Lafosse, Richard A.

    2008-01-01

    The objective of this work was to provide forecasters with a tool to indicate the warm season climatological probability of one or more lightning strikes within a circle at a site within a specified time interval. This paper described the AMU work conducted in developing flow regime based climatologies of lightning probabilities for the SLF and seven airports in the NWS MLB CWA in east-central Florida. The paper also described the GUI developed by the AMU that is used to display the data for the operational forecasters. There were challenges working with gridded lightning data as well as the code that accompanied the gridded data. The AMU modified the provided code to be able to produce the climatologies of lightning probabilities based on eight flow regimes for 5-, 10-, 20-, and 30-n mi circles centered on eight sites in 1-, 3-, and 6-hour increments.

  9. Surface-slip equations for multicomponent nonequilibrium air flow

    NASA Technical Reports Server (NTRS)

    Gupta, R. N.; Scott, C. D.; Moss, J. N.

    1985-01-01

    Equations are presented for the surface-slip (or jump) values of species concentration, pressure, velocity, and temperature in the low-Reynolds number, high-altitude flight regime of a space vehicle. The equations are obtained from closed form solutions of the mass, momentum, and energy flux equations using the Chapman-Enskog velocity distribution function. This function represents a solution of the Boltzmann equation in the Navier-Stokes approximation. The analysis, obtained for nonequilibrium multicomponent air flow, includes the finite-rate surface catalytic recombination and changes in the internal energy during reflection from the surface. Expressions for the various slip quantities were obtained in a form which can be employed in flowfield computations. A consistent set of equations is provided for multicomponent, binary, and single species mixtures. Expression is also provided for the finite-rate, species-concentration boundary condition for a multicomponent mixture in absence of slip.

  10. 30 CFR 57.22213 - Air flow (III mines).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Air flow (III mines). 57.22213 Section 57.22213... Methane in Metal and Nonmetal Mines Ventilation § 57.22213 Air flow (III mines). The quantity of air... longwall and continuous miner sections. The quantity of air across each face at a work place shall be at...

  11. 30 CFR 57.22213 - Air flow (III mines).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Air flow (III mines). 57.22213 Section 57.22213... Methane in Metal and Nonmetal Mines Ventilation § 57.22213 Air flow (III mines). The quantity of air... longwall and continuous miner sections. The quantity of air across each face at a work place shall be at...

  12. 40 CFR 1065.225 - Intake-air flow meter.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Intake-air flow meter. 1065.225 Section 1065.225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related Measurements § 1065.225 Intake-air...

  13. 40 CFR 1065.225 - Intake-air flow meter.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Intake-air flow meter. 1065.225 Section 1065.225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related Measurements § 1065.225 Intake-air...

  14. 40 CFR 1065.225 - Intake-air flow meter.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Intake-air flow meter. 1065.225 Section 1065.225 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments Flow-Related Measurements § 1065.225 Intake-air...

  15. Upper air teleconnections to Ob River flows and tree rings

    NASA Astrophysics Data System (ADS)

    Meko, David; Panyushkina, Irina; Agafonov, Leonid

    2015-04-01

    The Ob River, one of the world's greatest rivers, with a catchment basin about the size of Western Europe, contributes 12% or more of the annual freshwater inflow to the Arctic Ocean. The input of heat and fresh water is important to the global climate system through effects on sea ice, salinity, and the thermohaline circulation of the ocean. As part of a tree-ring project to obtain multi-century long information on variability of Ob River flows, a network of 18 sites of Pinus, Larix, Populus and Salix has been collected along the Ob in the summers of 2013 and 2014. Analysis of collections processed so far indicates a significant relationship of tree-growth to river discharge. Moderation of the floodplain air temperature regime by flooding appears to be an important driver of the tree-ring response. In unraveling the relationship of tree-growth to river flows, it is important to identify atmospheric circulation features directly linked to observed time series variations of flow and tree growth. In this study we examine statistical links between primary teleconnection modes of Northern Hemisphere upper-air (500 mb) circulation, Ob River flow, and tree-ring chronologies. Annual discharge at the mouth of the Ob River is found to be significantly positively related to the phase of the East Atlantic (EA) pattern, the second prominent mode of low-frequency variability over the North Atlantic. The EA pattern, consisting of a north-south dipole of pressure-anomaly centers spanning the North Atlantic from east to west, is associated with a low-pressure anomaly centered over the Ob River Basin, and with a pattern of positive precipitation anomaly of the same region. The positive correlation of discharge and EA is consistent with these know patterns, and is contrasted with generally negative (though smaller) correlations between EA and tree-ring chronologies. The signs of correlations are consistent with a conceptual model of river influence on tree growth through air

  16. The metabolic regimes of flowing waters

    USGS Publications Warehouse

    Bernhardt, Emily S.; Heffernan, Jim B.; Grimm, Nancy B.; Stanley, Emily H.; Harvey, Judson; Arroita, M.; Appling, Alison; Cohen, M.J.; McDowell, William H.; Hall, R.O.; Read, Jordan S.; Roberts, B.J.; Stets, Edward; Yackulic, Charles B.

    2018-01-01

    The processes and biomass that characterize any ecosystem are fundamentally constrained by the total amount of energy that is either fixed within or delivered across its boundaries. Ultimately, ecosystems may be understood and classified by their rates of total and net productivity and by the seasonal patterns of photosynthesis and respiration. Such understanding is well developed for terrestrial and lentic ecosystems but our understanding of ecosystem phenology has lagged well behind for rivers. The proliferation of reliable and inexpensive sensors for monitoring dissolved oxygen and carbon dioxide is underpinning a revolution in our understanding of the ecosystem energetics of rivers. Here, we synthesize our current understanding of the drivers and constraints on river metabolism, and set out a research agenda aimed at characterizing, classifying and modeling the current and future metabolic regimes of flowing waters.

  17. 40 CFR 90.416 - Intake air flow measurement specifications.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 20 2010-07-01 2010-07-01 false Intake air flow measurement... Gaseous Exhaust Test Procedures § 90.416 Intake air flow measurement specifications. (a) If used, the engine intake air flow measurement method used must have a range large enough to accurately measure the...

  18. Determination of gas & liquid two-phase flow regime transitions in wellbore annulus by virtual mass force coefficient when gas cut

    NASA Astrophysics Data System (ADS)

    Qu, Junbo; Yan, Tie; Sun, Xiaofeng; Chen, Ye; Pan, Yi

    2017-10-01

    With the development of drilling technology to deeper stratum, overflowing especially gas cut occurs frequently, and then flow regime in wellbore annulus is from the original drilling fluid single-phase flow into gas & liquid two-phase flow. By using averaged two-fluid model equations and the basic principle of fluid mechanics to establish the continuity equations and momentum conservation equations of gas phase & liquid phase respectively. Relationship between pressure and density of gas & liquid was introduced to obtain hyperbolic equation, and get the expression of the dimensionless eigenvalue of the equation by using the characteristic line method, and analyze wellbore flow regime to get the critical gas content under different virtual mass force coefficients. Results show that the range of equation eigenvalues is getting smaller and smaller with the increase of gas content. When gas content reaches the critical point, the dimensionless eigenvalue of equation has no real solution, and the wellbore flow regime changed from bubble flow to bomb flow. When virtual mass force coefficients are 0.50, 0.60, 0.70 and 0.80 respectively, the critical gas contents are 0.32, 0.34, 0.37 and 0.39 respectively. The higher the coefficient of virtual mass force, the higher gas content in wellbore corresponding to the critical point of transition flow regime, which is in good agreement with previous experimental results. Therefore, it is possible to determine whether there is a real solution of the dimensionless eigenvalue of equation by virtual mass force coefficient and wellbore gas content, from which we can obtain the critical condition of wellbore flow regime transformation. It can provide theoretical support for the accurate judgment of the annular flow regime.

  19. The Role of Forests in Regulating the River Flow Regime of Large Basins of the World

    NASA Astrophysics Data System (ADS)

    Salazar, J. F.; Villegas, J. C.; Mercado-Bettin, D. A.; Rodríguez, E.

    2016-12-01

    Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we explore potential linkages between the presence of forests and the capacity of river basins for regulating river flows. Regulation is defined here as the capacity of river basins to attenuate the amplitude of the river flow regime, that is to reduce the difference between high and low flows. We first use scaling theory to show how scaling properties of observed river flows can be used to classify river basins as regulated or unregulated. This parsimonious classification is based on a physical interpretation of the scaling properties (particularly the scaling exponents) that is novel (most previous studies have focused on the interpretation of the scaling exponents for floods only), and widely-applicable to different basins (the only assumption is that river flows in a given river basin exhibit scaling properties through well-known power laws). Then we show how this scaling framework can be used to explore global-change-induced temporal variations in the regulation capacity of river basins. Finally, we propose a conceptual hypothesis (the "Forest reservoir concept") to explain how large-scale forests can exert important effects on the long-term water balance partitioning and regulation capacity of large basins of the world. Our quantitative results are based on data analysis (river flows and land cover features) from 22 large basins of the world, with emphasis in the Amazon river and its main tributaries. Collectively, our findings support the hypothesis that forest cover enhances the capacity of large river basins to maintain relatively high mean river flows, as well as to regulate (ameliorate) extreme river flows. Advancing towards this quantitative understanding of the relation between forest cover and river flow regimes is

  20. The Role of Forests in Regulating the River Flow Regime of Large Basins of the World

    NASA Astrophysics Data System (ADS)

    Salazar, J. F.; Villegas, J. C.; Mercado-Bettin, D. A.; Rodríguez, E.

    2017-12-01

    Many natural and social phenomena depend on river flow regimes that are being altered by global change. Understanding the mechanisms behind such alterations is crucial for predicting river flow regimes in a changing environment. Here we explore potential linkages between the presence of forests and the capacity of river basins for regulating river flows. Regulation is defined here as the capacity of river basins to attenuate the amplitude of the river flow regime, that is to reduce the difference between high and low flows. We first use scaling theory to show how scaling properties of observed river flows can be used to classify river basins as regulated or unregulated. This parsimonious classification is based on a physical interpretation of the scaling properties (particularly the scaling exponents) that is novel (most previous studies have focused on the interpretation of the scaling exponents for floods only), and widely-applicable to different basins (the only assumption is that river flows in a given river basin exhibit scaling properties through well-known power laws). Then we show how this scaling framework can be used to explore global-change-induced temporal variations in the regulation capacity of river basins. Finally, we propose a conceptual hypothesis (the "Forest reservoir concept") to explain how large-scale forests can exert important effects on the long-term water balance partitioning and regulation capacity of large basins of the world. Our quantitative results are based on data analysis (river flows and land cover features) from 22 large basins of the world, with emphasis in the Amazon river and its main tributaries. Collectively, our findings support the hypothesis that forest cover enhances the capacity of large river basins to maintain relatively high mean river flows, as well as to regulate (ameliorate) extreme river flows. Advancing towards this quantitative understanding of the relation between forest cover and river flow regimes is

  1. Validating alternative methodologies to estimate the regime of temporary rivers when flow data are unavailable.

    PubMed

    Gallart, F; Llorens, P; Latron, J; Cid, N; Rieradevall, M; Prat, N

    2016-09-15

    Hydrological data for assessing the regime of temporary rivers are often non-existent or scarce. The scarcity of flow data makes impossible to characterize the hydrological regime of temporary streams and, in consequence, to select the correct periods and methods to determine their ecological status. This is why the TREHS software is being developed, in the framework of the LIFE Trivers project. It will help managers to implement adequately the European Water Framework Directive in this kind of water body. TREHS, using the methodology described in Gallart et al. (2012), defines six transient 'aquatic states', based on hydrological conditions representing different mesohabitats, for a given reach at a particular moment. Because of its qualitative nature, this approach allows using alternative methodologies to assess the regime of temporary rivers when there are no observed flow data. These methods, based on interviews and high-resolution aerial photographs, were tested for estimating the aquatic regime of temporary rivers. All the gauging stations (13) belonging to the Catalan Internal Catchments (NE Spain) with recurrent zero-flow periods were selected to validate this methodology. On the one hand, non-structured interviews were conducted with inhabitants of villages near the gauging stations. On the other hand, the historical series of available orthophotographs were examined. Flow records measured at the gauging stations were used to validate the alternative methods. Flow permanence in the reaches was estimated reasonably by the interviews and adequately by aerial photographs, when compared with the values estimated using daily flows. The degree of seasonality was assessed only roughly by the interviews. The recurrence of disconnected pools was not detected by flow records but was estimated with some divergences by the two methods. The combination of the two alternative methods allows substituting or complementing flow records, to be updated in the future through

  2. [Application of laminar air flow techniques in burn treatment].

    PubMed

    Chen, Hua-de; Lai, Wen; Zheng, Shao-yi; Gao, Hui; Xiong, Bing; Bian, Hui-ning; Liu, Zuo-An; Wei, Li-jun

    2005-12-01

    To evaluate the value of laminar flow in the treatment of burns. The air in the laminar flow chamber and the wound tissues of the patients were sampled for bacterial detection. The number and stains of bacterial colony from different classes of laminar air flow chambers at different time points were inspected and compared. The bacterial number was 0 in the laminar flow chamber of 1000 grade, which was obviously different from that in the public area. The mortality was obviously decreased in the laminar air flow chamber with shorter treatment time and hospitalization. No wound infection occurred and the wounds healed smoothly in all these patients. The application of laminar air flow can be helpful for the treatment of severe burns.

  3. Flow regimes in a shallow rotating cylindrical annulus with temperature gradients imposed on the horizontal boundaries

    NASA Technical Reports Server (NTRS)

    Hathaway, D. H.; Fowlis, W. W.

    1986-01-01

    Experimental flow regime diagrams are determined for a new rotating cylindrical annulus configuration which permits a measure of control over the internal vertical temperature gradient. The new annulus has radial temperature gradients imposed on plane horizontal thermally conducting endwalls (with the cylindrical sidewalls as insulators) and is considered to be more relevant to atmospheric dynamics studies than the classical cylindrical annulus. Observations have revealed that, in addition to the axisymmetric flow and nonaxisymmetric baroclinic wave flow which occur in the classical annulus, two additional nonaxisymmetric flow types occur in the new annulus: boundary-layer thermal convection and deep thermal convection. Flow regime diagrams for three different values of the imposed vertical temperature difference are presented, and explanations for the flow transitions are offered. The new annulus provides scientific backup for the proposed Atmospheric General Circulation Experiment for Spacelab. The apparatus diagram is included.

  4. Flow adjustment inside large finite-size wind farms approaching the infinite wind farm regime

    NASA Astrophysics Data System (ADS)

    Wu, Ka Ling; Porté-Agel, Fernando

    2017-04-01

    Due to the increasing number and the growing size of wind farms, the distance among them continues to decrease. Thus, it is necessary to understand how these large finite-size wind farms and their wakes could interfere the atmospheric boundary layer (ABL) dynamics and adjacent wind farms. Fully-developed flow inside wind farms has been extensively studied through numerical simulations of infinite wind farms. The transportation of momentum and energy is only vertical and the advection of them is neglected in these infinite wind farms. However, less attention has been paid to examine the length of wind farms required to reach such asymptotic regime and the ABL dynamics in the leading and trailing edges of the large finite-size wind farms. Large eddy simulations are performed in this study to investigate the flow adjustment inside large finite-size wind farms in conventionally-neutral boundary layer with the effect of Coriolis force and free-atmosphere stratification from 1 to 5 K/km. For the large finite-size wind farms considered in the present work, when the potential temperature lapse rate is 5 K/km, the wind farms exceed the height of the ABL by two orders of magnitude for the incoming flow inside the farms to approach the fully-developed regime. An entrance fetch of approximately 40 times of the ABL height is also required for such flow adjustment. At the fully-developed flow regime of the large finite-size wind farms, the flow characteristics match those of infinite wind farms even though they have different adjustment length scales. The role of advection at the entrance and exit regions of the large finite-size wind farms is also examined. The interaction between the internal boundary layer developed above the large finite-size wind farms and the ABL under different potential temperature lapse rates are compared. It is shown that the potential temperature lapse rate plays a role in whether the flow inside the large finite-size wind farms adjusts to the fully

  5. Flow regime alterations under changing climate in two river basins: Implications for freshwater ecosystems

    USGS Publications Warehouse

    Gibson, C.A.; Meyer, J.L.; Poff, N.L.; Hay, L.E.; Georgakakos, A.

    2005-01-01

    We examined impacts of future climate scenarios on flow regimes and how predicted changes might affect river ecosystems. We examined two case studies: Cle Elum River, Washington, and Chattahoochee-Apalachicola River Basin, Georgia and Florida. These rivers had available downscaled global circulation model (GCM) data and allowed us to analyse the effects of future climate scenarios on rivers with (1) different hydrographs, (2) high future water demands, and (3) a river-floodplain system. We compared observed flow regimes to those predicted under future climate scenarios to describe the extent and type of changes predicted to occur. Daily stream flow under future climate scenarios was created by either statistically downscaling GCMs (Cle Elum) or creating a regression model between climatological parameters predicted from GCMs and stream flow (Chattahoochee-Apalachicola). Flow regimes were examined for changes from current conditions with respect to ecologically relevant features including the magnitude and timing of minimum and maximum flows. The Cle Elum's hydrograph under future climate scenarios showed a dramatic shift in the timing of peak flows and lower low flow of a longer duration. These changes could mean higher summer water temperatures, lower summer dissolved oxygen, and reduced survival of larval fishes. The Chattahoochee-Apalachicola basin is heavily impacted by dams and water withdrawals for human consumption; therefore, we made comparisons between pre-large dam conditions, current conditions, current conditions with future demand, and future climate scenarios with future demand to separate climate change effects and other anthropogenic impacts. Dam construction, future climate, and future demand decreased the flow variability of the river. In addition, minimum flows were lower under future climate scenarios. These changes could decrease the connectivity of the channel and the floodplain, decrease habitat availability, and potentially lower the ability

  6. Effect of air flow on tubular solar still efficiency

    PubMed Central

    2013-01-01

    Background An experimental work was reported to estimate the increase in distillate yield for a compound parabolic concentrator-concentric tubular solar still (CPC-CTSS). The CPC dramatically increases the heating of the saline water. A novel idea was proposed to study the characteristic features of CPC for desalination to produce a large quantity of distillate yield. A rectangular basin of dimension 2 m × 0.025 m × 0.02 m was fabricated of copper and was placed at the focus of the CPC. This basin is covered by two cylindrical glass tubes of length 2 m with two different diameters of 0.02 m and 0.03 m. The experimental study was operated with two modes: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively. Findings The experimental study was operated with two modes: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. Conclusions On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively. PMID:23587020

  7. Effect of air flow on tubular solar still efficiency.

    PubMed

    Thirugnanasambantham, Arunkumar; Rajan, Jayaprakash; Ahsan, Amimul; Kandasamy, Vinothkumar

    2013-01-01

    An experimental work was reported to estimate the increase in distillate yield for a compound parabolic concentrator-concentric tubular solar still (CPC-CTSS). The CPC dramatically increases the heating of the saline water. A novel idea was proposed to study the characteristic features of CPC for desalination to produce a large quantity of distillate yield. A rectangular basin of dimension 2 m × 0.025 m × 0.02 m was fabricated of copper and was placed at the focus of the CPC. This basin is covered by two cylindrical glass tubes of length 2 m with two different diameters of 0.02 m and 0.03 m. The experimental study was operated with two modes: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively. THE EXPERIMENTAL STUDY WAS OPERATED WITH TWO MODES: without and with air flow between inner and outer tubes. The rate of air flow was fixed throughout the experiment at 4.5 m/s. On the basis of performance results, the water collection rate was 1445 ml/day without air flow and 2020 ml/day with air flow and the efficiencies were 16.2% and 18.9%, respectively.

  8. On the definition of dominant force regimes for flow boiling heat transfer by using single mini-tubes

    NASA Astrophysics Data System (ADS)

    Baba, Soumei; Sawada, Kenichiro; Kubota, Chisato; Kawanami, Osamu; Asano, Hitoshi; Inoue, Koichi; Ohta, Haruhiko

    Recent increase in the size of space platforms requires the management of larger amount of waste heat under high heat flux conditions and the transportation of it along a long distance to the radiator. Flow boiling applied to the thermal management system in space attracts much attention as promising means to realize high-performance heat transfer and transport because of large latent heat of vaporization. In microgravity two-phase flow phenomena are quite different from those under 1-g condition because buoyancy effects are significantly reduced and surface tension becomes dominant. By the similar reason, flow boiling characteristics in mini channels are not the same as those in channels of normal sizes. In the present stage, however, the boundary between the regimes of body force dominated and of surface tension dominated is not clear. The design of space thermal devices, operated under the conditions where no effect of gravity is expected, will improve the reliability of their ground tests, provided that the boundaries of dominant force regimes are clarified quantitatively in advance. In flow boiling in mini channels or in parallel channels, back flow could be occurred because of rapid growth of bubbles in a confined space, resulting flow rate fluctuation. Flow boiling heat transfer characteristics in mini channels can be changed considerably by the existence of inlet flow rate fluctuation. It is important to pay attention to experimental accuracy and to use a single circular mini-tube to compare heat transfer characteristics with those of normal size tubes. In the present paper, effects of tube orientations, i.e. vertical upward flow, vertical downward flow and horizontal flow, on flow boiling heat transfer characteristics is investigated for FC72 flowing in single mini-tubes with inner diameters of 0.13 and 0.51 mm to establish a reliable dominant force regime map. If the regime map is described by using dimensionless groups of Bond, Weber and Froude numbers

  9. 30 CFR 57.22213 - Air flow (III mines).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Air flow (III mines). 57.22213 Section 57.22213... Methane in Metal and Nonmetal Mines Ventilation § 57.22213 Air flow (III mines). The quantity of air coursed through the last open crosscut in pairs or sets of entries, or through other ventilation openings...

  10. Predicting ecological flow regime at ungaged sites: A comparison of methods

    USGS Publications Warehouse

    Murphy, Jennifer C.; Knight, Rodney R.; Wolfe, William J.; Gain, W. Scott

    2012-01-01

    Nineteen ecologically relevant streamflow characteristics were estimated using published rainfall–runoff and regional regression models for six sites with observed daily streamflow records in Kentucky. The regional regression model produced median estimates closer to the observed median for all but two characteristics. The variability of predictions from both models was generally less than the observed variability. The variability of the predictions from the rainfall–runoff model was greater than that from the regional regression model for all but three characteristics. Eight characteristics predicted by the rainfall–runoff model display positive or negative bias across all six sites; biases are not as pronounced for the regional regression model. Results suggest that a rainfall–runoff model calibrated on a single characteristic is less likely to perform well as a predictor of a range of other characteristics (flow regime) when compared with a regional regression model calibrated individually on multiple characteristics used to represent the flow regime. Poor model performance may misrepresent hydrologic conditions, potentially distorting the perceived risk of ecological degradation. Without prior selection of streamflow characteristics, targeted calibration, and error quantification, the widespread application of general hydrologic models to ecological flow studies is problematic. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

  11. Identifying hydrological regime and eco-flow threshold of small and medium flood of the Xiaoqing River in Jinan city

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Cao, Sheng-Le

    2017-06-01

    It was known that hydrological regime was the main influencing factor of river ecosystem, but the regime of different flow rates of urban rivers was poorly understood. We collected daily inflows at the Huangtai station of the Xiaoqing River from 1960 to 2014 and divided the data into three periods. Then we calculated hydrological parameters by the method of EFCs (Environmental Flow Components) and analyzed the tendency and change rates of each component respectively in the three periods. Combined with the ecological significance of environmental flow components, we identified the small and medium flood had the greatest impact on the river regime and ecosystem. And then we used the hydraulic parameters in the good ecosystem period as control conditions, to calculate the ecological threshold of the flow component under the current situation. This study could provide technical support for restoring and improving hydrological regime and ecological environment of the Xiaoqing River in Jinan city.

  12. En route air traffic flow simulation.

    DOT National Transportation Integrated Search

    1971-01-01

    The report covers the conception, design, development, and initial implementation of an advanced simulation technique applied to a study of national air traffic flow and its control by En Route Air Route Traffic Control Centers (ARTCC). It is intende...

  13. The Effect of Fluid Properties on Two-Phase Regimes of Flow in a Wide Rectangular Microchannel

    NASA Astrophysics Data System (ADS)

    Ronshin, F. V.; Cheverda, V. V.; Chinnov, E. A.; Kabov, O. A.

    2018-04-01

    We have experimentally studied a two-phase flow in a microchannel with a height of 150 μm and a width of 20 mm. Different liquids have been used, namely, a purified Milli-Q water, an 50% aqueous-ethanol solution, and FC-72. Before and after the experiment, the height of the microchannel was controlled, as well as the wettability of its walls and surface tension of liquids. Using the schlieren method, the main characteristics of two-phase flow in wide ranges of gas- and liquid-flow rates have been revealed. The flow regime-formation mechanism has been found to depend on the properties of the liquid used. The flow regime has been registered when the droplets moving along the microchannel are vertical liquid bridges. It has been shown that, when using FC-72 liquid, a film of liquid is formed on the upper channel wall in the whole range of gas- and liquid-flow rates.

  14. Two-phase flow regimes in a horizontal microchannel with the height of 50 μm and width of 10 mm

    NASA Astrophysics Data System (ADS)

    Fina, V. P.; Ronshin, F. V.

    2017-11-01

    Two-phase flows of distilled deionized nanofiltered water and nitrogen gas in a microchannel with a height of 50 μm and a width of 10 mm have been investigated experimentally. The schlieren method has been used to determine main features of the two-phase flow in the microchannel. This method allows detecting the liquid film on the lower and upper walls of the microchannel as well as droplets of various shapes and sizes or vertical liquid bridges. Two-phase flow regimes have been observed, and their boundaries precisely determined using post-processing of the recordings. The following flow regimes have been distinguished: bubble, churn, jet, stratified and annular. Comparison of regime maps for channels of different widths has been carried out, and this parameter showed to have a significant impact on the boundaries between the regimes in microchannels of a height of less than 100 μm.

  15. Transition regime analytical solution to gas mass flow rate in a rectangular micro channel

    NASA Astrophysics Data System (ADS)

    Dadzie, S. Kokou; Dongari, Nishanth

    2012-11-01

    We present an analytical model predicting the experimentally observed gas mass flow rate in rectangular micro channels over slip and transition regimes without the use of any fitting parameter. Previously, Sone reported a class of pure continuum regime flows that requires terms of Burnett order in constitutive equations of shear stress to be predicted appropriately. The corrective terms to the conventional Navier-Stokes equation were named the ghost effect. We demonstrate in this paper similarity between Sone ghost effect model and newly so-called 'volume diffusion hydrodynamic model'. A generic analytical solution to gas mass flow rate in a rectangular micro channel is then obtained. It is shown that the volume diffusion hydrodynamics allows to accurately predict the gas mass flow rate up to Knudsen number of 5. This can be achieved without necessitating the use of adjustable parameters in boundary conditions or parametric scaling laws for constitutive relations. The present model predicts the non-linear variation of pressure profile along the axial direction and also captures the change in curvature with increase in rarefaction.

  16. Visualization of various working fluids flow regimes in gravity heat pipe

    NASA Astrophysics Data System (ADS)

    Nemec, Patrik

    Heat pipe is device working with phase changes of working fluid inside hermetically closed pipe at specific pressure. The phase changes of working fluid from fluid to vapour and vice versa help heat pipe to transport high heat flux. Amount of heat flux transferred by heat pipe, of course depends on kind of working fluid. The article deal about visualization of various working fluids flow regimes in glass gravity heat pipe by high speed camera and processes casing inside during heat pipe operation. Experiment working fluid flow visualization is performed with two glass heat pipes with different inner diameter (13 mm and 22 mm) filled with water, ethanol and fluorinert FC 72. The working fluid flow visualization explains the phenomena as a working fluid boiling, nucleation of bubbles, and vapour condensation on the wall, vapour and condensate flow interaction, flow down condensate film thickness on the wall occurred during the heat pipe operation.

  17. Situational Lightning Climatologies for Central Florida: Phase IV: Central Florida Flow Regime Based Climatologies of Lightning Probabilities

    NASA Technical Reports Server (NTRS)

    Bauman, William H., III

    2009-01-01

    The threat of lightning is a daily concern during the warm season in Florida. Research has revealed distinct spatial and temporal distributions of lightning occurrence that are strongly influenced by large-scale atmospheric flow regimes. Previously, the Applied Meteorology Unit (AMU) calculated the gridded lightning climatologies based on seven flow regimes over Florida for 1-, 3- and 6-hr intervals in 5-, 10-, 20-, and 30-NM diameter range rings around the Shuttle Landing Facility (SLF) and eight other airfields in the National Weather Service in Melbourne (NWS MLB) county warning area (CWA). In this update to the work, the AMU recalculated the lightning climatologies for using individual lightning strike data to improve the accuracy of the climatologies. The AMU included all data regardless of flow regime as one of the stratifications, added monthly stratifications, added three years of data to the period of record and used modified flow regimes based work from the AMU's Objective Lightning Probability Forecast Tool, Phase II. The AMU made changes so the 5- and 10-NM radius range rings are consistent with the aviation forecast requirements at NWS MLB, while the 20- and 30-NM radius range rings at the SLF assist the Spaceflight Meteorology Group in making forecasts for weather Flight Rule violations during Shuttle landings. The AMU also updated the graphical user interface with the new data.

  18. Wind-Driven Ecological Flow Regimes Downstream from Hydropower Dams

    NASA Astrophysics Data System (ADS)

    Kern, J.; Characklis, G. W.

    2012-12-01

    challenge, the following study was designed to investigate the potential for wind power integration to alter riparian flow regimes below hydroelectric dams. A hydrological model of a three-dam cascade in the Roanoke River basin (Virginia, USA) is interfaced with a simulated electricity market (i.e. a unit commitment problem) representing the Dominion Zone of PJM Interconnection. Incorporating forecasts of electricity demand, hydro capacity and wind availability, a mixed-integer optimization program minimizes the system cost of meeting hourly demand and reserve requirements by means of a diverse generation portfolio (e.g. nuclear, fossil, hydro, and biomass). A secondary 'balancing' energy market is executed if real-time wind generation is less than the day-ahead forecast, calling upon reserved generation resources to meet the supply shortfall. Hydropower release schedules are determined across a range of wind development scenarios (varying wind's fraction of total installed generating capacity, as well as its geographical source region). Flow regimes for each wind development scenario are compared against both historical and simulated flows under current operations (negligible wind power), as well as simulated natural flows (dam removal), in terms of ecologically relevant flow metrics. Results quantify the ability of wind power development to alter within-week stream flows downstream from hydropower dams.

  19. Estimating the Natural Flow Regime of Rivers With Long-Standing Development: The Northern Branch of the Rio Grande

    NASA Astrophysics Data System (ADS)

    Blythe, Todd L.; Schmidt, John C.

    2018-02-01

    An estimate of a river's natural flow regime is useful for water resource planning and ecosystem rehabilitation by providing insight into the predisturbance form and function of a river. The natural flow regime of most rivers has been perturbed by development during the 20th century and in some cases, before stream gaging began. The temporal resolution of natural flows estimated using traditional methods is typically not sufficient to evaluate cues that drive native ecosystem function. Additionally, these traditional methods are watershed specific and require large amounts of data to produce accurate results. We present a mass balance method that estimates natural flows at daily time step resolution for the northern branch of the Rio Grande, upstream from the Rio Conchos, that relies only on easily obtained streamflow data. Using an analytical change point method, we identified periods of the measured flow regime during the 20th century for comparison with the estimated natural flows. Our results highlight the significant deviation from natural conditions that occurred during the 20th century. The total annual flow of the northern branch is 95% lower than it would be in the absence of human use. The current 2 year flood has decreased by more than 60%, is shorter in duration, and peaks later in the year. When compared to unregulated flows estimated using traditional mass balance accounting methods, our approach provides similar results.

  20. 30 CFR 57.22211 - Air flow (I-A mines).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Air flow (I-A mines). 57.22211 Section 57.22211... Methane in Metal and Nonmetal Mines Ventilation § 57.22211 Air flow (I-A mines). The average air velocity in the last open crosscut in pairs or sets of developing entries, or through other ventilation...

  1. Modeling Food Delivery Dynamics For Juvenile Salmonids Under Variable Flow Regimes

    NASA Astrophysics Data System (ADS)

    Harrison, L.; Utz, R.; Anderson, K.; Nisbet, R.

    2010-12-01

    Traditional approaches for assessing instream flow needs for salmonids have typically focused on the importance of physical habitat in determining fish habitat selection. This somewhat simplistic approach does not account for differences in food delivery rates to salmonids that arise due to spatial variability in river morphology, hydraulics and temporal variations in the flow regime. Explicitly linking how changes in the flow regime influences food delivery dynamics is an important step in advancing process-based bioenergetic models that seek to predict growth rates of salmonids across various life-stages. Here we investigate how food delivery rates for juvenile salmonids vary both spatially and with flow magnitude in a meandering reach of the Merced River, CA. We utilize a two-dimensional (2D) hydrodynamic model and discrete particle tracking algorithm to simulate invertebrate drift transport rates at baseflow and a near-bankfull discharge. Modeling results indicate that at baseflow, the maximum drift density occurs in the channel thalweg, while drift densities decrease towards the channel margins due to the process of organisms settling out of the drift. During high-flow events, typical of spring dam-releases, the invertebrate drift transport pathway follows a similar trajectory along the high velocity core and the drift concentrations are greatest in the channel centerline, though the zone of invertebrate transport occupies a greater fraction of the channel width. Based on invertebrate supply rates alone, feeding juvenile salmonids would be expected to be distributed down the channel centerline where the maximum predicted food delivery rates are located in this reach. However, flow velocities in these channel sections are beyond maximum sustainable swimming speeds for most juvenile salmonids. Our preliminary findings suggest that a lack of low velocity refuge may prevent juvenile salmonids from deriving energy from the areas with maximum drift density in this

  2. A Modeling Approach for Evaluating the Coupled Riparian Vegetation-Geomorphic Response to Altered Flow Regimes

    NASA Astrophysics Data System (ADS)

    Manners, R.; Wilcox, A. C.; Merritt, D. M.

    2016-12-01

    The ecogeomorphic response of riparian ecosystems to a change in hydrologic properties is difficult to predict because of the interactions and feedbacks among plants, water, and sediment. Most riparian models of community dynamics assume a static channel, yet geomorphic processes strongly control the establishment and survival of riparian vegetation. Using a combination of approaches that includes empirical relationships and hydrodynamic models, we model the coupled vegetation-topographic response of three cross-sections on the Yampa and Green Rivers in Dinosaur National Monument, to a shift in the flow regime. The locations represent the variable geomorphology and vegetation composition of these canyon-bound rivers. We account for the inundation and hydraulic properties of vegetation plots surveyed over three years within International River Interface Cooperative (iRIC) Fastmech, equipped with a vegetation module that accounts for flexible stems and plant reconfiguration. The presence of functional groupings of plants, or those plants that respond similarly to environmental factors such as water availability and disturbance are determined from flow response curves developed for the Yampa River. Using field measurements of vegetation morphology, distance from the channel centerline, and dominant particle size and modeled inundation properties we develop an empirical relationship between these variables and topographic change. We evaluate vegetation and channel form changes over decadal timescales, allowing for the integration of processes over time. From our analyses, we identify thresholds in the flow regime that alter the distribution of plants and reduce geomorphic complexity, predominately through side-channel and backwater infilling. Simplification of some processes (e.g., empirically-derived sedimentation) and detailed treatment of others (e.g., plant-flow interactions) allows us to model the coupled dynamics of riparian ecosystems and evaluate the impact of

  3. Real-Time Aerodynamic Parameter Estimation without Air Flow Angle Measurements

    NASA Technical Reports Server (NTRS)

    Morelli, Eugene A.

    2010-01-01

    A technique for estimating aerodynamic parameters in real time from flight data without air flow angle measurements is described and demonstrated. The method is applied to simulated F-16 data, and to flight data from a subscale jet transport aircraft. Modeling results obtained with the new approach using flight data without air flow angle measurements were compared to modeling results computed conventionally using flight data that included air flow angle measurements. Comparisons demonstrated that the new technique can provide accurate aerodynamic modeling results without air flow angle measurements, which are often difficult and expensive to obtain. Implications for efficient flight testing and flight safety are discussed.

  4. Modeling the transition between upper plane bed regime and sheet flow without an active layer formulation. Preliminary results.

    NASA Astrophysics Data System (ADS)

    Viparelli, E.; Hernandez Moreira, R. R.; Blom, A.

    2015-12-01

    A perusal of the literature on bedload transport revealed that, notwithstanding the large number of studies on bedform morphology performed in the past decades, the upper plane bed regime has not been thoroughly investigated and the distinction between the upper plane bed and sheet flow transport regimes is still poorly defined. Previous experimental work demonstrated that the upper plane bed regime is characterized by long wavelength and small amplitude bedforms that migrate downstream. These bedforms, however, were not observed in experiments on sheet flow transport suggesting that the upper plane bed and the sheet flow are two different regimes. We thus designed and performed experiments in a sediment feed flume in the hydraulic laboratory of the Department of Civil and Environmental Engineering at the University of South Carolina at Columbia to study the transition from upper plane bed to sheet flow regime. Periodic measurements of water surface and bed elevation, bedform geometry and thicknesses of the bedload layer were performed by eyes, and with cameras, movies and a system of six ultrasonic probes that record the variations of bed elevation at a point over time. We used the time series of bed elevations to determine the probability functions of bed elevation. These probability functions are implemented in a continuous model of river morphodynamics, i.e. a model that does not use the active layer approximation to describe the sediment fluxes between the bedload and the deposit and that should thus be able to capture the details of the vertical and streamwise variation of the deposit grain size distribution. This model is validated against the experimental results for the case of uniform material. We then use the validated model in the attempt to study if and how the spatial distribution of grain sizes in the deposit changes from upper plane bed regime to sheet flow and if these results are influenced by the imposed rates of base level rise.

  5. Dynamic regimes of buoyancy-affected two-phase flow in unconsolidated porous media.

    PubMed

    Stöhr, M; Khalili, A

    2006-03-01

    The invasion and subsequent flow of a nonwetting fluid (NWF) in a three-dimensional, unconsolidated porous medium saturated with a wetting fluid of higher density and viscosity have been studied experimentally using a light-transmission technique. Distinct dynamic regimes have been found for different relative magnitudes of viscous, capillary, and gravity forces. It is shown that the ratio of viscous and hydrostatic pressure gradients can be used as a relevant dimensionless number K for the characterization of the different flow regimes. For low values of K, the invasion is characterized by the migration and fragmentation of isolated clusters of the NWF resulting from the prevalence of gravity and capillary forces. At high values of K, the dominance of viscous and gravity forces leads to an anisotropic fingerlike invasion. When the invasion stops after the breakthrough of the NWF at the open upper boundary, the invasion structure retracts under the influence of gravity and transforms into stable vertical channels. It is shown that the stability of these channels is the result of a balance between hydrostatic and viscous pressure gradients.

  6. Spool Valve for Switching Air Flows Between Two Beds

    NASA Technical Reports Server (NTRS)

    Dean, W. Clark

    2005-01-01

    U.S. Patent 6,142,151 describes a dual-bed ventilation system for a space suit, with emphasis on a multiport spool valve that switches air flows between two chemical beds that adsorb carbon dioxide and water vapor. The valve is used to alternately make the air flow through one bed while exposing the other bed to the outer-space environment to regenerate that bed through vacuum desorption of CO2 and H2O. Oxygen flowing from a supply tank is routed through a pair of periodically switched solenoid valves to drive the spool valve in a reciprocating motion. The spool valve equalizes the pressures of air in the beds and the volumes of air flowing into and out of the beds during the alternations between the adsorption and desorption phases, in such a manner that the volume of air that must be vented to outer space is half of what it would be in the absence of pressure equalization. Oxygen that has been used to actuate the spool valve in its reciprocating motion is released into the ventilation loop to replenish air lost to vacuum during the previous desorption phase of the operating cycle.

  7. Thermal imaging for cold air flow visualisation and analysis

    NASA Astrophysics Data System (ADS)

    Grudzielanek, M.; Pflitsch, A.; Cermak, J.

    2012-04-01

    In this work we present first applications of a thermal imaging system for animated visualization and analysis of cold air flow in field studies. The development of mobile thermal imaging systems advanced very fast in the last decades. The surface temperature of objects, which is detected with long-wave infrared radiation, affords conclusions in different problems of research. Modern thermal imaging systems allow infrared picture-sequences and a following data analysis; the systems are not exclusive imaging methods like in the past. Thus, the monitoring and analysing of dynamic processes became possible. We measured the cold air flow on a sloping grassland area with standard methods (sonic anemometers and temperature loggers) plus a thermal imaging system measuring in the range from 7.5 to 14µm. To analyse the cold air with the thermal measurements, we collected the surface infrared temperatures at a projection screen, which was located in cold air flow direction, opposite the infrared (IR) camera. The intention of using a thermal imaging system for our work was: 1. to get a general idea of practicability in our problem, 2. to assess the value of the extensive and more detailed data sets and 3. to optimise visualisation. The results were very promising. Through the possibility of generating time-lapse movies of the image sequences in time scaling, processes of cold air flow, like flow waves, turbulence and general flow speed, can be directly identified. Vertical temperature gradients and near-ground inversions can be visualised very well. Time-lapse movies will be presented. The extensive data collection permits a higher spatial resolution of the data than standard methods, so that cold air flow attributes can be explored in much more detail. Time series are extracted from the IR data series, analysed statistically, and compared to data obtained using traditional systems. Finally, we assess the usefulness of the additional measurement of cold air flow with thermal

  8. Hydrological classification of natural flow regimes to support environmental flow assessments in intensively regulated Mediterranean rivers, Segura River Basin (Spain).

    PubMed

    Belmar, Oscar; Velasco, Josefa; Martinez-Capel, Francisco

    2011-05-01

    Hydrological classification constitutes the first step of a new holistic framework for developing regional environmental flow criteria: the "Ecological Limits of Hydrologic Alteration (ELOHA)". The aim of this study was to develop a classification for 390 stream sections of the Segura River Basin based on 73 hydrological indices that characterize their natural flow regimes. The hydrological indices were calculated with 25 years of natural monthly flows (1980/81-2005/06) derived from a rainfall-runoff model developed by the Spanish Ministry of Environment and Public Works. These indices included, at a monthly or annual basis, measures of duration of droughts and central tendency and dispersion of flow magnitude (average, low and high flow conditions). Principal Component Analysis (PCA) indicated high redundancy among most hydrological indices, as well as two gradients: flow magnitude for mainstream rivers and temporal variability for tributary streams. A classification with eight flow-regime classes was chosen as the most easily interpretable in the Segura River Basin, which was supported by ANOSIM analyses. These classes can be simplified in 4 broader groups, with different seasonal discharge pattern: large rivers, perennial stable streams, perennial seasonal streams and intermittent and ephemeral streams. They showed a high degree of spatial cohesion, following a gradient associated with climatic aridity from NW to SE, and were well defined in terms of the fundamental variables in Mediterranean streams: magnitude and temporal variability of flows. Therefore, this classification is a fundamental tool to support water management and planning in the Segura River Basin. Future research will allow us to study the flow alteration-ecological response relationship for each river type, and set the basis to design scientifically credible environmental flows following the ELOHA framework.

  9. Validation of the Chemistry Module for the Euler Solver in Unified Flow Solver

    DTIC Science & Technology

    2012-03-01

    traveling through the atmosphere there are three types of flow regimes that exist; the first is the continuum regime, second is the rarified regime and...The second method has been used in a program called Unified Flow Solver (UFS). UFS is currently being developed under collaborative efforts the Air...thermal non-equilibrium case and finally to a thermo-chemical non- equilibrium case. The data from the simulations will be compared to a second code

  10. COMIS -- an international multizone air-flow and contaminant transport model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Feustel, H.E.

    1998-08-01

    A number of interzonal models have been developed to calculate air flows and pollutant transport mechanisms in both single and multizone buildings. A recent development in multizone air-flow modeling, the COMIS model, has a number of capabilities that go beyond previous models, much as COMIS can be used as either a stand-alone air-flow model with input and output features or as an infiltration module for thermal building simulation programs. COMIS was designed during a 12 month workshop at Lawrence Berkeley National Laboratory (LBNL) in 1988-89. In 1990, the Executive Committee of the International Energy Agency`s Energy Conservation in Buildings andmore » Community Systems program created a working group on multizone air-flow modeling, which continued work on COMIS. The group`s objectives were to study physical phenomena causing air flow and pollutant (e.g., moisture) transport in multizone buildings, develop numerical modules to be integrated in the previously designed multizone air flow modeling system, and evaluate the computer code. The working group supported by nine nations, officially finished in late 1997 with the release of IISiBat/COMIS 3.0, which contains the documented simulation program COMIS, the user interface IISiBat, and reports describing the evaluation exercise.« less

  11. Analysis of the Hydrodynamics and Heat Transfer Aspects of Microgravity Two-Phase Flows

    NASA Technical Reports Server (NTRS)

    Rezkallah, Kamiel S.

    1996-01-01

    Experimental results for void fractions, flow regimes, and heat transfer rates in two-phase, liquid-gas flows are summarized in this paper. The data was collected on-board NASA's KC-135 reduced gravity aircraft in a 9.525 mm circular tube (i.d.), uniformly heated at the outer surface. Water and air flows were examined as well as three glycerol/water solutions and air. Results are reported for the water-air data.

  12. Impacts of Land Use Change on the Natural Flow Regime: A Case Study in the Meramec River Watershed in Eastern Missouri, USA

    NASA Astrophysics Data System (ADS)

    Wu, C. L.; Knouft, J.; Chu, M.

    2017-12-01

    The natural flow regime within a watershed can be considered as the expected temporal patterns of streamflow variation in the absence of human impacts. While ecosystems have evolved to function under these conditions, the natural flow regime of most rivers has been significantly altered by human activities. Land use change, including the development of agriculture and urbanization, is a primary cause of the loss of natural flow regimes. These changes have altered discharge volume, timing, and variability, and consequently affected the structure and functioning of river ecosystems. The Meramec River watershed is located in east central Missouri and changes in land use have been the primary factor impacting flow regimes across the watershed. In this study, a watershed model, the Soil and Water Assessment Tool (SWAT), was developed to simulate a long-term time series of streamflow (1978-2014) within the watershed. Model performance was evaluated using statistical metrics and graphical technique including R-squared, Nash-Sutcliffe efficiency, cumulative error, and 1:1-ratio comparison between observed and simulated variables. The calibrated and validated SWAT model was then used to quantify the responses of the watershed when it was a forested natural landscape. An Indicator of Hydrologic Alteration (IHA) approach was applied to characterize the flow regime under the current landcover conditions as well as the simulated natural flow regime under the no land use change scenario. Differences in intra- and inter-annual ecologically relevant flow metrics were then compared using SWAT model outputs in conjunction with the IHA approach based on model outputs from current and no land use change conditions. This study provides a watershed-scale understanding of effects of land use change on a river's flow variability and provides a framework for the development of restoration plans for heavily altered watersheds.

  13. Compressed-air flow control system.

    PubMed

    Bong, Ki Wan; Chapin, Stephen C; Pregibon, Daniel C; Baah, David; Floyd-Smith, Tamara M; Doyle, Patrick S

    2011-02-21

    We present the construction and operation of a compressed-air driven flow system that can be used for a variety of microfluidic applications that require rapid dynamic response and precise control of multiple inlet streams. With the use of inexpensive and readily available parts, we describe how to assemble this versatile control system and further explore its utility in continuous- and pulsed-flow microfluidic procedures for the synthesis and analysis of microparticles.

  14. Terminal Air Flow Planning

    NASA Technical Reports Server (NTRS)

    Denery, Dallas G.; Erzberger, Heinz; Edwards, Thomas A. (Technical Monitor)

    1998-01-01

    The Center TRACON Automation System (CTAS) will be the basis for air traffic planning and control in the terminal area. The system accepts arriving traffic within an extended terminal area and optimizes the flow based on current traffic and airport conditions. The operational use of CTAS will be presented together with results from current operations.

  15. Observational changes to the natural flow regime in Lee Creek in relation to altered precipitation patterns and its implication for fishes

    USGS Publications Warehouse

    Gatlin, Michael R.; Long, James M.; Turton, Donald J.

    2015-01-01

    The natural flow regime is important for structuring streams and their resident ichthyofauna and alterations to this regime can have cascading consequences. We sought to determine if changes in hydrology could be attributed to changes in precipitation in a minimally altered watershed (Lee Creek). The stream flow regime was analyzed using Indicators of Hydrologic Alteration (IHA) software, and data from a nearby climate station were used to summarize concurrent precipitation patterns. We discovered that Lee Creek hydrology had become flashier (i.e., increased frequency of extreme events of shorter duration) since 1992 coincident with changes in precipitation patterns. Specifically, our results show fewer but more intense rain events within the Lee Creek watershed. Our research provides evidence that climate-induced changes to the natural flow regime are currently underway and additional research on its effects on the fish community is warranted.

  16. Shock shapes on blunt bodies in hypersonic-hypervelocity helium, air, and CO2 flows, and calibration results in Langley 6-inch expansion tube

    NASA Technical Reports Server (NTRS)

    Miller, C. G., III

    1975-01-01

    Shock shape results for flat-faced cylinders, spheres, and spherically blunted cones in various test gases, along with preliminary results from a calibration study performed in the Langley 6-inch expansion tube are presented. Free-stream velocities from 5 to 7 km/sec are generated at hypersonic conditions with helium, air, and CO2, resulting in normal shock density ratios from 4 to 19. Ideal-gas shock shape predictions, in which an effective ratio of specific heats is used as input, are compared with the measured results. The effect of model diameter is examined to provide insight to the thermochemical state of the flow in the shock layer. The regime for which equilibrium exists in the shock layer for the present air and CO2 test conditions is defined. Test core flow quality, test repeatability, and comparison of measured and predicted expansion-tube flow quantities are discussed.

  17. Validating alternative methodologies to estimate the hydrological regime of temporary streams when flow data are unavailable

    NASA Astrophysics Data System (ADS)

    Llorens, Pilar; Gallart, Francesc; Latron, Jérôme; Cid, Núria; Rieradevall, Maria; Prat, Narcís

    2016-04-01

    Aquatic life in temporary streams is strongly conditioned by the temporal variability of the hydrological conditions that control the occurrence and connectivity of diverse mesohabitats. In this context, the software TREHS (Temporary Rivers' Ecological and Hydrological Status) has been developed, in the framework of the LIFE Trivers project, to help managers for adequately implement the Water Framework Directive in this type of water bodies. TREHS, using the methodology described in Gallart et al (2012), defines six temporal 'aquatic states', based on the hydrological conditions representing different mesohabitats, for a given reach at a particular moment. Nevertheless, hydrological data for assessing the regime of temporary streams are often non-existent or scarce. The scarcity of flow data makes frequently impossible the characterization of temporary streams hydrological regimes and, as a consequence, the selection of the correct periods and methods to determine their ecological status. Because of its qualitative nature, the TREHS approach allows the use of alternative methodologies to assess the regime of temporary streams in the lack of observed flow data. However, to adapt the TREHS to this qualitative data both the temporal scheme (from monthly to seasonal) as well as the number of aquatic states (from 6 to 3) have been modified. Two alternatives complementary methodologies were tested within the TREHS framework to assess the regime of temporary streams: interviews and aerial photographs. All the gauging stations (13) belonging to the Catalan Internal Catchments (NE, Spain) with recurrent zero flows periods were selected to validate both methodologies. On one hand, non-structured interviews were carried out to inhabitants of villages and small towns near the gauging stations. Flow permanence metrics for input into TREHS were drawn from the notes taken during the interviews. On the other hand, the historical series of available aerial photographs (typically 10

  18. Evolutionary Concepts for Decentralized Air Traffic Flow Management

    NASA Technical Reports Server (NTRS)

    Adams, Milton; Kolitz, Stephan; Milner, Joseph; Odoni, Amedeo

    1997-01-01

    Alternative concepts for modifying the policies and procedures under which the air traffic flow management system operates are described, and an approach to the evaluation of those concepts is discussed. Here, air traffic flow management includes all activities related to the management of the flow of aircraft and related system resources from 'block to block.' The alternative concepts represent stages in the evolution from the current system, in which air traffic management decision making is largely centralized within the FAA, to a more decentralized approach wherein the airlines and other airspace users collaborate in air traffic management decision making with the FAA. The emphasis in the discussion is on a viable medium-term partially decentralized scenario representing a phase of this evolution that is consistent with the decision-making approaches embodied in proposed Free Flight concepts for air traffic management. System-level metrics for analyzing and evaluating the various alternatives are defined, and a simulation testbed developed to generate values for those metrics is described. The fundamental issue of modeling airline behavior in decentralized environments is also raised, and an example of such a model, which deals with the preservation of flight bank integrity in hub airports, is presented.

  19. Interrelationships of petiolar air canal architecture, water depth, and convective air flow in Nymphaea odorata (Nymphaeaceae).

    PubMed

    Richards, Jennifer H; Kuhn, David N; Bishop, Kristin

    2012-12-01

    Nymphaea odorata grows in water up to 2 m deep, producing fewer larger leaves in deeper water. This species has a convective flow system that moves gases from younger leaves through submerged parts to older leaves, aerating submerged parts. Petiolar air canals are the convective flow pathways. This study describes the structure of these canals, how this structure varies with water depth, and models how convective flow varies with depth. • Nymphaea odorata plants were grown at water depths from 30 to 90 cm. Lamina area, petiolar cross-sectional area, and number and area of air canals were measured. Field-collected leaves and leaves from juvenile plants were analyzed similarly. Using these data and data from the literature, we modeled how convective flow changes with water depth. • Petioles of N. odorata produce two central pairs of air canals; additional pairs are added peripherally, and succeeding pairs are smaller. The first three pairs account for 96% of air canal area. Air canals form 24% of petiolar cross-sectional area. Petiolar and air canal cross-sectional areas increase with water depth. Petiolar area scales with lamina area, but the slope of this relationship is lower in 90 cm water than at shallower depths. In our model, the rate of convective flow varied with depth and with the balance of influx to efflux leaves. • Air canals in N. odorata petioles increase in size and number in deeper water but at a decreasing amount in relation to lamina area. Convective flow also depends on the number of influx to efflux laminae.

  20. Natural laminar flow hits smoother air

    NASA Technical Reports Server (NTRS)

    Holmes, B. J.

    1985-01-01

    Natural laminar flow (NLF) may be attained in aircraft with lower cost, weight, and maintenance penalties than active flow laminarization by means of a slot suction system. A high performance general aviation jet aircraft possessing a moderate degree of NLF over wing, fuselage, empennage and engine nacelles will accrue a 24 percent reduction in total aircraft drag in the cruise regime. NASA-Langley has conducted NLF research centered on the use of novel airfoil profiles as well as composite and milled aluminum alloy construction methods which minimize three-dimensional aerodynamic surface roughness and waviness. It is noted that higher flight altitudes intrinsically reduce unit Reynolds numbers, thereby minimizing turbulence for a given cruise speed.

  1. Continuous spin detonation of poorly detonable fuel-air mixtures in annular combustors

    NASA Astrophysics Data System (ADS)

    Bykovskii, F. A.; Zhdan, S. A.

    2017-09-01

    This paper reports on the results of experimental investigations of continuous spin detonation of three fuel-air mixtures (syngas-air, CH4/H2-air, and kerosene/H2-air in a flow-type annular cylindrical combustor 503 mm in diameter. The limits of existence of continuous detonation in terms of the specific flow rates of the mixtures (minimum values) are determined. It is found that all gas mixtures, including the least detonable methane-air mixture, with addition of hydrogen can be burned in the continuous spin detonation regime.

  2. Two-phase damping and interface surface area in tubes with vertical internal flow

    NASA Astrophysics Data System (ADS)

    Béguin, C.; Anscutter, F.; Ross, A.; Pettigrew, M. J.; Mureithi, N. W.

    2009-01-01

    Two-phase flow is common in the nuclear industry. It is a potential source of vibration in piping systems. In this paper, two-phase damping in the bubbly flow regime is related to the interface surface area and, therefore, to flow configuration. Experiments were performed with a vertical tube clamped at both ends. First, gas bubbles of controlled geometry were simulated with glass spheres let to settle in stagnant water. Second, air was injected in stagnant alcohol to generate a uniform and measurable bubble flow. In both cases, the two-phase damping ratio is correlated to the number of bubbles (or spheres). Two-phase damping is directly related to the interface surface area, based on a spherical bubble model. Further experiments were carried out on tubes with internal two-phase air-water flows. A strong dependence of two-phase damping on flow parameters in the bubbly flow regime is observed. A series of photographs attests to the fact that two-phase damping in bubbly flow increases for a larger number of bubbles, and for smaller bubbles. It is highest immediately prior to the transition from bubbly flow to slug or churn flow regimes. Beyond the transition, damping decreases. It is also shown that two-phase damping increases with the tube diameter.

  3. The effect of neutrally buoyant finite-size particles on channel flows in the laminar-turbulent transition regime

    NASA Astrophysics Data System (ADS)

    Loisel, Vincent; Abbas, Micheline; Masbernat, Olivier; Climent, Eric

    2013-12-01

    The presence of finite-size particles in a channel flow close to the laminar-turbulent transition is simulated with the Force Coupling Method which allows two-way coupling with the flow dynamics. Spherical particles with channel height-to-particle diameter ratio of 16 are initially randomly seeded in a fluctuating flow above the critical Reynolds number corresponding to single phase flow relaminarization. When steady-state is reached, the particle volume fraction is homogeneously distributed in the channel cross-section (ϕ ≅ 5%) except in the near-wall region where it is larger due to inertia-driven migration. Turbulence statistics (intensity of velocity fluctuations, small-scale vortical structures, wall shear stress) calculated in the fully coupled two-phase flow simulations are compared to single-phase flow data in the transition regime. It is observed that particles increase the transverse r.m.s. flow velocity fluctuations and they break down the flow coherent structures into smaller, more numerous and sustained eddies, preventing the flow to relaminarize at the single-phase critical Reynolds number. When the Reynolds number is further decreased and the suspension flow becomes laminar, the wall friction coefficient recovers the evolution of the laminar single-phase law provided that the suspension viscosity is used in the Reynolds number definition. The residual velocity fluctuations in the suspension correspond to a regime of particulate shear-induced agitation.

  4. Simulation of air-droplet mixed phase flow in icing wind-tunnel

    NASA Astrophysics Data System (ADS)

    Mengyao, Leng; Shinan, Chang; Menglong, Wu; Yunhang, Li

    2013-07-01

    Icing wind-tunnel is the main ground facility for the research of aircraft icing, which is different from normal wind-tunnel for its refrigeration system and spraying system. In stable section of icing wind-tunnel, the original parameters of droplets and air are different, for example, to keep the nozzles from freezing, the droplets are heated while the temperature of air is low. It means that complex mass and heat transfer as well as dynamic interactive force would happen between droplets and air, and the parameters of droplet will acutely change along the passageway. Therefore, the prediction of droplet-air mixed phase flow is necessary in the evaluation of icing researching wind-tunnel. In this paper, a simplified droplet-air mixed phase flow model based on Lagrangian method was built. The variation of temperature, diameter and velocity of droplet, as well as the air flow field, during the flow process were obtained under different condition. With calculating three-dimensional air flow field by FLUENT, the droplet could be traced and the droplet distribution could also be achieved. Furthermore, the patterns about how initial parameters affect the parameters in test section were achieved. The numerical simulation solving the flow and heat and mass transfer characteristics in the mixing process is valuable for the optimization of experimental parameters design and equipment adjustment.

  5. Dripping and jetting regimes in co-flowing capillary jets: unforced measurements and response to driving

    NASA Astrophysics Data System (ADS)

    Baroud, Charles; Cordero, Maria-Luisa; Gallaire, Francois

    2011-11-01

    We study the breakup of drops in a co-flowing jet, within the confinement of a microfluidic channel. The breakup can occur right after the nozzle (dripping) or through the generation of a liquid jet that breaks up a long distance from the nozzle (jetting). Traditionally, these two regimes have been considered to reflect an absolutely unstable jet or a convectively unstable jet, respectively. We first provide measurements of the frequency of oscillation and breakup of the liquid jet; the dispersion relation thus obtained compares well with existing theories for convective instabilities in the case of the jetting regime. However, the theories in the absolutely unstable mode fail to predict the evolution of the frequency and drop size in the dripping regime. We also test the jet response to an external forcing, using a focused laser to locally heat the jet. The dripping regime is found to be insensitive to the perturbation and the frequency of drop formation remains unaltered. In contrast, the jetting regime locks to the external frequency, which translates into a modification of the drop size in agreement with the dispersion relations. This confirms the convective nature of the jetting regime. Permanent address: Universidad de Chile.

  6. 7 CFR 28.603 - Procedures for air flow tests of micronaire reading.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... of the United States for Fiber Fineness and Maturity § 28.603 Procedures for air flow tests of... 7 Agriculture 2 2010-01-01 2010-01-01 false Procedures for air flow tests of micronaire reading...) Air flow instrument complete with accessories to measure the fineness and maturity, in combination, of...

  7. Hypervelocity Air Flows With Finite Rate Chemistry

    DTIC Science & Technology

    1994-07-01

    run over a range of freestream con- ditions in both air and nitrogen to obtain conditions to examine flows from frozen to fully equilibrium gas flow ... chemistry . Currently, electron-beam equipment and instrumentation are being prepared at USC, Imperial College, and CUBRC for these studies. Also, instru

  8. Flow and performance of an air-curtain biological safety cabinet.

    PubMed

    Huang, Rong Fung; Chou, Chun I

    2009-06-01

    Using laser-assisted smoke flow visualization and tracer gas concentration detection techniques, this study examines aerodynamic flow properties and the characteristics of escape from containment, inward dispersion, and cross-cabinet contamination of a biological safety cabinet installed with an air curtain across the front aperture. The experimental method partially simulates the NSF/ANSI 49 standards with the difference that the biological tracer recommended by these standards is replaced by a mixture of 10% SF(6) in N(2). The air curtain is set up across the cabinet aperture plane by means of a narrow planar jet issued from the lower edge of the sash and a suction flow going through a suction slot installed at the front edge of the work surface. Varying the combination of jet velocity, suction flow velocity, and descending flow velocity reveals three types of characteristic flow modes: 'straight curtain', 'slightly concave curtain', and 'severely concave curtain'. Operating the cabinet in the straight curtain mode causes the air curtain to impinge on the doorsill and therefore induces serious escape from containment. In the severely concave curtain mode, drastically large inward dispersion and cross-cabinet contamination were observed because environmental air entered into the cabinet and a three-dimensional vortical flow structure formed in the cabinet. The slightly concave curtain mode presents a smooth and two-dimensional flow pattern with an air curtain separating the outside atmosphere from the inside space of the cabinet, and therefore exhibited negligibly small escape from containment, inward dispersion, and cross-cabinet contamination.

  9. E × B flow shear drive of the linear low- n modes of EHO in the QH-mode regime [ E × B flow shear drive of EHO in the QH-mode regime

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, G. S.; Wan, B. N.; Wang, Y. F.

    A new mechanism is identified for driving the edge harmonic oscillations (EHOs) in the quiescent H-mode (QH-mode) regime, where a strong E × B flow shear destabilizes low-n kink/peeling modes, separately from the previously found Kelvin-Helmholtz drive. We find that the differential advection of mode vorticity by sheared E × B flows modifies the two-dimensional pattern of mode electrostatic potential perpendicular to the magnetic field lines, which in turn causes a radial expansion of the mode structure, an increase of field line bending away from the mode rational surface, and a reduction of inertial stabilization. This enhances the kink drivemore » as the parallel wavenumber increases significantly away from the rational surface where the magnetic shear is also strong. A newly developed model reproduces the observations that at high E × B flow shear only a few low-n modes remain unstable, consistent with the EHO behavior, while at low E × B flow shear the unstable mode spectrum is significantly broadened, consistent with the low-n broadband electromagnetic turbulence behavior observed recently in the DIII-D tokamak. This destabilization is also shown to be independent of the sign of the flow shear, as observed experimentally, and has not been taken into 2 / 46 account in previous pedestal linear stability analyses. Verification of the veracity of this EHO mechanism will require analysis of the nonlinear evolution of low-n kink/peeling modes so destabilized in the linear regime.« less

  10. E × B flow shear drive of the linear low- n modes of EHO in the QH-mode regime [ E × B flow shear drive of EHO in the QH-mode regime

    DOE PAGES

    Xu, G. S.; Wan, B. N.; Wang, Y. F.; ...

    2017-07-18

    A new mechanism is identified for driving the edge harmonic oscillations (EHOs) in the quiescent H-mode (QH-mode) regime, where a strong E × B flow shear destabilizes low-n kink/peeling modes, separately from the previously found Kelvin-Helmholtz drive. We find that the differential advection of mode vorticity by sheared E × B flows modifies the two-dimensional pattern of mode electrostatic potential perpendicular to the magnetic field lines, which in turn causes a radial expansion of the mode structure, an increase of field line bending away from the mode rational surface, and a reduction of inertial stabilization. This enhances the kink drivemore » as the parallel wavenumber increases significantly away from the rational surface where the magnetic shear is also strong. A newly developed model reproduces the observations that at high E × B flow shear only a few low-n modes remain unstable, consistent with the EHO behavior, while at low E × B flow shear the unstable mode spectrum is significantly broadened, consistent with the low-n broadband electromagnetic turbulence behavior observed recently in the DIII-D tokamak. This destabilization is also shown to be independent of the sign of the flow shear, as observed experimentally, and has not been taken into 2 / 46 account in previous pedestal linear stability analyses. Verification of the veracity of this EHO mechanism will require analysis of the nonlinear evolution of low-n kink/peeling modes so destabilized in the linear regime.« less

  11. Validating the MFiX-DEM Model for Flow Regime Prediction in a 3D Spouted Bed

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Banerjee, Subhodeep; Guenther, Chris; Rogers, William A.

    The spout-fluidized bed reactor with relatively large oxygen carrier particles offers several advantages in chemical looping combustion operation using solid fuels. The large difference in size and weight between the oxygen carrier particles and the smaller coal or ash particles allows the oxygen carrier to be easily segregated for recirculation; the increased solids mixing due to dynamic flow pattern in the spout-fluidization regime prevents agglomeration. The primary objective in this work is to determine the effectiveness of the MFiX-DEM model in predicting the flow regime in a spouted bed. Successful validation of the code will allow the user to finemore » tune the operating conditions of a spouted bed to achieve the desired operating condition.« less

  12. Numerical Analysis of Flow Evolution in a Helium Jet Injected into Ambient Air

    NASA Technical Reports Server (NTRS)

    Satti, Rajani P.; Agrawal, Ajay K.

    2005-01-01

    A computational model to study the stability characteristics of an evolving buoyant helium gas jet in ambient air environment is presented. Numerical formulation incorporates a segregated approach to solve for the transport equations of helium mass fraction coupled with the conservation equations of mixture mass and momentum using a staggered grid method. The operating parameters correspond to the Reynolds number varying from 30 to 300 to demarcate the flow dynamics in oscillating and non-oscillating regimes. Computed velocity and concentration fields were used to analyze the flow structure in the evolving jet. For Re=300 case, results showed that an instability mode that sets in during the evolution process in Earth gravity is absent in zero gravity, signifying the importance of buoyancy. Though buoyancy initiates the instability, below a certain jet exit velocity, diffusion dominates the entrainment process to make the jet non-oscillatory as observed for the Re=30 case. Initiation of the instability was found to be dependent on the interaction of buoyancy and momentum forces along the jet shear layer.

  13. Ion-neutral Clustering of Bile Acids in Electrospray Ionization Across UPLC Flow Regimes

    NASA Astrophysics Data System (ADS)

    Brophy, Patrick; Broeckling, Corey D.; Murphy, James; Prenni, Jessica E.

    2018-02-01

    Bile acid authentic standards were used as model compounds to quantitatively evaluate complex in-source phenomenon on a UPLC-ESI-TOF-MS operated in the negative mode. Three different diameter columns and a ceramic-based microfluidic separation device were utilized, allowing for detailed descriptions of bile acid behavior across a wide range of flow regimes and instantaneous concentrations. A custom processing algorithm based on correlation analysis was developed to group together all ion signals arising from a single compound; these grouped signals produce verified compound spectra for each bile acid at each on-column mass loading. Significant adduction was observed for all bile acids investigated under all flow regimes and across a wide range of bile acid concentrations. The distribution of bile acid containing clusters was found to depend on the specific bile acid species, solvent flow rate, and bile acid concentration. Relative abundancies of each cluster changed non-linearly with concentration. It was found that summing all MS level (low collisional energy) ions and ion-neutral adducts arising from a single compound improves linearity across the concentration range (0.125-5 ng on column) and increases the sensitivity of MS level quantification. The behavior of each cluster roughly follows simple equilibrium processes consistent with our understanding of electrospray ionization mechanisms and ion transport processes occurring in atmospheric pressure interfaces. [Figure not available: see fulltext.

  14. Parametric Studies of Flow Separation using Air Injection

    NASA Technical Reports Server (NTRS)

    Zhang, Wei

    2004-01-01

    Boundary Layer separation causes the airfoil to stall and therefore imposes dramatic performance degradation on the airfoil. In recent years, flow separation control has been one of the active research areas in the field of aerodynamics due to its promising performance improvements on the lifting device. These active flow separation control techniques include steady and unsteady air injection as well as suction on the airfoil surface etc. This paper will be focusing on the steady and unsteady air injection on the airfoil. Although wind tunnel experiments revealed that the performance improvements on the airfoil using injection techniques, the details of how the key variables such as air injection slot geometry and air injection angle etc impact the effectiveness of flow separation control via air injection has not been studied. A parametric study of both steady and unsteady air injection active flow control will be the main objective for this summer. For steady injection, the key variables include the slot geometry, orientation, spacing, air injection velocity as well as the injection angle. For unsteady injection, the injection frequency will also be investigated. Key metrics such as lift coefficient, drag coefficient, total pressure loss and total injection mass will be used to measure the effectiveness of the control technique. A design of experiments using the Box-Behnken Design is set up in order to determine how each of the variables affects each of the key metrics. Design of experiment is used so that the number of experimental runs will be at minimum and still be able to predict which variables are the key contributors to the responses. The experiments will then be conducted in the 1ft by 1ft wind tunnel according to the design of experiment settings. The data obtained from the experiments will be imported into JMP, statistical software, to generate sets of response surface equations which represent the statistical empirical model for each of the metrics as

  15. Hydrologic regimes as potential drivers of morphologic divergence in fish

    USGS Publications Warehouse

    Bruckerhoff, Lindsey; Magoulick, Daniel D.

    2017-01-01

    Fishes often exhibit phenotypic divergence across gradients of abiotic and biotic selective pressures. In streams, many of the known selective pressures driving phenotypic differentiation are largely influenced by hydrologic regimes. Because flow regimes drive so many attributes of lotic systems, we hypothesized fish exhibit phenotypic divergence among streams with different flow regimes. We used a comparative field study to investigate the morphological divergence of Campostoma anomalom (central stonerollers) among streams characterized by highly variable, intermittent flow regimes and streams characterized by relatively stable, groundwater flow regimes. We also conducted a mesocosm experiment to compare the plastic effects of one component of flow regimes, water velocity, on morphology of fish from different flow regimes. We observed differences in shape between flow regimes likely driven by differences in allometric growth patterns. Although we observed differences in morphology across flow regimes in the field, C. anomalum did not exhibit morphologic plasticity in response to water velocity alone. This study contributes to the understanding of how complex environmental factors drive phenotypic divergence and may provide insight into the evolutionary consequences of disrupting natural hydrologic patterns, which are increasingly threatened by climate change and anthropogenic alterations.

  16. A probabilistic approach to quantifying spatial patterns of flow regimes and network-scale connectivity

    NASA Astrophysics Data System (ADS)

    Garbin, Silvia; Alessi Celegon, Elisa; Fanton, Pietro; Botter, Gianluca

    2017-04-01

    The temporal variability of river flow regime is a key feature structuring and controlling fluvial ecological communities and ecosystem processes. In particular, streamflow variability induced by climate/landscape heterogeneities or other anthropogenic factors significantly affects the connectivity between streams with notable implication for river fragmentation. Hydrologic connectivity is a fundamental property that guarantees species persistence and ecosystem integrity in riverine systems. In riverine landscapes, most ecological transitions are flow-dependent and the structure of flow regimes may affect ecological functions of endemic biota (i.e., fish spawning or grazing of invertebrate species). Therefore, minimum flow thresholds must be guaranteed to support specific ecosystem services, like fish migration, aquatic biodiversity and habitat suitability. In this contribution, we present a probabilistic approach aiming at a spatially-explicit, quantitative assessment of hydrologic connectivity at the network-scale as derived from river flow variability. Dynamics of daily streamflows are estimated based on catchment-scale climatic and morphological features, integrating a stochastic, physically based approach that accounts for the stochasticity of rainfall with a water balance model and a geomorphic recession flow model. The non-exceedance probability of ecologically meaningful flow thresholds is used to evaluate the fragmentation of individual stream reaches, and the ensuing network-scale connectivity metrics. A multi-dimensional Poisson Process for the stochastic generation of rainfall is used to evaluate the impact of climate signature on reach-scale and catchment-scale connectivity. The analysis shows that streamflow patterns and network-scale connectivity are influenced by the topology of the river network and the spatial variability of climatic properties (rainfall, evapotranspiration). The framework offers a robust basis for the prediction of the impact of

  17. Effect of groundwater flow on remediation of dissolved-phase VOC contamination using air sparging.

    PubMed

    Reddy, K R; Adams, J A

    2000-02-25

    This paper presents two-dimensional laboratory experiments performed to study how groundwater flow may affect the injected air zone of influence and remedial performance, and how injected air may alter subsurface groundwater flow and contaminant migration during in situ air sparging. Tests were performed by subjecting uniform sand profiles contaminated with dissolved-phase benzene to a hydraulic gradient and two different air flow rates. The results of the tests were compared to a test subjected to a similar air flow rate but a static groundwater condition. The test results revealed that the size and shape of the zone of influence were negligibly affected by groundwater flow, and as a result, similar rates of contaminant removal were realized within the zone of influence with and without groundwater flow. The air flow, however, reduced the hydraulic conductivity within the zone of influence, reducing groundwater flow and subsequent downgradient contaminant migration. The use of a higher air flow rate further reduced the hydraulic conductivity and decreased groundwater flow and contaminant migration. Overall, this study demonstrated that air sparging may be effectively implemented to intercept and treat a migrating contaminant plume.

  18. Full-flow-regime storage-streamflow correlation patterns provide insights into hydrologic functioning over the continental US

    NASA Astrophysics Data System (ADS)

    Fang, Kuai; Shen, Chaopeng

    2017-09-01

    Interannual changes in low, median, and high regimes of streamflow have important implications for flood control, irrigation, and ecologic and human health. The Gravity Recovery and Climate Experiment (GRACE) satellites record global terrestrial water storage anomalies (TWSA), providing an opportunity to observe, interpret, and potentially utilize the complex relationships between storage and full-flow-regime streamflow. Here we show that utilizable storage-streamflow correlations exist throughout vastly different climates in the continental US (CONUS) across low- to high-flow regimes. A panoramic framework, the storage-streamflow correlation spectrum (SSCS), is proposed to examine macroscopic gradients in these relationships. SSCS helps form, corroborate or reject hypotheses about basin hydrologic behaviors. SSCS patterns vary greatly over CONUS with climate, land surface, and geologic conditions. Data mining analysis suggests that for catchments with hydrologic settings that favor storage over runoff, e.g., a large fraction of precipitation as snow, thick and highly-permeable permeable soil, SSCS values tend to be high. Based on our results, we form the hypotheses that groundwater flow dominates streamflows in Southeastern CONUS and Great Plains, while thin soils in a belt along the Appalachian Plateau impose alimit on water storage. SSCS also suggests shallow water table caused by high-bulk density soil and flat terrain induces rapid runoff in several regions. Our results highlight the importance of subsurface properties and groundwater flow in capturing flood and drought. We propose that SSCS can be used as a fundamental hydrologic signature to constrain models and to provide insights thatlead usto better understand hydrologic functioning.

  19. Annular fuel and air co-flow premixer

    DOEpatents

    Stevenson, Christian Xavier; Melton, Patrick Benedict; York, William David

    2013-10-15

    Disclosed is a premixer for a combustor including an annular outer shell and an annular inner shell. The inner shell defines an inner flow channel inside of the inner shell and is located to define an outer flow channel between the outer shell and the inner shell. A fuel discharge annulus is located between the outer flow channel and the inner flow channel and is configured to inject a fuel flow into a mixing area in a direction substantially parallel to an outer airflow through the outer flow channel and an inner flow through the inner flow channel. Further disclosed are a combustor including a plurality of premixers and a method of premixing air and fuel in a combustor.

  20. Observations of two-phase flow patterns in a horizontal circular channel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ewing, M.E.; Weinandy, J.J.; Christensen, R.N.

    1999-01-01

    Horizontal two-phase flow patterns were observed in a transparent circular channel (1.90 cm I.D.) using adiabatic mixtures of air and water. Visual identification of the flow regimes was supplemented with photographic data and the results were plotted on the flow regime map which has been proposed by Breber et al. for condensation applications. The results indicate general consistency between the observations and the predictions of the map, and, by providing data for different fluids and conditions from which the map was developed, support its general applicability.

  1. Influence of flow regime and channel morphology on larval drift and dispersion in a large regulated river

    NASA Astrophysics Data System (ADS)

    Erwin, S.; Jacobson, R. B.

    2013-12-01

    Larval drift is a critical phase of ontogenetic development for many species of lotic fishes. Downstream advection and dispersion of passively drifting larvae or eggs is controlled by the complex interaction of flow regime, channel planform, local channel morphology, and the resulting hydraulic gradients. In many regulated rivers, channel engineering and perturbations to the flow regime may disrupt natural drift processes and impact successful recruitment of native fishes. Here we explore the influence of flow regime and channel morphology on the downstream transport, dispersion, and retention of Pallid Sturgeon larvae, an endangered species endemic to the Mississippi River basin and the focus of significant conservation effort on the Missouri River. The transition from drifting free embryo to exogenously feeding larvae has been identified as a potential life stage bottleneck for the Pallid Sturgeon. Previous studies have indicated that river regulation and fragmentation may contribute to mortality of larval Pallid Sturgeon by reducing the extent of free-flowing river required by free embryos to complete the transition to exogenous feeding. Additionally, channelization may have increased the rate at which larvae are advected downstream out of the Missouri River basin. We describe the complex interactions and influence of morphologic and hydraulic factors on larval drift using an extensive library of hydroacoustic data collected along more than 1300 km of the Lower Missouri River. We use a one-dimensional advection-dispersion model to estimate total drift distance and employ the longitudinal dispersion coefficient as a measure to quantify the tendency towards dispersion or retention of passively drifting larvae in geomorphically distinct segments of river. We use a two-dimensional hydrodynamic model to evaluate the sensitivity of drift and dispersion to in-channel navigation structures and flood hydrology. Based on insights gained from the analysis of field data and

  2. Strategic guidelines for street canyon geometry to achieve sustainable street air quality

    NASA Astrophysics Data System (ADS)

    Chan, Andy T.; So, Ellen S. P.; Samad, Subash C.

    This paper is concerned with the motion of air within the urban street canyon and is directed towards a deeper understanding of pollutant dispersion with respect to various simple canyon geometries and source positions. Taking into account the present days typical urban configurations, three principal flow regimes "isolated roughness flow", "skimming flow" and "wake interference flow" (Boundary Layer Climates, 2nd edition, Methuen, London) and their corresponding pollutant dispersion characteristics are studied for various canopies aspect ratios, namely relative height ( h2/ h1), canyon height to width ratio ( h/ w) and canyon length to height ratio ( l/ h). A field-size canyon has been analyzed through numerical simulations using the standard k- ɛ turbulence closure model. It is found that the pollutant transport and diffusion is strongly dependent upon the type of flow regime inside the canyon and exchange between canyon and the above roof air. Some rules of thumbs have been established to get urban canyon geometries for efficient dispersion of pollutants.

  3. Heat-power working regimes of a high-frequency (0.44 MHz) 1000-kW induction plasmatron

    NASA Astrophysics Data System (ADS)

    Gorbanenko, V. M.; Farnasov, G. A.; Lisafin, A. B.

    2015-12-01

    The energy working regimes of a superpower high-frequency induction (HFI) plasmatron with a high-frequency (HF) generator are studied. The HFI plasmatron with a power of 1000 kVA and a working frequency of 440 kHz, in which air is used as a plasma-forming gas, can be used for treatment of various oxide powder materials. The energy regimes substantially influence finish products and their costs. Various working regimes of the HFI plasma unit and the following characteristics are studied: the dependence of the vibration power on the anode power, the dependence of the power losses on the anode power at various of plasma-forming gas flow rates, and the coefficients of efficiency of the plasmatron and the HFI-plasma unit at various powers. The effect of the plasma-forming gas flow rate on the bulk temperature is determined.

  4. Flow and habitat effects on juvenile fish abundance in natural and altered flow regimes

    USGS Publications Warehouse

    Freeman, Mary C.; Bowen, Z.H.; Bovee, K.D.; Irwin, E.R.

    2001-01-01

    Conserving biological resources native to large river systems increasingly depends on how flow-regulated segments of these rivers are managed. Improving management will require a better understanding of linkages between river biota and temporal variability of flow and instream habitat. However, few studies have quantified responses of native fish populations to multiyear (>2 yr) patterns of hydrologic or habitat variability in flow-regulated systems. To provide these data, we quantified young-of-year (YOY) fish abundance during four years in relation to hydrologic and habitat variability in two segments of the Tallapoosa River in the southeastern United States. One segment had an unregulated flow regime, whereas the other was flow-regulated by a peak-load generating hydropower dam. We sampled fishes annually and explored how continuously recorded flow data and physical habitat simulation models (PHABSIM) for spring (April-June) and summer (July-August) preceding each sample explained fish abundances. Patterns of YOY abundance in relation to habitat availability (median area) and habitat persistence (longest period with habitat area continuously above the long-term median area) differed between unregulated and flow-regulated sites. At the unregulated site, YOY abundances were most frequently correlated with availability of shallow-slow habitat in summer (10 species) and persistence of shallow-slow and shallow-fast habitat in spring (nine species). Additionally, abundances were negatively correlated with 1-h maximum flow in summer (five species). At the flow-regulated site, YOY abundances were more frequently correlated with persistence of shallow-water habitats (four species in spring; six species in summer) than with habitat availability or magnitude of flow extremes. The associations of YOY with habitat persistence at the flow-regulated site corresponded to the effects of flow regulation on habitat patterns. Flow regulation reduced median flows during spring and

  5. Consistent lattice Boltzmann modeling of low-speed isothermal flows at finite Knudsen numbers in slip-flow regime: Application to plane boundaries

    NASA Astrophysics Data System (ADS)

    Silva, Goncalo; Semiao, Viriato

    2017-07-01

    The first nonequilibrium effect experienced by gaseous flows in contact with solid surfaces is the slip-flow regime. While the classical hydrodynamic description holds valid in bulk, at boundaries the fluid-wall interactions must consider slip. In comparison to the standard no-slip Dirichlet condition, the case of slip formulates as a Robin-type condition for the fluid tangential velocity. This makes its numerical modeling a challenging task, particularly in complex geometries. In this work, this issue is handled with the lattice Boltzmann method (LBM), motivated by the similarities between the closure relations of the reflection-type boundary schemes equipping the LBM equation and the slip velocity condition established by slip-flow theory. Based on this analogy, we derive, as central result, the structure of the LBM boundary closure relation that is consistent with the second-order slip velocity condition, applicable to planar walls. Subsequently, three tasks are performed. First, we clarify the limitations of existing slip velocity LBM schemes, based on discrete analogs of kinetic theory fluid-wall interaction models. Second, we present improved slip velocity LBM boundary schemes, constructed directly at discrete level, by extending the multireflection framework to the slip-flow regime. Here, two classes of slip velocity LBM boundary schemes are considered: (i) linear slip schemes, which are local but retain some calibration requirements and/or operation limitations, (ii) parabolic slip schemes, which use a two-point implementation but guarantee the consistent prescription of the intended slip velocity condition, at arbitrary plane wall discretizations, further dispensing any numerical calibration procedure. Third and final, we verify the improvements of our proposed slip velocity LBM boundary schemes against existing ones. The numerical tests evaluate the ability of the slip schemes to exactly accommodate the steady Poiseuille channel flow solution, over

  6. Consistent lattice Boltzmann modeling of low-speed isothermal flows at finite Knudsen numbers in slip-flow regime: Application to plane boundaries.

    PubMed

    Silva, Goncalo; Semiao, Viriato

    2017-07-01

    The first nonequilibrium effect experienced by gaseous flows in contact with solid surfaces is the slip-flow regime. While the classical hydrodynamic description holds valid in bulk, at boundaries the fluid-wall interactions must consider slip. In comparison to the standard no-slip Dirichlet condition, the case of slip formulates as a Robin-type condition for the fluid tangential velocity. This makes its numerical modeling a challenging task, particularly in complex geometries. In this work, this issue is handled with the lattice Boltzmann method (LBM), motivated by the similarities between the closure relations of the reflection-type boundary schemes equipping the LBM equation and the slip velocity condition established by slip-flow theory. Based on this analogy, we derive, as central result, the structure of the LBM boundary closure relation that is consistent with the second-order slip velocity condition, applicable to planar walls. Subsequently, three tasks are performed. First, we clarify the limitations of existing slip velocity LBM schemes, based on discrete analogs of kinetic theory fluid-wall interaction models. Second, we present improved slip velocity LBM boundary schemes, constructed directly at discrete level, by extending the multireflection framework to the slip-flow regime. Here, two classes of slip velocity LBM boundary schemes are considered: (i) linear slip schemes, which are local but retain some calibration requirements and/or operation limitations, (ii) parabolic slip schemes, which use a two-point implementation but guarantee the consistent prescription of the intended slip velocity condition, at arbitrary plane wall discretizations, further dispensing any numerical calibration procedure. Third and final, we verify the improvements of our proposed slip velocity LBM boundary schemes against existing ones. The numerical tests evaluate the ability of the slip schemes to exactly accommodate the steady Poiseuille channel flow solution, over

  7. Flow Regime Study in a High Density Circulating Fluidized Bed Riser with an Abrupt Exit

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mei, J.S.; Shadle, L.J.; Yue, P.C.

    2007-01-01

    Flow regime study was conducted in a 0.3 m diameter, 15.5 m height circulating fluidized bed (CFB) riser with an abrupt exit at the National Energy Technology Laboratory of the U.S. Department of Energy. Local particle velocities were measured at various radial positions and riser heights using an optical fiber probe. On-line measurement of solid circulating rate was continuously recorded by the Spiral. Glass beads of mean diameter 61 μm and particle density of 2,500 kg/m3 were used as bed material. The CFB riser was operated at various superficial gas velocities ranging from 3 to 7.6 m/s and solid massmore » flux from 20 to 550 kg/m2-s. At a constant riser gas velocity, transition from fast fluidization to dense suspension upflow (DSU) regime started at the bottom of the riser with increasing solid flux. Except at comparatively low riser gas velocity and solid flux, the apparent solid holdup at the top exit region was higher than the middle section of the riser. The solid fraction at this top region could be much higher than 7% under high riser gas velocity and solid mass flux. The local particle velocity showed downward flow near the wall at the top of the riser due to its abrupt exit. This abrupt geometry reflected the solids and, therefore, caused solid particles traveling downward along the wall. However, at location below, but near, the top of the riser the local particle velocities were observed flowing upward at the wall. Therefore, DSU was identified in the upper region of the riser with an abrupt exit while the fully developed region, lower in the riser, was still exhibiting core-annular flow structure. Our data were compared with the flow regime boundaries proposed by Kim et al. [1] for distinguishing the dilute pneumatic transport, fast fluidization, and DSU.« less

  8. Rapid Induction of Therapeutic Hypothermia Using Transnasal High Flow Dry Air

    PubMed Central

    Chava, Raghuram; Raghavan, Madhavan Srinivas; Halperin, Henry; Maqbool, Farhan; Geocadin, Romergryko; Quinones-Hinojosa, Alfredo; Kolandaivelu, Aravindan; Rosen, Benjamin A.

    2017-01-01

    Early induction of therapeutic hypothermia (TH) is recommended in out-of-hospital cardiac arrest (CA); however, currently no reliable methods exist to initiate cooling. We investigated the effect of high flow transnasal dry air on brain and body temperatures in adult porcine animals. Adult porcine animals (n = 23) under general anesthesia were subject to high flow of transnasal dry air. Mouth was kept open to create a unidirectional airflow, in through the nostrils and out through the mouth. Brain, internal jugular, and aortic temperatures were recorded. The effect of varying airflow rate and the air humidity (0% or 100%) on the temperature profiles were recorded. The degree of brain cooling was measured as the differential temperature from baseline. A 10-minute exposure of high flow dry air caused rapid cooling of brain and gradual cooling of the jugular and the aortic temperatures in all animals. The degree of brain cooling was flow dependent and significantly higher at higher airflow rates (0.8°C ± 0.3°C, 1.03°C ± 0.6°C, and 1.3°C ± 0.7°C for 20, 40, and 80 L, respectively, p < 0.05 for all comparisons). Air temperature had minimal effect on the brain cooling over 10 minutes with similar decrease in temperature at 4°C and 30°C. At a constant flow rate (40 LPM) and temperature, the degree of cooling over 10 minutes during dry air exposure was significantly higher compared to humid air (100% saturation) (1.22°C ± 0.35°C vs. 0.21°C ± 0.12°C, p < 0.001). High flow transnasal dry air causes flow dependent cooling of the brain and the core temperatures in intubated porcine animals. The mechanism of cooling appears to be evaporation of nasal mucus as cooling is mitigated by humidifying the air. This mechanism may be exploited to initiate TH in CA. PMID:27635468

  9. Rapid Induction of Therapeutic Hypothermia Using Transnasal High Flow Dry Air.

    PubMed

    Chava, Raghuram; Zviman, Menekhem; Raghavan, Madhavan Srinivas; Halperin, Henry; Maqbool, Farhan; Geocadin, Romergryko; Quinones-Hinojosa, Alfredo; Kolandaivelu, Aravindan; Rosen, Benjamin A; Tandri, Harikrishna

    2017-03-01

    Early induction of therapeutic hypothermia (TH) is recommended in out-of-hospital cardiac arrest (CA); however, currently no reliable methods exist to initiate cooling. We investigated the effect of high flow transnasal dry air on brain and body temperatures in adult porcine animals. Adult porcine animals (n = 23) under general anesthesia were subject to high flow of transnasal dry air. Mouth was kept open to create a unidirectional airflow, in through the nostrils and out through the mouth. Brain, internal jugular, and aortic temperatures were recorded. The effect of varying airflow rate and the air humidity (0% or 100%) on the temperature profiles were recorded. The degree of brain cooling was measured as the differential temperature from baseline. A 10-minute exposure of high flow dry air caused rapid cooling of brain and gradual cooling of the jugular and the aortic temperatures in all animals. The degree of brain cooling was flow dependent and significantly higher at higher airflow rates (0.8°C ± 0.3°C, 1.03°C ± 0.6°C, and 1.3°C ± 0.7°C for 20, 40, and 80 L, respectively, p < 0.05 for all comparisons). Air temperature had minimal effect on the brain cooling over 10 minutes with similar decrease in temperature at 4°C and 30°C. At a constant flow rate (40 LPM) and temperature, the degree of cooling over 10 minutes during dry air exposure was significantly higher compared to humid air (100% saturation) (1.22°C ± 0.35°C vs. 0.21°C ± 0.12°C, p < 0.001). High flow transnasal dry air causes flow dependent cooling of the brain and the core temperatures in intubated porcine animals. The mechanism of cooling appears to be evaporation of nasal mucus as cooling is mitigated by humidifying the air. This mechanism may be exploited to initiate TH in CA.

  10. Air and groundwater flow at the interface between fractured host rock and a bentonite buffer

    NASA Astrophysics Data System (ADS)

    Dessirier, B.; Jarsjo, J.; Frampton, A.

    2014-12-01

    Designs of deep geological repositories for spent nuclear fuel include several levels of confinement. The Swedish and Finnish concept KBS-3 targets for example sparsely fractured crystalline bedrock as host formation and would have the waste canisters embedded in an engineered buffer of compacted MX-80 bentonite. The host rock is a highly heterogeneous dual porosity material containing fractures and a rock matrix. Bentonite is a complex expansive porous material. Its water content and mechanical properties are interdependent. Beyond the specific physics of unsaturated flow and transport in each medium, the interface between them is critical. Detailed knowledge of the transitory two-phase flow regime, induced by the insertion of the unsaturated buffer in a saturated rock environment, is necessary to assess the performance of planned KBS-3 deposition holes. A set of numerical simulations based on the equations of two-phase flow for water and air in porous media were conducted to investigate the dynamics of air and groundwater flow near the rock/bentonite interface in the period following installation of the unsaturated bentonite buffer. We assume state of the two-phase flow parameter values for bentonite from laboratory water uptake tests and typical fracture and rock properties from the Äspö Hard rock laboratory (Sweden) gathered under several field characterization campaigns. The results point to desaturation of the rock domain as far as 10 cm away from the interface into matrix-dominated regions for up to 160 days. Similar observations were made during the Bentonite Rock Interaction Experiment (BRIE) at the Äspö HRL, with a desaturation sustained for even longer times. More than the mere time to mechanical and hydraulic equilibrium, the occurrence of sustained unsaturated conditions opens the possibility for biogeochemical processes that could be critical in the safety assessment of the planned repository.

  11. Characteristics Air Flow in Room Chamber Test Refrigerator Household Energy Consumption with Inlet Flow Variation

    NASA Astrophysics Data System (ADS)

    Susanto, Edy; Idrus Alhamid, M.; Nasruddin; Budihardjo

    2018-03-01

    Room Chamber is the most important in making a good Testing Laboratory. In this study, the 2-D modeling conducted to assess the effect placed the inlet on designing a test chamber room energy consumption of household refrigerators. Where the geometry room chamber is rectangular and approaching the enclosure conditions. Inlet varied over the side parallel to the outlet and compared to the inlet where the bottom is made. The purpose of this study was to determine and define the characteristics of the airflow in the room chamber using CFD simulation. CFD method is used to obtain flow characteristics in detail, in the form of vector flow velocity and temperature distribution inside the chamber room. The result found that the position of the inlet parallel to the outlet causes air flow cannot move freely to the side of the floor, even flow of air moves up toward the outlet. While by making the inlet is below, the air can move freely from the bottom up to the side of the chamber room wall as well as to help uniform flow.

  12. Air-sea interaction regimes in the sub-Antarctic Southern Ocean and Antarctic marginal ice zone revealed by icebreaker measurements

    NASA Astrophysics Data System (ADS)

    Yu, Lisan; Jin, Xiangze; Schulz, Eric W.; Josey, Simon A.

    2017-08-01

    This study analyzed shipboard air-sea measurements acquired by the icebreaker Aurora Australis during its off-winter operation in December 2010 to May 2012. Mean conditions over 7 months (October-April) were compiled from a total of 22 ship tracks. The icebreaker traversed the water between Hobart, Tasmania, and the Antarctic continent, providing valuable in situ insight into two dynamically important, yet poorly sampled, regimes: the sub-Antarctic Southern Ocean and the Antarctic marginal ice zone (MIZ) in the Indian Ocean sector. The transition from the open water to the ice-covered surface creates sharp changes in albedo, surface roughness, and air temperature, leading to consequential effects on air-sea variables and fluxes. Major effort was made to estimate the air-sea fluxes in the MIZ using the bulk flux algorithms that are tuned specifically for the sea-ice effects, while computing the fluxes over the sub-Antarctic section using the COARE3.0 algorithm. The study evidenced strong sea-ice modulations on winds, with the southerly airflow showing deceleration (convergence) in the MIZ and acceleration (divergence) when moving away from the MIZ. Marked seasonal variations in heat exchanges between the atmosphere and the ice margin were noted. The monotonic increase in turbulent latent and sensible heat fluxes after summer turned the MIZ quickly into a heat loss regime, while at the same time the sub-Antarctic surface water continued to receive heat from the atmosphere. The drastic increase in turbulent heat loss in the MIZ contrasted sharply to the nonsignificant and seasonally invariant turbulent heat loss over the sub-Antarctic open water.Plain Language SummaryThe icebreaker Aurora Australis is a research and supply vessel that is regularly chartered by the Australian Antarctic Division during the southern summer to operate in waters between Hobart, Tasmania, and Antarctica. The vessel serves as the main lifeline to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18487056','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18487056"><span>Characterization of two-phase <span class="hlt">flow</span> <span class="hlt">regimes</span> in horizontal tubes using 81mKr tracer experiments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oriol, Jean; Leclerc, Jean Pierre; Berne, Philippe; Gousseau, Georges; Jallut, Christian; Tochon, Patrice; Clement, Patrice</p> <p>2008-10-01</p> <p>The diagnosis of heat exchangers on duty with respect to <span class="hlt">flow</span> mal-distributions needs the development of non-intrusive inlet-outlet experimental techniques in order to perform an online fault diagnosis. Tracer experiments are an example of such techniques. They can be applied to mono-phase heat exchangers but also to multi-phase ones. In this case, the tracer experiments are more difficult to perform. In order to check for the capabilities of tracer experiments to be used for the <span class="hlt">flow</span> mal-distribution diagnosis in the case of multi-phase heat exchangers, we present here a preliminary study on the simplest possible system: two-phase <span class="hlt">flows</span> in a horizontal tube. (81m)Kr is used as gas tracer and properly collimated NaI (TI) crystal scintillators as detectors. The specific shape of the tracer response allows two-phase <span class="hlt">flow</span> <span class="hlt">regimes</span> to be characterized. Signal analysis allows the estimation of the gas phase real average velocity and consequently of the liquid phase real average velocity as well as of the volumetric void fraction. These results are compared successfully to those obtained with liquid phase tracer experiments previously presented by Oriol et al. 2007. Characterization of the two-phase <span class="hlt">flow</span> <span class="hlt">regimes</span> and liquid dispersion in horizontal and vertical tubes using coloured tracer and no intrusive optical detector. Chem. Eng. Sci. 63(1), 24-34, as well as to those given by correlations from literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130010461','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130010461"><span><span class="hlt">Flow</span> <span class="hlt">Regime</span> Based Climatologies of Lightning Probabilities for Spaceports and Airports</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bauman, William H., III; Volmer, Matthew; Sharp, David; Spratt, Scott; Lafosse, Richard A.</p> <p>2007-01-01</p> <p>Objective: provide forecasters with a "first guess" climatological lightning probability tool (1) Focus on Space Shuttle landings and NWS T AFs (2) Four circles around sites: 5-, 10-, 20- and 30 n mi (4) Three time intervals: hourly, every 3 hr and every 6 hr It is based on: (1) NLDN gridded data (2) <span class="hlt">Flow</span> <span class="hlt">regime</span> (3) Warm season months of May-Sep for years 1989-2004 Gridded data and available code yields squares, not circles Over 850 spread sheets converted into manageable user-friendly web-based GUI</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013PhDT........74Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013PhDT........74Z"><span>Gas-solid fluidized bed reactors: Scale-up, <span class="hlt">flow</span> <span class="hlt">regimes</span> identification and hydrodynamics</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaid, Faraj Muftah</p> <p></p> <p>This research studied the scale-up, <span class="hlt">flow</span> <span class="hlt">regimes</span> identification and hydrodynamics of fluidized beds using 6-inch and 18- inch diameter columns and different particles. One of the objectives was to advance the scale-up of gas-solid fluidized bed reactors by developing a new mechanistic methodology for hydrodynamic similarity based on matching the radial or diameter profile of gas phase holdup, since gas dynamics dictate the hydrodynamics of these reactors. This has been successfully achieved. However, the literature reported scale-up methodology based on matching selected dimensionless groups was examined and it was found that it was not easy to match the dimensionless groups and hence, there was some deviation in the hydrodynamics of the studied two different fluidized beds. A new technique based on gamma ray densitometry (GRD) was successfully developed and utilized to on-line monitor the implementation of scale-up, to identify the <span class="hlt">flow</span> <span class="hlt">regime</span>, and to measure the radial or diameter profiles of gas and solids holdups. CFD has been demonstrated as a valuable tool to enable the implementation of the newly developed scale-up methodology based on finding the conditions that provide similar or closer radial profile or cross sectional distribution of the gas holdup. As gas velocity increases, solids holdup in the center region of the column decreases in the fully developed region of both 6 inch and 18 inch diameter columns. Solids holdup increased with the increase in the particles size and density. Upflowing particles velocity increased with the gas velocity and became steeper at high superficial gas velocity at all axial heights where the center line velocity became higher than that in the wall region. Smaller particles size and lower density gave larger upflowing particles velocity. Minimum fluidization velocity and transition velocity from bubbly to churn turbulent <span class="hlt">flow</span> <span class="hlt">regimes</span> were found to be lower in 18 inch diameter column compared to those obtained in 6 inch</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018EPJWC.18002103S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018EPJWC.18002103S"><span>CFD study on the effects of boundary conditions on <span class="hlt">air</span> <span class="hlt">flow</span> through an <span class="hlt">air</span>-cooled condenser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sumara, Zdeněk; Šochman, Michal</p> <p>2018-06-01</p> <p>This study focuses on the effects of boundary conditions on effectiveness of an <span class="hlt">air</span>-cooled condenser (ACC). Heat duty of ACC is very often calculated for ideal uniform velocity field which does not correspond to reality. Therefore, this study studies the effect of wind and different landscapes on <span class="hlt">air</span> <span class="hlt">flow</span> through ACC. For this study software OpenFOAM was used and the <span class="hlt">flow</span> was simulated with the use of RANS equations. For verification of numerical setup a model of one ACC cell with dimensions of platform 1.5×1.5 [m] was used. In this experiment static pressures behind fan and <span class="hlt">air</span> <span class="hlt">flows</span> through a model of surface of condenser for different rpm of fan were measured. In OpenFOAM software a virtual clone of this experiment was built and different meshes, turbulent models and numerical schemes were tested. After tuning up numerical setup virtual model of real ACC system was built. Influence of wind, landscape and height of ACC on <span class="hlt">air</span> <span class="hlt">flow</span> through ACC has been investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999PhDT.......120W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999PhDT.......120W"><span>Condensation and single-phase heat transfer coefficient and <span class="hlt">flow</span> <span class="hlt">regime</span> visualization in microchannel tubes for HFC-134A</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Wei-Wen William</p> <p></p> <p>This dissertation is to document experimental, local condensation and single-phase heat transfer and <span class="hlt">flow</span> data of the minute diameter, microchannel tube and to develop correlation methods for optimizing the design of horizontal-microchannel condensers. It is essential to collect local data as the condensation progresses through several different <span class="hlt">flow</span> patterns, since as more liquid is formed, the mechanism conducting heat transfer and <span class="hlt">flow</span> is also changing. Therefore, the identification of the <span class="hlt">flow</span> pattern is as important as the thermal and dynamic data. The experimental results were compared with correlation and <span class="hlt">flow</span> <span class="hlt">regime</span> maps from literature. The experiment using refrigerant HFC-134a in flat, multi-port aluminum tubing with 1.46mm hydraulic diameter was conducted. The characteristic of single-phase friction can be described with the analytical solution of square channel. The Gnielinski correlation provided good prediction of single-phase turbulent <span class="hlt">flow</span> heat transfer. Higher mass fluxes and qualities resulted in increased condensation heat transfer and were more effective in the shear-dominated annular <span class="hlt">flow</span>. The effect of temperature gradient from wall to refrigerant attributed profoundly in the gravity-dominated wavy/slug <span class="hlt">flow</span>. Two correlation based on different <span class="hlt">flow</span> mechanisms were developed for specified <span class="hlt">flow</span> <span class="hlt">regimes</span>. Finally, an asymptotic correlation was successfully proposed to account for the entire data regardless of <span class="hlt">flow</span> patterns. Data taken from experiment and observations obtained from <span class="hlt">flow</span> visualization, resulted in a better understanding of the physics in microchannel condensation, optimized designs in the microchannel condensers are now possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017WRR....5310354B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017WRR....5310354B"><span>What Do They Have in Common? Drivers of Streamflow Spatial Correlation and Prediction of <span class="hlt">Flow</span> <span class="hlt">Regimes</span> in Ungauged Locations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Betterle, A.; Radny, D.; Schirmer, M.; Botter, G.</p> <p>2017-12-01</p> <p>The spatial correlation of daily streamflows represents a statistical index encapsulating the similarity between hydrographs at two arbitrary catchment outlets. In this work, a process-based analytical framework is utilized to investigate the hydrological drivers of streamflow spatial correlation through an extensive application to 78 pairs of stream gauges belonging to 13 unregulated catchments in the eastern United States. The analysis provides insight on how the observed heterogeneity of the physical processes that control <span class="hlt">flow</span> dynamics ultimately affect streamflow correlation and spatial patterns of <span class="hlt">flow</span> <span class="hlt">regimes</span>. Despite the variability of recession properties across the study catchments, the impact of heterogeneous drainage rates on the streamflow spatial correlation is overwhelmed by the spatial variability of frequency and intensity of effective rainfall events. Overall, model performances are satisfactory, with root mean square errors between modeled and observed streamflow spatial correlation below 10% in most cases. We also propose a method for estimating streamflow correlation in the absence of discharge data, which proves useful to predict streamflow <span class="hlt">regimes</span> in ungauged areas. The method consists in setting a minimum threshold on the modeled <span class="hlt">flow</span> correlation to individuate hydrologically similar sites. Catchment outlets that are most correlated (ρ>0.9) are found to be characterized by analogous streamflow distributions across a broad range of <span class="hlt">flow</span> <span class="hlt">regimes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080041530','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080041530"><span><span class="hlt">Air</span> <span class="hlt">Flow</span> and Pressure Drop Measurements Across Porous Oxides</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fox, Dennis S.; Cuy, Michael D.; Werner, Roger A.</p> <p>2008-01-01</p> <p>This report summarizes the results of <span class="hlt">air</span> <span class="hlt">flow</span> tests across eight porous, open cell ceramic oxide samples. During ceramic specimen processing, the porosity was formed using the sacrificial template technique, with two different sizes of polystyrene beads used for the template. The samples were initially supplied with thicknesses ranging from 0.14 to 0.20 in. (0.35 to 0.50 cm) and nonuniform backside morphology (some areas dense, some porous). Samples were therefore ground to a thickness of 0.12 to 0.14 in. (0.30 to 0.35 cm) using dry 120 grit SiC paper. Pressure drop versus <span class="hlt">air</span> <span class="hlt">flow</span> is reported. Comparisons of samples with thickness variations are made, as are pressure drop estimates. As the density of the ceramic material increases the maximum corrected <span class="hlt">flow</span> decreases rapidly. Future sample sets should be supplied with samples of similar thickness and having uniform surface morphology. This would allow a more consistent determination of <span class="hlt">air</span> <span class="hlt">flow</span> versus processing parameters and the resulting porosity size and distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MeScT..29f4002S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MeScT..29f4002S"><span>Measurement of the refractive index of <span class="hlt">air</span> in a low-pressure <span class="hlt">regime</span> and the applicability of traditional empirical formulae</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schödel, René; Walkov, Alexander; Voigt, Michael; Bartl, Guido</p> <p>2018-06-01</p> <p>The refractive index of <span class="hlt">air</span> is a major limiting factor in length measurements by interferometry, which are mostly performed under atmospheric conditions. Therefore, especially in the last century, measurement and description of the <span class="hlt">air</span> refractive index was a key point in order to achieve accuracy in the realisation of the length by interferometry. Nevertheless, interferometric length measurements performed in vacuum are much more accurate since the wavelength of the light is not affected by the <span class="hlt">air</span> refractive index. However, compared with thermal conditions in <span class="hlt">air</span>, in high vacuum heat conduction is missing. In such a situation, dependent on the radiative thermal equilibrium, a temperature distribution can be very inhomogeneous. Using a so-called contact gas instead of high vacuum is a very effective way to enable heat conduction on nearly the same level as under atmospheric pressure conditions whereby keeping the effect of the <span class="hlt">air</span> refractive index on a small level. As physics predicts, and as we have demonstrated previously, helium seems like the optimal contact gas because of its large heat conduction and its refractive index that can be calculated from precisely known parameters. On the other hand, helium gas situated in a vacuum chamber could easily be contaminated, e.g. by <span class="hlt">air</span> leakage from outside. Above the boiling point of oxygen (‑183 °C) it is therefore beneficial to use dry <span class="hlt">air</span> as a contact gas. In such an approach, the <span class="hlt">air</span> refractive index could be calculated based on measured quantities for pressure and temperature. However, existing formulas for the <span class="hlt">air</span> refractive index are not valid in the low-pressure <span class="hlt">regime</span>. Although it seems reasonable that the refractivity (n  ‑  1) of dry <span class="hlt">air</span> simply downscales with the pressure, to our knowledge there is no experimental evidence for the applicability of any empirical formula. This evidence is given in the present paper which reports on highly accurate measurements of the <span class="hlt">air</span> refractive index for the</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDQ14011T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDQ14011T"><span>Ultrahigh throughput microfluidic platform for in-<span class="hlt">air</span> production of microscale droplets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tirandazi, Pooyan; Healy, John; Hidrovo, Carlos H.</p> <p>2017-11-01</p> <p>In-<span class="hlt">air</span> droplet formation inside microfluidic networks is an alternative technique to the conventional in-liquid systems for creating uniform, microscale droplets. Recent works have highlighted and quantified the use of a gaseous continuous phase for controlled generation of droplets in the Dripping <span class="hlt">regime</span> in planar structures. Here we demonstrate a new class of non-planar droplet-based systems which rely on controlled breakup of a liquid microjet within a high speed <span class="hlt">flow</span> of <span class="hlt">air</span> inside a confined microfluidic <span class="hlt">flow</span>-focusing PDMS channel. We investigate the physics of confined gas-liquid <span class="hlt">flows</span> and the effect of geometry on the behavior of a liquid water jet in a gaseous <span class="hlt">flow</span>. Droplet breakup in the Jetting <span class="hlt">regime</span> is studied both numerically and experimentally and the results are compared. We show droplet production capability at rates higher than 100 KHz with droplets ranging from 15-30 μm in diameter and a polydispersity index of less than 15%. This work represents an important investigation into the Jetting <span class="hlt">regime</span> in confined microchannels. The ability to control jet behavior, generation rate, and droplet size in gas-liquid microflows will further expand the potential applications of this system for high throughput operations in material synthesis and biochemical analysis. We acknowledge funding support from NSF CAREER Award Grant CBET-1522841.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5397122','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5397122"><span>A Low-Power Thermal-Based Sensor System for Low <span class="hlt">Air</span> <span class="hlt">Flow</span> Detection</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Arifuzzman, AKM; Haider, Mohammad Rafiqul; Allison, David B.</p> <p>2016-01-01</p> <p>Being able to rapidly detect a low <span class="hlt">air</span> <span class="hlt">flow</span> rate with high accuracy is essential for various applications in the automotive and biomedical industries. We have developed a thermal-based low <span class="hlt">air</span> <span class="hlt">flow</span> sensor with a low-power sensor readout for biomedical applications. The thermal-based <span class="hlt">air</span> <span class="hlt">flow</span> sensor comprises a heater and three pairs of temperature sensors that sense temperature differences due to laminar <span class="hlt">air</span> <span class="hlt">flow</span>. The thermal-based <span class="hlt">flow</span> sensor was designed and simulated by using laminar <span class="hlt">flow</span>, heat transfer in solids and fluids physics in COMSOL MultiPhysics software. The proposed sensor can detect <span class="hlt">air</span> <span class="hlt">flow</span> as low as 0.0064 m/sec. The readout circuit is based on a current- controlled ring oscillator in which the output frequency of the ring oscillator is proportional to the temperature differences of the sensors. The entire readout circuit was designed and simulated by using a 130-nm standard CMOS process. The sensor circuit features a small area and low-power consumption of about 22.6 µW with an 800 mV power supply. In the simulation, the output frequency of the ring oscillator and the change in thermistor resistance showed a high linearity with an R2 value of 0.9987. The low-power dissipation, high linearity and small dimensions of the proposed <span class="hlt">flow</span> sensor and circuit make the system highly suitable for biomedical applications. PMID:28435186</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29636511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29636511"><span><span class="hlt">Regimes</span> of <span class="hlt">Flow</span> over Complex Structures of Endothelial Glycocalyx: A Molecular Dynamics Simulation Study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, Xi Zhuo; Feng, Muye; Ventikos, Yiannis; Luo, Kai H</p> <p>2018-04-10</p> <p><span class="hlt">Flow</span> patterns on surfaces grafted with complex structures play a pivotal role in many engineering and biomedical applications. In this research, large-scale molecular dynamics (MD) simulations are conducted to study the <span class="hlt">flow</span> over complex surface structures of an endothelial glycocalyx layer. A detailed structure of glycocalyx has been adopted and the <span class="hlt">flow</span>/glycocalyx system comprises about 5,800,000 atoms. Four cases involving varying external forces and modified glycocalyx configurations are constructed to reveal intricate fluid behaviour. <span class="hlt">Flow</span> profiles including temporal evolutions and spatial distributions of velocity are illustrated. Moreover, streamline length and vorticity distributions under the four scenarios are compared and discussed to elucidate the effects of external forces and glycocalyx configurations on <span class="hlt">flow</span> patterns. Results show that sugar chain configurations affect streamline length distributions but their impact on vorticity distributions is statistically insignificant, whilst the influence of the external forces on both streamline length and vorticity distributions are trivial. Finally, a <span class="hlt">regime</span> diagram for <span class="hlt">flow</span> over complex surface structures is proposed to categorise <span class="hlt">flow</span> patterns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=128826&keyword=Reddy&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=128826&keyword=Reddy&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>MODELING <span class="hlt">AIR</span> <span class="hlt">FLOW</span> DYNAMICS IN RADON MITIGATION SYSTEMS: A SIMPLIFIED APPROACH</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>The paper refines and extends an earlier study--relating to the design of optimal radon mitigation systems based on subslab depressurization-- that suggested that subslab <span class="hlt">air</span> <span class="hlt">flow</span> induced by a central suction point be treated as radial <span class="hlt">air</span> <span class="hlt">flow</span> through a porous bed contained betw...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol33/pdf/CFR-2014-title40-vol33-sec1065-240.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol33/pdf/CFR-2014-title40-vol33-sec1065-240.pdf"><span>40 CFR 1065.240 - Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span> meters.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related Measurements... interval. You may use the difference between a diluted exhaust <span class="hlt">flow</span> meter and a dilution <span class="hlt">air</span> meter to... compression-ignition engines, two-stroke spark-ignition engines, or four-stroke spark-ignition engines at or...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhCS.739a2011A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhCS.739a2011A"><span>Design and Implementation of Automatic <span class="hlt">Air</span> <span class="hlt">Flow</span> Rate Control System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Akbar, A.; Saputra, C.; Munir, M. M.; Khairurrijal</p> <p>2016-08-01</p> <p>Venturimeter is an apparatus that can be used to measure the <span class="hlt">air</span> <span class="hlt">flow</span> rate. In this experiment we designed a venturimeter which equipped with a valve that is used to control the <span class="hlt">air</span> <span class="hlt">flow</span> rate. The difference of pressure between the cross sections was measured with the differential pressure sensor GA 100-015WD which can calculate the difference of pressures from 0 to 3737.33 Pa. A 42M048C Z36 stepper motor was used to control the valve. The precision of this motor rotation is about 0.15 °. A Graphical User Interface (GUI) was developed to monitor and set the value of <span class="hlt">flow</span> rate then an 8-bit microcontroller was used to process the control system In this experiment- the venturimeter has been examined to get the optimal parameter of controller. The results show that the controller can set the stable output <span class="hlt">air</span> <span class="hlt">flow</span> rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013MS%26E...52b2040C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MS%26E...52b2040C"><span><span class="hlt">Air</span>-structure coupling features analysis of mining contra-rotating axial <span class="hlt">flow</span> fan cascade</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Q. G.; Sun, W.; Li, F.; Zhang, Y. J.</p> <p>2013-12-01</p> <p>The interaction between contra-rotating axial <span class="hlt">flow</span> fan blade and working gas has been studied by means of establishing <span class="hlt">air</span>-structure coupling control equation and combining Computational Fluid Dynamics (CFD) and Computational solid mechanics (CSM). Based on the single <span class="hlt">flow</span> channel model, the Finite Volume Method was used to make the field discrete. Additionally, the SIMPLE algorithm, the Standard k-ε model and the Arbitrary Lagrangian-Eulerian dynamic grids technology were utilized to get the airflow motion by solving the discrete governing equations. At the same time, the Finite Element Method was used to make the field discrete to solve dynamic response characteristics of blade. Based on weak coupling method, data exchange from the fluid solver and the solid solver was processed on the coupling interface. Then interpolation was used to obtain the coupling characteristics. The results showed that the blade's maximum amplitude was on the tip of the last-stage blade and aerodynamic force signal could reflect the blade working conditions to some extent. By analyzing the <span class="hlt">flow</span> <span class="hlt">regime</span> in contra-rotating axial <span class="hlt">flow</span> fan, it could be found that the vortex core region was mainly in the blade surface, the hub and the blade clearance. In those regions, the turbulence intensity was very high. The last-stage blade's operating life is shorter than that of the pre-stage blade due to the fatigue fracture occurs much more easily on the last-stage blade which bears more stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1817143S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1817143S"><span>Detailed predictions of climate induced changes in the thermal and <span class="hlt">flow</span> <span class="hlt">regimes</span> in mountain streams of the Iberian Peninsula</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Santiago, José M.; Muñoz-Mas, Rafael; García de Jalón, Diego; Solana, Joaquín; Alonso, Carlos; Martínez-Capel, Francisco; Ribalaygua, Jaime; Pórtoles, Javier; Monjo, Robert</p> <p>2016-04-01</p> <p>Streamflow and temperature <span class="hlt">regimes</span> are well-known to influence on the availability of suitable physical habitat for instream biological communities. General Circulation Models (GCMs) have predicted significant changes in timing and geographic distribution of precipitation and atmospheric temperature for the ongoing century. However, differences in these predictions may arise when focusing on different spatial and temporal scales. Therefore, to perform substantiated mitigation and management actions detailed scales are necessary to adequately forecast the consequent thermal and <span class="hlt">flow</span> <span class="hlt">regimes</span>. Regional predictions are relatively abundant but detailed ones, both spatially and temporally, are still scarce. The present study aimed at predicting the effects of climate change on the thermal and <span class="hlt">flow</span> <span class="hlt">regime</span> in the Iberian Peninsula, refining the resolution of previous studies. For this purpose, the study encompassed 28 sites at eight different mountain rivers and streams in the central part of the Iberian Peninsula (Spain). The daily <span class="hlt">flow</span> was modelled using different daily, monthly and quarterly lags of the historical precipitation and temperature time series. These precipitation-runoff models were developed by means of M5 model trees. On the other hand water temperature was modelled at similar time scale by means of nonlinear regression from dedicated site-specific data. The developed models were used to simulate the temperature and <span class="hlt">flow</span> <span class="hlt">regime</span> under two Representative Concentration Pathway (RCPs) climate change scenarios (RCP 4.5 and RCP 8.5) until the end of the present century by considering nine different GCMs, which were pertinently downscaled. The precipitation-runoff models achieved high accuracy (NSE>0.7), especially in regards of the low <span class="hlt">flows</span> of the historical series. Results concomitantly forecasted <span class="hlt">flow</span> reductions between 7 and 17 % (RCP4.5) and between 8 and 49% (RCP8.5) of the annual average in the most cases, being variable the magnitude and timing at each</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4377272','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4377272"><span>Drought-induced changes in <span class="hlt">flow</span> <span class="hlt">regimes</span> lead to long-term losses in mussel-provided ecosystem services</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vaughn, Caryn C; Atkinson, Carla L; Julian, Jason P</p> <p>2015-01-01</p> <p>Extreme hydro-meteorological events such as droughts are becoming more frequent, intense, and persistent. This is particularly true in the south central USA, where rapidly growing urban areas are running out of water and human-engineered water storage and management are leading to broad-scale changes in <span class="hlt">flow</span> <span class="hlt">regimes</span>. The Kiamichi River in southeastern Oklahoma, USA, has high fish and freshwater mussel biodiversity. However, water from this rural river is desired by multiple urban areas and other entities. Freshwater mussels are large, long-lived filter feeders that provide important ecosystem services. We ask how observed changes in mussel biomass and community composition resulting from drought-induced changes in <span class="hlt">flow</span> <span class="hlt">regimes</span> might lead to changes in river ecosystem services. We sampled mussel communities in this river over a 20-year period that included two severe droughts. We then used laboratory-derived physiological rates and river-wide estimates of species-specific mussel biomass to estimate three aggregate ecosystem services provided by mussels over this time period: biofiltration, nutrient recycling (nitrogen and phosphorus), and nutrient storage (nitrogen, phosphorus, and carbon). Mussel populations declined over 60%, and declines were directly linked to drought-induced changes in <span class="hlt">flow</span> <span class="hlt">regimes</span>. All ecosystem services declined over time and mirrored biomass losses. Mussel declines were exacerbated by human water management, which has increased the magnitude and frequency of hydrologic drought in downstream reaches of the river. Freshwater mussels are globally imperiled and declining around the world. Summed across multiple streams and rivers, mussel losses similar to those we document here could have considerable consequences for downstream water quality although lost biofiltration and nutrient retention. While we cannot control the frequency and severity of climatological droughts, water releases from reservoirs could be used to augment stream <span class="hlt">flows</span> and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvL.120t4502H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvL.120t4502H"><span><span class="hlt">Regimes</span> of Coriolis-Centrifugal Convection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Horn, Susanne; Aurnou, Jonathan M.</p> <p>2018-05-01</p> <p>Centrifugal buoyancy affects all rotating turbulent convection phenomena, but is conventionally ignored in rotating convection studies. Here, we include centrifugal buoyancy to investigate what we call Coriolis-centrifugal convection (C3 ), characterizing two so far unexplored <span class="hlt">regimes</span>, one where the <span class="hlt">flow</span> is in quasicyclostrophic balance (QC <span class="hlt">regime</span>) and another where the <span class="hlt">flow</span> is in a triple balance between pressure gradient, Coriolis and centrifugal buoyancy forces (CC <span class="hlt">regime</span>). The transition to centrifugally dominated dynamics occurs when the Froude number Fr equals the radius-to-height aspect ratio γ . Hence, turbulent convection experiments with small γ may encounter centrifugal effects at lower Fr than traditionally expected. Further, we show analytically that the direct effect of centrifugal buoyancy yields a reduction of the Nusselt number Nu. However, indirectly, it can cause a simultaneous increase of the viscous dissipation and thereby Nu through a change of the <span class="hlt">flow</span> morphology. These direct and indirect effects yield a net Nu suppression in the CC <span class="hlt">regime</span> and a net Nu enhancement in the QC <span class="hlt">regime</span>. In addition, we demonstrate that C3 may provide a simplified, yet self-consistent, model system for tornadoes, hurricanes, and typhoons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29864299','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29864299"><span><span class="hlt">Regimes</span> of Coriolis-Centrifugal Convection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Horn, Susanne; Aurnou, Jonathan M</p> <p>2018-05-18</p> <p>Centrifugal buoyancy affects all rotating turbulent convection phenomena, but is conventionally ignored in rotating convection studies. Here, we include centrifugal buoyancy to investigate what we call Coriolis-centrifugal convection (C^{3}), characterizing two so far unexplored <span class="hlt">regimes</span>, one where the <span class="hlt">flow</span> is in quasicyclostrophic balance (QC <span class="hlt">regime</span>) and another where the <span class="hlt">flow</span> is in a triple balance between pressure gradient, Coriolis and centrifugal buoyancy forces (CC <span class="hlt">regime</span>). The transition to centrifugally dominated dynamics occurs when the Froude number Fr equals the radius-to-height aspect ratio γ. Hence, turbulent convection experiments with small γ may encounter centrifugal effects at lower Fr than traditionally expected. Further, we show analytically that the direct effect of centrifugal buoyancy yields a reduction of the Nusselt number Nu. However, indirectly, it can cause a simultaneous increase of the viscous dissipation and thereby Nu through a change of the <span class="hlt">flow</span> morphology. These direct and indirect effects yield a net Nu suppression in the CC <span class="hlt">regime</span> and a net Nu enhancement in the QC <span class="hlt">regime</span>. In addition, we demonstrate that C^{3} may provide a simplified, yet self-consistent, model system for tornadoes, hurricanes, and typhoons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol19/pdf/CFR-2012-title40-vol19-sec86-313-79.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol19/pdf/CFR-2012-title40-vol19-sec86-313-79.pdf"><span>40 CFR 86.313-79 - <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>...; diesel engines. 86.313-79 Section 86.313-79 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Emission Regulations for New Gasoline-Fueled and Diesel-Fueled Heavy-Duty Engines; Gaseous Exhaust Test Procedures § 86.313-79 <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines. (a) The <span class="hlt">air</span> <span class="hlt">flow</span> measurement...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol19/pdf/CFR-2013-title40-vol19-sec86-313-79.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol19/pdf/CFR-2013-title40-vol19-sec86-313-79.pdf"><span>40 CFR 86.313-79 - <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>...; diesel engines. 86.313-79 Section 86.313-79 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Emission Regulations for New Gasoline-Fueled and Diesel-Fueled Heavy-Duty Engines; Gaseous Exhaust Test Procedures § 86.313-79 <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines. (a) The <span class="hlt">air</span> <span class="hlt">flow</span> measurement...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol18/pdf/CFR-2010-title40-vol18-sec86-313-79.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol18/pdf/CFR-2010-title40-vol18-sec86-313-79.pdf"><span>40 CFR 86.313-79 - <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>...; diesel engines. 86.313-79 Section 86.313-79 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Emission Regulations for New Gasoline-Fueled and Diesel-Fueled Heavy-Duty Engines; Gaseous Exhaust Test Procedures § 86.313-79 <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines. (a) The <span class="hlt">air</span> <span class="hlt">flow</span> measurement...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol18/pdf/CFR-2011-title40-vol18-sec86-313-79.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol18/pdf/CFR-2011-title40-vol18-sec86-313-79.pdf"><span>40 CFR 86.313-79 - <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>...; diesel engines. 86.313-79 Section 86.313-79 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY... Emission Regulations for New Gasoline-Fueled and Diesel-Fueled Heavy-Duty Engines; Gaseous Exhaust Test Procedures § 86.313-79 <span class="hlt">Air</span> <span class="hlt">flow</span> measurement specifications; diesel engines. (a) The <span class="hlt">air</span> <span class="hlt">flow</span> measurement...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol34/pdf/CFR-2013-title40-vol34-sec1065-240.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol34/pdf/CFR-2013-title40-vol34-sec1065-240.pdf"><span>40 CFR 1065.240 - Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span> meters.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related Measurements... interval. You may use the difference between a diluted exhaust <span class="hlt">flow</span> meter and a dilution <span class="hlt">air</span> meter to... compression-ignition engines, 2-stroke spark-ignition engines, and 4-stroke spark-ignition engines below 19 kW...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol33/pdf/CFR-2011-title40-vol33-sec1065-240.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title40-vol33/pdf/CFR-2011-title40-vol33-sec1065-240.pdf"><span>40 CFR 1065.240 - Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span> meters.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related Measurements... interval. You may use the difference between a diluted exhaust <span class="hlt">flow</span> meter and a dilution <span class="hlt">air</span> meter to... compression-ignition engines, 2-stroke spark-ignition engines, and 4-stroke spark-ignition engines below 19 kW...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol34/pdf/CFR-2012-title40-vol34-sec1065-240.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol34/pdf/CFR-2012-title40-vol34-sec1065-240.pdf"><span>40 CFR 1065.240 - Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span> meters.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related Measurements... interval. You may use the difference between a diluted exhaust <span class="hlt">flow</span> meter and a dilution <span class="hlt">air</span> meter to... compression-ignition engines, 2-stroke spark-ignition engines, and 4-stroke spark-ignition engines below 19 kW...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009MeScT..20k4005S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009MeScT..20k4005S"><span>Investigation and visualization of liquid-liquid <span class="hlt">flow</span> in a vertically mounted Hele-Shaw cell: <span class="hlt">flow</span> <span class="hlt">regimes</span>, velocity and shape of droplets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shad, S.; Gates, I. D.; Maini, B. B.</p> <p>2009-11-01</p> <p>The motion and shape of a liquid drop <span class="hlt">flowing</span> within a continuous, conveying liquid phase in a vertical Hele-Shaw cell were investigated experimentally. The continuous phase was more viscous and wetted the bounding walls of the Hele-Shaw cell. The gap between the Hele-Shaw plates was set equal to 0.0226 cm. Four different <span class="hlt">flow</span> <span class="hlt">regimes</span> were observed: (a) small-droplet <span class="hlt">flow</span>, (b) elongated-droplet <span class="hlt">flow</span>, (c) churn <span class="hlt">flow</span> and (d) channel <span class="hlt">flow</span>. At low capillary number, that is, when capillary forces are larger than viscous forces, the droplet shape was irregular and changed with time and distance, and it moved with lower velocity than that of the conveying phase. At higher capillary number, several different shapes of stabilized elongated and flattened drops were observed. In contrast to gas-liquid systems, the velocities of droplets are higher than that of conveying liquid. New correlations derived from dimensionless analysis and fitted to the experimental data were generated to predict the elongated-drop velocity and aspect ratio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.fs.usda.gov/treesearch/pubs/38692','TREESEARCH'); return false;" href="https://www.fs.usda.gov/treesearch/pubs/38692"><span><span class="hlt">Flow</span> <span class="hlt">regime</span>, temperature, and biotic interactions drive differential declines of trout species under climate change [includes Supporting Information</span></a></p> <p><a target="_blank" href="http://www.fs.usda.gov/treesearch/">Treesearch</a></p> <p>Seth J. Wenger; Daniel J. Isaak; Charlie Luce; Helen M. Neville; Kurt D. Fausch; Jason B. Dunham; Daniel C. Dauwalter; Michael K. Young; Marketa M. Elsner; Bruce E. Rieman; Alan F. Hamlet; Jack E. Williams</p> <p>2011-01-01</p> <p>Broad-scale studies of climate change effects on freshwater species have focused mainly on temperature, ignoring critical drivers such as <span class="hlt">flow</span> <span class="hlt">regime</span> and biotic interactions. We use downscaled outputs from general circulation models coupled with a hydrologic model to forecast the effects of altered <span class="hlt">flows</span> and increased temperatures on four interacting species of trout...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..DFDH19006A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..DFDH19006A"><span>Circumventing Imprecise Geometric Information and Development of a Unified Modeling Technique for Various <span class="hlt">Flow</span> <span class="hlt">Regimes</span> in Capillary Tubes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abbasi, Bahman</p> <p>2012-11-01</p> <p>Owing to their manufacturability and reliability, capillary tubes are the most common expansion devices in household refrigerators. Therefore, investigating <span class="hlt">flow</span> properties in the capillary tubes is of immense appeal in the said business. The models to predict pressure drop in two-phase internal <span class="hlt">flows</span> invariably rely upon highly precise geometric information. The manner in which capillary tubes are manufactured makes them highly susceptible to geometric imprecisions, which renders geometry-based models unreliable to the point of obsoleteness. Aware of the issue, manufacturers categorize capillary tubes based on Nitrogen <span class="hlt">flow</span> rate through them. This categorization method presents an opportunity to substitute geometric details with Nitrogen <span class="hlt">flow</span> data as the basis for customized models. The simulation tools developed by implementation of this technique have the singular advantage of being applicable across <span class="hlt">flow</span> <span class="hlt">regimes</span>. Thus the error-prone process of identifying compatible correlations is eliminated. Equally importantly, compressibility and chocking effects can be incorporated in the same model. The outcome is a standalone correlation that provides accurate predictions, regardless of any particular fluid or <span class="hlt">flow</span> <span class="hlt">regime</span>. Thereby, exploratory investigations for capillary tube design and optimization are greatly simplified. Bahman Abbasi, Ph.D., is Lead Advanced Systems Engineer at General Electric Appliances in Louisville, KY. He conducts research projects across disciplines in the household refrigeration industry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/1015257','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/1015257"><span>Characterizing <span class="hlt">flow</span> <span class="hlt">regimes</span> for floodplain forest conservation: An assessment of factors affecting sapling growth and survivorship on three cold desert rivers</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Andersen, D.C.</p> <p>2005-01-01</p> <p>I analyzed annual height growth and survivorship of Fremont cottonwood (Populus fremontii S. Watson) saplings on three floodplains in Colorado and Utah to assess responses to interannual variation in <span class="hlt">flow</span> <span class="hlt">regime</span> and summer precipitation. Mammal exclosures, supplemented with an insecticide treatment at one site, were used to assess <span class="hlt">flow</span> <span class="hlt">regime</span> – herbivore interactions. Multiple regression analyses on data collected over 7–11 years indicated that growth of continuously injury-free saplings was positively related to either peak discharge or the maximum 30-day discharge but was not related to interannual decline in the late-summer river stage (ΔWMIN) or precipitation. Growth was fastest where ΔWMIN was smallest and depth to the late-summer water table moderate (≤1.5 m). Survivorship increased with ΔWMIN where the water table was at shallow depths. Herbivory reduced long-term height growth and survivorship by up to 60% and 50%, respectively. The results support the concept that <span class="hlt">flow</span> history and environmental context determine whether a particular <span class="hlt">flow</span> will have a net positive or negative influence on growth and survivorship and suggest that the <span class="hlt">flow</span> <span class="hlt">regime</span> that best promotes sapling growth and survival along managed rivers features a short spring flood pulse and constant base <span class="hlt">flow</span>, with no interannual variation in the hydrograph. Because environmental contexts vary, interannual variation may be necessary for best overall stand performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA587244','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA587244"><span>Application of the Moment Method in the Slip and Transition <span class="hlt">Regime</span> for Microfluidic <span class="hlt">Flows</span></span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2011-01-01</p> <p>systems ( MEMS ), fluid <span class="hlt">flow</span> at the micro- and nano-scale has received considerable attention [1]. A basic understanding of the nature of <span class="hlt">flow</span> and heat ...Couette <span class="hlt">Flow</span> Many MEMS devices contain oscillating parts where <span class="hlt">air</span> (viscous) damping plays an important role. To understand the damping mechanisms...transfer in these devices is considered essential for efficient design and control of MEMS . Engineering applications for gas microflows include</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JThSc..26..308H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JThSc..26..308H"><span><span class="hlt">Flow</span> development through HP & LP turbines, Part II: Effects of the hub endwall secondary sealing <span class="hlt">air</span> <span class="hlt">flow</span> on the turbine's mainstream <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Jialin; Du, Qiang; Liu, Jun; Wang, Pei; Liu, Guang; Liu, Hongrui; Du, Meimei</p> <p>2017-08-01</p> <p>Although many literatures have been focused on the underneath <span class="hlt">flow</span> and loss mechanism, very few experiments and simulations have been done under the engines' representative working conditions or considering the real cavity structure as a whole. This paper aims at realizing the goal of design of efficient turbine and scrutinizing the velocity distribution in the vicinity of the rim seal. With the aid of numerical method, a numerical model describing the <span class="hlt">flow</span> pattern both in the purge <span class="hlt">flow</span> spot and within the mainstream <span class="hlt">flow</span> path is established, fluid migration and its accompanied <span class="hlt">flow</span> mechanism within the realistic cavity structure (with rim seal structure and considering mainstream & secondary <span class="hlt">air</span> <span class="hlt">flow</span>'s interaction) is used to evaluate both the <span class="hlt">flow</span> pattern and the underneath <span class="hlt">flow</span> mechanism within the inward rotating cavity. Meanwhile, the underneath <span class="hlt">flow</span> and loss mechanism are also studied in the current paper. The computational results show that the sealing <span class="hlt">air</span> <span class="hlt">flow</span>'s ingestion and ejection are highly interwound with each other in both upstream and downstream <span class="hlt">flow</span> of the rim seal. Both the down-stream blades' potential effects as well as the upstream blades' wake trajectory can bring about the ingestion of the hot gas <span class="hlt">flow</span> within the cavity, abrupt increase of the static pressure is believed to be the main reason. Also, the results indicate that sealing <span class="hlt">air</span> <span class="hlt">flow</span> ejected through the rear cavity will cause unexpected loss near the outlet section of the blades in the downstream of the HP rotor passages.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000PhDT.......483U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000PhDT.......483U"><span>Creep of Ni(3)Al in the temperature <span class="hlt">regime</span> of anomalous <span class="hlt">flow</span> behavior</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uchic, Michael David</p> <p></p> <p>Much attention has been paid to understanding the dynamics of dislocation motion and substructure formation in Ni3Al in the anomalous <span class="hlt">flow</span> <span class="hlt">regime</span>. However, most of the experimental work that has been performed in the lowest temperatures of the anomalous <span class="hlt">flow</span> <span class="hlt">regime</span> has been under constant-strain-rate conditions. An alternative and perhaps more fundamental way to probe the plastic behavior of materials is a monotonic creep test, in which the stress and temperature are held constant while the time-dependent strain is measured. The aim of this study is to use constant-stress experiments to further explore the plastic <span class="hlt">flow</span> anomaly in L12 alloys at low temperatures. Tension creep experiments have been carried out on <123> oriented single crystals of Ni75Al24Ta1 at temperatures between 293 and 473 K. We have observed primary creep leading to exhaustion at all temperatures and stresses, with creep rates declining faster than predicted by the logarithmic creep law. The total strain and creep strain have an anomalous dependence on temperature, which is consistent with the <span class="hlt">flow</span> stress anomaly. We have also observed other unusual behavior in our creep experiments; for example, the reinitiation of plastic <span class="hlt">flow</span> at low temperatures after a modest increment in applied stress shows a sigmoidal response, i.e., there is a significant time delay before the plastic strain rate accelerates to a maximum value. We also examined the ability to reinitiate plastic <span class="hlt">flow</span> in samples that have been crept to exhaustion by simply lowering the test temperature. In addition, we have also performed conventional constant-displacement-rate experiments in the same temperature range. From these experiments, we have discovered that unlike most metals, Ni3Al displays a negative dependence of the work hardening rate (WHR) with increasing strain rate. For tests at intermediate temperatures (373 and 423 K), the WHRs of crystals tested at moderately high strain rates (10-2 s-1) are half the WHRs of crystals</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21361434','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21361434"><span>Measurement of the resistivity of porous materials with an alternating <span class="hlt">air-flow</span> method.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dragonetti, Raffaele; Ianniello, Carmine; Romano, Rosario A</p> <p>2011-02-01</p> <p><span class="hlt">Air-flow</span> resistivity is a main parameter governing the acoustic behavior of porous materials for sound absorption. The international standard ISO 9053 specifies two different methods to measure the <span class="hlt">air-flow</span> resistivity, namely a steady-state <span class="hlt">air-flow</span> method and an alternating <span class="hlt">air-flow</span> method. The latter is realized by the measurement of the sound pressure at 2 Hz in a small rigid volume closed partially by the test sample. This cavity is excited with a known volume-velocity sound source implemented often with a motor-driven piston oscillating with prescribed area and displacement magnitude. Measurements at 2 Hz require special instrumentation and care. The authors suggest an alternating <span class="hlt">air-flow</span> method based on the ratio of sound pressures measured at frequencies higher than 2 Hz inside two cavities coupled through a conventional loudspeaker. The basic method showed that the imaginary part of the sound pressure ratio is useful for the evaluation of the <span class="hlt">air-flow</span> resistance. Criteria are discussed about the choice of a frequency range suitable to perform simplified calculations with respect to the basic method. These criteria depend on the sample thickness, its nonacoustic parameters, and the measurement apparatus as well. The proposed measurement method was tested successfully with various types of acoustic materials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPJWC..9202062P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPJWC..9202062P"><span>Visualization of the <span class="hlt">air</span> <span class="hlt">flow</span> behind the automotive benchmark vent</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pech, Ondrej; Jedelsky, Jan; Caletka, Petr; Jicha, Miroslav</p> <p>2015-05-01</p> <p>Passenger comfort in cars depends on appropriate function of the cabin HVAC system. A great attention is therefore paid to the effective function of automotive vents and proper formation of the <span class="hlt">flow</span> behind the ventilation outlet. The article deals with the visualization of <span class="hlt">air</span> <span class="hlt">flow</span> from the automotive benchmark vent. The visualization was made for two different shapes of the inlet channel connected to the benchmark vent. The smoke visualization with the laser knife was used. The influence of the shape of the inlet channel to the airflow direction, its enlargement and position of <span class="hlt">air</span> <span class="hlt">flow</span> axis were investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1263830-characterizing-sub-daily-flow-regimes-implications-hydrologic-resolution-ecohydrology-studies','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1263830-characterizing-sub-daily-flow-regimes-implications-hydrologic-resolution-ecohydrology-studies"><span>Characterizing Sub-Daily <span class="hlt">Flow</span> <span class="hlt">Regimes</span>: Implications of Hydrologic Resolution on Ecohydrology Studies</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Bevelhimer, Mark S.; McManamay, Ryan A.; O'Connor, B.</p> <p>2014-05-26</p> <p>Natural variability in <span class="hlt">flow</span> is a primary factor controlling geomorphic and ecological processes in riverine ecosystems. Within the hydropower industry, there is growing pressure from environmental groups and natural resource managers to change reservoir releases from daily peaking to run-of-river operations on the basis of the assumption that downstream biological communities will improve under a more natural <span class="hlt">flow</span> <span class="hlt">regime</span>. In this paper, we discuss the importance of assessing sub-daily <span class="hlt">flows</span> for understanding the physical and ecological dynamics within river systems. We present a variety of metrics for characterizing sub-daily <span class="hlt">flow</span> variation and use these metrics to evaluate general trends amongmore » streams affected by peaking hydroelectric projects, run-of-river projects and streams that are largely unaffected by <span class="hlt">flow</span> altering activities. Univariate and multivariate techniques were used to assess similarity among different stream types on the basis of these sub-daily metrics. For comparison, similar analyses were performed using analogous metrics calculated with mean daily <span class="hlt">flow</span> values. Our results confirm that sub-daily <span class="hlt">flow</span> metrics reveal variation among and within streams that are not captured by daily <span class="hlt">flow</span> statistics. Using sub-daily <span class="hlt">flow</span> statistics, we were able to quantify the degree of difference between unaltered and peaking streams and the amount of similarity between unaltered and run-of-river streams. The sub-daily statistics were largely uncorrelated with daily statistics of similar scope. Furthermore, on short temporal scales, sub-daily statistics reveal the relatively constant nature of unaltered streamreaches and the highly variable nature of hydropower-affected streams, whereas daily statistics show just the opposite over longer temporal scales.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040053536','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040053536"><span>Flamelet Formation In Hele-Shaw <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wichman, I. S.; Olson, S. L.</p> <p>2003-01-01</p> <p>A Hele-Shaw <span class="hlt">flow</span> apparatus constructed at Michigan State University (MSU) produces conditions that reduce influences of buoyancy-driven <span class="hlt">flows</span>. In addition, in the MSU Hele-Shaw apparatus it is possible to adjust the heat losses from the fuel sample (0.001 in. thick cellulose) and the <span class="hlt">flow</span> speed of the approaching oxidizer <span class="hlt">flow</span> (<span class="hlt">air</span>) so that the "flamelet <span class="hlt">regime</span> of flame spread" is entered. In this <span class="hlt">regime</span> various features of the flame-to-smolder (and vice versa) transition can be studied. For the relatively wide (approx. 17.5 cm) and long (approx. 20 cm) samples used, approximately ten flamelets existed at all times. The flamelet behavior was studied mechanistically and statistically. A heat transfer analysis of the dominant heat transfer mechanisms was conducted. Results indicate that radiation and conduction processes are important, and that a simple 1-D model using the Broido-Shafizadeh model for cellulose decomposition chemistry can describe aspects of the flamelet spread process. Introduction</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930091863','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930091863"><span>Intercooler cooling-<span class="hlt">air</span> weight <span class="hlt">flow</span> and pressure drop for minimum drag loss</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reuter, J George; Valerino, Michael F</p> <p>1944-01-01</p> <p>An analysis has been made of the drag losses in airplane flight of cross-<span class="hlt">flow</span> plate and tubular intercoolers to determine the cooling-<span class="hlt">air</span> weight <span class="hlt">flow</span> and pressure drop that give a minimum drag loss for any given cooling effectiveness and, thus, a maximum power-plant net gain due to charge-<span class="hlt">air</span> cooling. The drag losses considered in this analysis are those due to (1) the extra drag imposed on the airplane by the weight of the intercooler, its duct, and its supports and (2) the drag sustained by the cooling <span class="hlt">air</span> in <span class="hlt">flowing</span> through the intercooler and its duct. The investigation covers a range of conditions of altitude, airspeed, lift-drag ratio, supercharger-pressure ratio, and supercharger adiabatic efficiency. The optimum values of cooling <span class="hlt">air</span> pressure drop and weight <span class="hlt">flow</span> ratio are tabulated. Curves are presented to illustrate the results of the analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16083119','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16083119"><span>Groundwater remediation engineering sparging using acetylene--study on the <span class="hlt">flow</span> distribution of <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zheng, Yan-Mei; Zhang, Ying; Huang, Guo-Qiang; Jiang, Bin; Li, Xin-Gang</p> <p>2005-01-01</p> <p><span class="hlt">Air</span> sparging (AS) is an emerging method to remove VOCs from saturated soils and groundwater. <span class="hlt">Air</span> sparging performance highly depends on the <span class="hlt">air</span> distribution resulting in the aquifer. In order to study gas <span class="hlt">flow</span> characterization, a two-dimensional experimental chamber was designed and installed. In addition, the method by using acetylene as the tracer to directly image the gas distribution results of AS process has been put forward. Experiments were performed with different injected gas <span class="hlt">flow</span> rates. The gas <span class="hlt">flow</span> patterns were found to depend significantly on the injected gas <span class="hlt">flow</span> rate, and the characterization of gas <span class="hlt">flow</span> distributions in porous media was very different from the acetylene tracing study. Lower and higher gas <span class="hlt">flow</span> rates generally yield more irregular in shape and less effective gas distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840025341','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840025341"><span>An experimental investigation of gas jets in confined swirling <span class="hlt">air</span> <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mongia, H.; Ahmed, S. A.; Mongia, H. C.</p> <p>1984-01-01</p> <p>The fluid dynamics of jets in confined swirling <span class="hlt">flows</span> which is of importance to designers of turbine combustors and solid fuel ramjets used to power missiles fired from cannons were examined. The fluid dynamics of gas jets of different densities in confined swirling <span class="hlt">flows</span> were investigated. Mean velocity and turbulence measurements are made with a one color, one component laser velocimeter operating in the forward scatter mode. It is shown that jets in confined <span class="hlt">flow</span> with large area ratio are highly dissipative which results in both <span class="hlt">air</span> and helium/<span class="hlt">air</span> jet centerline velocity decays. For <span class="hlt">air</span> jets, the jet like behavior in the tube center disappears at about 20 diameters downstream of the jet exit. This phenomenon is independent of the initial jet velocity. The turbulence field at this point also decays to that of the background swirling <span class="hlt">flow</span>. A jet like behavior in the tube center is noticed even at 40 diameters for the helium/<span class="hlt">air</span> jets. The subsequent <span class="hlt">flow</span> and turbulence field depend highly on the initial jet velocity. The jets are fully turbulent, and the cause of this difference in behavior is attributed to the combined action swirl and density difference. This observation can have significant impact on the design of turbine combustors and solid fuel ramjets subject to spin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70148485','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70148485"><span>Influence of channel morphology and <span class="hlt">flow</span> <span class="hlt">regime</span> on larval drift of pallid sturgeon in the Lower Missouri River</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Erwin, Susannah O.; Jacobson, Robert B.</p> <p>2015-01-01</p> <p>The transition from drifting free embryo to exogenously feeding larvae has been identified as a potential life-stage bottleneck for the endangered Missouri River pallid sturgeon. Previous studies have indicated that river regulation and fragmentation may contribute to the mortality of larval pallid sturgeon by reducing the extent of free-<span class="hlt">flowing</span> river available to free embryos to complete ontogenetic development. Calculations of total drift distance based on mean velocity, however, do not address the potential for complex channels and <span class="hlt">flow</span> patterns to increase retention or longitudinal dispersion of free embryos. We use a one-dimensional advection–dispersion model to estimate total drift distance and employ the longitudinal dispersion coefficient as a metric to quantify the tendency towards dispersion or retention of passively drifting larvae. We describe the effects of different styles of channel morphology on larval dispersion and consider the implications of <span class="hlt">flow</span> <span class="hlt">regime</span> modifications on retention of free embryos within the Lower Missouri River. The results illustrate the complex interactions of local morphology, engineered structures, and hydraulics that determine patterns of dispersion in riverine environments and inform how changes to channel morphology and <span class="hlt">flow</span> <span class="hlt">regime</span> may alter dispersion of drifting organisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.891a2054T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.891a2054T"><span>Gas dynamics and mixture formation in swirled <span class="hlt">flows</span> with precession of <span class="hlt">air</span> <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tretyakov, V. V.; Sviridenkov, A. A.</p> <p>2017-10-01</p> <p>The effect of precessing <span class="hlt">air</span> <span class="hlt">flow</span> on the processes of mixture formation in the wake of the front winding devices of the combustion chambers is considered. Visual observations have shown that at different times the shape of the atomized jet is highly variable and has signs of precessing motion. The experimental data on the distribution of the velocity and concentration fields of the droplet fuel in the working volume of the flame tube of a typical combustion chamber are obtained. The method of calculating <span class="hlt">flows</span> consisted in integrating the complete system of Reynolds equations written in Euler variables and closed with the two-parameter model of turbulence k-ε. Calculation of the concentration fields of droplet and vapor fuel is based on the use of models for disintegration into droplets of fuel jets, fragmentation of droplets and analysis of motion and evaporation of individual droplets in the <span class="hlt">air</span> <span class="hlt">flow</span>. Comparison of the calculation results with experimental data showed their good agreement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/513622','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/513622"><span>The fabrication of plastic cages for suspension in mass <span class="hlt">air</span> <span class="hlt">flow</span> racks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nielsen, F H; Bailey, B</p> <p>1979-08-01</p> <p>A cage for suspension in mass <span class="hlt">air</span> <span class="hlt">flow</span> racks was constructed of plastic and used to house rats. Little or no difficulty was encountered with the mass <span class="hlt">air</span> <span class="hlt">flow</span> rack-suspended cage system during the 4 years it was used for the study of trace elements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.H41F1050S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.H41F1050S"><span>Tracing Nitrate Contributions to Streams During Varying <span class="hlt">Flow</span> <span class="hlt">Regimes</span> at the Sleepers River Research Watershed, Vermont, USA</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sebestyen, S. D.; Shanley, J. B.; Boyer, E. W.; Ohte, N.; Doctor, D. H.; Kendall, C.</p> <p>2003-12-01</p> <p>Quantifying sources and transformations of nitrate in headwater catchments is fundamental to understanding the movement of nitrogen to streams. At the Sleepers River Research Watershed in northeastern Vermont (USA), we are using multiple chemical tracer and mixing model approaches to quantify sources and transport of nitrate to streams under varying <span class="hlt">flow</span> <span class="hlt">regimes</span>. We sampled streams, lysimeters, and wells at nested locations from the headwaters to the outlet of the 41 ha W-9 watershed under the entire range of <span class="hlt">flow</span> <span class="hlt">regimes</span> observed throughout 2002-2003, including baseflow and multiple events (stormflow and snowmelt). Our results suggest that nitrogen sources, and consequently stream nitrate concentrations, are rapidly regenerated during several weeks of baseflow and nitrogen is flushed from the watershed by stormflow events that follow baseflow periods. Both basic chemistry data (anions, cations, & dissolved organic carbon) and isotopic data (nitrate, dissolved organic carbon, and dissolved inorganic carbon) indicate that nitrogen source contributions vary depending upon the extent of saturation in the watershed, the initiation of shallow subsurface water inputs, and other hydrological processes. Stream nitrate concentrations typically peak with discharge and are higher on the falling than the rising limb of the hydrograph. Our data also indicate the importance of terrestrial and aquatic biogeochemical processes, in addition to hydrological connectivity in controlling how nitrate moves from the terrestrial landscape to streams. Our detailed sampling data from multiple <span class="hlt">flow</span> <span class="hlt">regimes</span> are helping to identify and quantify the "hot spots" and "hot moments" of biogeochemical and hydrological processes that control nitrogen fluxes in streams.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006SedG..190..227F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006SedG..190..227F"><span>Upper <span class="hlt">flow</span> <span class="hlt">regime</span> sheets, lenses and scour fills: Extending the range of architectural elements for fluvial sediment bodies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fielding, Christopher R.</p> <p>2006-08-01</p> <p>Fluvial strata dominated internally by sedimentary structures of interpreted upper <span class="hlt">flow</span> <span class="hlt">regime</span> origin are moderately common in the rock record, yet their abundance is not appreciated and many examples may go unnoticed. A spectrum of sedimentary structures is recognised, all of which occur over a wide range of scale: 1. cross-bedding with humpback, sigmoidal and ultimately low-angle cross-sectional foreset geometries (interpreted as recording the transition from dune to upper plane bed bedform stability field), 2. planar/flat lamination with parting lineation, characteristic of the upper plane bed phase, 3. flat and low-angle lamination with minor convex-upward elements, characteristic of the transition from upper plane bed to antidune stability fields, 4. convex-upward bedforms, down- and up-palaeocurrent-dipping, low-angle cross-bedding and symmetrical drapes, interpreted as the product of antidunes, and 5. backsets terminating updip against an upstream-dipping erosion surface, interpreted as recording chute and pool conditions. In some fluvial successions, the entirety or substantial portions of channel sandstone bodies may be made up of such structures. These Upper <span class="hlt">Flow</span> <span class="hlt">Regime</span> Sheets, Lenses and Scour Fills (UFR) are defined herein as an extension of Miall's [Miall, A.D., 1985. Architectural-element analysis: a new method of facies analysis applied to fluvial deposits. Earth Sci. Rev. 22: 261-308.] Laminated Sand Sheets architectural element. Given the conditions that favour preservation of upper <span class="hlt">flow</span> <span class="hlt">regime</span> structures (rapid changes in <span class="hlt">flow</span> strength), it is suggested that the presence of UFR elements in ancient fluvial successions may indicate sediment accumulation under the influence of a strongly seasonal palaeoclimate that involves a pronounced seasonal peak in precipitation and runoff.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22390593-gas-kinetic-unified-algorithm-hypersonic-flows-covering-various-flow-regimes-solving-boltzmann-model-equation-nonequilibrium-effect','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22390593-gas-kinetic-unified-algorithm-hypersonic-flows-covering-various-flow-regimes-solving-boltzmann-model-equation-nonequilibrium-effect"><span>Gas-kinetic unified algorithm for hypersonic <span class="hlt">flows</span> covering various <span class="hlt">flow</span> <span class="hlt">regimes</span> solving Boltzmann model equation in nonequilibrium effect</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Li, Zhihui; Ma, Qiang; Wu, Junlin</p> <p>2014-12-09</p> <p>Based on the Gas-Kinetic Unified Algorithm (GKUA) directly solving the Boltzmann model equation, the effect of rotational non-equilibrium is investigated recurring to the kinetic Rykov model with relaxation property of rotational degrees of freedom. The spin movement of diatomic molecule is described by moment of inertia, and the conservation of total angle momentum is taken as a new Boltzmann collision invariant. The molecular velocity distribution function is integrated by the weight factor on the internal energy, and the closed system of two kinetic controlling equations is obtained with inelastic and elastic collisions. The optimization selection technique of discrete velocity ordinatemore » points and numerical quadrature rules for macroscopic <span class="hlt">flow</span> variables with dynamic updating evolvement are developed to simulate hypersonic <span class="hlt">flows</span>, and the gas-kinetic numerical scheme is constructed to capture the time evolution of the discretized velocity distribution functions. The gas-kinetic boundary conditions in thermodynamic non-equilibrium and numerical procedures are studied and implemented by directly acting on the velocity distribution function, and then the unified algorithm of Boltzmann model equation involving non-equilibrium effect is presented for the whole range of <span class="hlt">flow</span> <span class="hlt">regimes</span>. The hypersonic <span class="hlt">flows</span> involving non-equilibrium effect are numerically simulated including the inner <span class="hlt">flows</span> of shock wave structures in nitrogen with different Mach numbers of 1.5-Ma-25, the planar ramp <span class="hlt">flow</span> with the whole range of Knudsen numbers of 0.0009-Kn-10 and the three-dimensional re-entering <span class="hlt">flows</span> around tine double-cone body.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950019279','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950019279"><span>Hot-wire calibration in subsonic/transonic <span class="hlt">flow</span> <span class="hlt">regimes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nagabushana, K. A.; Ash, Robert L.</p> <p>1995-01-01</p> <p>A different approach for calibrating hot-wires, which simplifies the calibration procedure and reduces the tunnel run-time by an order of magnitude was sought. In general, it is accepted that the directly measurable quantities in any <span class="hlt">flow</span> are velocity, density, and total temperature. Very few facilities have the capability of varying the total temperature over an adequate range. However, if the overheat temperature parameter, a(sub w), is used to calibrate the hot-wire then the directly measurable quantity, voltage, will be a function of the <span class="hlt">flow</span> variables and the overheat parameter i.e., E = f(u,p,a(sub w), T(sub w)) where a(sub w) will contain the needed total temperature information. In this report, various methods of evaluating sensitivities with different dependent and independent variables to calibrate a 3-Wire hot-wire probe using a constant temperature anemometer (CTA) in subsonic/transonic <span class="hlt">flow</span> <span class="hlt">regimes</span> is presented. The advantage of using a(sub w) as the independent variable instead of total temperature, t(sub o), or overheat temperature parameter, tau, is that while running a calibration test it is not necessary to know the recovery factor, the coefficients in a wire resistance to temperature relationship for a given probe. It was deduced that the method employing the relationship E = f (u,p,a(sub w)) should result in the most accurate calibration of hot wire probes. Any other method would require additional measurements. Also this method will allow calibration and determination of accurate temperature fluctuation information even in atmospheric wind tunnels where there is no ability to obtain any temperature sensitivity information at present. This technique greatly simplifies the calibration process for hot-wires, provides the required calibration information needed in obtaining temperature fluctuations, and reduces both the tunnel run-time and the test matrix required to calibrate hotwires. Some of the results using the above techniques are presented</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HMT....54..353L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HMT....54..353L"><span>Recognition and measurement gas-liquid two-phase <span class="hlt">flow</span> in a vertical concentric annulus at high pressures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Hao; Sun, Baojiang; Guo, Yanli; Gao, Yonghai; Zhao, Xinxin</p> <p>2018-02-01</p> <p>The <span class="hlt">air</span>-water <span class="hlt">flow</span> characteristics under pressure in the range of 1-6 MPa in a vertical annulus were evaluated in this report. Time-resolved bubble rising velocity and void fraction were also measured using an electrical void fraction meter. The results showed that the pressure has remarkable effect on the density, bubble size and rise velocity of the gas. Four <span class="hlt">flow</span> patterns (bubble, cap-bubble, cap-slug, and churn) were also observed instead of Taylor bubble at high pressure. Additionally, the transition process from bubble to cap-bubble was investigated at atmospheric and high pressures, respectively. The results revealed that the <span class="hlt">flow</span> <span class="hlt">regime</span> transition criteria for atmospheric pressure do not work at high pressure, hence a new <span class="hlt">flow</span> <span class="hlt">regime</span> transition model for annular <span class="hlt">flow</span> channel geometry was developed to predict the <span class="hlt">flow</span> <span class="hlt">regime</span> transition, which thereafter exhibited high accuracy at high pressure condition.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1210133Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1210133Z"><span><span class="hlt">Air</span>-sea fluxes of momentum and mass in the presence of wind waves</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zülicke, Christoph</p> <p>2010-05-01</p> <p>An <span class="hlt">air</span>-sea interaction model (ASIM) is developed including the effect of wind waves on momentum and mass transfer. This includes the derivation of profiles of dissipation rate, <span class="hlt">flow</span> speed and concentration from a certain height to a certain depth. Simplified assumptions on the turbulent closure, skin - bulk matching and the spectral wave model allow for an analytic treatment. Particular emphasis was put on the inclusion of primary (gravity) waves and secondary (capillary-gravity) waves. The model was tuned to match wall-<span class="hlt">flow</span> theory and data on wave height and slope. Growing waves reduce the <span class="hlt">air</span>-side turbulent stress and lead to an increasing drag coefficient. In the sea, breaking waves inject turbulent kinetic energy and accelerate the transfer. Cross-reference with data on wave-related momentum and energy flux, dissipation rate and transfer velocity was sufficient. The evaluation of ASIM allowed for the analytical calculation of bulk formulae for the wind-dependent gas transfer velocity including information on the <span class="hlt">air</span>-side momentum transfer (drag coefficient) and the sea-side gas transfer (Dalton number). The following <span class="hlt">regimes</span> have been identified: the smooth waveless <span class="hlt">regime</span> with a transfer velocity proportional to (wind) × (diffusion)2-3, the primary wave <span class="hlt">regime</span> with a wind speed dependence proportional to (wind)1-4 × (diffusion)1-2-(waveage)1-4 and the secondary wave <span class="hlt">regime</span> including a more-than-linear wind speed dependence like (wind)15-8 × (diffusion)1-2 × (waveage)5-8. These findings complete the current understanding of <span class="hlt">air</span>-sea interaction for medium winds between 2 and 20 m s^-1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvE..97c2404S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvE..97c2404S"><span>Effect of ac electric field on the dynamics of a vesicle under shear <span class="hlt">flow</span> in the small deformation <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sinha, Kumari Priti; Thaokar, Rochish M.</p> <p>2018-03-01</p> <p>Vesicles or biological cells under simultaneous shear and electric field can be encountered in dielectrophoretic devices or designs used for continuous <span class="hlt">flow</span> electrofusion or electroporation. In this work, the dynamics of a vesicle subjected to simultaneous shear and uniform alternating current (ac) electric field is investigated in the small deformation limit. The coupled equations for vesicle orientation and shape evolution are derived theoretically, and the resulting nonlinear equations are handled numerically to generate relevant phase diagrams that demonstrate the effect of electrical parameters on the different dynamical <span class="hlt">regimes</span> such as tank treading (TT), vacillating breathing (VB) [called trembling (TR) in this work], and tumbling (TU). It is found that while the electric Mason number (Mn), which represents the relative strength of the electrical forces to the shear forces, promotes the TT <span class="hlt">regime</span>, the response itself is found to be sensitive to the applied frequency as well as the conductivity ratio. While higher outer conductivity promotes orientation along the <span class="hlt">flow</span> axis, orientation along the electric field is favored when the inner conductivity is higher. Similarly a switch of orientation from the direction of the electric field to the direction of <span class="hlt">flow</span> is possible by a mere change of frequency when the outer conductivity is higher. Interestingly, in some cases, a coupling between electric field-induced deformation and shear can result in the system admitting an intermediate TU <span class="hlt">regime</span> while attaining the TT <span class="hlt">regime</span> at high Mn. The results could enable designing better dielectrophoretic devices wherein the residence time as well as the dynamical states of the vesicular suspension can be controlled as per the application.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/32616','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/32616"><span>Big data analytics : predicting traffic <span class="hlt">flow</span> <span class="hlt">regimes</span> from simulated connected vehicle messages using data analytics and machine learning.</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>2016-12-25</p> <p>The key objectives of this study were to: 1. Develop advanced analytical techniques that make use of a dynamically configurable connected vehicle message protocol to predict traffic <span class="hlt">flow</span> <span class="hlt">regimes</span> in near-real time in a virtual environment and examine ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/866433','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/866433"><span>Split-<span class="hlt">flow</span> regeneration in absorptive <span class="hlt">air</span> separation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Weimer, Robert F.</p> <p>1987-01-01</p> <p>A chemical absorptive separation of <span class="hlt">air</span> in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent <span class="hlt">flow</span>, reduced energy demand and reduced capital costs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvF...3b4101D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvF...3b4101D"><span>Direct numerical simulation of a compressible boundary-layer <span class="hlt">flow</span> past an isolated three-dimensional hump in a high-speed subsonic <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>De Grazia, D.; Moxey, D.; Sherwin, S. J.; Kravtsova, M. A.; Ruban, A. I.</p> <p>2018-02-01</p> <p>In this paper we study the boundary-layer separation produced in a high-speed subsonic boundary layer by a small wall roughness. Specifically, we present a direct numerical simulation (DNS) of a two-dimensional boundary-layer <span class="hlt">flow</span> over a flat plate encountering a three-dimensional Gaussian-shaped hump. This work was motivated by the lack of DNS data of boundary-layer <span class="hlt">flows</span> past roughness elements in a similar <span class="hlt">regime</span> which is typical of civil aviation. The Mach and Reynolds numbers are chosen to be relevant for aeronautical applications when considering small imperfections at the leading edge of wings. We analyze different heights of the hump: The smaller heights result in a weakly nonlinear <span class="hlt">regime</span>, while the larger result in a fully nonlinear <span class="hlt">regime</span> with an increasing laminar separation bubble arising downstream of the roughness element and the formation of a pair of streamwise counterrotating vortices which appear to support themselves.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010WRR....46.7533T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010WRR....46.7533T"><span>Restoring a <span class="hlt">flow</span> <span class="hlt">regime</span> through the coordinated operation of a multireservoir system: The case of the Zambezi River basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tilmant, A.; Beevers, L.; Muyunda, B.</p> <p>2010-07-01</p> <p>Large storage facilities in hydropower-dominated river basins have traditionally been designed and managed to maximize revenues from energy generation. In an attempt to mitigate the externalities downstream due to a reduction in <span class="hlt">flow</span> fluctuation, minimum <span class="hlt">flow</span> requirements have been imposed to reservoir operators. However, it is now recognized that a varying <span class="hlt">flow</span> <span class="hlt">regime</span> including <span class="hlt">flow</span> pulses provides the best conditions for many aquatic ecosystems. This paper presents a methodology to derive a trade-off relationship between hydropower generation and ecological preservation in a system with multiple reservoirs and stochastic inflows. Instead of imposing minimum <span class="hlt">flow</span> requirements, the method brings more flexibility to the allocation process by building upon environmental valuation studies to derive simple demand curves for environmental goods and services, which are then used in a reservoir optimization model together with the demand for energy. The objective here is not to put precise monetary values on environmental <span class="hlt">flows</span> but to see the marginal changes in release policies should those values be considered. After selecting appropriate risk indicators for hydropower generation and ecological preservation, the trade-off curve provides a concise way of exploring the extent to which one of the objectives must be sacrificed in order to achieve more of the other. The methodology is illustrated with the Zambezi River basin where large man-made reservoirs have disrupted the hydrological <span class="hlt">regime</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29727951','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29727951"><span>Highlighting the importance of transitional ventilation <span class="hlt">regimes</span> in the management of Mediterranean show caves (Nerja-Pintada system, southern Spain).</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liñán, C; Del Rosal, Y; Carrasco, F; Vadillo, I; Benavente, J; Ojeda, L</p> <p>2018-08-01</p> <p>This study shows the utilization of the <span class="hlt">air</span> CO 2 exhaled by a very high number of visitors in the Nerja Cave as both a tracer and an additional tool to precisely evaluate the <span class="hlt">air</span> circulation through the entire karst system, which includes non-touristic passages, originally free of anthropogenic CO 2 . The analysis of the temporal - spatial evolution of the CO 2 content and other monitoring data measured from January 2015 to December 2016 in the Nerja-Pintada system, including <span class="hlt">air</span> microbiological controls, has allowed us to define a new general ventilation model, of great interest for the conservation of the subterranean environment. During the annual cycle four different ventilation <span class="hlt">regimes</span> and two ventilation modes (UAF-mode and DAF-mode) exist which determine the significance of the anthropogenic impact within the caves. During the winter <span class="hlt">regime</span>, the strong ventilation <span class="hlt">regime</span> and the airflow directions from the lowest to the highest entrance (UAF-mode) contribute to the rapid elimination of anthropogenic CO 2 , and this affects the whole karstic system. During the summer <span class="hlt">regime</span> the DAF-mode ventilation (with airflows from the highest to the lowest entrances) is activated. Although the number of visitors is maximum and the natural ventilation of the karstic system is the lowest of the annual cycle, the anthropogenic impact only affects the Tourist Galleries. The transitional ventilation <span class="hlt">regimes</span> -spring and autumn- are the most complex of the annual cycle, with changing <span class="hlt">air-flow</span> directions (from UAF-mode to DAF-mode and vice versa) at diurnal and poly diurnal scale, which conditions the range of the anthropogenic impact in each sector of the karst system. The activation of the DAF-mode has been observed when the temperature difference between the external and <span class="hlt">air</span> cave is higher than 5°C. Copyright © 2018 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS.992a2005B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS.992a2005B"><span>Schlieren <span class="hlt">flow</span> visualization of helium atmospheric plasma jet and influence of the gas <span class="hlt">flow</span> rate and applied voltage frequency</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borghei, S. M.; Vaziri, N.; Alibabaei, S.</p> <p>2018-03-01</p> <p>We used schlieren photography to visualize the influence of gas <span class="hlt">flow</span> rates of 1, 2.5, 5, 10 L/min and of the applied voltage frequency on a helium atmospheric plasma jet induced at the nozzle of a capillary tube. The expansion of the gas in the surrounding medium (<span class="hlt">air</span>) was analyzed in the two different modes – plasma on/plasma off. Changes in the above parameters affect the gas <span class="hlt">flow</span> <span class="hlt">regime</span> and the hydrodynamics of the jet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009APS..DFD.PW010P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009APS..DFD.PW010P"><span>Effects of <span class="hlt">flow</span> on insulin fibril formation at an <span class="hlt">air</span>/water interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Posada, David; Heldt, Caryn; Sorci, Mirco; Belfort, Georges; Hirsa, Amir</p> <p>2009-11-01</p> <p>The amyloid fibril formation process, which is implicated in several diseases such as Alzheimer's and Huntington's, is characterized by the conversion of monomers to oligomers and then to fibrils. Besides well-studied factors such as pH, temperature and concentration, the kinetics of this process are significantly influenced by the presence of solid or fluid interfaces and by <span class="hlt">flow</span>. By studying the nucleation and growth of a model system (insulin fibrils) in a well-defined <span class="hlt">flow</span> field with an <span class="hlt">air</span>/water interface, we can identify the <span class="hlt">flow</span> conditions that impact protein aggregation kinetics both in the bulk solution and at the <span class="hlt">air</span>/water interface. The present <span class="hlt">flow</span> system (deep-channel surface viscometer) consists of an annular region bounded by stationary inner and outer cylinders, an <span class="hlt">air</span>/water interface, and a floor driven at constant rotation. We show the effects of Reynolds number on the kinetics of the fibrillation process both in the bulk solution and at the <span class="hlt">air</span>/water interface, as well as on the structure of the resultant amyloid aggregates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=126363&keyword=Reddy&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=126363&keyword=Reddy&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>SIMPLIFIED MODELING OF <span class="hlt">AIR</span> <span class="hlt">FLOW</span> DYNAMICS IN SSD RADON MITIGATION SYSTEMS FOR RESIDENCES WITH GRAVEL BEDS</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>In an attempt to better understand the dynamics of subslab <span class="hlt">air</span> <span class="hlt">flow</span>, the report suggests that subslab <span class="hlt">air</span> <span class="hlt">flow</span> induced by a central suction point be treated as radial <span class="hlt">air</span> <span class="hlt">flow</span> through a porous bed contained between two impermeable disks. (NOTE: Many subslab depressurization syste...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25242150','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25242150"><span><span class="hlt">Flow</span> <span class="hlt">regime</span> in a restored wetland determines trophic links and species composition in the aquatic macroinvertebrate community.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>González-Ortegón, E; Walton, M E M; Moghaddam, B; Vilas, C; Prieto, A; Kennedy, H A; Pedro Cañavate, J; Le Vay, L</p> <p>2015-01-15</p> <p>In a restored wetland (South of Spain), where different <span class="hlt">flow</span> <span class="hlt">regimes</span> control water exchange with the adjacent Guadalquivir estuary, the native Palaemon varians coexists with an exotic counterpart species Palaemon macrodactylus. This controlled m\\acrocosm offers an excellent opportunity to investigate how the effects of water management, through different <span class="hlt">flow</span> <span class="hlt">regimes</span>, and the presence of a non-native species affect the aquatic community and the trophic niche (by gut contents and C-N isotopic composition) of the native shrimp Palaemon varians. We found that increased water exchange rate (5% day(-1) in mixed ponds vs. 0.1% day(-1) in extensive ponds) modified the aquatic community of this wetland; while extensive ponds are dominated by isopods and amphipods with low presence of P. macrodactylus, mixed ponds presented high biomass of mysids, corixids, copepods and both shrimp species. An estuarine origin of nutrients and primary production might explain seasonal and spatial differences found among ponds of this wetland. A combined analysis of gut contents and isotopic composition of the native and the exotic species showed that: (1) native P. varians is mainly omnivorous (2) while the non-native P. macrodactylus is more zooplanktivorous and (3) a dietary overlap occurred when both species coexist at mixed ponds where a higher water exchange and high abundance of mysids and copepods diversifies the native species' diet. Thus differences in the trophic ecology of both species are clearly explained by water management. This experimental study is a valuable tool for integrated management between river basin and wetlands since it allows quantification of wetland community changes in response to the <span class="hlt">flow</span> <span class="hlt">regime</span>. Copyright © 2014 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015RScI...86g5103Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015RScI...86g5103Z"><span>Time-resolved fast-neutron radiography of <span class="hlt">air</span>-water two-phase <span class="hlt">flows</span> in a rectangular channel by an improved detection system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zboray, Robert; Dangendorf, Volker; Mor, Ilan; Bromberger, Benjamin; Tittelmeier, Kai</p> <p>2015-07-01</p> <p>In a previous work, we have demonstrated the feasibility of high-frame-rate, fast-neutron radiography of generic <span class="hlt">air</span>-water two-phase <span class="hlt">flows</span> in a 1.5 cm thick, rectangular <span class="hlt">flow</span> channel. The experiments have been carried out at the high-intensity, white-beam facility of the Physikalisch-Technische Bundesanstalt, Germany, using an multi-frame, time-resolved detector developed for fast neutron resonance radiography. The results were however not fully optimal and therefore we have decided to modify the detector and optimize it for the given application, which is described in the present work. Furthermore, we managed to improve the image post-processing methodology and the noise suppression. Using the tailored detector and the improved post-processing, significant increase in the image quality and an order of magnitude lower exposure times, down to 3.33 ms, have been achieved with minimized motion artifacts. Similar to the previous study, different two-phase <span class="hlt">flow</span> <span class="hlt">regimes</span> such as bubbly slug and churn <span class="hlt">flows</span> have been examined. The enhanced imaging quality enables an improved prediction of two-phase <span class="hlt">flow</span> parameters like the instantaneous volumetric gas fraction, bubble size, and bubble velocities. Instantaneous velocity fields around the gas enclosures can also be more robustly predicted using optical <span class="hlt">flow</span> methods as previously.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol34/pdf/CFR-2012-title40-vol34-sec1065-225.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title40-vol34/pdf/CFR-2012-title40-vol34-sec1065-225.pdf"><span>40 CFR 1065.225 - Intake-<span class="hlt">air</span> <span class="hlt">flow</span> meter.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-07-01</p> <p>... concentrations, if the same signal is used in a chemical-balance calculation to determine work from brake... tube, or a hot-wire anemometer. Note that your overall system for measuring intake-<span class="hlt">air</span> <span class="hlt">flow</span> must meet...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/7152233','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/7152233"><span>Split-<span class="hlt">flow</span> regeneration in absorptive <span class="hlt">air</span> separation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Weimer, R.F.</p> <p>1987-11-24</p> <p>A chemical absorptive separation of <span class="hlt">air</span> in multiple stage of absorption and desorption is performed with partial recycle of absorbent between stages of desorption necessary to match equilibrium conditions in the various stages of absorption. This allows reduced absorbent <span class="hlt">flow</span>, reduced energy demand and reduced capital costs. 4 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-MSFC-1701359.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-MSFC-1701359.html"><span>Boeing engineers perform <span class="hlt">air</span> <span class="hlt">flow</span> balance testing.</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2017-10-05</p> <p>Boeing engineers, Chris Chapman, left, Greg Clark, center, and Ashesh Patel, right, perform <span class="hlt">air</span> <span class="hlt">flow</span> balance testing on NASA's new Basic Express Racks. The racks, developed at Marshall, will expand the capabilities for science research aboard the International Space Station. Delivery to the station is scheduled for late 2018.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACPD...1518577P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACPD...1518577P"><span>The influence of synoptic weather <span class="hlt">regimes</span> on UK <span class="hlt">air</span> quality: regional model studies of tropospheric column NO2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pope, R. J.; Savage, N. H.; Chipperfield, M. P.; Ordóñez, C.; Neal, L. S.</p> <p>2015-07-01</p> <p>Synoptic meteorology can have a significant influence on UK <span class="hlt">air</span> quality. Cyclonic (anticyclonic) conditions lead to the dispersion (accumulation) of <span class="hlt">air</span> pollutants away from (over) source regions. Meteorology also modifies atmospheric chemistry processes such as photolysis and wet deposition. Previous studies have shown a relationship between observed satellite tropospheric column NO2 and synoptic meteorology in different seasons. Here, we test whether the UK Met Office <span class="hlt">Air</span> Quality in the Unified Model (AQUM) can reproduce these observations and then use the model to determine the controlling factors. We show that AQUM successfully captures the observed relationships, when sampled under the Lamb Weather Types, an objective classification of midday UK circulation patterns. By using a range of idealised NOx-like tracers with different e-folding lifetimes, we show that under different synoptic <span class="hlt">regimes</span> the NO2 lifetime in AQUM is approximately 6 h in summer and 12 h in winter. The longer lifetime can explain why synoptic spatial column NO2 variations are more significant in winter compared to summer, due to less NO2 photochemical loss. We also show that cyclonic conditions have more seasonality in column NO2 than anticyclonic conditions as they result in more extreme spatial departures from the wintertime seasonal average. Within a season (summer or winter) under different synoptic <span class="hlt">regimes</span>, a large proportion of the spatial pattern in the UK column NO2 field can be explained by the idealised model tracers, showing that transport is an important factor in governing the variability of UK <span class="hlt">air</span> quality on seasonal synoptic timescales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/935165-flow-regime-study-circulating-fluidized-bed-riser-abrupt-exit-high-density-suspension','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/935165-flow-regime-study-circulating-fluidized-bed-riser-abrupt-exit-high-density-suspension"><span><span class="hlt">Flow</span> <span class="hlt">Regime</span> Study in a Circulating Fluidized Bed Riser with an Abrupt Exit: [1] High Density Suspension</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Mei, J.S.; Lee, G.T.; Seachman, S.M.</p> <p>2008-05-13</p> <p><span class="hlt">Flow</span> <span class="hlt">regime</span> study was conducted in a 0.3 m diameter, 15.5 m tall circulating fluidized bed (CFB) riser with an abrupt exit at the National Energy Technology Laboratory of the U. S. Department of Energy. A statistical designed test series was conducted including four (4) operating set points and a duplicated center point (therefore a total of 6 operating set points). Glass beads of mean diameter 200 μm and particle density of 2,430 kg/m3 were used as bed material. The CFB riser was operated at various superficial gas velocities ranging from 5.6 to 7.6 m/s and solid mass flux frommore » a low of 86 to a high of 303 kg/m2-s. Results of the apparent solids fraction profile as well as the radial particle velocity profile were analyzed in order to identify the presence of Dense Suspension Upflow (DSU) conditions. DSU <span class="hlt">regime</span> was found to exist at the bottom of the riser, while the middle section of the riser was still exhibiting core-annular <span class="hlt">flow</span> structure. Due to the abrupt geometry of the exit, the DSU <span class="hlt">regime</span> was also found at the top of the riser. In addition the effects of the azimuthal angle, riser gas velocity, and mass solids flux on the particle velocity were investigated and are discussed in this paper.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880016034','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880016034"><span>Cluster analysis of multiple planetary <span class="hlt">flow</span> <span class="hlt">regimes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mo, Kingtse; Ghil, Michael</p> <p>1987-01-01</p> <p>A modified cluster analysis method was developed to identify spatial patterns of planetary <span class="hlt">flow</span> <span class="hlt">regimes</span>, and to study transitions between them. This method was applied first to a simple deterministic model and second to Northern Hemisphere (NH) 500 mb data. The dynamical model is governed by the fully-nonlinear, equivalent-barotropic vorticity equation on the sphere. Clusters of point in the model's phase space are associated with either a few persistent or with many transient events. Two stationary clusters have patterns similar to unstable stationary model solutions, zonal, or blocked. Transient clusters of wave trains serve as way stations between the stationary ones. For the NH data, cluster analysis was performed in the subspace of the first seven empirical orthogonal functions (EOFs). Stationary clusters are found in the low-frequency band of more than 10 days, and transient clusters in the bandpass frequency window between 2.5 and 6 days. In the low-frequency band three pairs of clusters determine, respectively, EOFs 1, 2, and 3. They exhibit well-known regional features, such as blocking, the Pacific/North American (PNA) pattern and wave trains. Both model and low-pass data show strong bimodality. Clusters in the bandpass window show wave-train patterns in the two jet exit regions. They are related, as in the model, to transitions between stationary clusters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1786e0012P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1786e0012P"><span>DSMC computations of hypersonic <span class="hlt">flow</span> separation and re-attachment in the transition to continuum <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Prakash, Ram; Gai, Sudhir L.; O'Byrne, Sean; Brown, Melrose</p> <p>2016-11-01</p> <p>The <span class="hlt">flow</span> over a `tick' shaped configuration is performed using two Direct Simulation Monte Carlo codes: the DS2V code of Bird and the code from Sandia National Laboratory, called SPARTA. The configuration creates a <span class="hlt">flow</span> field, where the <span class="hlt">flow</span> is expanded initially but then is affected by the adverse pressure gradient induced by a compression surface. The <span class="hlt">flow</span> field is challenging in the sense that the full <span class="hlt">flow</span> domain is comprised of localized areas spanning continuum and transitional <span class="hlt">regimes</span>. The present work focuses on the capability of SPARTA to model such <span class="hlt">flow</span> conditions and also towards a comparative evaluation with results from DS2V. An extensive grid adaptation study is performed using both the codes on a model with a sharp leading edge and the converged results are then compared. The computational predictions are evaluated in terms of surface parameters such as heat flux, shear stress, pressure and velocity slip. SPARTA consistently predicts higher values for these surface properties. The skin friction predictions of both the codes don't give any indication of separation but the velocity slip plots indicate an incipient separation behavior at the corner. The differences in the results are attributed towards the <span class="hlt">flow</span> resolution at the leading edge that dictates the downstream <span class="hlt">flow</span> characteristics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvF...3c3303S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvF...3c3303S"><span>Effect of a surface tension gradient on the slip <span class="hlt">flow</span> along a superhydrophobic <span class="hlt">air</span>-water interface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, Dong; Song, Baowei; Hu, Haibao; Du, Xiaosong; Du, Peng; Choi, Chang-Hwan; Rothstein, Jonathan P.</p> <p>2018-03-01</p> <p>Superhydrophobic surfaces have been shown to produce significant drag reduction in both laminar and turbulent <span class="hlt">flows</span> by introducing an apparent slip velocity along an <span class="hlt">air</span>-water interface trapped within the surface roughness. In the experiments presented within this study, we demonstrate the existence of a surface tension gradient associated with the resultant Marangoni <span class="hlt">flow</span> along an <span class="hlt">air</span>-water interface that causes the slip velocity and slip length to be significantly reduced. In this study, the slip velocity along a millimeter-sized <span class="hlt">air</span>-water interface was investigated experimentally. This large-scale <span class="hlt">air</span>-water interface facilitated a detailed investigation of the interfacial velocity profiles as the <span class="hlt">flow</span> rate, interfacial curvature, and interface geometry were varied. For the <span class="hlt">air</span>-water interfaces supported above continuous grooves (concentric rings within a torsional shear <span class="hlt">flow</span>) where no surface tension gradient exists, a slip velocity as high as 30% of the bulk velocity was observed. However, for the <span class="hlt">air</span>-water interfaces supported above discontinuous grooves (rectangular channels in a Poiseuille <span class="hlt">flow</span>), the presence of a surface tension gradient reduced the slip velocity and in some cases resulted in an interfacial velocity that was opposite to the main <span class="hlt">flow</span> direction. The curvature of the <span class="hlt">air</span>-water interface in the spanwise direction was found to dictate the details of the interfacial <span class="hlt">flow</span> profile with reverse <span class="hlt">flow</span> in the center of the interface for concave surfaces and along the outside of the interface for convex surfaces. The deflection of the <span class="hlt">air</span>-water interface was also found to greatly affect the magnitude of the slip. Numerical simulations imposed with a relatively small surface tension gradient along the <span class="hlt">air</span>-water interface were able to predict both the reduced slip velocity and back <span class="hlt">flow</span> along the <span class="hlt">air</span>-water interface.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ThApC.129..607V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ThApC.129..607V"><span>Climate change impact assessment on <span class="hlt">flow</span> <span class="hlt">regime</span> by incorporating spatial correlation and scenario uncertainty</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vallam, P.; Qin, X. S.</p> <p>2017-07-01</p> <p>Flooding risk is increasing in many parts of the world and may worsen under climate change conditions. The accuracy of predicting flooding risk relies on reasonable projection of meteorological data (especially rainfall) at the local scale. The current statistical downscaling approaches face the difficulty of projecting multi-site climate information for future conditions while conserving spatial information. This study presents a combined Long Ashton Research Station Weather Generator (LARS-WG) stochastic weather generator and multi-site rainfall simulator RainSim (CLWRS) approach to investigate <span class="hlt">flow</span> <span class="hlt">regimes</span> under future conditions in the Kootenay Watershed, Canada. To understand the uncertainty effect stemming from different scenarios, the climate output is fed into a hydrologic model. The results showed different variation trends of annual peak <span class="hlt">flows</span> (in 2080-2099) based on different climate change scenarios and demonstrated that the hydrological impact would be driven by the interaction between snowmelt and peak <span class="hlt">flows</span>. The proposed CLWRS approach is useful where there is a need for projection of potential climate change scenarios.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFD.M6003K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFD.M6003K"><span>Visualization of an <span class="hlt">air</span>-water interface on superhydrophobic surfaces in turbulent channel <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Hyunseok; Park, Hyungmin</p> <p>2017-11-01</p> <p>In the present study, three-dimensional deformation of <span class="hlt">air</span>-water interface on superhydrophobic surfaces in turbulent channel <span class="hlt">flows</span> at the Reynolds numbers of Re = 3000 and 10000 is measured with RICM (Reflection Interference Contrast Microscopy) technique. Two different types of roughness feature of circular hole and rectangular grate are considered, whose depth is 20 μm and diameter (or width) is varied between 20-200 μm. Since the <span class="hlt">air</span>-water interface is always at de-pinned state at the considered condition, <span class="hlt">air</span>-water interface shape and its sagging velocity is maintained to be almost constant as time goes one. In comparison with the previous results under the laminar <span class="hlt">flow</span>, due to turbulent characteristics of the <span class="hlt">flow</span>, sagging velocity is much faster. Based on the measured sagging profiles, a modified model to describe the <span class="hlt">air</span>-water interface dynamics under turbulent <span class="hlt">flows</span> is suggested. Supported by City of Seoul through Seoul Urban Data Science Laboratory Project (Grant No 0660-20170004) administered by SNU Big Data Institute.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26343789','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26343789"><span>Elasto-Aerodynamics-Driven Triboelectric Nanogenerator for Scavenging <span class="hlt">Air-Flow</span> Energy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Shuhua; Mu, Xiaojing; Wang, Xue; Gu, Alex Yuandong; Wang, Zhong Lin; Yang, Ya</p> <p>2015-10-27</p> <p>Efficient scavenging the kinetic energy from <span class="hlt">air-flow</span> represents a promising approach for obtaining clean, sustainable electricity. Here, we report an elasto-aerodynamics-driven triboelectric nanogenerator (TENG) based on contact electrification. The reported TENG consists of a Kapton film with two Cu electrodes at each side, fixed on two ends in an acrylic fluid channel. The relationship between the TENG output power density and its fluid channel dimensions is systematically studied. TENG with a fluid channel size of 125 × 10 × 1.6 mm(3) delivers the maximum output power density of about 9 kW/m(3) under a loading resistance of 2.3 MΩ. Aero-elastic flutter effect explains the <span class="hlt">air-flow</span> induced vibration of Kapton film well. The output power scales nearly linearly with parallel wiring of multiple TENGs. Connecting 10 TENGs in parallel gives an output power of 25 mW, which allows direct powering of a globe light. The TENG is also utilized to scavenge human breath induced <span class="hlt">air-flow</span> energy to sustainably power a human body temperature sensor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMNH51D1931E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMNH51D1931E"><span>An experimental study of geyser-like <span class="hlt">flows</span> induced by a pressurized <span class="hlt">air</span> pocket</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elayeb, I. S.; Leon, A.; Choi, Y.; Alnahit, A. O.</p> <p>2015-12-01</p> <p>Previous studies argues that the entrapment of pressurized <span class="hlt">air</span> pockets within combined sewer systems can produce geyser <span class="hlt">flows</span>, which is an oscillating jetting of a mixture of gas-liquid <span class="hlt">flows</span>. To verify that pressurized <span class="hlt">air</span> pockets can effectively produce geysers, laboratory experiments were conducted. However, past experiments were conducted in relatively small-scale apparatus (i.e. maximum φ2" vertical shaft). This study conducted a set of experiments in a larger apparatus. The experimental setup consists of an upstream head tank, a downstream head tank, a horizontal pipe (46.5ft long, φ6") and a vertical pipe (10ft long, φ6"). The initial condition for the experiments is constant <span class="hlt">flow</span> discharge through the horizontal pipe. The experiments are initiated by injecting an <span class="hlt">air</span> pocket with pre-determined volume and pressure at the upstream end of the horizontal pipe. The <span class="hlt">air</span> pocket propagates through the horizontal pipe until it arrives to the vertical shaft, where it is released producing a geyser-like <span class="hlt">flow</span>. Three <span class="hlt">flow</span> rates in the horizontal pipe and three injected <span class="hlt">air</span> pressures were tested. The variables measured were pressure at two locations in the horizontal pipe and two locations in the vertical pipe. High resolution videos at two regions in the vertical shaft were also recorded. To gain further insights in the physics of <span class="hlt">air</span>-water interaction, the laboratory experiments were complemented with numerical simulations conducted using a commercial 3D CFD model, previously validated with experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPSJ...86l4502Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPSJ...86l4502Y"><span>Estimation of <span class="hlt">Flow</span> Channel Parameters for <span class="hlt">Flowing</span> Gas Mixed with <span class="hlt">Air</span> in Atmospheric-pressure Plasma Jets</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yambe, Kiyoyuki; Saito, Hidetoshi</p> <p>2017-12-01</p> <p>When the working gas of an atmospheric-pressure non-equilibrium (cold) plasma <span class="hlt">flows</span> into free space, the diameter of the resulting <span class="hlt">flow</span> channel changes continuously. The shape of the channel is observed through the light emitted by the working gas of the atmospheric-pressure plasma. When the plasma jet forms a conical shape, the diameter of the cylindrical shape, which approximates the conical shape, defines the diameter of the <span class="hlt">flow</span> channel. When the working gas <span class="hlt">flows</span> into the atmosphere from the inside of a quartz tube, the gas mixes with <span class="hlt">air</span>. The molar ratio of the working gas and <span class="hlt">air</span> is estimated from the corresponding volume ratio through the relationship between the diameter of the cylindrical plasma channel and the inner diameter of the quartz tube. The Reynolds number is calculated from the kinematic viscosity of the mixed gas and the molar ratio. The gas <span class="hlt">flow</span> rates for the upper limit of laminar <span class="hlt">flow</span> and the lower limit of turbulent <span class="hlt">flow</span> are determined by the corresponding Reynolds numbers estimated from the molar ratio. It is confirmed that the plasma jet length and the internal plasma length associated with strong light emission increase with the increasing gas <span class="hlt">flow</span> rate until the rate for the upper limit of laminar <span class="hlt">flow</span> and the lower limit of turbulent <span class="hlt">flow</span>, respectively. Thus, we are able to explain the increasing trend in the plasma lengths with the diameter of the <span class="hlt">flow</span> channel and the molar ratio by using the cylindrical approximation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..263f2016N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..263f2016N"><span>Diffusion thermo effects on unsteady MHD free convection <span class="hlt">flow</span> of a Kuvshinski fluid past a vertical porous plate in slip <span class="hlt">flow</span> <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Narsu, Sivakumar; Rushi Kumar, B.</p> <p>2017-11-01</p> <p>The main purpose of this work is to investigate the diffusion-thermo effects on unsteady combined convection magneto-hydromagnetic boundary layer <span class="hlt">flow</span> of viscous electrically conducting and chemically reacting fluid over a vertical permeable radiated plate embedded in a highly porous medium. The slip <span class="hlt">flow</span> <span class="hlt">regime</span> is applied at the porous interface a uniform magnetic field is applied normal to the fluid <span class="hlt">flow</span> direction which absorbs the fluid with suction that varies with time. The dimensionless governing equations are solved analytically using two terms harmonic and non-harmonic functions. The expressions for the fields of velocity, temperature and concentration are obtained. For engineering interest we also calculated the physical quantities the skin friction coefficient, Nusselt and Sherwood number are derived. The effects of various physical parameters on the <span class="hlt">flow</span> quantities are studied through graphs and tables. For the validity, we have checked our results with previously published work and found good agreement with already existing studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3655160','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3655160"><span>An Open-Access Modeled Passenger <span class="hlt">Flow</span> Matrix for the Global <span class="hlt">Air</span> Network in 2010</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Huang, Zhuojie; Wu, Xiao; Garcia, Andres J.; Fik, Timothy J.; Tatem, Andrew J.</p> <p>2013-01-01</p> <p>The expanding global <span class="hlt">air</span> network provides rapid and wide-reaching connections accelerating both domestic and international travel. To understand human movement patterns on the network and their socioeconomic, environmental and epidemiological implications, information on passenger <span class="hlt">flow</span> is required. However, comprehensive data on global passenger <span class="hlt">flow</span> remain difficult and expensive to obtain, prompting researchers to rely on scheduled flight seat capacity data or simple models of <span class="hlt">flow</span>. This study describes the construction of an open-access modeled passenger <span class="hlt">flow</span> matrix for all airports with a host city-population of more than 100,000 and within two transfers of <span class="hlt">air</span> travel from various publicly available <span class="hlt">air</span> travel datasets. Data on network characteristics, city population, and local area GDP amongst others are utilized as covariates in a spatial interaction framework to predict the <span class="hlt">air</span> transportation <span class="hlt">flows</span> between airports. Training datasets based on information from various transportation organizations in the United States, Canada and the European Union were assembled. A log-linear model controlling the random effects on origin, destination and the airport hierarchy was then built to predict passenger <span class="hlt">flows</span> on the network, and compared to the results produced using previously published models. Validation analyses showed that the model presented here produced improved predictive power and accuracy compared to previously published models, yielding the highest successful prediction rate at the global scale. Based on this model, passenger <span class="hlt">flows</span> between 1,491 airports on 644,406 unique routes were estimated in the prediction dataset. The airport node characteristics and estimated passenger <span class="hlt">flows</span> are freely available as part of the Vector-Borne Disease Airline Importation Risk (VBD-<span class="hlt">Air</span>) project at: www.vbd-<span class="hlt">air</span>.com/data. PMID:23691194</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23691194','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23691194"><span>An open-access modeled passenger <span class="hlt">flow</span> matrix for the global <span class="hlt">air</span> network in 2010.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Zhuojie; Wu, Xiao; Garcia, Andres J; Fik, Timothy J; Tatem, Andrew J</p> <p>2013-01-01</p> <p>The expanding global <span class="hlt">air</span> network provides rapid and wide-reaching connections accelerating both domestic and international travel. To understand human movement patterns on the network and their socioeconomic, environmental and epidemiological implications, information on passenger <span class="hlt">flow</span> is required. However, comprehensive data on global passenger <span class="hlt">flow</span> remain difficult and expensive to obtain, prompting researchers to rely on scheduled flight seat capacity data or simple models of <span class="hlt">flow</span>. This study describes the construction of an open-access modeled passenger <span class="hlt">flow</span> matrix for all airports with a host city-population of more than 100,000 and within two transfers of <span class="hlt">air</span> travel from various publicly available <span class="hlt">air</span> travel datasets. Data on network characteristics, city population, and local area GDP amongst others are utilized as covariates in a spatial interaction framework to predict the <span class="hlt">air</span> transportation <span class="hlt">flows</span> between airports. Training datasets based on information from various transportation organizations in the United States, Canada and the European Union were assembled. A log-linear model controlling the random effects on origin, destination and the airport hierarchy was then built to predict passenger <span class="hlt">flows</span> on the network, and compared to the results produced using previously published models. Validation analyses showed that the model presented here produced improved predictive power and accuracy compared to previously published models, yielding the highest successful prediction rate at the global scale. Based on this model, passenger <span class="hlt">flows</span> between 1,491 airports on 644,406 unique routes were estimated in the prediction dataset. The airport node characteristics and estimated passenger <span class="hlt">flows</span> are freely available as part of the Vector-Borne Disease Airline Importation Risk (VBD-<span class="hlt">Air</span>) project at: www.vbd-<span class="hlt">air</span>.com/data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26918522','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26918522"><span>Plant pneumatics: stem <span class="hlt">air</span> <span class="hlt">flow</span> is related to embolism - new perspectives on methods in plant hydraulics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pereira, Luciano; Bittencourt, Paulo R L; Oliveira, Rafael S; Junior, Mauro B M; Barros, Fernanda V; Ribeiro, Rafael V; Mazzafera, Paulo</p> <p>2016-07-01</p> <p>Wood contains a large amount of <span class="hlt">air</span>, even in functional xylem. <span class="hlt">Air</span> embolisms in the xylem affect water transport and can determine plant growth and survival. Embolisms are usually estimated with laborious hydraulic methods, which can be prone to several artefacts. Here, we describe a new method for estimating embolisms that is based on <span class="hlt">air</span> <span class="hlt">flow</span> measurements of entire branches. To calculate the amount of <span class="hlt">air</span> <span class="hlt">flowing</span> out of the branch, a vacuum was applied to the cut bases of branches under different water potentials. We first investigated the source of <span class="hlt">air</span> by determining whether it came from inside or outside the branch. Second, we compared embolism curves according to <span class="hlt">air</span> <span class="hlt">flow</span> or hydraulic measurements in 15 vessel- and tracheid-bearing species to test the hypothesis that the <span class="hlt">air</span> <span class="hlt">flow</span> is related to embolism. <span class="hlt">Air</span> <span class="hlt">flow</span> came almost exclusively from <span class="hlt">air</span> inside the branch during the 2.5-min measurements and was strongly related to embolism. We propose a new embolism measurement method that is simple, effective, rapid and inexpensive, and that allows several measurements on the same branch, thus opening up new possibilities for studying plant hydraulics. © 2016 The Authors. New Phytologist © 2016 New Phytologist Trust.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDD18009Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDD18009Z"><span><span class="hlt">Flow</span> behaviour and transitions in surfactant-laden gas-liquid vertical <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zadrazil, Ivan; Chakraborty, Sourojeet; Matar, Omar; Markides, Christos</p> <p>2016-11-01</p> <p>The aim of this work is to elucidate the effect of surfactant additives on vertical gas-liquid counter-current pipe <span class="hlt">flows</span>. Two experimental campaigns were undertaken, one with water and one with a light oil (Exxsol D80) as the liquid phase; in both cases <span class="hlt">air</span> was used as the gaseous phase. Suitable surfactants were added to the liquid phase up to the critical micelle concentration (CMC); measurements in the absence of additives were also taken, for benchmarking. The experiments were performed in a 32-mm bore and 5-m long vertical pipe, over a range of superficial velocities (liquid: 1 to 7 m/s, gas: 1 to 44 m/s). High-speed axial- and side-view imaging was performed at different lengths along the pipe, together with pressure drop measurements. <span class="hlt">Flow</span> <span class="hlt">regime</span> maps were then obtained describing the observed <span class="hlt">flow</span> behaviour and related phenomena, i.e., downwards/upwards annular <span class="hlt">flow</span>, flooding, bridging, gas/liquid entrainment, oscillatory film <span class="hlt">flow</span>, standing waves, climbing films, churn <span class="hlt">flow</span> and dryout. Comparisons of the <span class="hlt">air</span>-water and oil-water results will be presented and discussed, along with the role of the surfactants in affecting overall and detailed <span class="hlt">flow</span> behaviour and transitions; in particular, a possible mechanism underlying the phenomenon of flooding will be presented. EPSRC UK Programme Grant EP/K003976/1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E3SWC..3704001M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E3SWC..3704001M"><span>Hydrological and hydroclimatic <span class="hlt">regimes</span> in the Ouergha watershed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Msatef, Karim; Benaabidate, Lahcen; Bouignane, Aziz</p> <p>2018-05-01</p> <p>This work consists in studying the hydrological and hydroclimatic <span class="hlt">regime</span> of the Ouergha watershed and frequency analysis of extreme <span class="hlt">flows</span> and extreme rainfall for peak estimation and return periods, in order to prevention and forecasting against risks (flood...). Hydrological <span class="hlt">regime</span> analysis showed a <span class="hlt">regime</span> of the rain type, characterized by rainfed abundance with very high winter <span class="hlt">flows</span>, so strong floods. The annual module and the different coefficients show hydroclimatic fluctuations in relation to a semihumid climate. The water balance has highlighted the importance of the volumes of water conveyed upstream than downstream, thus confirming the morphometric parameters of watershed and the lithological nature. Frequency study of <span class="hlt">flows</span> and extreme rainfall showed that these <span class="hlt">flows</span> governed by dissymmetrical laws based on methods Gumbel, GEV, Gamma and Log Pearson III.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100003381','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100003381"><span>Experimental and Numerical Investigation of <span class="hlt">Flow</span> Properties of Supersonic Helium-<span class="hlt">Air</span> Jets</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miller, Steven A. E.; Veltin, Jeremy</p> <p>2010-01-01</p> <p>Heated high speed subsonic and supersonic jets operating on- or off-design are a source of noise that is not yet fully understood. Helium-<span class="hlt">air</span> mixtures can be used in the correct ratio to simulate the total temperature ratio of heated <span class="hlt">air</span> jets and hence have the potential to provide inexpensive and reliable <span class="hlt">flow</span> and acoustic measurements. This study presents a combination of <span class="hlt">flow</span> measurements of helium-<span class="hlt">air</span> high speed jets and numerical simulations of similar helium-<span class="hlt">air</span> mixture and heated <span class="hlt">air</span> jets. Jets issuing from axisymmetric convergent and convergent-divergent nozzles are investigated, and the results show very strong similarity with heated <span class="hlt">air</span> jet measurements found in the literature. This demonstrates the validity of simulating heated high speed jets with helium-<span class="hlt">air</span> in the laboratory, together with the excellent agreement obtained in the presented data between the numerical predictions and the experiments. The very close match between the numerical and experimental data also validates the frozen chemistry model used in the numerical simulation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3161569','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3161569"><span><span class="hlt">Flow</span> <span class="hlt">regime</span>, temperature, and biotic interactions drive differential declines of trout species under climate change</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wenger, Seth J.; Isaak, Daniel J.; Luce, Charles H.; Neville, Helen M.; Fausch, Kurt D.; Dunham, Jason B.; Dauwalter, Daniel C.; Young, Michael K.; Elsner, Marketa M.; Rieman, Bruce E.; Hamlet, Alan F.; Williams, Jack E.</p> <p>2011-01-01</p> <p>Broad-scale studies of climate change effects on freshwater species have focused mainly on temperature, ignoring critical drivers such as <span class="hlt">flow</span> <span class="hlt">regime</span> and biotic interactions. We use downscaled outputs from general circulation models coupled with a hydrologic model to forecast the effects of altered <span class="hlt">flows</span> and increased temperatures on four interacting species of trout across the interior western United States (1.01 million km2), based on empirical statistical models built from fish surveys at 9,890 sites. Projections under the 2080s A1B emissions scenario forecast a mean 47% decline in total suitable habitat for all trout, a group of fishes of major socioeconomic and ecological significance. We project that native cutthroat trout Oncorhynchus clarkii, already excluded from much of its potential range by nonnative species, will lose a further 58% of habitat due to an increase in temperatures beyond the species’ physiological optima and continued negative biotic interactions. Habitat for nonnative brook trout Salvelinus fontinalis and brown trout Salmo trutta is predicted to decline by 77% and 48%, respectively, driven by increases in temperature and winter flood frequency caused by warmer, rainier winters. Habitat for rainbow trout, Oncorhynchus mykiss, is projected to decline the least (35%) because negative temperature effects are partly offset by <span class="hlt">flow</span> <span class="hlt">regime</span> shifts that benefit the species. These results illustrate how drivers other than temperature influence species response to climate change. Despite some uncertainty, large declines in trout habitat are likely, but our findings point to opportunities for strategic targeting of mitigation efforts to appropriate stressors and locations. PMID:21844354</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70034334','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70034334"><span><span class="hlt">Flow</span> <span class="hlt">regime</span>, temperature, and biotic interactions drive differential declines of trout species under climate change</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wenger, S.J.; Isaak, D.J.; Luce, C.H.; Neville, H.M.; Fausch, K.D.; Dunham, J.B.; Dauwalter, D.C.; Young, M.K.; Elsner, M.M.; Rieman, B.E.; Hamlet, A.F.; Williams, J.E.</p> <p>2011-01-01</p> <p>Broad-scale studies of climate change effects on freshwater species have focused mainly on temperature, ignoring critical drivers such as <span class="hlt">flow</span> <span class="hlt">regime</span> and biotic interactions. We use downscaled outputs from general circulation models coupled with a hydrologic model to forecast the effects of altered <span class="hlt">flows</span> and increased temperatures on four interacting species of trout across the interior western United States (1.01 million km2), based on empirical statistical models built from fish surveys at 9,890 sites. Projections under the 2080s A1B emissions scenario forecast a mean 47% decline in total suitable habitat for all trout, a group of fishes of major socioeconomic and ecological significance. We project that native cutthroat trout Oncorhynchus clarkii, already excluded from much of its potential range by nonnative species, will lose a further 58% of habitat due to an increase in temperatures beyond the species' physiological optima and continued negative biotic interactions. Habitat for nonnative brook trout Salvelinus fontinalis and brown trout Salmo trutta is predicted to decline by 77% and 48%, respectively, driven by increases in temperature and winter flood frequency caused by warmer, rainier winters. Habitat for rainbow trout, Oncorhynchus mykiss, is projected to decline the least (35%) because negative temperature effects are partly offset by <span class="hlt">flow</span> <span class="hlt">regime</span> shifts that benefit the species. These results illustrate how drivers other than temperature influence species response to climate change. Despite some uncertainty, large declines in trout habitat are likely, but our findings point to opportunities for strategic targeting of mitigation efforts to appropriate stressors and locations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..MAR.T1333M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..MAR.T1333M"><span>Analysis of the Angle of Maximal Stability and <span class="hlt">Flow</span> <span class="hlt">Regime</span> Transitions in Different Proportions of Bi-phasic Granular Matter Mixtures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maquiling, Joel Tiu; Visaga, Shane Marie</p> <p></p> <p>This study investigates the dependence of the critical angle θc of stability on different mass ratios γ of layered bi-phasic granular matter mixtures and on the critical angle of its mono-disperse individual components. It also aims to investigate and explain <span class="hlt">regime</span> transitions of granular matter <span class="hlt">flowing</span> down a tilted rough inclined plane. Critical angles and <span class="hlt">flow</span> <span class="hlt">regimes</span> for a bi-phasic mixture of sago spheres and bi-phasic pepper mixture of fine powder and rough spheres were observed and measured using video analysis. The critical angles θc MD of mono-disperse granular matter and θc BP of biphasic granular matter mixtures were observed and compared. All types of <span class="hlt">flow</span> <span class="hlt">regimes</span> and a supramaximal critical angle of stability exist at mass ratio γ = 0.5 for all biphasic granular matter mixtures. The θc BP of sago spheres was higher than the θc MD of sago spheres. Moreover, the θc BP of the pepper mixture was in between the θc MD of fine pepper and θc MD of rough pepper spheres. Comparison of different granular material shows that θc MD is not simply a function of particle diameter but of particle roughness as well. Results point to a superposition mechanism of the critical angles of biphasic sphere mixtures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JHyd..325..241S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JHyd..325..241S"><span>Predicting streamflow <span class="hlt">regime</span> metrics for ungauged streamsin Colorado, Washington, and Oregon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanborn, Stephen C.; Bledsoe, Brian P.</p> <p>2006-06-01</p> <p>Streamflow prediction in ungauged basins provides essential information for water resources planning and management and ecohydrological studies yet remains a fundamental challenge to the hydrological sciences. A methodology is presented for stratifying streamflow <span class="hlt">regimes</span> of gauged locations, classifying the <span class="hlt">regimes</span> of ungauged streams, and developing models for predicting a suite of ecologically pertinent streamflow metrics for these streams. Eighty-four streamflow metrics characterizing various <span class="hlt">flow</span> <span class="hlt">regime</span> attributes were computed along with physical and climatic drainage basin characteristics for 150 streams with little or no streamflow modification in Colorado, Washington, and Oregon. The diverse hydroclimatology of the study area necessitates <span class="hlt">flow</span> <span class="hlt">regime</span> stratification and geographically independent clusters were identified and used to develop separate predictive models for each <span class="hlt">flow</span> <span class="hlt">regime</span> type. Multiple regression models for <span class="hlt">flow</span> magnitude, timing, and rate of change metrics were quite accurate with many adjusted R2 values exceeding 0.80, while models describing streamflow variability did not perform as well. Separate stratification schemes for high, low, and average <span class="hlt">flows</span> did not considerably improve models for metrics describing those particular aspects of the <span class="hlt">regime</span> over a scheme based on the entire <span class="hlt">flow</span> <span class="hlt">regime</span>. Models for streams identified as 'snowmelt' type were improved if sites in Colorado and the Pacific Northwest were separated to better stratify the processes driving streamflow in these regions thus revealing limitations of geographically independent streamflow clusters. This study demonstrates that a broad suite of ecologically relevant streamflow characteristics can be accurately modeled across large heterogeneous regions using this framework. Applications of the resulting models include stratifying biomonitoring sites and quantifying linkages between specific aspects of <span class="hlt">flow</span> <span class="hlt">regimes</span> and aquatic community structure. In particular, the results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26577357','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26577357"><span>Classification of Unsteady <span class="hlt">Flow</span> Patterns in a Rotodynamic Blood Pump: Introduction of Non-Dimensional <span class="hlt">Regime</span> Map.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shu, Fangjun; Vandenberghe, Stijn; Brackett, Jaclyn; Antaki, James F</p> <p>2015-09-01</p> <p>Rotodynamic blood pumps (also known as rotary or continuous <span class="hlt">flow</span> blood pumps) are commonly evaluated in vitro under steady <span class="hlt">flow</span> conditions. However, when these devices are used clinically as ventricular assist devices (VADs), the <span class="hlt">flow</span> is pulsatile due to the contribution of the native heart. This study investigated the influence of this unsteady <span class="hlt">flow</span> upon the internal hemodynamics of a centrifugal blood pump. The <span class="hlt">flow</span> field within the median axial plane of the <span class="hlt">flow</span> path was visualized with particle image velocimetry (PIV) using a transparent replica of the Levacor VAD. The replica was inserted in a dynamic cardiovascular simulator that synchronized the image acquisition to the cardiac cycle. As compared to steady <span class="hlt">flow</span>, pulsatile conditions produced periodic, transient recirculation regions within the impeller and separation in the outlet diffuser. Dimensional analysis revealed that the <span class="hlt">flow</span> characteristics could be uniquely described by the non-dimensional <span class="hlt">flow</span> coefficient (Φ) and its time derivative ([Formula: see text]), thereby eliminating impeller speed from the experimental matrix. Four <span class="hlt">regimes</span> within the Φ-[Formula: see text] plane were found to classify the <span class="hlt">flow</span> patterns, well-attached or disturbed. These results and methods can be generalized to provide insights for both design and operation of rotodynamic blood pumps for safety and efficacy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..197a2086R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..197a2086R"><span>Design and analysis of <span class="hlt">Air</span> <span class="hlt">flow</span> duct for improving the thermal performance of disc brake rotor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Raja, T.; Mathiselvan, G.; Sreenivasulureddy, M.; Goldwin Xavier, X.</p> <p>2017-05-01</p> <p>safety in automotive engineering has been considered as a number one priority in development of new vehicle. A brake system is one of the most critical systems in the vehicle, without which the vehicle will put a passenger in an unsafe position. Temperature distribution on disc rotor brake and the performance brake of disc rotor is influenced by the <span class="hlt">air</span> <span class="hlt">flow</span> around the disc rotor. In this paper, the effect of <span class="hlt">air</span> <span class="hlt">flow</span> over the disc rotor is analyzed using the CFD software. The <span class="hlt">air</span> <span class="hlt">flow</span> over the disc rotor is increased by using a duct to supply more <span class="hlt">air</span> <span class="hlt">flow</span> over the disc rotor. The duct is designed to supply more <span class="hlt">air</span> to the rotor surface and it can be placed in front of the vehicle for better performance. Increasing the <span class="hlt">air</span> <span class="hlt">flow</span> around the rotor will maximize the heat convection from the rotor surface. The rotor life and the performance can be improved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol1/pdf/CFR-2010-title30-vol1-sec57-22212.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol1/pdf/CFR-2010-title30-vol1-sec57-22212.pdf"><span>30 CFR 57.22212 - <span class="hlt">Air</span> <span class="hlt">flow</span> (I-C, II-A, and V-A mines).</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... Standards for Methane in Metal and Nonmetal Mines Ventilation § 57.22212 <span class="hlt">Air</span> <span class="hlt">flow</span> (I-C, II-A, and V-A mines). <span class="hlt">Air</span> <span class="hlt">flow</span> across each working face shall be sufficient to carry away any accumulation of methane, smoke...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990053986&hterms=gas+behaviour&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgas%2Bbehaviour','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990053986&hterms=gas+behaviour&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dgas%2Bbehaviour"><span>Experimental Observations on a Low Strain Counter-<span class="hlt">Flow</span> Diffusion Flame: <span class="hlt">Flow</span> and Bouyancy Effects</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sutula, J. A.; Torero, J. L.; Ezekoye, O. A.</p> <p>1999-01-01</p> <p> the nature of the stagnation plane for strain rates smaller than 100 (1/s). These experiments were conducted with a non-reacting <span class="hlt">flow</span>. Video images of a propane <span class="hlt">air</span> diffusion flame were used to describe the behaviour of a diffusion flame in this <span class="hlt">regime</span>. Flame geometry and pulsation frequency are described.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ACP....1511201P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ACP....1511201P"><span>The influence of synoptic weather <span class="hlt">regimes</span> on UK <span class="hlt">air</span> quality: regional model studies of tropospheric column NO2</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pope, R. J.; Savage, N. H.; Chipperfield, M. P.; Ordóñez, C.; Neal, L. S.</p> <p>2015-10-01</p> <p>Synoptic meteorology can have a significant influence on UK <span class="hlt">air</span> quality. Cyclonic conditions lead to the dispersion of <span class="hlt">air</span> pollutants away from source regions, while anticyclonic conditions lead to their accumulation over source regions. Meteorology also modifies atmospheric chemistry processes such as photolysis and wet deposition. Previous studies have shown a relationship between observed satellite tropospheric column NO2 and synoptic meteorology in different seasons. Here, we test whether the UK Met Office <span class="hlt">Air</span> Quality in the Unified Model (AQUM) can reproduce these observations and then use the model to explore the relative importance of various factors. We show that AQUM successfully captures the observed relationships when sampled under the Lamb weather types, an objective classification of midday UK circulation patterns. By using a range of idealized NOx-like tracers with different e-folding lifetimes, we show that under different synoptic <span class="hlt">regimes</span> the NO2 lifetime in AQUM is approximately 6 h in summer and 12 h in winter. The longer lifetime can explain why synoptic spatial tropospheric column NO2 variations are more significant in winter compared to summer, due to less NO2 photochemical loss. We also show that cyclonic conditions have more seasonality in tropospheric column NO2 than anticyclonic conditions as they result in more extreme spatial departures from the wintertime seasonal average. Within a season (summer or winter) under different synoptic <span class="hlt">regimes</span>, a large proportion of the spatial pattern in the UK tropospheric column NO2 field can be explained by the idealized model tracers, showing that transport is an important factor in governing the variability of UK <span class="hlt">air</span> quality on seasonal synoptic timescales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23726713','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23726713"><span>Hydrodynamic effects of <span class="hlt">air</span> sparging on hollow fiber membranes in a bubble column reactor.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xia, Lijun; Law, Adrian Wing-Keung; Fane, Anthony G</p> <p>2013-07-01</p> <p><span class="hlt">Air</span> sparging is now a standard approach to reduce concentration polarization and fouling of membrane modules in membrane bioreactors (MBRs). The hydrodynamic shear stresses, bubble-induced turbulence and cross <span class="hlt">flows</span> scour the membrane surfaces and help reduce the deposit of foulants onto the membrane surface. However, the detailed quantitative knowledge on the effect of <span class="hlt">air</span> sparging remains lacking in the literature due to the complex hydrodynamics generated by the gas-liquid <span class="hlt">flows</span>. To date, there is no valid model that describes the relationship between the membrane fouling performance and the <span class="hlt">flow</span> hydrodynamics. The present study aims to examine the impact of hydrodynamics induced by <span class="hlt">air</span> sparging on the membrane fouling mitigation in a quantitative manner. A modelled hollow fiber module was placed in a cylindrical bubble column reactor at different axial heights with the trans-membrane pressure (TMP) monitored under constant flux conditions. The configuration of bubble column without the membrane module immersed was identical to that studied by Gan et al. (2011) using Phase Doppler Anemometry (PDA), to ensure a good quantitative understanding of turbulent <span class="hlt">flow</span> conditions along the column height. The experimental results showed that the meandering <span class="hlt">flow</span> <span class="hlt">regime</span> which exhibits high <span class="hlt">flow</span> instability at the 0.3 m is more beneficial to fouling alleviation compared with the steady <span class="hlt">flow</span> circulation <span class="hlt">regime</span> at the 0.6 m. The filtration tests also confirmed the existence of an optimal superficial <span class="hlt">air</span> velocity beyond which a further increase is of no significant benefit on the membrane fouling reduction. In addition, the alternate aeration provided by two <span class="hlt">air</span> stones mounted at the opposite end of the diameter of the bubble column was also studied to investigate the associated <span class="hlt">flow</span> dynamics and its influence on the membrane filtration performance. It was found that with a proper switching interval and membrane module orientation, the membrane fouling can be effectively</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15...28H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15...28H"><span>Relief, nocturnal cold-<span class="hlt">air</span> <span class="hlt">flow</span> and <span class="hlt">air</span> quality in Kigali, Rwanda</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henninger, Sascha</p> <p>2013-04-01</p> <p>, this result is not reassuringly, because all measured residential districts in Kigali exceeded the recommendations of the WHO, too. This suggests that the inhabitants of Kigali are exposed to enormous levels of PM10 during most of their time outdoors. So PM10 levels are increasing in areas with high rates of traffic due to the exhaust of the vehicles and the stirring up of dust from the ground, but also in fact of burning wood for cooking etc. within the residential districts. Hazardous measuring trips could be detected for nighttime measurements. Because of high temperatures, high solar radiation and a non-typical missing cloud cover the urban surface could heat up extremely, which produced a cold-<span class="hlt">air</span> <span class="hlt">flow</span> from the ridges and the slopes down to the "Marais" at night. This cold-<span class="hlt">air</span> <span class="hlt">flow</span> takes away the suspended particulate matters, which tends to accumulate within the "Marais" on the bottom of the hills, the places where most residential neighborhoods could be found and agricultural fields were used. The distinctive relief caused an accumulation within small valleys. Unfortunately, these are the favourite places of living and agriculture and this tends to high indoor-<span class="hlt">air</span> pollution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JPhCS.925a2011K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JPhCS.925a2011K"><span>Experimental study and empirical prediction of fuel <span class="hlt">flow</span> parameters under <span class="hlt">air</span> evolution conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kitanina, E. E.; Kitanin, E. L.; Bondarenko, D. A.; Kravtsov, P. A.; Peganova, M. M.; Stepanov, S. G.; Zherebzov, V. L.</p> <p>2017-11-01</p> <p><span class="hlt">Air</span> evolution in kerosene under the effect of gravity <span class="hlt">flow</span> with various hydraulic resistances in the pipeline was studied experimentally. The study was conducted at pressure ranging from 0.2 to 1.0 bar and temperature varying between -20°C and +20°C. Through these experiments, the oversaturation limit beyond which dissolved <span class="hlt">air</span> starts evolving intensively from the fuel was established and the correlations for the calculation of pressure losses and <span class="hlt">air</span> evolution on local loss elements were obtained. A method of calculating two-phase <span class="hlt">flow</span> behaviour in a titled pipeline segment with very low mass <span class="hlt">flow</span> quality and fairly high volume <span class="hlt">flow</span> quality was developed. The complete set of empirical correlations obtained by experimental analysis was implemented in the engineering code. The software simulation results were repeatedly verified against our experimental findings and Airbus test data to show that the two-phase <span class="hlt">flow</span> simulation agrees quite well with the experimental results obtained in the complex branched pipelines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/875029','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/875029"><span>Use of exhaust gas as sweep <span class="hlt">flow</span> to enhance <span class="hlt">air</span> separation membrane performance</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Dutart, Charles H.; Choi, Cathy Y.</p> <p>2003-01-01</p> <p>An intake <span class="hlt">air</span> separation system for an internal combustion engine is provided with purge gas or sweep <span class="hlt">flow</span> on the permeate side of separation membranes in the <span class="hlt">air</span> separation device. Exhaust gas from the engine is used as a purge gas <span class="hlt">flow</span>, to increase oxygen flux in the separation device without increasing the nitrogen flux.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDA14005K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDA14005K"><span><span class="hlt">Flow</span> control of a centrifugal fan in a commercial <span class="hlt">air</span> conditioner</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Jiyu; Bang, Kyeongtae; Choi, Haecheon; Seo, Eung Ryeol; Kang, Yonghun</p> <p>2015-11-01</p> <p><span class="hlt">Air</span>-conditioning fans require a low noise level to provide user comfort and quietness. The aerodynamic noise sources are generated by highly unsteady, turbulent structures near the fan blade. In this study, we investigate the <span class="hlt">flow</span> characteristics of a centrifugal fan in an <span class="hlt">air</span>-conditioner indoor unit and suggest control ideas to develop a low noise fan. The experiment is conducted at the operation condition where the Reynolds number is 163000 based on the blade tip velocity and chord length. Intermittent separation occurs at the blade leading edge and thus <span class="hlt">flow</span> significantly fluctuates there, whereas vortex shedding occurs at the blade trailing edge. Furthermore, the discharge <span class="hlt">flow</span> observed in the axial plane near the shroud shows low-frequency intermittent behaviors, resulting in high Reynolds stresses. To control these <span class="hlt">flow</span> structures, we modify the shapes of the blade leading edge and shroud of the centrifugal fan and obtain noise reduction. The <span class="hlt">flow</span> characteristics of the base and modified fans will be discussed. Supported by 0420-20130051.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018HMT....54.1467Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018HMT....54.1467Y"><span>Correlations for heat transfer coefficient and friction factor for turbulent <span class="hlt">flow</span> of <span class="hlt">air</span> through square and hexagonal ducts with twisted tape insert</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yadav, Rupesh J.; Kore, Sandeep S.; Joshi, Prathamesh S.</p> <p>2018-05-01</p> <p>The experimental and numerical Nusselt number and friction factor investigation for turbulent <span class="hlt">flow</span> through a non-circular duct with twisted-tape inserts have been presented. The non-circular ducts include square, hexagonal duct. The results of non-circular ducts are compared with circular duct. All the ducts have same equivalent diameter. The twist ratios used for the experiment are Y = 3.5, 4.5, 5.5 and 6.5. Experiments were carried out on square duct, hexagonal duct and circular duct. The Reynolds number lied between 10,000 and 1, 05,000. The present study is restricted to the <span class="hlt">flow</span> of <span class="hlt">air</span> at Pr = 0.7 only and within a narrow temperature range of 40 to 75 ΟC, within which the compressible nature of <span class="hlt">air</span> can be neglected. The results reveal that, both Nusselt number and friction factor increases as the side of non-circular duct increases. Maximum Nusselt number and friction factor is obtained in case of circular duct with twisted tape. Further the correlations of Nu and f are given for different non circular duct with twisted tape insert for engineering applications for the turbulent <span class="hlt">regime</span>. Since the thermal performance factor (η) is observed to be within the range of 0.8 to 1.13 for both circular and noncircular ducts, the overall benefit of using twisted tape in the <span class="hlt">flow</span> field shall nevertheless be marginal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=335821&keyword=climate%20change&subject=climate%20change%20research&showcriteria=2&fed_org_id=111&datebeginpublishedpresented=04/29/2012&dateendpublishedpresented=04/29/2017&sortby=pubdateyear','PESTICIDES'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?direntryid=335821&keyword=climate%20change&subject=climate%20change%20research&showcriteria=2&fed_org_id=111&datebeginpublishedpresented=04/29/2012&dateendpublishedpresented=04/29/2017&sortby=pubdateyear"><span>Managing fish habitat for <span class="hlt">flow</span> and temperature extremes ...</span></a></p> <p><a target="_blank" href="http://www.epa.gov/pesticides/search.htm">EPA Pesticide Factsheets</a></p> <p></p> <p></p> <p>Summer low <span class="hlt">flows</span> and stream temperature maxima are key drivers affecting the sustainability of fish populations. Thus, it is critical to understand both the natural templates of spatiotemporal variability, how these are shifting due to anthropogenic influences of development and climate change, and how these impacts can be moderated by natural and constructed green infrastructure. Low <span class="hlt">flow</span> statistics of New England streams have been characterized using a combination of regression equations to describe long-term averages as a function of indicators of hydrologic <span class="hlt">regime</span> (rain- versus snow-dominated), precipitation, evapotranspiration or temperature, surface water storage, baseflow recession rates, and impervious cover. Difference equations have been constructed to describe interannual variation in low <span class="hlt">flow</span> as a function of changing <span class="hlt">air</span> temperature, precipitation, and ocean-atmospheric teleconnection indices. Spatial statistical network models have been applied to explore fine-scale variability of thermal <span class="hlt">regimes</span> along stream networks in New England as a function of variables describing natural and altered energy inputs, groundwater contributions, and retention time. Low <span class="hlt">flows</span> exacerbate temperature impacts by reducing thermal inertia of streams to energy inputs. Based on these models, we can construct scenarios of fish habitat suitability using current and projected future climate and the potential for preservation and restoration of historic habitat <span class="hlt">regimes</span> th</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980000402','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980000402"><span>Dynamic <span class="hlt">Flow</span> Management Problems in <span class="hlt">Air</span> Transportation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Patterson, Sarah Stock</p> <p>1997-01-01</p> <p>In 1995, over six hundred thousand licensed pilots flew nearly thirty-five million flights into over eighteen thousand U.S. airports, logging more than 519 billion passenger miles. Since demand for <span class="hlt">air</span> travel has increased by more than 50% in the last decade while capacity has stagnated, congestion is a problem of undeniable practical significance. In this thesis, we will develop optimization techniques that reduce the impact of congestion on the national airspace. We start by determining the optimal release times for flights into the airspace and the optimal speed adjustment while airborne taking into account the capacitated airspace. This is called the <span class="hlt">Air</span> Traffic <span class="hlt">Flow</span> Management Problem (TFMP). We address the complexity, showing that it is NP-hard. We build an integer programming formulation that is quite strong as some of the proposed inequalities are facet defining for the convex hull of solutions. For practical problems, the solutions of the LP relaxation of the TFMP are very often integral. In essence, we reduce the problem to efficiently solving large scale linear programming problems. Thus, the computation times are reasonably small for large scale, practical problems involving thousands of flights. Next, we address the problem of determining how to reroute aircraft in the airspace system when faced with dynamically changing weather conditions. This is called the <span class="hlt">Air</span> Traffic <span class="hlt">Flow</span> Management Rerouting Problem (TFMRP) We present an integrated mathematical programming approach for the TFMRP, which utilizes several methodologies, in order to minimize delay costs. In order to address the high dimensionality, we present an aggregate model, in which we formulate the TFMRP as a multicommodity, integer, dynamic network <span class="hlt">flow</span> problem with certain side constraints. Using Lagrangian relaxation, we generate aggregate <span class="hlt">flows</span> that are decomposed into a collection of flight paths using a randomized rounding heuristic. This collection of paths is used in a packing integer</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28456826','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28456826"><span>Comparison of Descemet stripping under continuous <span class="hlt">air</span> <span class="hlt">flow</span>, manual <span class="hlt">air</span> injection and balanced salt solution for DMEK: a pilot study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gabbay, I E; Bahar, I; Nahum, Y; Livny, E</p> <p>2017-08-01</p> <p>Descemet's membrane endothelial keratoplasty (DMEK) involves removal of the recipient's Descemet membrane (DM) prior to transplanting the donor's DM. When using balanced salt solution (BSS) or ophthalmic viscosurgical devices (OVDs), visualization of the host's DM during its stripping may be inadequate and may result in Descemet remnants and could lead to sub-optimal surgical results. Previous articles described excellent visualization when utilizing <span class="hlt">air</span> injection but this requires repeated <span class="hlt">air</span> injection into the anterior chamber (AC). We present a pilot study that compares different techniques under which DM stripping can be performed: with continuous automated <span class="hlt">air</span> infusion, with manual <span class="hlt">air</span> infusion, and with BSS. We retrospectively compared video footage of DM stripping with BSS, with continuous <span class="hlt">air</span> and with manual injection of <span class="hlt">air</span> into the AC to determine DM stripping duration and the number of times the surgeon had to insert and retrieve a surgical instrument from the AC. Thirty videos of 10 consecutive cases of the three DM stripping techniques were evaluated. DM stripping duration was 3.26 (±1.32), 3.92 (±1.2) and 12.9 (±3.98) minutes for BSS, continuous <span class="hlt">air</span> <span class="hlt">flow</span>, and manual <span class="hlt">air</span> injection, respectively. Frequency of instrument retrieval (FIR) was 3.6 (±1.71), 1.5 (±0.71) and 15.1 (±3.28) for BSS, continuous <span class="hlt">air</span> <span class="hlt">flow</span>, and manual <span class="hlt">air</span> injection, respectively. Continuous <span class="hlt">air</span> <span class="hlt">flow</span> and BSS were both statistically different than manual <span class="hlt">air</span> injection into the AC (p < 0.05), but did not differ from one another statistically. DM stripping during posterior lamellar surgery is imperative for favorable post-operative results and prevention of complications. Performing this step under <span class="hlt">air</span> in the AC contributes to better visualization and an efficient surgery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29738920','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29738920"><span>Non-contact ultrasonic gas <span class="hlt">flow</span> metering using <span class="hlt">air</span>-coupled leaky Lamb waves.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fan, Zichuan; Jiang, Wentao; Wright, William M D</p> <p>2018-04-23</p> <p>This paper describes a completely non-contact ultrasonic method of gas <span class="hlt">flow</span> metering using <span class="hlt">air</span>-coupled leaky Lamb waves. To show proof of principle, a simplified representation of gas <span class="hlt">flow</span> in a duct, comprising two separated thin isotropic plates with a gas <span class="hlt">flowing</span> between them, has been modelled and investigated experimentally. An airborne compression wave emitted from an <span class="hlt">air</span>-coupled capacitive ultrasonic transducer excited a leaky Lamb wave in the first plate in a non-contact manner. The leakage of this Lamb wave crossed the gas <span class="hlt">flow</span> at an angle between the two plates as a compression wave, and excited a leaky Lamb wave in the second plate. An <span class="hlt">air</span>-coupled capacitive ultrasonic transducer on the opposite side of this second plate then detected the airborne compression wave leakage from the second Lamb wave. As the gas <span class="hlt">flow</span> shifted the wave field between the two plates, the point of Lamb wave excitation in the second plate was displaced in proportion to the gas <span class="hlt">flow</span> rate. Two such measurements, in opposite directions, formed a completely non-contact contra-propagating Lamb wave <span class="hlt">flow</span> meter, allowing measurement of the <span class="hlt">flow</span> velocity between the plates. A COMSOL Multiphysics® model was used to visualize the wave fields, and accurately predicted the time differences that were then measured experimentally. Experiments using different Lamb wave frequencies and plate materials were also similarly verified. This entirely non-contact airborne approach to Lamb wave <span class="hlt">flow</span> metering could be applied in place of clamp-on techniques in thin-walled ducts or pipes. Copyright © 2018 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750013493','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750013493"><span>Program and charts for determining shock tube, and expansion tunnel <span class="hlt">flow</span> quantities for real <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miller, C. G., III; Wilder, S. E.</p> <p>1975-01-01</p> <p>A computer program in FORTRAN 4 language was written to determine shock tube, expansion tube, and expansion tunnel <span class="hlt">flow</span> quantities for real-<span class="hlt">air</span> test gas. This program permits, as input data, a number of possible combinations of <span class="hlt">flow</span> quantities generally measured during a test. The versatility of the program is enhanced by the inclusion of such effects as a standing or totally reflected shock at the secondary diaphragm, thermochemical-equilibrium <span class="hlt">flow</span> expansion and frozen <span class="hlt">flow</span> expansion for the expansion tube and expansion tunnel, attenuation of the <span class="hlt">flow</span> in traversing the acceleration section of the expansion tube, real <span class="hlt">air</span> as the acceleration gas, and the effect of wall boundary layer on the acceleration section <span class="hlt">air</span> <span class="hlt">flow</span>. Charts which provide a rapid estimation of expansion tube performance prior to a test are included.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850027672','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850027672"><span>Character of energy <span class="hlt">flow</span> in <span class="hlt">air</span> shower core</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mizushima, K.; Asakimori, K.; Maeda, T.; Kameda, T.; Misaki, Y.</p> <p>1985-01-01</p> <p>Energy per charged particle near the core of <span class="hlt">air</span> showers was measured by 9 energy <span class="hlt">flow</span> detectors, which were the combination of Cerenkov counters and scintillators. Energy per particle of each detector was normalized to energy at 2m from the core. The following results were obtained as to the energy <span class="hlt">flow</span>: (1) integral frequency distribution of mean energy per particle (averaged over 9 detectors) is composed of two groups separated distinctly; and (2) showers contained in one group show an anisotropy of arrival direction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864528','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864528"><span>A MEMS-based <span class="hlt">Air</span> <span class="hlt">Flow</span> Sensor with a Free-standing Micro-cantilever Structure</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wang, Yu-Hsiang; Lee, Chia-Yen; Chiang, Che-Ming</p> <p>2007-01-01</p> <p>This paper presents a micro-scale <span class="hlt">air</span> <span class="hlt">flow</span> sensor based on a free-standing cantilever structure. In the fabrication process, MEMS techniques are used to deposit a silicon nitride layer on a silicon wafer. A platinum layer is deposited on the silicon nitride layer to form a piezoresistor, and the resulting structure is then etched to create a freestanding micro-cantilever. When an <span class="hlt">air</span> <span class="hlt">flow</span> passes over the surface of the cantilever beam, the beam deflects in the downward direction, resulting in a small variation in the resistance of the piezoelectric layer. The <span class="hlt">air</span> <span class="hlt">flow</span> velocity is determined by measuring the change in resistance using an external LCR meter. The experimental results indicate that the <span class="hlt">flow</span> sensor has a high sensitivity (0.0284 Ω/ms-1), a high velocity measurement limit (45 ms-1) and a rapid response time (0.53 s). PMID:28903233</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Th%26Ae..24..691C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Th%26Ae..24..691C"><span>Numerical investigation of the <span class="hlt">air</span> injection effect on the cavitating <span class="hlt">flow</span> in Francis hydro turbine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chirkov, D. V.; Shcherbakov, P. K.; Cherny, S. G.; Skorospelov, V. A.; Turuk, P. A.</p> <p>2017-09-01</p> <p>At full and over load operating points, some Francis turbines experience strong self-excited pressure and power oscillations. These oscillations are occuring due to the hydrodynamic instability of the cavitating fluid <span class="hlt">flow</span>. In many cases, the amplitude of such pulsations may be reduced substantially during the turbine operation by the <span class="hlt">air</span> injection/ admission below the runner. Such an effect is investigated numerically in the present work. To this end, the hybrid one-three-dimensional model of the <span class="hlt">flow</span> of the mixture "liquid-vapor" in the duct of a hydroelectric power station, which was proposed previously by the present authors, is augmented by the second gaseous component — the noncondensable <span class="hlt">air</span>. The boundary conditions and the numerical method for solving the equations of the model are described. To check the accuracy of computing the interface "liquid-gas", the numerical method was applied at first for solving the dam break problem. The algorithm was then used for modeling the <span class="hlt">flow</span> in a hydraulic turbine with <span class="hlt">air</span> injection below the runner. It is shown that with increasing <span class="hlt">flow</span> rate of the injected <span class="hlt">air</span>, the amplitude of pressure pulsations decreases. The mechanism of the <span class="hlt">flow</span> structure alteration in the draft tube cone has been elucidated, which leads to <span class="hlt">flow</span> stabilization at <span class="hlt">air</span> injection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhFl...29i5104A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhFl...29i5104A"><span>In-cylinder <span class="hlt">air-flow</span> characteristics of different intake port geometries using tomographic PIV</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Agarwal, Avinash Kumar; Gadekar, Suresh; Singh, Akhilendra Pratap</p> <p>2017-09-01</p> <p>For improving the in-cylinder <span class="hlt">flow</span> characteristics of intake <span class="hlt">air</span>/charge and for strengthening the turbulence intensity, specific intake port geometries have shown significant potential in compression ignition engines. In this experimental study, effects of intake port geometries on <span class="hlt">air-flow</span> characteristics were investigated using tomographic particle imaging velocimetry (TPIV). Experiments were performed using three experimental conditions, namely, swirl port open (SPO), tangential port open (TPO), and both port open (BPO) configurations in a single cylinder optical research engine. <span class="hlt">Flow</span> investigations were carried out in a volumetric section located in the middle of the intake and exhaust valves. Particle imaging velocimetry (PIV) images were captured using two high speed cameras at a crank angle resolution of 2° in the intake and compression strokes. The captured PIV images were then pre-processed and post-processed to obtain the final <span class="hlt">air-flow</span>-field. Effects of these two intake ports on <span class="hlt">flow</span>-field are presented for <span class="hlt">air</span> velocity, vorticity, average absolute velocity, and turbulent kinetic energy. Analysis of these <span class="hlt">flow</span>-fields suggests the dominating nature of the swirl port over the tangential port for the BPO configuration and higher rate of <span class="hlt">flow</span> energy dissipation for the TPO configuration compared to the SPO and BPO configurations. These findings of TPIV investigations were experimentally verified by combustion and particulate characteristics of the test engine in thermal cylinder head configuration. Combustion results showed that the SPO configuration resulted in superior combustion amongst all three port configurations. Particulate characteristics showed that the TPO configuration resulted in higher particulate compared to other port configurations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..226a2007Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..226a2007Z"><span>Study of Mouthguard Design for Endurance and <span class="hlt">Air-Flow</span> Intake</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zaman, I.; Rozlan, S. A. M.; Manshoor, B.; Ngali, M. Z.; Khalid, A.; Amin, N. A. M.</p> <p>2017-08-01</p> <p>Mouthguard is one of the important device for athletes. Wearing a mouthguard is a must to prevent them from any orofacial injuries occurs during their sport activities. Therefore, to make sure it is safe and comfort, a study on the mouthguard design is carried out to investigate the performance of the mouthguard, in term of stress distribution and <span class="hlt">air</span> <span class="hlt">flow</span> path by improving the pressure difference between ambient and the oral cavity pressure. A preliminary design has been study to simulate its total deformation and stress, in terms of Von Mises Stress by using ANSYS 15.0 Workbench. From the results, the critical parts are identified on the preliminary design and later being used to improve the design to the new one. By increasing the thickness of the preliminary design, the total deformation has been decreased for about 0.20 mm to 0.16 mm for the exerted external forces ranging from 50-500 N, whereas, for internal forces ranging from 100-600 N have reduced deformation from 0.24 mm to 1.44 mm. The simulation process is then followed by the <span class="hlt">air</span> <span class="hlt">flow</span> study in the oral cavity with an open mouth about 0.5 mm when the athlete is doing exercise with speed 4.43 m/s of <span class="hlt">air</span> <span class="hlt">flow</span> into a mouth. The finding indicates that the modified mouthguard has large value of velocity streamline compared to the preliminary design which is supported by significant pressure difference of 401.86 Pa, compared to 140.09 Pa of the preliminary design. Velocity stream line also shows that the higher speeds occur in the near mouthguard, that is, between the bottom surfaces of the mouthguard and the lower teeth. The results demonstrated that the thicker the mouthguard, the better it is for prevention but less in <span class="hlt">air</span> <span class="hlt">flow</span> distribution into the oral cavity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005Geomo..69....1W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005Geomo..69....1W"><span>Quantifying downstream impacts of impoundment on <span class="hlt">flow</span> <span class="hlt">regime</span> and channel planform, lower Trinity River, Texas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wellmeyer, Jessica L.; Slattery, Michael C.; Phillips, Jonathan D.</p> <p>2005-07-01</p> <p>As human population worldwide has grown, so has interest in harnessing and manipulating the <span class="hlt">flow</span> of water for the benefit of humans. The Trinity River of eastern Texas is one such watershed greatly impacted by engineering and urbanization. Draining the Dallas-Fort Worth metroplex, just under 30 reservoirs are in operation in the basin, regulating <span class="hlt">flow</span> while containing public supplies, supporting recreation, and providing flood control. Lake Livingston is the lowest, as well as largest, reservoir in the basin, a mere 95 km above the Trinity's outlet near Galveston Bay. This study seeks to describe and quantify channel activity and <span class="hlt">flow</span> <span class="hlt">regime</span>, identifying effects of the 1968 closure of Livingston dam. Using historic daily and peak discharge data from USGS gauging stations, <span class="hlt">flow</span> duration curves are constructed, identifying pre- and post-dam <span class="hlt">flow</span> conditions. A digital historic photo archive was also constructed using six sets of aerial photographs spanning from 1938 to 1995, and three measures of channel activity applied using a GIS. Results show no changes in high <span class="hlt">flow</span> conditions following impoundment, while low <span class="hlt">flows</span> are elevated. However, the entire post-dam period is characterized by significantly higher rainfall, which may be obscuring the full impact of <span class="hlt">flow</span> regulation. Channel activity rates do not indicate a more stabilized planform following dam closure; rather they suggest that the Trinity River is adjusting itself to the stress of Livingston dam in a slow, gradual process that may not be apparent in a modern time scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1440..854K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1440..854K"><span>Numerical analysis of <span class="hlt">air-flow</span> and temperature field in a passenger car compartment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kamar, Haslinda Mohamed; Kamsah, Nazri; Mohammad Nor, Ahmad Miski</p> <p>2012-06-01</p> <p>This paper presents a numerical study on the temperature field inside a passenger's compartment of a Proton Wira saloon car using computational fluid dynamics (CFD) method. The main goal is to investigate the effects of different glazing types applied onto the front and rear windscreens of the car on the distribution of <span class="hlt">air</span>-temperature inside the passenger compartment in the steady-state conditions. The <span class="hlt">air-flow</span> condition in the passenger's compartment is also investigated. Fluent CFD software was used to develop a three-dimensional symmetrical model of the passenger's compartment. Simplified representations of the driver and one rear passenger were incorporated into the CFD model of the passenger's compartment. Two types of glazing were considered namely clear insulated laminated tint (CIL) with a shading coefficient of 0.78 and green insulated laminate tint (GIL) with a shading coefficient of 0.5. Results of the CFD analysis were compared with those obtained when the windscreens are made up of clear glass having a shading coefficient of 0.86. Results of the CFD analysis show that for a given glazing material, the temperature of the <span class="hlt">air</span> around the driver is slightly lower than the <span class="hlt">air</span> around the rear passenger. Also, the use of GIL glazing material on both the front and rear windscreens significantly reduces the <span class="hlt">air</span> temperature inside the passenger's compartment of the car. This contributes to a better thermal comfort condition to the occupants. Swirling <span class="hlt">air</span> <span class="hlt">flow</span> condition occurs in the passenger compartment. The <span class="hlt">air-flow</span> intensity and velocity are higher along the side wall of the passenger's compartment compared to that along the middle section of the compartment. It was also found that the use of glazing materials on both the front and rear windscreen has no significant effects on the <span class="hlt">air-flow</span> condition inside the passenger's compartment of the car.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/8788','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/8788"><span>Impact of <span class="hlt">flow</span> regulation and power plant effluents on the <span class="hlt">flow</span> and temperature <span class="hlt">regimes</span> of the Chattahoochee River; Atlanta to Whitesburg, Georgia</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Faye, Robert E.; Jobson, Harvey E.; Land, Larry F.</p> <p>1978-01-01</p> <p>A calibrated and verified transient-<span class="hlt">flow</span> temperature model was used to evaluate the effects of <span class="hlt">flow</span> regulation and powerplant loadings on the natural temperature <span class="hlt">regime</span> of the Chattahoochee River in northeast Georgia. Estimates were made of both instantaneous and average natural temperatures in the river during an 8-day period in August 1976. Differences between the computed average natural temperature and an independent estimateof natural temperature based on observed equilibrium temperatures were less than 0.5C. The combined thermal effects of <span class="hlt">flow</span> regulation and powerplant effluents resulted in mean daily river temperatures downstreams of the powerplants about equal to or less than computed mean natural temperatures. The range and rates of change of computed natural diurnal temperature fluctuations were considerably less than those presently observed (1976) in the river. Except during periods of peak water-supply demand, differences between computed year 2000 river temperatures and observed present-day temperatures were less than 2C. (Woodard-USGS)</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMEP21B0892H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMEP21B0892H"><span>Changes in Bedform Shape at the Transition Between Upper Plane-Bed and Sheet-<span class="hlt">Flow</span> Bedload Transport <span class="hlt">Regimes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hernandez Moreira, R. R.; Huffman, B.; Vautin, D.; Viparelli, E.</p> <p>2015-12-01</p> <p>The interactions between <span class="hlt">flow</span> hydrodynamics and bedform characteristics at the transition between upper plane-bed bedload transport <span class="hlt">regime</span> and sheet-<span class="hlt">flow</span> have not yet been thoroughly described and still remain poorly understood. The present study focuses on the experimental study of this transition in open channel mode. The experiments were performed in the hydraulic laboratory of the Department of Civil and Environmental Engineering of the University of South Carolina in a sediment-feed flume, 9-m long by 19-cm wide with uniform material sediment of geometric mean grain size diameter of 1.11 mm. Sediment feed rates ranged between 0.5 kg/min and 20 kg/min with two different <span class="hlt">flow</span> rates of 20 l/s and 30 l/s. We recorded periodic measurements of water surface and bed elevation to estimate the global <span class="hlt">flow</span> parameters, e.g. mean <span class="hlt">flow</span> velocity and bed shear stress, and to determine when the <span class="hlt">flow</span> and the sediment transport reached conditions of mobile bed equilibrium. We define mobile bed equilibrium as a condition in which the mean bed elevation does not change in time. At equilibrium, measurements of bed elevation fluctuations were taken with an ultrasonic transducer system at six discrete locations. In the runs with low and medium feed rates, i.e. smaller than ~12 kg/min, the long wavelength and small amplitude bedforms typical of the upper plane bed <span class="hlt">regime</span>, which were observed in previous experimental work, formed and migrated downstream. In particular, with increasing feed rates, the amplitude of the bedforms decreases and their geometry changes, from well-defined triangular shapes, to rounded shapes to flat bed with very small amplitude, long wavelength undulations. The decrease in amplitude corresponds to a decrease in form drag and an increase in the thickness of the bedload layer. The ultrasonic measurements are analyzed to statistically describe the observed transition in terms of probability distribution functions of the bed elevation fluctuations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930091664','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930091664"><span>Fuel Spray and Flame Formation in a Compression-Ignition Engine Employing <span class="hlt">Air</span> <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rothrock, A M; Waldron, C D</p> <p>1937-01-01</p> <p>The effects of <span class="hlt">air</span> <span class="hlt">flow</span> on fuel spray and flame formation in a high-speed compression-ignition engine have been investigated by means of the NACA combustion apparatus. The process was studied by examining high-speed motion pictures taken at the rate of 2,200 frames a second. The combustion chamber was of the flat-disk type used in previous experiments with this apparatus. The <span class="hlt">air</span> <span class="hlt">flow</span> was produced by a rectangular displacer mounted on top of the engine piston. Three fuel-injection nozzles were tested: a 0.020-inch single-orifice nozzle, a 6-orifice nozzle, and a slit nozzle. The <span class="hlt">air</span> velocity within the combustion chamber was estimated to reach a value of 425 feet a second. The results show that in no case was the form of the fuel spray completely destroyed by the <span class="hlt">air</span> jet although in some cases the direction of the spray was changed and the spray envelope was carried away by the moving <span class="hlt">air</span>. The distribution of the fuel in the combustion chamber of a compression-ignition engine can be regulated to some extent by the design of the combustion chamber, by the design of the fuel-injection nozzle, and by the use of <span class="hlt">air</span> <span class="hlt">flow</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27081931','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27081931"><span>Cold <span class="hlt">air</span> drainage <span class="hlt">flows</span> subsidize montane valley ecosystem productivity.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Novick, Kimberly A; Oishi, A Christopher; Miniat, Chelcy Ford</p> <p>2016-12-01</p> <p>In mountainous areas, cold <span class="hlt">air</span> drainage from high to low elevations has pronounced effects on local temperature, which is a critical driver of many ecosystem processes, including carbon uptake and storage. Here, we leverage new approaches for interpreting ecosystem carbon flux observations in complex terrain to quantify the links between macro-climate condition, drainage <span class="hlt">flows</span>, local microclimate, and ecosystem carbon cycling in a southern Appalachian valley. Data from multiple long-running climate stations and multiple eddy covariance flux towers are combined with simple models for ecosystem carbon fluxes. We show that cold <span class="hlt">air</span> drainage into the valley suppresses local temperature by several degrees at night and for several hours before and after sunset, leading to reductions in growing season respiration on the order of ~8%. As a result, we estimate that drainage <span class="hlt">flows</span> increase growing season and annual net carbon uptake in the valley by >10% and >15%, respectively, via effects on microclimate that are not be adequately represented in regional- and global-scale terrestrial ecosystem models. Analyses driven by chamber-based estimates of soil and plant respiration reveal cold <span class="hlt">air</span> drainage effects on ecosystem respiration are dominated by reductions to the respiration of aboveground biomass. We further show that cold <span class="hlt">air</span> drainage proceeds more readily when cloud cover and humidity are low, resulting in the greatest enhancements to net carbon uptake in the valley under clear, cloud-free (i.e., drought-like) conditions. This is a counterintuitive result that is neither observed nor predicted outside of the valley, where nocturnal temperature and respiration increase during dry periods. This result should motivate efforts to explore how topographic <span class="hlt">flows</span> may buffer eco-physiological processes from macroscale climate change. © 2016 John Wiley & Sons Ltd.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1322489-measurement-size-dependent-dynamic-shape-factors-quartz-particles-two-flow-regimes','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1322489-measurement-size-dependent-dynamic-shape-factors-quartz-particles-two-flow-regimes"><span>Measurement of Size-dependent Dynamic Shape Factors of Quartz Particles in Two <span class="hlt">Flow</span> <span class="hlt">Regimes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Alexander, Jennifer M.; Bell, David M.; Imre, D.</p> <p>2016-08-02</p> <p>Understanding and modeling the behavior of quartz dust particles, commonly found in the atmosphere, requires knowledge of many relevant particles properties, including particle shape. This study uses a single particle mass spectrometer, a differential mobility analyzer, and an aerosol particle mass analyzer to measure quartz aerosol particles mobility, aerodynamic, and volume equivalent diameters, mass, composition, effective density, and dynamic shape factor as a function of particle size, in both the free molecular and transition <span class="hlt">flow</span> <span class="hlt">regimes</span>. The results clearly demonstrate that dynamic shape factors can vary significantly as a function of particle size. For the quartz samples studied here, themore » dynamic shape factors increase with size, indicating that larger particles are significantly more aspherical than smaller particles. In addition, dynamic shape factors measured in the free-molecular (χv) and transition (χt) <span class="hlt">flow</span> <span class="hlt">regimes</span> can be significantly different, and these differences vary with the size of the quartz particles. For quartz, χv of small (d < 200 nm) particles is 1.25, while χv of larger particles (d ~ 440 nm) is 1.6, with a continuously increasing trend with particle size. In contrast χt, of small particles starts at 1.1 increasing slowly to 1.34 for 550 nm diameter particles. The multidimensional particle characterization approach used here goes beyond determination of average properties for each size, to provide additional information about how the particle dynamic shape factor may vary even for particles with the same mass and volume equivalent diameter.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28903233','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28903233"><span>A MEMS-based <span class="hlt">Air</span> <span class="hlt">Flow</span> Sensor with a Free-standing Micro-cantilever Structure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yu-Hsiang; Lee, Chia-Yen; Chiang, Che-Ming</p> <p>2007-10-17</p> <p>This paper presents a micro-scale <span class="hlt">air</span> <span class="hlt">flow</span> sensor based on a free-standingcantilever structure. In the fabrication process, MEMS techniques are used to deposit asilicon nitride layer on a silicon wafer. A platinum layer is deposited on the silicon nitridelayer to form a piezoresistor, and the resulting structure is then etched to create afreestanding micro-cantilever. When an <span class="hlt">air</span> <span class="hlt">flow</span> passes over the surface of the cantileverbeam, the beam deflects in the downward direction, resulting in a small variation in theresistance of the piezoelectric layer. The <span class="hlt">air</span> <span class="hlt">flow</span> velocity is determined by measuring thechange in resistance using an external LCR meter. The experimental results indicate that theflow sensor has a high sensitivity (0.0284 ω/ms -1 ), a high velocity measurement limit (45ms -1 ) and a rapid response time (0.53 s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJWC.14302054K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJWC.14302054K"><span>Experimental investigation of cavitation induced <span class="hlt">air</span> release</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kowalski, Karoline; Pollak, Stefan; Hussong, Jeanette</p> <p></p> <p>Variations in cross-sectional areas may lead to pressure drops below a critical value, such that cavitation and <span class="hlt">air</span> release are provoked in hydraulic systems. Due to a relatively slow dissolution of gas bubbles, the performance of hydraulic systems will be affected on long time scales by the gas phase. Therefore predictions of <span class="hlt">air</span> production rates are desirable to describe the system characteristics. Existing investigations on generic geometries such as micro-orifice <span class="hlt">flows</span> show an outgassing process due to hydrodynamic cavitation which takes place on time scales far shorter than diffusion processes. The aim of the present investigation is to find a correlation between global, hydrodynamic <span class="hlt">flow</span> characteristics and cavitation induced undissolved gas fractions generated behind generic <span class="hlt">flow</span> constrictions such as an orifice or venturi tube. Experimental investigations are realised in a cavitation channel that enables an independent adjustment of the pressure level upstream and downstream of the orifice. Released <span class="hlt">air</span> fractions are determined by means of shadowgraphy imaging. First results indicate that an increased cavitation activity leads to a rapid increase in undissolved gas volume only in the choking <span class="hlt">regime</span>. The frequency distribution of generated gas bubble size seems to depend only indirectly on the cavitation intensity driven by an increase of downstream coalescence events due to a more densely populated bubbly <span class="hlt">flow</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29847095','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29847095"><span><span class="hlt">Air-Flow</span>-Driven Triboelectric Nanogenerators for Self-Powered Real-Time Respiratory Monitoring.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Meng; Zhang, Jiahao; Tang, Yingjie; Li, Jun; Zhang, Baosen; Liang, Erjun; Mao, Yanchao; Wang, Xudong</p> <p>2018-06-04</p> <p>Respiration is one of the most important vital signs of humans, and respiratory monitoring plays an important role in physical health management. A low-cost and convenient real-time respiratory monitoring system is extremely desirable. In this work, we demonstrated an <span class="hlt">air-flow</span>-driven triboelectric nanogenerator (TENG) for self-powered real-time respiratory monitoring by converting mechanical energy of human respiration into electric output signals. The operation of the TENG was based on the <span class="hlt">air-flow</span>-driven vibration of a flexible nanostructured polytetrafluoroethylene (n-PTFE) thin film in an acrylic tube. This TENG can generate distinct real-time electric signals when exposed to the <span class="hlt">air</span> <span class="hlt">flow</span> from different breath behaviors. It was also found that the accumulative charge transferred in breath sensing corresponds well to the total volume of <span class="hlt">air</span> exchanged during the respiration process. Based on this TENG device, an intelligent wireless respiratory monitoring and alert system was further developed, which used the TENG signal to directly trigger a wireless alarm or dial a cell phone to provide timely alerts in response to breath behavior changes. This research offers a promising solution for developing self-powered real-time respiratory monitoring devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvE..95f3110P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvE..95f3110P"><span>Experimental investigations on characteristics of stable water electrospray in <span class="hlt">air</span> without discharge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Park, Inyong; Hong, Won Seok; Kim, Sang Bok; Kim, Sang Soo</p> <p>2017-06-01</p> <p>An experimental study was conducted to resolve previous conflicting results on water electrospray in <span class="hlt">air</span> at atmospheric pressure. Using a small <span class="hlt">flow</span> rate relative to that used in previous studies and a small nonmetallic nozzle, we observed stable electrospray of water in <span class="hlt">air</span> without discharge and distinguished three distinct operating <span class="hlt">regimes</span> for applied voltage and <span class="hlt">flow</span> rate. The well-known cone-jet mode was observed and the general scaling law of the generated droplet size in the cone-jet mode was confirmed by direct visualization of the meniscus, jet, and generated droplets. We also observed and analyzed whipping motion in the electrified water jet.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/6871478','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/6871478"><span>One-dimensional drift-flux model and constitutive equations for relative motion between phases in various two-phase <span class="hlt">flow</span> <span class="hlt">regimes</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ishii, M.</p> <p>1977-10-01</p> <p>In view of the practical importance of the drift-flux model for two-phase <span class="hlt">flow</span> analysis in general and in the analysis of nuclear-reactor transients and accidents in particular, the kinematic constitutive equation for the drift velocity has been studied for various two-phase <span class="hlt">flow</span> <span class="hlt">regimes</span>. The constitutive equation that specifies the relative motion between phases in the drift-flux model has been derived by taking into account the interfacial geometry, the body-force field, shear stresses, and the interfacial momentum transfer, since these macroscopic effects govern the relative velocity between phases. A comparison of the model with various experimental data over various <span class="hlt">flow</span> regimesmore » and a wide range of <span class="hlt">flow</span> parameters shows a satisfactory agreement.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70011481','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70011481"><span>Permafrost, heat <span class="hlt">flow</span>, and the geothermal <span class="hlt">regime</span> at Prudhoe Bay, Alaska.</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lachenbruch, A.H.; Sass, J.H.; Marshall, B.V.; Moses, T.H.</p> <p>1982-01-01</p> <p>Temperature measurements through permafrost in the oil field at Prudhoe Bay, Alaska, combined with laboratory measurements of the thermal conductivity of drill cutting permit an evaluation of in situ thermal properties and an understanding of the general factors that control the geothermal <span class="hlt">regime</span>. A sharp contrast in temperatire gradient at c600m represents a contrast in thermal conductivity caused by the downward change from interstitial ice to interstitial water at the base of permafrost under near steady state conditions. These results yield a heat <span class="hlt">flow</span> of c1.3HFU, which is similar to other values on the Alaskan Arctic Coast: the anomalously deep permafrost is a result of the anomalously high conductivity of the siliceous ice-rich sediments. With confirmation of the permafrost configuration by offshore drilling, heat conduction models can yield reliable new information on the chronology of arctic shoreline. -from Authors</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LatJP..53b..20S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LatJP..53b..20S"><span>Experimental and Numerical Analysis of <span class="hlt">Air</span> <span class="hlt">Flow</span>, Heat Transfer and Thermal Comfort in Buildings with Different Heating Systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sabanskis, A.; Virbulis, J.</p> <p>2016-04-01</p> <p>Monitoring of temperature, humidity and <span class="hlt">air</span> <span class="hlt">flow</span> velocity is performed in 5 experimental buildings with the inner size of 3×3×3 m3 located in Riga, Latvia. The buildings are equipped with different heating systems, such as an <span class="hlt">air-air</span> heat pump, <span class="hlt">air</span>-water heat pump, capillary heating mat on the ceiling and electric heater. Numerical simulation of <span class="hlt">air</span> <span class="hlt">flow</span> and heat transfer by convection, conduction and radiation is carried out using OpenFOAM software and compared with experimental data. Results are analysed regarding the temperature and <span class="hlt">air</span> <span class="hlt">flow</span> distribution as well as thermal comfort.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890043107&hterms=surfactants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsurfactants','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890043107&hterms=surfactants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsurfactants"><span><span class="hlt">Flow</span> visualization study of grooved surface/surfactant/<span class="hlt">air</span> sheet interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reed, Jason C.; Weinstein, Leonard M.</p> <p>1989-01-01</p> <p>The effects of groove geometry, surfactants, and airflow rate have been ascertained by a <span class="hlt">flow</span>-visualization study of grooved-surface models which addresses the possible conditions for skin friction-reduction in marine vehicles. It is found that the grooved surface geometry holds the injected bubble stream near the wall and, in some cases, results in a 'tube' of <span class="hlt">air</span> which remains attached to the wall. It is noted that groove dimension and the use of surfactants can substantially affect the stability of this <span class="hlt">air</span> tube; deeper grooves, surfactants with high contact angles, and angled <span class="hlt">air</span> injection, are all found to increase the stability of the attached <span class="hlt">air</span> tube, while convected disturbances and high shear increase interfacial instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.6420S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.6420S"><span>Coupled modelling of <span class="hlt">flow</span> and biofilm in a laminar <span class="hlt">flow</span> <span class="hlt">regime</span> through a high-resolution fluid-structure interaction (FSI) solver</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sinha, Sumit; Hardy, Richard; Smith, Gregory; Kazemifar, Farzan; Christensen, Kenneth; Best, Jim</p> <p>2017-04-01</p> <p>Biofilms are ubiquitously present in fluvial systems, growing on almost all wetted surface and has a significant impact on both water quantity, in terms of ambient <span class="hlt">flow</span> condition, as well as water quality, biofilms growing in water distribution system leads to unwanted contamination. The local hydraulic conditions have a significant impact on the biofilm lifecycle as in order to sustain their growth biofilms draw essential nutrients either from the <span class="hlt">flow</span> or from the surface on which they grow. This implies that in convection dominated <span class="hlt">flow</span>, nutrient transfer from water, would nurture the growth of biofilms. However, at higher <span class="hlt">flow</span> rates biofilms are subjected to higher stresses which may lead to their detachment. Furthermore, biofilms in ambient <span class="hlt">flow</span> conditions oscillate and therefore alter the local <span class="hlt">flow</span> conditions. There is, therefore, a complex feedback between biofilms and <span class="hlt">flow</span> which have has implications for <span class="hlt">flow</span> dynamics and water quality issues in riverine ecosystems. The research presented here describes a fluid-structure interaction solver to examine the coupled nature of biofilm oscillations due to the ambient <span class="hlt">flow</span> and its feedback on the local <span class="hlt">flow</span> structures. The fluid <span class="hlt">flow</span> is modelled by the incompressible Navier-Stokes equations and structural deformation of the biofilm is modeled by applying a linear elastic model. The governing equations are numerically solved through Finite Volume methodology based on cell-centered scheme. Simulations are conducted in a laminar <span class="hlt">regime</span> for a biofilm streamer modelled as moving slender plate. The temporal evolution of the pressure, <span class="hlt">flow</span> structures are examined in the vicinity of the biofilm. Further investigations examine the impact of changing Reynolds number on the oscillation frequency as well as drag and lift forces experienced by the biofilm. The changing frequency of biofilm oscillation with varying Reynolds number is characterized by the Strouhal number (St). Our investigation reveals that as the <span class="hlt">flow</span> separates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JPhCS.166a2017C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JPhCS.166a2017C"><span>Transition to chaos of a vertical collapsible tube conveying <span class="hlt">air</span> <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Castillo Flores, F.; Cros, A.</p> <p>2009-05-01</p> <p>"Sky dancers", the large collapsible tubes used as advertising, are studied in this work through a simple experimental device. Our study is devoted to the nonlinear dynamics of this system and to its transition to chaos. Firstly, we have shown that after a collapse occurs, the <span class="hlt">air</span> fills the tube at a different speed rate from the <span class="hlt">flow</span> velocity. Secondly, the temporal intermittency is studied as the <span class="hlt">flow</span> rate is increased. A statistical analysis shows that the chaotic times maintain roughly the same value by increasing <span class="hlt">air</span> speed. On the other hand, laminar times become shorter, until the system reaches a completely chaotic state.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title30-vol1/pdf/CFR-2011-title30-vol1-sec57-22212.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title30-vol1/pdf/CFR-2011-title30-vol1-sec57-22212.pdf"><span>30 CFR 57.22212 - <span class="hlt">Air</span> <span class="hlt">flow</span> (I-C, II-A, and V-A mines).</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-07-01</p> <p>... 30 Mineral Resources 1 2011-07-01 2011-07-01 false <span class="hlt">Air</span> <span class="hlt">flow</span> (I-C, II-A, and V-A mines). 57.22212 Section 57.22212 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND... Standards for Methane in Metal and Nonmetal Mines Ventilation § 57.22212 <span class="hlt">Air</span> <span class="hlt">flow</span> (I-C, II-A, and V-A mines...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JAP...107i3303P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JAP...107i3303P"><span>Transitions between corona, glow, and spark <span class="hlt">regimes</span> of nanosecond repetitively pulsed discharges in <span class="hlt">air</span> at atmospheric pressure</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pai, David Z.; Lacoste, Deanna A.; Laux, Christophe O.</p> <p>2010-05-01</p> <p>In atmospheric pressure <span class="hlt">air</span> preheated from 300 to 1000 K, the nanosecond repetitively pulsed (NRP) method has been used to generate corona, glow, and spark discharges. Experiments have been performed to determine the parameter space (applied voltage, pulse repetition frequency, ambient gas temperature, and interelectrode gap distance) of each discharge <span class="hlt">regime</span>. In particular, the experimental conditions necessary for the glow <span class="hlt">regime</span> of NRP discharges have been determined, with the notable result that there exists a minimum and maximum gap distance for its existence at a given ambient gas temperature. The minimum gap distance increases with decreasing gas temperature, whereas the maximum does not vary appreciably. To explain the experimental results, an analytical model is developed to explain the corona-to-glow (C-G) and glow-to-spark (G-S) transitions. The C-G transition is analyzed in terms of the avalanche-to-streamer transition and the breakdown field during the conduction phase following the establishment of a conducting channel across the discharge gap. The G-S transition is determined by the thermal ionization instability, and we show analytically that this transition occurs at a certain reduced electric field for the NRP discharges studied here. This model shows that the electrode geometry plays an important role in the existence of the NRP glow <span class="hlt">regime</span> at a given gas temperature. We derive a criterion for the existence of the NRP glow <span class="hlt">regime</span> as a function of the ambient gas temperature, pulse repetition frequency, electrode radius of curvature, and interelectrode gap distance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26860399','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26860399"><span>Tracheostomy Tube Type and Inner Cannula Selection Impact Pressure and Resistance to <span class="hlt">Air</span> <span class="hlt">Flow</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pryor, Lee N; Baldwin, Claire E; Ward, Elizabeth C; Cornwell, Petrea L; O'Connor, Stephanie N; Chapman, Marianne J; Bersten, Andrew D</p> <p>2016-05-01</p> <p>Advancements in tracheostomy tube design now provide clinicians with a range of options to facilitate communication for individuals receiving ventilator assistance through a cuffed tube. Little is known about the impact of these modern design features on resistance to <span class="hlt">air</span> <span class="hlt">flow</span>. We undertook a bench model test to measure pressure-<span class="hlt">flow</span> characteristics and resistance of a range of tubes of similar outer diameter, including those enabling subglottic suction and speech. A constant inspiratory ± expiratory <span class="hlt">air</span> <span class="hlt">flow</span> was generated at increasing <span class="hlt">flows</span> up to 150 L/min through each tube (with or without optional, mandatory, or interchangeable inner cannula). Driving pressures were measured, and resistance was calculated (cm H2O/L/s). Pressures changed with increasing <span class="hlt">flow</span> (P < .001) and tube type (P < .001), with differing patterns of pressure change according to the type of tube (P < .001) and direction of <span class="hlt">air</span> <span class="hlt">flow</span>. The single-lumen reference tube encountered the lowest inspiratory and expiratory pressures compared with all double-lumen tubes (P < .001); placement of an optional inner cannula increased bidirectional tube resistance by a factor of 3. For a tube with interchangeable inner cannulas, the type of cannula altered pressure and resistance differently (P < .001); the speech cannula in particular amplified pressure-<span class="hlt">flow</span> changes and increased tube resistance by more than a factor of 4. Tracheostomy tube type and inner cannula selection imposed differing pressures and resistance to <span class="hlt">air</span> <span class="hlt">flow</span> during inspiration and expiration. These differences may be important when selecting airway equipment or when setting parameters for monitoring, particularly for patients receiving supported ventilation or during the weaning process. Copyright © 2016 by Daedalus Enterprises.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JThSc..27..184M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JThSc..27..184M"><span>Comparative Study of Convective Heat Transfer Performance of Steam and <span class="hlt">Air</span> <span class="hlt">Flow</span> in Rib Roughened Channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ma, Chao; Ji, Yongbin; Ge, Bing; Zang, Shusheng; Chen, Hua</p> <p>2018-04-01</p> <p>A comparative experimental study of heat transfer characteristics of steam and <span class="hlt">air</span> <span class="hlt">flow</span> in rectangular channels roughened with parallel ribs was conducted by using an infrared camera. Effects of Reynolds numbers and rib angles on the steam and <span class="hlt">air</span> convective heat transfer have been obtained and compared with each other for the Reynolds number from about 4,000 to 15,000. For all the ribbed channels the rib pitch to height ratio (p/e) is 10, and the rib height to the channel hydraulic diameter ratio is 0.078, while the rib angles are varied from 90° to 45°. Based on experimental results, it can be found that, even though the heat transfer distributions of steam and <span class="hlt">air</span> <span class="hlt">flow</span> in the ribbed channels are similar to each other, the steam <span class="hlt">flow</span> can obtain higher convective heat transfer enhancement capability, and the heat transfer enhancement of both the steam and <span class="hlt">air</span> becomes greater with the rib angle deceasing from 90° to 45°. At Reynolds number of about 12,000, the area-averaged Nusselt numbers of the steam <span class="hlt">flow</span> is about 13.9%, 14.2%, 19.9% and 23.9% higher than those of the <span class="hlt">air</span> <span class="hlt">flow</span> for the rib angles of 90°, 75°, 60° and 45° respectively. With the experimental results the correlations for Nusselt number in terms of Reynolds number and rib angle for the steam and <span class="hlt">air</span> <span class="hlt">flow</span> in the ribbed channels were developed respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4551065','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4551065"><span><span class="hlt">Flow</span> characteristics of an inclined <span class="hlt">air</span>-curtain range hood in a draft</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>CHEN, Jia-Kun</p> <p>2015-01-01</p> <p>The inclined <span class="hlt">air</span>-curtain technology was applied to build an inclined <span class="hlt">air</span>-curtain range hood. A draft generator was applied to affect the inclined <span class="hlt">air</span>-curtain range hood in three directions: lateral (θ=0°), oblique (θ=45°), and front (θ=90°). The three suction <span class="hlt">flow</span> rates provided by the inclined <span class="hlt">air</span>-curtain range hood were 10.1, 10.9, and 12.6 m3/min. The laser-assisted <span class="hlt">flow</span> visualization technique and the tracer-gas test method were used to investigate the performance of the range hood under the influence of a draft. The results show that the inclined <span class="hlt">air</span>-curtain range hood has a strong ability to resist the negative effect of a front draft until the draft velocity is greater than 0.5 m/s. The oblique draft affected the containment ability of the inclined <span class="hlt">air</span>-curtain range hood when the draft velocity was larger than 0.3 m/s. When the lateral draft effect was applied, the capture efficiency of the inclined <span class="hlt">air</span>-curtain range hood decreased quickly in the draft velocity from 0.2 m/s to 0.3 m/s. However, the capture efficiencies of the inclined <span class="hlt">air</span>-curtain range hood under the influence of the front draft were higher than those under the influence of the oblique draft from 0.3 m/s to 0.5 m/s. PMID:25810445</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25810445','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25810445"><span><span class="hlt">Flow</span> characteristics of an inclined <span class="hlt">air</span>-curtain range hood in a draft.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Jia-Kun</p> <p>2015-01-01</p> <p>The inclined <span class="hlt">air</span>-curtain technology was applied to build an inclined <span class="hlt">air</span>-curtain range hood. A draft generator was applied to affect the inclined <span class="hlt">air</span>-curtain range hood in three directions: lateral (θ=0°), oblique (θ=45°), and front (θ=90°). The three suction <span class="hlt">flow</span> rates provided by the inclined <span class="hlt">air</span>-curtain range hood were 10.1, 10.9, and 12.6 m(3)/min. The laser-assisted <span class="hlt">flow</span> visualization technique and the tracer-gas test method were used to investigate the performance of the range hood under the influence of a draft. The results show that the inclined <span class="hlt">air</span>-curtain range hood has a strong ability to resist the negative effect of a front draft until the draft velocity is greater than 0.5 m/s. The oblique draft affected the containment ability of the inclined <span class="hlt">air</span>-curtain range hood when the draft velocity was larger than 0.3 m/s. When the lateral draft effect was applied, the capture efficiency of the inclined <span class="hlt">air</span>-curtain range hood decreased quickly in the draft velocity from 0.2 m/s to 0.3 m/s. However, the capture efficiencies of the inclined <span class="hlt">air</span>-curtain range hood under the influence of the front draft were higher than those under the influence of the oblique draft from 0.3 m/s to 0.5 m/s.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015WRR....51.1758G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015WRR....51.1758G"><span>Transient response of Salix cuttings to changing water level <span class="hlt">regimes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gorla, L.; Signarbieux, C.; Turberg, P.; Buttler, A.; Perona, P.</p> <p>2015-03-01</p> <p>Sustainable water management requires an understanding of the effects of <span class="hlt">flow</span> regulation on riparian ecomorphological processes. We investigated the transient response of Salix viminalis by examining the effect of water-level <span class="hlt">regimes</span> on its above-ground and below-ground biomass. Four sets of Salix cuttings, three juveniles (in the first growing season) and one mature (1 year old), were planted and initially grown under the same water-level <span class="hlt">regime</span> for 1 month. We imposed three different water-level <span class="hlt">regime</span> treatments representing natural variability, a seasonal trend with no peaks, and minimal <span class="hlt">flow</span> (characteristic of hydropower) consisting of a constant water level and natural flood peaks. We measured sap flux, stem water potential, photosynthesis, growth parameters, and final root architecture. The mature cuttings were not affected by water table dynamics, but the juveniles displayed causal relationships between the changing water <span class="hlt">regime</span>, plant growth, and root distribution during a 2 month transient period. For example, a 50% drop in mean sap flux corresponded with a -1.5 Mpa decrease in leaf water potential during the first day after the water <span class="hlt">regime</span> was changed. In agreement with published field observations, the cuttings concentrated their roots close to the mean water table of the corresponding treatment, allowing survival under altered conditions and resilience to successive stress events. Juvenile development was strongly impacted by the minimum <span class="hlt">flow</span> <span class="hlt">regime</span>, leading to more than 60% reduction of both above-ground and below-ground biomass, with respect to the other treatments. Hence, we suggest avoiding minimum <span class="hlt">flow</span> <span class="hlt">regimes</span> where Salix restoration is prioritized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MeScT..29e5301H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MeScT..29e5301H"><span>Fabrication and evaluation of a graphene oxide-based cantilever-type <span class="hlt">flow</span>-meter for subsonic gas <span class="hlt">flow</span> rate measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hamdollahi, Hassan; Rahbar-Shahrouzi, Javad</p> <p>2018-05-01</p> <p>In this paper, a cantilever-type <span class="hlt">flow</span> meter was fabricated to measure the rate of <span class="hlt">air</span> <span class="hlt">flow</span> in turbulent subsonic <span class="hlt">regimes</span> such as purged gases. In the fabrication process, a piezoresistive material was coated on an interdigitated electric board as a substrate. The piezoresistive layer was a blend of latex as the polymeric matrix and graphene oxide as the sensing nanomaterial agent, which was reduced by solvothermal reduction method. The piezoresistive blend was dip-coated on a substrate with dotted pattern and was then reduced at 240 °C for 1 h in every coating step. When an <span class="hlt">air</span> <span class="hlt">flow</span> passed over the surface of the cantilever beam, the beam was bent in the downward direction, resulting in small variations in the resistance of the piezoresistive layer and a change in the bending angle of the cantilever which were measured simultaneously. The <span class="hlt">air</span> <span class="hlt">flow</span> rate was acquired via calibrating electrical resistance changes by Arduino and Wheatstone bridge circuit. The blending angle of the substrate caused by the interaction between the airflow and the cantilever and recorded by the camera and image processing was ultimately compared with the simulation results. The <span class="hlt">flow</span> meter accuracy as a percentage of full scale (% FS) was calculated to be  ±5.8%, and mean deviation was equal to 2.1 (% FS) with the appropriate response time of 0.70 s at the <span class="hlt">air</span> <span class="hlt">flow</span> range of 100‑240 m s‑1. Highlights • A cantilever-type <span class="hlt">flow</span> meter was fabricated to measure the high-speed <span class="hlt">air</span> <span class="hlt">flow</span> rate. • The sensitive piezoresistive material was composed of GO and latex. • The dip-coating method was used to deposit the piezoresistive layer on the fiberglass substrate. • The impact of effective parameters on the performance of the <span class="hlt">flow</span> meter was investigated. • A simulation study was performed and the results were compared with the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17280560','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17280560"><span>Determination of ethane, pentane and isoprene in exhaled <span class="hlt">air</span>--effects of breath-holding, <span class="hlt">flow</span> rate and purified <span class="hlt">air</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lärstad, M A E; Torén, K; Bake, B; Olin, A-C</p> <p>2007-01-01</p> <p>Exhaled ethane, pentane and isoprene have been proposed as biomarkers of oxidative stress. The objectives were to explore whether ethane, pentane and isoprene are produced within the airways and to explore the effect of different sampling parameters on analyte concentrations. The <span class="hlt">flow</span> dependency of the analyte concentrations, the concentrations in dead-space and alveolar <span class="hlt">air</span> after breath-holding and the influence of inhaling purified <span class="hlt">air</span> on analyte concentrations were investigated. The analytical method involved thermal desorption from sorbent tubes and gas chromatography. The studied group comprised 13 subjects with clinically stable asthma and 14 healthy controls. Ethane concentrations decreased slightly, but significantly, at higher <span class="hlt">flow</span> rates in subjects with asthma (P = 0.0063) but not in healthy controls. Pentane levels were increased at higher <span class="hlt">flow</span> rates both in healthy and asthmatic subjects (P = 0.022 and 0.0063 respectively). Isoprene levels were increased at higher <span class="hlt">flow</span> rates, but only significantly in healthy subjects (P = 0.0034). After breath-holding, no significant changes in ethane levels were observed. Pentane and isoprene levels increased significantly after 20 s of breath-holding. Inhalation of purified <span class="hlt">air</span> before exhalation resulted in a substantial decrease in ethane levels, a moderate decrease in pentane levels and an increase in isoprene levels. The major fractions of exhaled ethane, pentane and isoprene seem to be of systemic origin. There was, however, a tendency for ethane to be <span class="hlt">flow</span> rate dependent in asthmatic subjects, although to a very limited extent, suggesting that small amounts of ethane may be formed in the airways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25921636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25921636"><span>Experimental and numerical investigations on reliability of <span class="hlt">air</span> barrier on oil containment in <span class="hlt">flowing</span> water.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lu, Jinshu; Xu, Zhenfeng; Xu, Song; Xie, Sensen; Wu, Haoxiao; Yang, Zhenbo; Liu, Xueqiang</p> <p>2015-06-15</p> <p><span class="hlt">Air</span> barriers have been recently developed and employed as a new type of oil containment boom. This paper presents systematic investigations on the reliability of <span class="hlt">air</span> barriers on oil containments with the involvement of <span class="hlt">flowing</span> water, which represents the commonly-seen shearing current in reality, by using both laboratory experiments and numerical simulations. Both the numerical and experimental investigations are carried out in a model scale. In the investigations, a submerged pipe with apertures is installed near the bottom of a tank to generate the <span class="hlt">air</span> bubbles forming the <span class="hlt">air</span> curtain; and, the shearing water <span class="hlt">flow</span> is introduced by a narrow inlet near the mean free surface. The effects of the aperture configurations (including the size and the spacing of the aperture) and the location of the pipe on the effectiveness of the <span class="hlt">air</span> barrier on preventing oil spreading are discussed in details with consideration of different <span class="hlt">air</span> discharges and velocities of the <span class="hlt">flowing</span> water. The research outcome provides a foundation for evaluating and/or improve the reliability of a <span class="hlt">air</span> barrier on preventing spilled oil from further spreading. Copyright © 2015 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1955c0032Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1955c0032Z"><span>Influence of ventilation structure on <span class="hlt">air</span> <span class="hlt">flow</span> distribution of large turbo-generator</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Liying; Ding, Shuye; Zhao, Zhijun; Yang, Jingmo</p> <p>2018-04-01</p> <p>For the 350 MW <span class="hlt">air</span> - cooled turbo—generator, the rotor body is ventilated by sub -slots and 94 radial ventilation ducts and the end adopts arc segment and the straight section to acquire the wind. The stator is ventilated with five inlets and eight outlet <span class="hlt">air</span> branches. In order to analyze the cooling effect of different ventilation schemes, a global physical model including the stator, rotor, casing and fan is established, and the assumptions and boundary conditions of the solution domain are given. the finite volume method is used to solve the problem, and the <span class="hlt">air</span> <span class="hlt">flow</span> distribution characteristics of each part of the motor under different ventilation schemes are obtained. The results show that the baffle at the end of the rotor can eliminate the eddy current at the end of the rotor, and make the <span class="hlt">flow</span> distribution of cooling <span class="hlt">air</span> more uniform and reasonable. The conclusions can provide reference for the design of motor ventilation structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ems..confE.242T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ems..confE.242T"><span>Meteorological determinants of <span class="hlt">air</span> quality</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Turoldo, F.; Del Frate, S.; Gallai, I.; Giaiotti, D. B.; Montanari, F.; Stel, F.; Goi, D.</p> <p>2010-09-01</p> <p><span class="hlt">Air</span> quality is the result of complex phenomena, among which the major role is played by human emissions of pollutants. Atmospheric processes act as determinants, e.g., modulating, dumping or amplifying the effects of emissions as an orchestra's director does with musical instruments. In this work, a series of small-scale and meso-scale meteorological determinants of <span class="hlt">air</span>-quality are presented as they are observed in an area characterized by complex orography (Friuli Venezia Giulia, in the north-eastern side of Italy). In particular, attention is devoted to: i) meso-scale <span class="hlt">flows</span> favouring the persistence of high concentrations of particulate matter; ii) meso-scale periodic <span class="hlt">flows</span> (breezes) favouring high values of particulate matter; iii) local-scale thermodynamic behaviour favouring high atmospheric values of nitrogen oxides. The effects of these different classes of determinants are shown through comparisons between anthropic emissions (mainly traffic) and ground-based measurements. The relevance of complex orography (relatively steep relieves near to the sea) is shown for the meso-scale <span class="hlt">flows</span> and, in particular, for local-scale periodic <span class="hlt">flows</span>, which favour the increase of high pollutants concentrations mainly in summer, when the breezes <span class="hlt">regime</span> is particularly relevant. Part of these results have been achieved through the ETS - Alpine Space EU project iMONITRAF!</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3767942','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3767942"><span>Vision and <span class="hlt">air</span> <span class="hlt">flow</span> combine to streamline flying honeybees</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Taylor, Gavin J.; Luu, Tien; Ball, David; Srinivasan, Mandyam V.</p> <p>2013-01-01</p> <p>Insects face the challenge of integrating multi-sensory information to control their flight. Here we study a ‘streamlining' response in honeybees, whereby honeybees raise their abdomen to reduce drag. We find that this response, which was recently reported to be mediated by optic <span class="hlt">flow</span>, is also strongly modulated by the presence of <span class="hlt">air</span> <span class="hlt">flow</span> simulating a head wind. The Johnston's organs in the antennae were found to play a role in the measurement of the <span class="hlt">air</span> speed that is used to control the streamlining response. The response to a combination of visual motion and wind is complex and can be explained by a model that incorporates a non-linear combination of the two stimuli. The use of visual and mechanosensory cues increases the strength of the streamlining response when the stimuli are present concurrently. We propose this multisensory integration will make the response more robust to transient disturbances in either modality. PMID:24019053</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol32/pdf/CFR-2010-title40-vol32-sec1065-240.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title40-vol32/pdf/CFR-2010-title40-vol32-sec1065-240.pdf"><span>40 CFR 1065.240 - Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span> meters.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-07-01</p> <p>... interval. You may use the difference between a diluted exhaust <span class="hlt">flow</span> meter and a dilution <span class="hlt">air</span> meter to.... We recommend that you use a diluted exhaust <span class="hlt">flow</span> meter that meets the specifications in Table 1 of... verification in § 1065.307 and the calibration and verifications in § 1065.340 and § 1065.341. You may use the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930086103','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930086103"><span>Preliminary analysis of problem of determining experimental performance of <span class="hlt">air</span>-cooled turbine II : methods for determining cooling-<span class="hlt">air-flow</span> characteristics</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ellerbrock, Herman H , Jr</p> <p>1950-01-01</p> <p>In the determination of the performance of an <span class="hlt">air</span>-cooled turbine, the cooling-<span class="hlt">air-flow</span> characteristics between the root and the tip of the blades must be evaluated. The methods, which must be verified and the unknown functions evaluated, that are expected to permit the determination of pressure, temperature, and velocity through the blade cooling-<span class="hlt">air</span> passages from specific investigation are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeCoA.184...88M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeCoA.184...88M"><span>Carbon dioxide, ground <span class="hlt">air</span> and carbon cycling in Gibraltar karst</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mattey, D. P.; Atkinson, T. C.; Barker, J. A.; Fisher, R.; Latin, J.-P.; Durrell, R.; Ainsworth, M.</p> <p>2016-07-01</p> <p>We put forward a general conceptual model of CO2 behaviour in the vadose zone of karst aquifers, based on physical principles of <span class="hlt">air</span> <span class="hlt">flow</span> through porous media and caves, combined with a geochemical interpretation of cave monitoring data. This 'Gibraltar model' links fluxes of water, <span class="hlt">air</span> and carbon through the soil with the porosity of the vadose zone, the circulation of ground <span class="hlt">air</span> and the ventilation of caves. Gibraltar hosts many natural caves whose locations span the full length and vertical range of the Rock. We report results of an 8-year monitoring study of carbon in soil organic matter and bedrock carbonate, dissolved inorganic carbon in vadose waters, and gaseous CO2 in soil, cave and ground <span class="hlt">air</span>. Results show that the <span class="hlt">regime</span> of cave <span class="hlt">air</span> CO2 results from the interaction of cave ventilation with a reservoir of CO2-enriched ground <span class="hlt">air</span> held within the smaller voids of the bedrock. The pCO2 of ground <span class="hlt">air</span>, and of vadose waters that have been in close contact with it, are determined by multiple factors that include recharge patterns, vegetation productivity and root respiration, and conversion of organic matter to CO2 within the soil, the epikarst and the whole vadose zone. Mathematical modelling and field observations show that ground <span class="hlt">air</span> is subject to a density-driven circulation that reverses seasonally, as the difference between surface and underground temperatures reverses in sign. The Gibraltar model suggests that cave <span class="hlt">air</span> pCO2 is not directly related to CO2 generated in the soil or the epikarstic zone, as is often assumed. Ground <span class="hlt">air</span> CO2 formed by the decay of organic matter (OM) washed down into the deeper unsaturated zone is an important additional source of pCO2. In Gibraltar the addition of OM-derived CO2 is the dominant control on the pCO2 of ground <span class="hlt">air</span> and the Ca-hardness of waters within the deep vadose zone. The seasonal <span class="hlt">regime</span> of CO2 in cave <span class="hlt">air</span> depends on the position of a cave in relation to the density-driven ground <span class="hlt">air</span> circulation pattern which</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018EPJWC.18002033H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018EPJWC.18002033H"><span>Effect of <span class="hlt">flow</span> velocity on the process of <span class="hlt">air</span>-steam condensation in a vertical tube condenser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Havlík, Jan; Dlouhý, Tomáš</p> <p>2018-06-01</p> <p>This article describes the influence of <span class="hlt">flow</span> velocity on the condensation process in a vertical tube. For the case of condensation in a vertical tube condenser, both the pure steam condensation process and the <span class="hlt">air</span>-steam mixture condensation process were theoretically and experimentally analyzed. The influence of steam <span class="hlt">flow</span> velocity on the value of the heat transfer coefficient during the condensation process was evaluated. For the condensation of pure steam, the influence of <span class="hlt">flow</span> velocity on the value of the heat transfer coefficient begins to be seen at higher speeds, conversely, this effect is negligible at low values of steam velocity. On the other hand, for the <span class="hlt">air</span>-steam mixture condensation, the influence of <span class="hlt">flow</span> velocity must always be taken into account. The <span class="hlt">flow</span> velocity affects the water vapor diffusion process through non-condensing <span class="hlt">air</span>. The presence of <span class="hlt">air</span> significantly reduces the value of the heat transfer coefficient. This drop in the heat transfer coefficient is significant at low velocities; on the contrary, the decrease is relatively small at high values of the velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990064092','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990064092"><span>Bubble Generation in a Continuous Liquid <span class="hlt">Flow</span> Under Reduced Gravity Conditions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pais, Salvatore Cezar</p> <p>1999-01-01</p> <p>The present work reports a study of bubble generation under reduced gravity conditions for both co-<span class="hlt">flow</span> and cross-<span class="hlt">flow</span> configurations. Experiments were performed aboard the DC-9 Reduced Gravity Aircraft at NASA Glenn Research Center, using an <span class="hlt">air</span>-water system. Three different <span class="hlt">flow</span> tube diameters were used: 1.27, 1.9, and 2.54 cm. Two different ratios of <span class="hlt">air</span> injection nozzle to tube diameters were considered: 0.1 and 0.2. Gas and liquid volumetric <span class="hlt">flow</span> rates were varied from 10 to 200 ml/s. It was experimentally observed that with increasing superficial liquid velocity, the bubbles generated decreased in size. The bubble diameter was shown to increase with increasing <span class="hlt">air</span> injection nozzle diameters. As the tube diameter was increased, the size of the detached bubbles increased. Likewise, as the superficial liquid velocity was increased, the frequency of bubble formation increased and thus the time to detach forming bubbles decreased. Independent of the <span class="hlt">flow</span> configuration (for either single nozzle or multiple nozzle gas injection), void fraction and hence <span class="hlt">flow</span> <span class="hlt">regime</span> transition can be controlled in a somewhat precise manner by solely varying the gas and liquid volumetric <span class="hlt">flow</span> rates. On the other hand, it is observed that uniformity of bubble size can be controlled more accurately by using single nozzle gas injection than by using multiple port injection, since this latter system gives rise to unpredictable coalescence of adjacent bubbles. A theoretical model, based on an overall force balance, is employed to study single bubble generation in the dynamic and bubbly <span class="hlt">flow</span> <span class="hlt">regime</span>. Under conditions of reduced gravity, the gas momentum flux enhances bubble detachment; however, the surface tension forces at the nozzle tip inhibits bubble detachment. Liquid drag and inertia can act either as attaching or detaching force, depending on the relative velocity of the bubble with respect to the surrounding liquid. Predictions of the theoretical model compare well with performed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840012482','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840012482"><span>Characteristics of inhomogeneous jets in confined swirling <span class="hlt">air</span> <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>So, R. M. C.; Ahmed, S. A.</p> <p>1984-01-01</p> <p>An experimental program to study the characteristics of inhomogeneous jets in confined swirling <span class="hlt">flows</span> to obtain detailed and accurate data for the evaluation and improvement of turbulent transport modeling for combustor <span class="hlt">flows</span> is discussed. The work was also motivated by the need to investigate and quantify the influence of confinement and swirl on the characteristics of inhomogeneous jets. The <span class="hlt">flow</span> facility was constructed in a simple way which allows easy interchange of different swirlers and the freedom to vary the jet Reynolds number. The velocity measurements were taken with a one color, one component DISA Model 55L laser-Doppler anemometer employing the forward scatter mode. Standard statistical methods are used to evaluate the various moments of the signals to give the <span class="hlt">flow</span> characteristics. The present work was directed at the understanding of the velocity field. Therefore, only velocity and turbulence data of the axial and circumferential components are reported for inhomogeneous jets in confined swirling <span class="hlt">air</span> <span class="hlt">flows</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhRvF...3e4501A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhRvF...3e4501A"><span>Role of medium heterogeneity and viscosity contrast in miscible <span class="hlt">flow</span> <span class="hlt">regimes</span> and mixing zone growth: A computational pore-scale approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Afshari, Saied; Hejazi, S. Hossein; Kantzas, Apostolos</p> <p>2018-05-01</p> <p>Miscible displacement of fluids in porous media is often characterized by the scaling of the mixing zone length with displacement time. Depending on the viscosity contrast of fluids, the scaling law varies between the square root relationship, a sign for dispersive transport <span class="hlt">regime</span> during stable displacement, and the linear relationship, which represents the viscous fingering <span class="hlt">regime</span> during an unstable displacement. The presence of heterogeneities in a porous medium significantly affects the scaling behavior of the mixing length as it interacts with the viscosity contrast to control the mixing of fluids in the pore space. In this study, the dynamics of the <span class="hlt">flow</span> and transport during both unit and adverse viscosity ratio miscible displacements are investigated in heterogeneous packings of circular grains using pore-scale numerical simulations. The pore-scale heterogeneity level is characterized by the variations of the grain diameter and velocity field. The growth of mixing length is employed to identify the nature of the miscible transport <span class="hlt">regime</span> at different viscosity ratios and heterogeneity levels. It is shown that as the viscosity ratio increases to higher adverse values, the scaling law of mixing length gradually shifts from dispersive to fingering nature up to a certain viscosity ratio and remains almost the same afterwards. In heterogeneous media, the mixing length scaling law is observed to be generally governed by the variations of the velocity field rather than the grain size. Furthermore, the normalization of mixing length temporal plots with respect to the governing parameters of viscosity ratio, heterogeneity, medium length, and medium aspect ratio is performed. The results indicate that mixing length scales exponentially with log-viscosity ratio and grain size standard deviation while the impact of aspect ratio is insignificant. For stable <span class="hlt">flows</span>, mixing length scales with the square root of medium length, whereas it changes linearly with length during</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760007981','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760007981"><span>Two lighter than <span class="hlt">air</span> systems in opposing flight <span class="hlt">regimes</span>: An unmanned short haul, heavy load transport balloon and a manned, light payload airship</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pohl, R. A.</p> <p>1975-01-01</p> <p>Lighter Than <span class="hlt">Air</span> vehicles are generally defined or categorized by the shape of the balloon, payload capacity and operational flight <span class="hlt">regime</span>. Two balloon systems that are classed as being in opposite categories are described. One is a cable guided, helium filled, short haul, heavy load transport Lighter Than <span class="hlt">Air</span> system with a natural shaped envelope. The other is a manned, aerodynamic shaped airship which utilizes hot <span class="hlt">air</span> as the buoyancy medium and is in the light payload class. While the airship is in the design/fabrication phase with flight tests scheduled for the latter part of 1974, the transport balloon system has been operational for some eight years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/21153932-effects-air-flow-directions-composting-process-temperature-profile','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/21153932-effects-air-flow-directions-composting-process-temperature-profile"><span>Effects of <span class="hlt">air</span> <span class="hlt">flow</span> directions on composting process temperature profile</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kulcu, Recep; Yaldiz, Osman</p> <p>2008-07-01</p> <p>In this study, chicken manure mixed with carnation wastes was composted by using three different <span class="hlt">air</span> <span class="hlt">flow</span> directions: R1-sucking (downward), R2-blowing (upward) and R3-mixed. The aim was to find out the most appropriate <span class="hlt">air</span> <span class="hlt">flow</span> direction type for composting to provide more homogenous temperature distribution in the reactors. The efficiency of each aeration method was evaluated by monitoring the evolution of parameters such as temperature, moisture content, CO{sub 2} and O{sub 2} ratio in the material and dry material losses. Aeration of the reactors was managed by radial fans. The results showed that R3 resulted in a more homogenous temperaturemore » distribution and high dry material loss throughout the composting process. The most heterogeneous temperature distribution and the lowest dry material loss were obtained in R2.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDE18002B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDE18002B"><span>Spanwise structure of the <span class="hlt">flow</span> past a fixed or freely vibrating cylinder in the early turbulent <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bourguet, Remi; Gsell, Simon; Braza, Marianna</p> <p>2017-11-01</p> <p>The <span class="hlt">flow</span> patterns developing downstream of slender bodies with bluff cross-section have been the object of intense research in the past decades. Particular attention was paid to the vortex patterns emerging in the plane perpendicular to the body axis. In the present study, focus is placed on the spanwise structure of the <span class="hlt">flow</span>, in the early turbulent <span class="hlt">regime</span>. The existence of dominant spanwise wavelengths had already been reported. However, many aspects remained to be explored, among others, the streamwise evolution of the spanwise patterns and their possible alteration when the body oscillates. These aspects are examined here on the basis of direct numerical simulations of the <span class="hlt">flow</span> past a circular cylinder at Reynolds number 3900. The body is either fixed or subjected to vortex-induced vibrations. A systematic analysis of the spanwise patterns reveals persistent trends of their amplitude and wavelength in the different compartments of the <span class="hlt">flow</span>, i.e. the separating shear layer and wake regions. Physical mechanisms are proposed to explain these trends. It is also found that the spanwise structure of the <span class="hlt">flow</span> is differently altered in these two regions once the cylinder vibrates, the alteration being concentrated in the separating shear layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720018688','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720018688"><span>Development of an <span class="hlt">air</span> <span class="hlt">flow</span> thermal balance calorimeter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sherfey, J. M.</p> <p>1972-01-01</p> <p>An <span class="hlt">air</span> <span class="hlt">flow</span> calorimeter, based on the idea of balancing an unknown rate of heat evolution with a known rate of heat evolution, was developed. Under restricted conditions, the prototype system is capable of measuring thermal wattages from 10 milliwatts to 1 watt, with an error no greater than 1 percent. Data were obtained which reveal system weaknesses and point to modifications which would effect significant improvements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.H43E1306H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.H43E1306H"><span>Effects of Urbanization on the <span class="hlt">Flow</span> <span class="hlt">Regimes</span> of Semi-Arid Southern California Streams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hawley, R. J.; Bledsoe, B. P.; Stein, E. D.</p> <p>2010-12-01</p> <p>Stream channel erosion and associated habitat degradation are pervasive in streams draining urban areas in the southwestern US. The prevalence of these impacts results from the inherent sensitivity of streams in semi-arid climates to changes in <span class="hlt">flow</span> and sediment <span class="hlt">regimes</span>, and past inattention to management of geomorphically effective <span class="hlt">flows</span>. Addressing this issue is difficult due to the lack of data linking ranges of <span class="hlt">flow</span> (from small to large runoff events) to geomorphic channel response. Forty-three U. S. Geological Survey gages with record lengths greater than ~15 yrs and watershed areas less than ~250 square kilometers were used to empirically model the effects of urbanization on streams in southern California. The watersheds spanned a gradient of urban development and ranged from 0 to 23% total impervious area in 2001. With little <span class="hlt">flow</span> control at the subdivision scale to date, most impervious area in the region is relatively well-connected to surface-drainage networks. Consequently, total impervious area was an effective surrogate for urbanization, and emerged as a significant (p < 0.05) predictor of instantaneous peak-<span class="hlt">flow</span> rates at the 1.5- and 2-yr recurrence intervals, with decreasing significance and influence at higher return periods. For example, peak factors for a watershed with 20% imperviousness were ~10, 6, and 2 for the 1.5-, 2-, and 5-yr <span class="hlt">flows</span>, respectively, with no discernable influence at <span class="hlt">flows</span> greater than the 10-yr event. Most importantly with respect to geomorphic response, urbanization extent was a significant predictor of duration density functions, which integrate the magnitude and duration of mean daily discharges. This approach expands on previous scaling procedures to produce histogram-style cumulative <span class="hlt">flow</span> duration graphs for ungaged sites based on urbanization extent and other watershed descriptors. Urbanization resulted in proportionally-longer durations of all geomorphically-effective <span class="hlt">flows</span>, with a more pronounced effect on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ExFl...51..949M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ExFl...51..949M"><span>Experiment on smooth, circular cylinders in cross-<span class="hlt">flow</span> in the critical Reynolds number <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miau, J. J.; Tsai, H. W.; Lin, Y. J.; Tu, J. K.; Fang, C. H.; Chen, M. C.</p> <p>2011-10-01</p> <p>Experiments were conducted for 2D circular cylinders at Reynolds numbers in the range of 1.73 × 105-5.86 × 105. In the experiment, two circular cylinder models made of acrylic and stainless steel, respectively, were employed, which have similar dimensions but different surface roughness. Particular attention was paid to the unsteady <span class="hlt">flow</span> behaviors inferred by the signals obtained from the pressure taps on the cylinder models and by a hot-wire probe in the near-wake region. At Reynolds numbers pertaining to the initial transition from the subcritical to the critical <span class="hlt">regimes</span>, pronounced pressure fluctuations were measured on the surfaces of both cylinder models, which were attributed to the excursion of unsteady <span class="hlt">flow</span> separation over a large circumferential region. At the Reynolds numbers almost reaching the one-bubble state, it was noted that the development of separation bubble might switch from one side to the other with time. Wavelet analysis of the pressure signals measured simultaneously at θ = ±90° further revealed that when no separation bubble was developed, the instantaneous vortex-shedding frequencies could be clearly resolved, about 0.2, in terms of the Strouhal number. The results of oil-film <span class="hlt">flow</span> visualization on the stainless steel cylinder of the one-bubble and two-bubble states showed that the <span class="hlt">flow</span> reattachment region downstream of a separation bubble appeared not uniform along the span of the model. Thus, the three dimensionality was quite evident.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=80892&Lab=NRMRL&keyword=public+AND+relations&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=80892&Lab=NRMRL&keyword=public+AND+relations&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>THE HYDROLOGIC SYSTEM: GEOMORPHIC AND HYDROGEOLOGIC CONTROLS ON SURFACE AND SUBSURFACE <span class="hlt">FLOW</span> <span class="hlt">REGIMES</span> IN RIPARIAN MEADOW ECOSYSTEMS IN THE CENTRAL GREAT BASIN</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Riparian corridors in upland watersheds in the Great Basin of central Nevada contain the majority of the region's biodiversity. Water, in both surface and subsurface <span class="hlt">flow</span> <span class="hlt">regimes</span>, is an important resource sustaining these sensitive ecosystems and other similar riparian ecosystem...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930081148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930081148"><span>Performance of a Compression-ignition Engine with a Precombustion Chamber Having High-Velocity <span class="hlt">Air</span> <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Spanogle, J A; Moore, C S</p> <p>1931-01-01</p> <p>Presented here are the results of performance tests made with a single-cylinder, four stroke cycle, compression-ignition engine. These tests were made on a precombustion chamber type of cylinder head designed to have <span class="hlt">air</span> velocity and tangential <span class="hlt">air</span> <span class="hlt">flow</span> in both the chamber and cylinder. The performance was investigated for variable load and engine speed, type of fuel spray, valve opening pressure, injection period and, for the spherical chamber, position of the injection spray relative to the <span class="hlt">air</span> <span class="hlt">flow</span>. The pressure variations between the pear-shaped precombustion chamber and the cylinder for motoring and full load conditions were determined with a Farnboro electric indicator. The combustion chamber designs tested gave good mixing of a single compact fuel spray with the <span class="hlt">air</span>, but did not control the ensuing combustion sufficiently. Relative to each other, the velocity of <span class="hlt">air</span> <span class="hlt">flow</span> was too high, the spray dispersion by injection too great, and the metering effect of the cylinder head passage insufficient. The correct relation of these factors is of the utmost importance for engine performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20365645','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20365645"><span>Mechanism of nonlinear <span class="hlt">flow</span> pattern selection in moderately non-Boussinesq mixed convection.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Suslov, Sergey A</p> <p>2010-02-01</p> <p>Nonlinear (non-Boussinesq) variations in fluid's density, viscosity, and thermal conductivity caused by a large temperature gradient in a <span class="hlt">flow</span> domain lead to a wide variety of instability phenomena in mixed convection channel <span class="hlt">flow</span> of a simple gas such as <span class="hlt">air</span>. It is known that in strongly nonisothermal <span class="hlt">flows</span>, the instabilities and the resulting <span class="hlt">flow</span> patterns are caused by competing buoyancy and shear effects [see S. A. Suslov and S. Paolucci, J. Fluid Mech. 302, 91 (1995)]. However, as is the case in the Boussinesq limit of small temperature gradients, in moderately non-Boussinesq <span class="hlt">regimes</span>, only a shear instability mechanism is active. Yet in contrast to Boussinesq <span class="hlt">flows</span>, multiple instability modes are still detected. By reducing the system of full governing Navier-Stokes equations to a dynamical system of coupled Landau-type disturbance amplitude equations we compute a comprehensive parametric map of various shear-driven instabilities observed in a representative moderately non-Boussinesq <span class="hlt">regime</span>. Subsequently, we analyze nonlinear interaction of unstable modes and reveal physical reasons for their appearance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770016106','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770016106"><span>A Green's function formulation for a nonlinear potential <span class="hlt">flow</span> solution applicable to transonic <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baker, A. J.; Fox, C. H., Jr.</p> <p>1977-01-01</p> <p>Routine determination of inviscid subsonic <span class="hlt">flow</span> fields about wing-body-tail configurations employing a Green's function approach for numerical solution of the perturbation velocity potential equation is successfully extended into the high subsonic subcritical <span class="hlt">flow</span> <span class="hlt">regime</span> and into the shock-free supersonic <span class="hlt">flow</span> <span class="hlt">regime</span>. A modified Green's function formulation, valid throughout a range of Mach numbers including transonic, that takes an explicit accounting of the intrinsic nonlinearity in the parent governing partial differential equations is developed. Some considerations pertinent to <span class="hlt">flow</span> field predictions in the transonic <span class="hlt">flow</span> <span class="hlt">regime</span> are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26ES..134a2027K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26ES..134a2027K"><span>On the calculation of <span class="hlt">air</span> <span class="hlt">flow</span> rates to ventilate closed-type stations in subway with the double-track tunnel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kiyanitsa, LA</p> <p>2018-03-01</p> <p>Metro is not only the most promising kind of public transport but also an important part of infrastructure in a modern city. As a place where large groups of people gather, subway is to ensure the required <span class="hlt">air</span> exchange at the passenger platforms of the stations. The <span class="hlt">air</span> <span class="hlt">flow</span> rate for <span class="hlt">airing</span> the stations is also determined based on the required temperature, humidity and MAC of gases. The present study estimates the required <span class="hlt">air</span> <span class="hlt">flow</span> rate at the passenger platform of the closed-type subway station with the double-track tunnel given the standard <span class="hlt">air</span> temperature, humidity and gas concentration, as well as based on the condition of the specified <span class="hlt">air</span> <span class="hlt">flow</span> feed and <span class="hlt">air</span> changes per hour. The article proposes the scheme of <span class="hlt">air</span> recirculation from the double-track tunnel to the station.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/891268','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/891268"><span>An integrated model for the natural <span class="hlt">flow</span> <span class="hlt">regime</span> in the Cerro Prieto hydrothermal system based upon petrological and isotope geochemical criteria</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Elders, W.A.; Williams, A.E.; Hoagland, J..</p> <p>1981-01-01</p> <p>Studies of cuttings and cores at Cerro Prieto have now been extended to more than 50 boreholes. The aims of this petrological and isotopic work are to determine the shape of the reservoir, its physical properties, and its temperature distribution and <span class="hlt">flow</span> <span class="hlt">regime</span> before the steam field was produced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS.946a2152L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS.946a2152L"><span>Charged particle capturing in <span class="hlt">air</span> <span class="hlt">flow</span> by linear Paul trap</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lapitsky, D. S.; Filinov, V. S.; Vladimirov, V. I.; Syrovatka, R. A.; Vasilyak, L. M.; Pecherkin, V. Ya; Deputatova, L. V.</p> <p>2018-01-01</p> <p>The paper presents the simulation results of micro- and nanoparticle capturing in an <span class="hlt">air</span> <span class="hlt">flows</span> by linear Paul traps in assumption that particles gain their charges in corona discharge, its electric field strength is restricted by Paschen equation and spherical shape of particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70024981','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70024981"><span>The influence of water depth and <span class="hlt">flow</span> <span class="hlt">regime</span> on phytoplankton biomass and community structure in a shallow, lowland river</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Leland, H.V.</p> <p>2003-01-01</p> <p>The taxonomic composition and biomass of phytoplankton in the San Joaquin River, California, were examined in relation to water depth, <span class="hlt">flow</span> <span class="hlt">regime</span>, and water chemistry. Without substantial tributary inflow, maintenance demands exceeded algal production during summer and autumn in this eutrophic, 'lowland type' river due to light-limiting conditions for algal growth. Streamflow from tributaries that drain the Sierra Nevada contributed to a substantial net gain in algal production during the spring and summer by increasing water transparency and the extent of turbulence. Abundances of the major taxa (centric diatoms, pennate diatoms and chlorophytes) indicated differing responses to the longitudinal variation in water depth and <span class="hlt">flow</span> <span class="hlt">regime</span>, with the areal extent of pools and other geomorphic features that influence time-for-development being a major contributing factor to the selection of species. Tychoplanktonic species were most abundant upstream and in tributaries that drain the San Joaquin Valley. Seasonally-varying factors such as water temperature that influence algal growth rates also contributed significantly to the selection of species. Nutrient limitation appears not to be a primary constraint on species selection in the phytoplankton of this river.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150018397','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150018397"><span>Combustion Characteristics in a Non-Premixed Cool-Flame <span class="hlt">Regime</span> of n-Heptane in Microgravity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Takahashi, Fumiaki; Katta, Viswanath R.; Hicks, Michael C.</p> <p>2015-01-01</p> <p>A series of distinct phenomena have recently been observed in single-fuel-droplet combustion tests performed on the International Space Station (ISS). This study attempts to simulate the observed flame behavior numerically using a gaseous n-heptane fuel source in zero gravity and a time-dependent axisymmetric (2D) code, which includes a detailed reaction mechanism (127 species and 1130 reactions), diffusive transport, and a radiation model (for CH4, CO, CO2, H2O, and soot). The calculated combustion characteristics depend strongly on the <span class="hlt">air</span> velocity around the fuel source. In a near-quiescent <span class="hlt">air</span> environment (< or = 2 mm/s), with a sufficiently large fuel injection velocity (1 cm/s), a growing spherical diffusion flame extinguishes at ˜1200 K due to radiative heat losses. This is typically followed by a transition to the low-temperature (cool-flame) <span class="hlt">regime</span> with a reaction zone (at ˜700 K) in close proximity to the fuel source. The 'cool flame' <span class="hlt">regime</span> is formed due to the negative temperature coefficient in the low-temperature chemistry. After a relatively long period (˜18 s) of the cool flame <span class="hlt">regime</span>, a flash re-ignition occurs, associated with flame-edge propagation and subsequent extinction of the re-ignited flame. In a low-speed (˜3 mm/s) airstream (which simulates the slight droplet movement), the diffusion flame is enhanced upstream and experiences a local extinction downstream at ˜1200 K, followed by steady flame pulsations (˜0.4 Hz). At higher <span class="hlt">air</span> velocities (4-10 mm/s), the locally extinguished flame becomes steady state. The present axisymmetric computational approach helps in revealing the non-premixed 'cool flame' structure and 2D flame-<span class="hlt">flow</span> interactions observed in recent microgravity droplet combustion experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18301479','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18301479"><span>Sagnac-interferometer-based fresnel <span class="hlt">flow</span> probe.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tselikov, A; Blake, J</p> <p>1998-10-01</p> <p>We used a near-diffraction-limited <span class="hlt">flow</span> or light-wave-interaction pipe to produce a Sagnac-interferometer-based Fresnel drag fluid flowmeter capable of detecting extremely small <span class="hlt">flow</span> rates. An optimized design of the pipe along with the use of a state-of-the-art Sagnac interferometer results in a minimum-detectable water <span class="hlt">flow</span> rate of 2.4 nl/s [1 drop/(5 h)]. The flowmeter's capability of measuring the water consumption by a small plant in real time has been demonstrated. We then designed an automated alignment system that finds and maintains the optimum fiber-coupling <span class="hlt">regime</span>, which makes the applications of the Fresnel-drag-based flowmeters practical, especially if the length of the interaction pipe is long. Finally, we have applied the automatic alignment technique to an <span class="hlt">air</span> flowmeter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1939b0054Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1939b0054Z"><span>Intensification process of <span class="hlt">air</span>-hydrogen mixture burning in the variable cross section channel by means of the <span class="hlt">air</span> jet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zamuraev, V. P.; Kalinina, A. P.</p> <p>2018-03-01</p> <p>The paper presents the results of numerical modeling of a transonic region formation in the flat channel. Hydrogen <span class="hlt">flows</span> into the channel through the holes in the wall. The jet of compressed <span class="hlt">air</span> is localized downstream the holes. The transonic region formation is formed by the burning of heterogeneous hydrogen-<span class="hlt">air</span> mixture. It was considered in the framework of the simplified chemical kinetics. The interesting feature of the <span class="hlt">regime</span> obtained is the following: the distribution of the Mach numbers is qualitatively similar to the case of pulse-periodic energy sources. This mode is a favorable prerequisite for the effective fuel combustion in the expanding part of the channel when injecting fuel into this part.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70171551','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70171551"><span><span class="hlt">Flow</span> <span class="hlt">regime</span> effects on mature Populus fremontii (Fremont cottonwood) productivity on two contrasting dryland river floodplains</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Andersen, Douglas C.</p> <p>2016-01-01</p> <p>I compared riparian cottonwood (Populus fremontii) productivity-discharge relationships in a relictual stand along the highly regulated Green River and in a naturally functioning stand along the unregulated Yampa River in semiarid northwest Colorado. I used multiple regression to model <span class="hlt">flow</span> effects on annual basal area increment (BAI) from 1982 to 2011, after removing any autocorrelation present. Each BAI series was developed from 20 trees whose mean size (67 cm diameter at breast height [DBH]) was equivalent in the two stands. BAI was larger in the Yampa River stand except in 2 y when defoliating leaf beetles were present there. I found no evidence for a Yampa flood-magnitude threshold above which BAI declined. <span class="hlt">Flow</span> variables explained ∼45% of residual BAI variability, with most explained by current-year maximum 90-d discharge (QM90) in the Yampa River stand and by a measure of the year-to-year change in QM90 in the Green River stand. The latter reflects a management-imposed ceiling on flood magnitude—Flaming Gorge Dam power plant capacity—infrequently exceeded during the study period. BAI in the relictual stand began to trend upward in 1992 when <span class="hlt">flows</span> started to mimic a natural <span class="hlt">flow</span> <span class="hlt">regime</span>. Mature Fremont cottonwoods appear to be ecologically resilient. Their productivity along regulated rivers might be optimized using multiyear environmental <span class="hlt">flow</span> designs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4759792','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4759792"><span>Do terrestrial hermit crabs sniff? <span class="hlt">Air</span> <span class="hlt">flow</span> and odorant capture by flicking antennules</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Koehl, M. A. R.</p> <p>2016-01-01</p> <p>Capture of odorant molecules by olfactory organs from the surrounding fluid is the first step of smelling. Sniffing intermittently moves fluid across sensory surfaces, increasing delivery rates of molecules to chemosensory receptors and providing discrete odour samples. Aquatic malacostracan crustaceans sniff by flicking olfactory antennules bearing arrays of chemosensory hairs (aesthetascs), capturing water in the arrays during downstroke and holding the sample during return stroke. Terrestrial malacostracans also flick antennules, but how their flicking affects odour capture from <span class="hlt">air</span> is not understood. The terrestrial hermit crab, Coenobita rugosus, uses antennules bearing shingle-shaped aesthetascs to capture odours. We used particle image velocimetry to measure fine-scale fluid <span class="hlt">flow</span> relative to a dynamically scaled physical model of a flicking antennule, and computational simulations to calculate diffusion to aesthetascs by odorant molecules carried in that <span class="hlt">flow</span>. <span class="hlt">Air</span> does not <span class="hlt">flow</span> into the aesthetasc array during flick downstrokes or recovery strokes. Odorants are captured from <span class="hlt">air</span> <span class="hlt">flowing</span> around the outside of the array during flick downstrokes, when aesthetascs face upstream and molecule capture rates are 21% higher than for stationary antennules. Bursts of flicking followed by pauses deliver discrete odour samples to olfactory sensors, causing intermittency in odour capture by a different mechanism than aquatic crustaceans use. PMID:26763332</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26763332','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26763332"><span>Do terrestrial hermit crabs sniff? <span class="hlt">Air</span> <span class="hlt">flow</span> and odorant capture by flicking antennules.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Waldrop, Lindsay D; Koehl, M A R</p> <p>2016-01-01</p> <p>Capture of odorant molecules by olfactory organs from the surrounding fluid is the first step of smelling. Sniffing intermittently moves fluid across sensory surfaces, increasing delivery rates of molecules to chemosensory receptors and providing discrete odour samples. Aquatic malacostracan crustaceans sniff by flicking olfactory antennules bearing arrays of chemosensory hairs (aesthetascs), capturing water in the arrays during downstroke and holding the sample during return stroke. Terrestrial malacostracans also flick antennules, but how their flicking affects odour capture from <span class="hlt">air</span> is not understood. The terrestrial hermit crab, Coenobita rugosus, uses antennules bearing shingle-shaped aesthetascs to capture odours. We used particle image velocimetry to measure fine-scale fluid <span class="hlt">flow</span> relative to a dynamically scaled physical model of a flicking antennule, and computational simulations to calculate diffusion to aesthetascs by odorant molecules carried in that <span class="hlt">flow</span>. <span class="hlt">Air</span> does not <span class="hlt">flow</span> into the aesthetasc array during flick downstrokes or recovery strokes. Odorants are captured from <span class="hlt">air</span> <span class="hlt">flowing</span> around the outside of the array during flick downstrokes, when aesthetascs face upstream and molecule capture rates are 21% higher than for stationary antennules. Bursts of flicking followed by pauses deliver discrete odour samples to olfactory sensors, causing intermittency in odour capture by a different mechanism than aquatic crustaceans use. © 2016 The Author(s).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3710649','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3710649"><span>Experimental Studies of Active and Passive <span class="hlt">Flow</span> Control Techniques Applied in a Twin <span class="hlt">Air</span>-Intake</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Joshi, Shrey; Jindal, Aman; Maurya, Shivam P.; Jain, Anuj</p> <p>2013-01-01</p> <p>The <span class="hlt">flow</span> control in twin <span class="hlt">air</span>-intakes is necessary to improve the performance characteristics, since the <span class="hlt">flow</span> traveling through curved and diffused paths becomes complex, especially after merging. The paper presents a comparison between two well-known techniques of <span class="hlt">flow</span> control: active and passive. It presents an effective design of a vortex generator jet (VGJ) and a vane-type passive vortex generator (VG) and uses them in twin <span class="hlt">air</span>-intake duct in different combinations to establish their effectiveness in improving the performance characteristics. The VGJ is designed to insert <span class="hlt">flow</span> from side wall at pitch angle of 90 degrees and 45 degrees. Corotating (parallel) and counterrotating (V-shape) are the configuration of vane type VG. It is observed that VGJ has the potential to change the <span class="hlt">flow</span> pattern drastically as compared to vane-type VG. While the VGJ is directed perpendicular to the side walls of the <span class="hlt">air</span>-intake at a pitch angle of 90 degree, static pressure recovery is increased by 7.8% and total pressure loss is reduced by 40.7%, which is the best among all other cases tested for VGJ. For bigger-sized VG attached to the side walls of the <span class="hlt">air</span>-intake, static pressure recovery is increased by 5.3%, but total pressure loss is reduced by only 4.5% as compared to all other cases of VG. PMID:23935422</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009BoLMe.133..277C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009BoLMe.133..277C"><span>Three-Dimensional Mapping of <span class="hlt">Air</span> <span class="hlt">Flow</span> at an Urban Canyon Intersection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Carpentieri, Matteo; Robins, Alan G.; Baldi, Sandro</p> <p>2009-11-01</p> <p>In this experimental work both qualitative (<span class="hlt">flow</span> visualisation) and quantitative (laser Doppler anemometry) methods were applied in a wind tunnel in order to describe the complex three-dimensional <span class="hlt">flow</span> field in a real environment (a street canyon intersection). The main aim was an examination of the mean <span class="hlt">flow</span>, turbulence and <span class="hlt">flow</span> pathlines characterising a complex three-dimensional urban location. The experiments highlighted the complexity of the observed <span class="hlt">flows</span>, particularly in the upwind region of the intersection. In this complex and realistic situation some details of the upwind <span class="hlt">flow</span>, such as the presence of two tall towers, play an important role in defining the <span class="hlt">flow</span> field within the intersection, particularly at roof level. This effect is likely to have a strong influence on the mass exchange mechanism between the canopy <span class="hlt">flow</span> and the <span class="hlt">air</span> aloft, and therefore the distribution of pollutants. This strong interaction between the <span class="hlt">flows</span> inside and outside the urban canopy is currently neglected in most state-of-the-art local scale dispersion models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.A24A2561T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.A24A2561T"><span>Impact of Ocean Surface Waves on <span class="hlt">Air</span>-Sea Momentum Flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tamura, H.; Drennan, W. M.; Collins, C. O., III; Graber, H. C.</p> <p>2016-02-01</p> <p>In this study, we investigated the structure of turbulent <span class="hlt">air</span> <span class="hlt">flow</span> over ocean waves. Observations of wind and waves were retrieved by <span class="hlt">air</span>-sea interaction spar (ASIS) buoys during the shoaling waves experiment (SHOWEX) in Duck, NC in 1999. It is shown that the turbulent velocity spectra and co-spectra for pure wind sea conditions follow the universal forms estimated by Miyake et al [1970]. In the presence of strong swells, the wave boundary layer was extended and the universal spectral scaling of u'w' broke down [Drennan et al, 1999]. On the other hand, the use of the peak wave frequency (fp) to reproduce the "universal spectra" succeeded at explaining the spectral structure of turbulent <span class="hlt">flow</span> field. The u'w' co-spectra become negative near the fp, which suggests the upward momentum transport (i.e., negative wind stress) induced by ocean waves. Finally, we propose three turbulent <span class="hlt">flow</span> structures for different wind-wave <span class="hlt">regimes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1885b0120B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1885b0120B"><span><span class="hlt">Air</span> <span class="hlt">flow</span> quality analysis of modenas engine exhaust system</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shahriman A., B.; Mohamad Syafiq A., K.; Hashim, M. S. M.; Razlan, Zuradzman M.; Khairunizam W. A., N.; Hazry, D.; Afendi, Mohd; Daud, R.; Rahman, M. D. Tasyrif Abdul; Cheng, E. M.; Zaaba, S. K.</p> <p>2017-09-01</p> <p>The simulation process being conducted to determine the <span class="hlt">air</span> <span class="hlt">flow</span> effect between the original exhaust system and modified exhaust system. The simulations are conducted to investigate the <span class="hlt">flow</span> distribution of exhaust gases that will affect the performance of the engine. The back <span class="hlt">flow</span> pressure in the original exhaust system is predicted toward this simulation. The design modification to the exhaust port, exhaust pipe, and exhaust muffler has been done during this simulation to reduce the back <span class="hlt">flow</span> effect. The new designs are introduced by enlarging the diameter of the exhaust port, enlarge the diameter of the exhaust pipe and created new design for the exhaust muffler. Based on the result obtained, there the pulsating <span class="hlt">flow</span> form at the original exhaust port that will increase the velocity and resulting the back pressure occur. The result for new design of exhaust port, the velocity is lower at the valve guide in the exhaust port. New design muffler shows that the streamline of the exhaust <span class="hlt">flow</span> move smoothly compare to the original muffler. It is proved by using the modification exhaust system, the back pressure are reduced and the engine performance can be improve.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1159373','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1159373"><span>Low-<span class="hlt">Flow</span> Liquid Desiccant <span class="hlt">Air</span>-Conditioning: Demonstrated Performance and Cost Implications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Kozubal, E.; Herrmann, L.; Deru, M.</p> <p>2014-09-01</p> <p>Cooling loads must be dramatically reduced when designing net-zero energy buildings or other highly efficient facilities. Advances in this area have focused primarily on reducing a building's sensible cooling loads by improving the envelope, integrating properly sized daylighting systems, adding exterior solar shading devices, and reducing internal heat gains. As sensible loads decrease, however, latent loads remain relatively constant, and thus become a greater fraction of the overall cooling requirement in highly efficient building designs, particularly in humid climates. This shift toward latent cooling is a challenge for heating, ventilation, and <span class="hlt">air</span>-conditioning (HVAC) systems. Traditional systems typically dehumidify by firstmore » overcooling <span class="hlt">air</span> below the dew-point temperature and then reheating it to an appropriate supply temperature, which requires an excessive amount of energy. Another dehumidification strategy incorporates solid desiccant rotors that remove water from <span class="hlt">air</span> more efficiently; however, these systems are large and increase fan energy consumption due to the increased airside pressure drop of solid desiccant rotors. A third dehumidification strategy involves high <span class="hlt">flow</span> liquid desiccant systems. These systems require a high maintenance separator to protect the <span class="hlt">air</span> distribution system from corrosive desiccant droplet carryover and so are more commonly used in industrial applications and rarely in commercial buildings. Both solid desiccant systems and most high-<span class="hlt">flow</span> liquid desiccant systems (if not internally cooled) add sensible energy which must later be removed to the <span class="hlt">air</span> stream during dehumidification, through the release of sensible heat during the sorption process.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26370197','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26370197"><span>Assessment of future variability in extreme precipitation and the potential effects on the wadi <span class="hlt">flow</span> <span class="hlt">regime</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gunawardhana, Luminda Niroshana; Al-Rawas, Ghazi A; Kazama, So; Al-Najar, Khalid A</p> <p>2015-10-01</p> <p>The objective of this study is to investigate how the magnitude and occurrence of extreme precipitation events are affected by climate change and to predict the subsequent impacts on the wadi <span class="hlt">flow</span> <span class="hlt">regime</span> in the Al-Khod catchment area, Muscat, Oman. The tank model, a lumped-parameter rainfall-runoff model, was used to simulate the wadi <span class="hlt">flow</span>. Precipitation extremes and their potential future changes were predicted using six-member ensembles of general circulation models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5). Yearly maxima of the daily precipitation and wadi <span class="hlt">flow</span> for varying return periods were compared for observed and projected data by fitting the generalized extreme value (GEV) distribution function. <span class="hlt">Flow</span> duration curves (FDC) were developed and compared for the observed and projected wadi <span class="hlt">flows</span>. The results indicate that extreme precipitation events consistently increase by the middle of the twenty-first century for all return periods (49-52%), but changes may become more profound by the end of the twenty-first century (81-101%). Consequently, the relative change in extreme wadi <span class="hlt">flow</span> is greater than twofolds for all of the return periods in the late twenty-first century compared to the relative changes that occur in the mid-century period. Precipitation analysis further suggests that greater than 50% of the precipitation may be associated with extreme events in the future. The FDC analysis reveals that changes in low-to-moderate <span class="hlt">flows</span> (Q60-Q90) may not be statistically significant, whereas increases in high <span class="hlt">flows</span> (Q5) are statistically robust (20 and 25% for the mid- and late-century periods, respectively).</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.U23D0076N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.U23D0076N"><span>Stability of Gas Hydrates on Continental Margins: Implications of Subsurface Fluid <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nunn, J. A.</p> <p>2008-12-01</p> <p>Gas hydrates are found at or just below the sediment-ocean interface in continental margins settings throughout the world. They are also found on land in high latitude regions such as the north slope of Alaska. While gas hydrate occurrence is common, gas hydrates are stable under a fairly restricted range of temperatures and pressures. In a purely conductive thermal <span class="hlt">regime</span>, near surface temperatures depend on basal heat <span class="hlt">flow</span>, thermal conductivity of sediments, and temperature at the sediment-water or sediment-<span class="hlt">air</span> interface. Thermal conductivity depends on porosity and sediment composition. Gas hydrates are most stable in areas of low heat <span class="hlt">flow</span> and high thermal conductivity which produce low temperature gradients. Older margins with thin continental crust and coarse grained sediments would tend to be colder. Another potentially important control on subsurface temperatures is advective heat transport by recharge/discharge of groundwater. Upward fluid <span class="hlt">flow</span> depresses temperature gradients over a purely conductive <span class="hlt">regime</span> with the same heat <span class="hlt">flow</span> which would make gas hydrates more stable. Downward fluid <span class="hlt">flow</span> would have the opposite effect. However, regional scale fluid <span class="hlt">flow</span> may substantially increase heat <span class="hlt">flow</span> in discharge areas which would destabilize gas hydrates. For example, discharge of topographically driven groundwater along the coast in the Central North Slope of Alaska has increased surface heat <span class="hlt">flow</span> in some areas by more than 50% over a purely conductive thermal <span class="hlt">regime</span>. Fluid <span class="hlt">flow</span> also alters the pressure <span class="hlt">regime</span> which can affect gas hydrate stability. Modeling results suggest a positive feedback between gas hydrate formation/disassociation and fluid <span class="hlt">flow</span>. Disassociation of gas hydrates or permafrost due to global warming could increase permeability. This could enhance fluid <span class="hlt">flow</span> and associated heat transport causing a more rapid and/or more spatially extensive gas hydrate disassociation than predicted solely from conductive propagation of temporal changes in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvF...2l4001V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvF...2l4001V"><span>Steady film <span class="hlt">flow</span> over a substrate with rectangular trenches forming <span class="hlt">air</span> inclusions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varchanis, S.; Dimakopoulos, Y.; Tsamopoulos, J.</p> <p>2017-12-01</p> <p>Film <span class="hlt">flow</span> along an inclined, solid substrate featuring periodic rectangular trenches may either completely wet the trench floor (Wenzel state) or get pinned on the entrance and exit corners of the trench (Cassie state) or assume other configurations in between these two extremes. Such intermediate configurations are examined in the present study. They are bounded by a second gas-liquid interface inside the trench, which adheres to its walls forming two three-phase contact lines, and encloses a different amount of <span class="hlt">air</span> under different physical conditions. The Galerkin finite-element method is used to solve the Navier-Stokes equations in a physical domain, which is adaptively remeshed. Multiple steady solutions, connected by turning points and transcritical bifurcations as well as isolated solution branches, are revealed by pseudo-arc-length continuation. Two possible configurations of a single <span class="hlt">air</span> inclusion inside the trench are examined: the inclusion either surrounds the upstream convex corner or is attached to the upstream trench wall. The penetration of the liquid inside the trench is enhanced primarily by increasing either the wettability of the substrate or capillary over viscous forces or by decreasing the <span class="hlt">flow</span> rate. <span class="hlt">Flow</span> hysteresis may occur when the liquid wetting of the upstream wall decreases abruptly, leading to drastically different <span class="hlt">flow</span> patterns for the same parameter values. The interplay of inertia, viscous, gravity, and capillary forces along with substrate wettability determines the volume of the <span class="hlt">air</span> encapsulated in the trench and the extent of deformation of the outer free surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20179887','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20179887"><span>[Aerodynamics study on pressure changes inside pressure-type whole-body plethysmograph produced by <span class="hlt">flowing</span> <span class="hlt">air</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Wei-Hua; Shen, Hua-Hao</p> <p>2010-02-25</p> <p>When using pressure-type plethysmography to test lung function of rodents, calculation of lung volume is always based on Boyle's law. The precondition of Boyle's law is that perfect <span class="hlt">air</span> is static. However, <span class="hlt">air</span> in the chamber is <span class="hlt">flowing</span> continuously when a rodent breathes inside the chamber. Therefore, Boyle's law, a principle of <span class="hlt">air</span> statics, may not be appropriate for measuring pressure changes of <span class="hlt">flowing</span> <span class="hlt">air</span>. In this study, we deduced equations for pressure changes inside pressure-type plethysmograph and then designed three experiments to testify the theoretic deduction. The results of theoretic deduction indicated that increased pressure was generated from two sources: one was based on Boyle's law, and the other was based on the law of conservation of momentum. In the first experiment, after injecting 0.1 mL, 0.2 mL, 0.4 mL of <span class="hlt">air</span> into the plethysmograph, the pressure inside the chamber increased sharply to a peak value, then promptly decreased to horizontal pressure. Peak values were significantly higher than the horizontal values (P<0.001). This observation revealed that <span class="hlt">flowing</span> <span class="hlt">air</span> made an extra effect on <span class="hlt">air</span> pressure in the plethysmograph. In the second experiment, the same volume of <span class="hlt">air</span> was injected into the plethysmograph at different frequencies (0, 0.5, 1, 2, 3 Hz) and pressure changes inside were measured. The results showed that, with increasing frequencies, the pressure changes in the chamber became significantly higher (P<0.001). In the third experiment, small animal ventilator and pipette were used to make two types of airflow with different functions of time. The pressure changes produced by the ventilator were significantly greater than those produced by the pipette (P<0.001). Based on the data obtained, we draw the conclusion that, the <span class="hlt">flow</span> of <span class="hlt">air</span> plays a role in pressure changes inside the plethysmograph, and the faster the airflow is, the higher the pressure changes reach. Furthermore, the type of airflow also influences the pressure changes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940011006','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011006"><span>Boundary layer <span class="hlt">flow</span> of <span class="hlt">air</span> over water on a flat plate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nelson, John; Alving, Amy E.; Joseph, Daniel D.</p> <p>1993-01-01</p> <p>A non-similar boundary layer theory for <span class="hlt">air</span> blowing over a water layer on a flat plate is formulated and studied as a two-fluid problem in which the position of the interface is unknown. The problem is considered at large Reynolds number (based on x), away from the leading edge. A simple non-similar analytic solution of the problem is derived for which the interface height is proportional to x(sub 1/4) and the water and <span class="hlt">air</span> <span class="hlt">flow</span> satisfy the Blasius boundary layer equations, with a linear profile in the water and a Blasius profile in the <span class="hlt">air</span>. Numerical studies of the initial value problem suggests that this asymptotic, non-similar <span class="hlt">air</span>-water boundary layer solution is a global attractor for all initial conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19790034302&hterms=bricks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbricks','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19790034302&hterms=bricks&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dbricks"><span>Effect of pyrolysis temperature and <span class="hlt">air</span> <span class="hlt">flow</span> on toxicity of gases from a polycarbonate polymer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hilado, C. J.; Brick, V. E.; Brauer, D. P.</p> <p>1978-01-01</p> <p>A polycarbonate polymer was evaluated for toxicity of pyrolysis gases generated at various temperatures without forced <span class="hlt">air</span> <span class="hlt">flow</span> and with 1 L/min <span class="hlt">air</span> <span class="hlt">flow</span>, using the toxicity screening test method developed at the University of San Francisco. Time to various animal responses decreased with increasing pyrolysis temperature over the range from 500 C to 800 C. There appeared to be no significant toxic effects at 400 C and lower temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPA....8f5004S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPA....8f5004S"><span>Numerical investigation of <span class="hlt">flow</span> past 17-cylinder array of square cylinders</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shams-ul-Islam, Nazeer, Ghazala; Ying, Zhou Chao</p> <p>2018-06-01</p> <p>In this work, <span class="hlt">flow</span> past 17-cylinder array is simulated using the two-dimensional lattice Boltzmann method. Effect of gap spacings (0.5 ≤ gx* ≤ 3, 0.5 ≤ gy* ≤ 3) and Reynolds number (Re = 75 - 150) is analyzed in details. Results are presented in the form of vorticity contours plots, time-histories of drag and lift coefficients and power spectrum of lift coefficient. Six distinct <span class="hlt">flow</span> <span class="hlt">regimes</span> are identified for different gap spacings and Reynolds numbers: steady <span class="hlt">flow</span> <span class="hlt">regime</span>, single bluff body <span class="hlt">flow</span> <span class="hlt">regime</span>, non-fully developed <span class="hlt">flow</span> <span class="hlt">regime</span>, chaotic <span class="hlt">flow</span> <span class="hlt">regime</span>, quasi-periodic-I <span class="hlt">flow</span> <span class="hlt">regime</span> and quasi-periodic-II <span class="hlt">flow</span> <span class="hlt">regime</span>. Chaotic <span class="hlt">flow</span> <span class="hlt">regime</span> is the mostly observed <span class="hlt">flow</span> <span class="hlt">regime</span> while the single bluff body <span class="hlt">flow</span> <span class="hlt">regime</span> rarely occurs for this configuration. It is observed that drag force along each cylinder in 17-cylinder array decreases in the streamwise direction for fixed Reynold number and gap spacing. C1 and C2 cylinders experience the maximum drag at small gap spacing and Reynolds number. Also the Reynolds number is found to be more effective on <span class="hlt">flow</span> characteristics as compared to gap spacings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22105461-air-flow-sensor-neonatal-mechanical-ventilation-applications-based-novel-fiber-optic-sensing-technique','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22105461-air-flow-sensor-neonatal-mechanical-ventilation-applications-based-novel-fiber-optic-sensing-technique"><span>An <span class="hlt">air</span> <span class="hlt">flow</span> sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Battista, L.; Sciuto, S. A.; Scorza, A.</p> <p>2013-03-15</p> <p>In this work, a simple and low-cost <span class="hlt">air</span> <span class="hlt">flow</span> sensor, based on a novel fiber-optic sensing technique has been developed for monitoring <span class="hlt">air</span> <span class="hlt">flows</span> rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of <span class="hlt">air</span> <span class="hlt">flow</span> acting on it;more » the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an <span class="hlt">air</span> <span class="hlt">flow</span> sensor suitable for the measurement of <span class="hlt">air</span> <span class="hlt">flow</span> rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the <span class="hlt">air</span> <span class="hlt">flow</span> sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 Multiplication-Sign 10{sup -4} m{sup 3}/s (18.0 l/min) for the mono-directional sensor and a measurement range of {+-}3.00 Multiplication-Sign 10{sup -4} m{sup 3}/s ({+-}18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the <span class="hlt">air</span> <span class="hlt">flow</span> rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23556844','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23556844"><span>An <span class="hlt">air</span> <span class="hlt">flow</span> sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Battista, L; Sciuto, S A; Scorza, A</p> <p>2013-03-01</p> <p>In this work, a simple and low-cost <span class="hlt">air</span> <span class="hlt">flow</span> sensor, based on a novel fiber-optic sensing technique has been developed for monitoring <span class="hlt">air</span> <span class="hlt">flows</span> rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of <span class="hlt">air</span> <span class="hlt">flow</span> acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an <span class="hlt">air</span> <span class="hlt">flow</span> sensor suitable for the measurement of <span class="hlt">air</span> <span class="hlt">flow</span> rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the <span class="hlt">air</span> <span class="hlt">flow</span> sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10(-4) m(3)∕s (18.0 l∕min) for the mono-directional sensor and a measurement range of ±3.00 × 10(-4) m(3)∕s (±18.0 l∕min) for the bi-directional sensor are experimentally evaluated, according to the <span class="hlt">air</span> <span class="hlt">flow</span> rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013RScI...84c5005B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013RScI...84c5005B"><span>An <span class="hlt">air</span> <span class="hlt">flow</span> sensor for neonatal mechanical ventilation applications based on a novel fiber-optic sensing technique</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Battista, L.; Sciuto, S. A.; Scorza, A.</p> <p>2013-03-01</p> <p>In this work, a simple and low-cost <span class="hlt">air</span> <span class="hlt">flow</span> sensor, based on a novel fiber-optic sensing technique has been developed for monitoring <span class="hlt">air</span> <span class="hlt">flows</span> rates supplied by a neonatal ventilator to support infants in intensive care units. The device is based on a fiber optic sensing technique allowing (a) the immunity to light intensity variations independent by measurand and (b) the reduction of typical shortcomings affecting all biomedical fields (electromagnetic interference and patient electrical safety). The sensing principle is based on the measurement of transversal displacement of an emitting fiber-optic cantilever due to action of <span class="hlt">air</span> <span class="hlt">flow</span> acting on it; the fiber tip displacement is measured by means of a photodiode linear array, placed in front of the entrance face of the emitting optical fiber in order to detect its light intensity profile. As the measurement system is based on a detection of the illumination pattern, and not on an intensity modulation technique, it results less sensitive to light intensity fluctuation independent by measurand than intensity-based sensors. The considered technique is here adopted in order to develop two different configurations for an <span class="hlt">air</span> <span class="hlt">flow</span> sensor suitable for the measurement of <span class="hlt">air</span> <span class="hlt">flow</span> rates typically occurring during mechanical ventilation of newborns: a mono-directional and a bi-directional transducer have been proposed. A mathematical model for the <span class="hlt">air</span> <span class="hlt">flow</span> sensor is here proposed and a static calibration of two different arrangements has been performed: a measurement range up to 3.00 × 10-4 m3/s (18.0 l/min) for the mono-directional sensor and a measurement range of ±3.00 × 10-4 m3/s (±18.0 l/min) for the bi-directional sensor are experimentally evaluated, according to the <span class="hlt">air</span> <span class="hlt">flow</span> rates normally encountered during tidal breathing of infants with a mass lower than 10 kg. Experimental data of static calibration result in accordance with the proposed theoretical model: for the mono-directional configuration, the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://dx.doi.org/10.1002/rra.1293','USGSPUBS'); return false;" href="http://dx.doi.org/10.1002/rra.1293"><span>Effects of hydrologic infrastructure on <span class="hlt">flow</span> <span class="hlt">regimes</span> of California's Central Valley rivers: Implications for fish populations</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Brown, Larry R.; Bauer, Marissa L.</p> <p>2010-01-01</p> <p>Alteration of natural <span class="hlt">flow</span> <span class="hlt">regimes</span> is generally acknowledged to have negative effects on native biota; however, methods for defining ecologically appropriate <span class="hlt">flow</span> <span class="hlt">regimes</span> in managed river systems are only beginning to be developed. Understanding how past and present water management has affected rivers is an important part of developing such tools. In this paper, we evaluate how existing hydrologic infrastructure and management affect streamflow characteristics of rivers in the Central Valley, California and discuss those characteristics in the context of habitat requirements of native and alien fishes. We evaluated the effects of water management by comparing observed discharges with estimated discharges assuming no water management ("full natural runoff"). Rivers in the Sacramento River drainage were characterized by reduced winter–spring discharges and augmented discharges in other months. Rivers in the San Joaquin River drainage were characterized by reduced discharges in all months but particularly in winter and spring. Two largely unaltered streams had hydrographs similar to those based on full natural runoff of the regulated rivers. The reduced discharges in the San Joaquin River drainage streams are favourable for spawning of many alien species, which is consistent with observed patterns of fish distribution and abundance in the Central Valley. However, other factors, such as water temperature, are also important to the relative success of native and alien resident fishes. As water management changes in response to climate change and societal demands, interdisciplinary programs of research and monitoring will be essential for anticipating effects on fishes and to avoid unanticipated ecological outcomes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMPP51C1076M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMPP51C1076M"><span>Optimal Ranking <span class="hlt">Regime</span> Analysis of Tree<span class="hlt">Flow</span> Dendrohydrological Reconstructions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mauget, S. A.</p> <p>2017-12-01</p> <p>The Optimal Ranking <span class="hlt">Regime</span> (ORR) method was used to identify 6-100 year time windows containing significant ranking sequences in 55 western U.S. streamflow reconstructions, and reconstructions of the level of the Great Salt Lake and San Francisco Bay salinity during 1500-2007. The method's ability to identify optimally significant and non-overlapping runs of low and high rankings allows it to re-express a reconstruction time series as a simplified sequence of <span class="hlt">regime</span> segments marking intra- to multi-decadal (IMD) periods of low or high streamflow, lake level, or salinity. Those ORR sequences, referred to here as Z-lines, can be plotted to identify consistent <span class="hlt">regime</span> patterns in the analysis of numerous reconstructions. The Z-lines for the 57 reconstructions evaluated here show a common pattern of IMD cycles of drought and pluvial periods during the late 16th and 17th centuries, a relatively dormant period during the 18th century, and the reappearance of alternating dry and wet IMD periods during the 19th and early 20th centuries. Although this pattern suggests the possibility of similarly active and inactive oceanic modes in the North Pacific and North Atlantic, such centennial-scale patterns are not evident in the ORR analyses of reconstructed Pacific Decadal Oscillation (PDO), El Niño-Southern Oscillation, and North Atlantic seas-surface temperature variation. But given the inconsistency in the analyses of four PDO reconstructions the possible role of centennial-scale oceanic mechanisms is uncertain. In future research the ORR method might be applied to climate reconstructions around the Pacific Basin to try to resolve this uncertainty. Given its ability to compare <span class="hlt">regime</span> patterns in climate reconstructions derived using different methods and proxies, the method may also be used in future research to evaluate long-term regional temperature reconstructions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MS%26E..270a2003A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MS%26E..270a2003A"><span>Two dimensional numerical analysis of aerodynamic characteristics for rotating cylinder on concentrated <span class="hlt">air</span> <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alias, M. S.; Rafie, A. S. Mohd; Marzuki, O. F.; Hamid, M. F. Abdul; Chia, C. C.</p> <p>2017-12-01</p> <p>Over the years, many studies have demonstrated the feasibility of the Magnus effect on spinning cylinder to improve lift production, which can be much higher than the traditional airfoil shape. With this characteristic, spinning cylinder might be used as a lifting device for short take-off distance aircraft or unmanned aerial vehicle (UAV). Nonetheless, there is still a gap in research to explain the use of spinning cylinder as a good lifting device. Computational method is used for this study to analyse the Magnus effect, in which two-dimensional finite element numerical analysis method is applied using ANSYS FLUENT software to examine the coefficients of lift and drag, and to investigate the <span class="hlt">flow</span> field around the rotating cylinder surface body. Cylinder size of 30mm is chosen and several configurations in steady and concentrated <span class="hlt">air</span> <span class="hlt">flows</span> have been evaluated. All in all, it can be concluded that, with the right configuration of the concentrated <span class="hlt">air</span> <span class="hlt">flow</span> setup, the rotating cylinder can be used as a lifting device for very short take-off since it can produce very high coefficient of lift (2.5 times higher) compared with steady <span class="hlt">air</span> <span class="hlt">flow</span> configuration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040053520','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040053520"><span>Piloted Ignition of Polypropylene/Glass Composites in a Forced <span class="hlt">Air</span> <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fernandez-Pello, A. C.; Rich, D.; Lautenberger, C.; Stefanovich, A.; Metha, S.; Torero, J.; Yuan, Z.; Ross, H.</p> <p>2003-01-01</p> <p>The Forced Ignition and Spread Test (FIST) is being used to study the flammability characteristics of combustible materials in forced convective <span class="hlt">flows</span>. The FIST methodology is based on the ASTM E-1321, Lateral Ignition and Flame Spread Test (LIFT) which is used to determine the ignition and flame spread characteristics of materials, and to produce 'Flammability Diagrams' of materials. The LIFT apparatus, however, relies on natural convection to bring <span class="hlt">air</span> to the combustion zone and the fuel vapor to the pilot flame, and thus cannot describe conditions where the oxidizer <span class="hlt">flow</span> velocity may change. The FIST on the other hand, by relying on a forced <span class="hlt">flow</span> as the dominant transport mechanism, can be used to examine variable oxidizer <span class="hlt">flow</span> characteristics, such as velocity, oxygen concentration, and turbulence intensity, and consequently has a wider applicability. Particularly important is its ability to determine the flammability characteristics of materials used in spacecraft since in the absence of gravity the only <span class="hlt">flow</span> present is that forced by the HVAC of the space facility. In this paper, we report work on the use of the FIST approach on the piloted ignition of a blended polypropylene fiberglass (PP/GL) composite material exposed to an external radiant flux in a forced convective <span class="hlt">flow</span> of <span class="hlt">air</span>. The effect of glass concentration under varying external radiant fluxes is examined and compared qualitatively with theoretical predictions of the ignition process. The results are used to infer the effect of glass content on the fire safety characteristics of composites.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhPl...23l3523Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhPl...23l3523Y"><span><span class="hlt">Flow</span>-field differences and electromagnetic-field properties of <span class="hlt">air</span> and N2 inductively coupled plasmas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Minghao; Yamada, Kazuhiko; Takahashi, Yusuke; Liu, Kai; Zhao, Tong</p> <p>2016-12-01</p> <p>A numerical model for simulating <span class="hlt">air</span> and nitrogen inductively coupled plasmas (ICPs) was developed considering thermochemical nonequilibrium and the third-order electron transport properties. A modified far-field electromagnetic model was introduced and tightly coupled with the <span class="hlt">flow</span> field equations to describe the Joule heating and inductive discharge phenomena. In total, 11 species and 49 chemical reactions of <span class="hlt">air</span>, which include 5 species and 8 chemical reactions of nitrogen, were employed to model the chemical reaction process. The internal energy transfers among translational, vibrational, rotational, and electronic energy modes of chemical species were taken into account to study thermal nonequilibrium effects. The low-Reynolds number Abe-Kondoh-Nagano k-ɛ turbulence model was employed to consider the turbulent heat transfer. In this study, the fundamental characteristics of an ICP <span class="hlt">flow</span>, such as the weak ionization, high temperature but low velocity in the torch, and wide area of the plasma plume, were reproduced by the developed numerical model. The <span class="hlt">flow</span> field differences between the <span class="hlt">air</span> and nitrogen ICP <span class="hlt">flows</span> inside the 10-kW ICP wind tunnel were made clear. The interactions between the electromagnetic and <span class="hlt">flow</span> fields were also revealed for an inductive discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999JApMe..38.1069B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999JApMe..38.1069B"><span>Wind-<span class="hlt">Flow</span> Patterns in the Grand Canyon as Revealed by Doppler Lidar.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Banta, Robert M.; Darby, Lisa S.; Kaufmann, Pirmin; Levinson, David H.; Zhu, Cui-Juan</p> <p>1999-08-01</p> <p>Many interesting <span class="hlt">flow</span> patterns were found in the Grand Canyon by a scanning Doppler lidar deployed to the south rim during the 1990 Wintertime Visibility Study. Three are analyzed in this study: 1) <span class="hlt">flow</span> reversal in the canyon, where the <span class="hlt">flow</span> in the canyon was in the opposite direction from the <span class="hlt">flow</span> above the canyon rim; 2) under strong, gusty <span class="hlt">flow</span> from the southwest, the <span class="hlt">flow</span> inside and above the canyon was from a similar direction and coupled; and 3) under light large-scale ambient <span class="hlt">flow</span>, the lidar found evidence of local, thermally forced up- and down-canyon winds in the bottom of the canyon.On the days with <span class="hlt">flow</span> reversal in the canyon, the strongest in-canyon <span class="hlt">flow</span> response was found for days with northwesterly <span class="hlt">flow</span> and a strong inversion at the canyon rim. The aerosol backscatter profiles were well mixed within the canyon but poorly mixed across the rim because of the inversion. The gusty southwest <span class="hlt">flow</span> days showed strong evidence of vertical mixing across the rim both in the momentum and in the aerosol backscatter profiles, as one would expect in turbulent <span class="hlt">flow</span>. The days with light ambient <span class="hlt">flow</span> showed poor vertical mixing even inside the canyon, where the jet of down-canyon <span class="hlt">flow</span> in the bottom of the canyon at night was often either cleaner or dirtier than the <span class="hlt">air</span> in the upper portions of the canyon. In a case study presented, the light ambient <span class="hlt">flow</span> <span class="hlt">regime</span> ended with an intrusion of polluted, gusty, southwesterly <span class="hlt">flow</span>. The polluted, high-backscatter <span class="hlt">air</span> took several hours to mix into the upper parts of the canyon. An example is also given of high-backscatter <span class="hlt">air</span> in the upper portions of the canyon being mixed rapidly down into a jet of cleaner <span class="hlt">air</span> in the bottom of the canyon in just a few minutes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5873458','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5873458"><span><span class="hlt">Air</span> sampling to assess potential generation of aerosolized viable bacteria during <span class="hlt">flow</span> cytometric analysis of unfixed bacterial suspensions</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Carson, Christine F; Inglis, Timothy JJ</p> <p>2018-01-01</p> <p>This study investigated aerosolized viable bacteria in a university research laboratory during operation of an acoustic-assisted <span class="hlt">flow</span> cytometer for antimicrobial susceptibility testing by sampling room <span class="hlt">air</span> before, during and after <span class="hlt">flow</span> cytometer use. The aim was to assess the risk associated with use of an acoustic-assisted <span class="hlt">flow</span> cytometer analyzing unfixed bacterial suspensions. <span class="hlt">Air</span> sampling in a nearby clinical laboratory was conducted during the same period to provide context for the existing background of microorganisms that would be detected in the <span class="hlt">air</span>. The three species of bacteria undergoing analysis by <span class="hlt">flow</span> cytometer in the research laboratory were Klebsiella pneumoniae, Burkholderia thailandensis and Streptococcus pneumoniae. None of these was detected from multiple 1000 L <span class="hlt">air</span> samples acquired in the research laboratory environment. The main cultured bacteria in both locations were skin commensal and environmental bacteria, presumed to have been disturbed or dispersed in laboratory <span class="hlt">air</span> by personnel movements during routine laboratory activities. The concentrations of bacteria detected in research laboratory <span class="hlt">air</span> samples were reduced after interventional cleaning measures were introduced and were lower than those in the diagnostic clinical microbiology laboratory. We conclude that our <span class="hlt">flow</span> cytometric analyses of unfixed suspensions of K. pneumoniae, B. thailandensis and S. pneumoniae do not pose a risk to cytometer operators or other personnel in the laboratory but caution against extrapolation of our results to other bacteria and/or different <span class="hlt">flow</span> cytometric experimental procedures. PMID:29608197</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22107841-velocity-void-distribution-counter-current-two-phase-flow','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22107841-velocity-void-distribution-counter-current-two-phase-flow"><span>Velocity and void distribution in a counter-current two-phase <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gabriel, S.; Schulenberg, T.; Laurien, E.</p> <p>2012-07-01</p> <p>Different <span class="hlt">flow</span> <span class="hlt">regimes</span> were investigated in a horizontal channel. Simulating a hot leg injection in case of a loss of coolant accident or <span class="hlt">flow</span> conditions in reflux condenser mode, the hydraulic jump and partially reversed <span class="hlt">flow</span> were identified as major constraints for a high amount of entrained water. Trying to simulate the reflux condenser mode, the test section now includes an inclined section connected to a horizontal channel. The channel is 90 mm high and 110 mm wide. Tests were carried out for water and <span class="hlt">air</span> at ambient pressure and temperature. High speed video-metry was applied to obtain velocities frommore » <span class="hlt">flow</span> pattern maps of the rising and falling fluid. In the horizontal part of the channel with partially reversed <span class="hlt">flow</span> the fluid velocities were measured by planar particle image velocimetry. To obtain reliable results for the gaseous phase, this analysis was extended by endoscope measurements. Additionally, a new method based on the optical refraction at the interface between <span class="hlt">air</span> and water in a back-light was used to obtain time-averaged void fraction. (authors)« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ExFl...46..549M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ExFl...46..549M"><span>Influence of surfactant upon <span class="hlt">air</span> entrainment hysteresis in curtain coating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marston, J. O.; Hawkins, V.; Decent, S. P.; Simmons, M. J. H.</p> <p>2009-03-01</p> <p>The onset of <span class="hlt">air</span> entrainment for curtain coating onto a pre-wetted substrate was studied experimentally in similar parameter <span class="hlt">regimes</span> to commercial coating ( Re = ρ Q/μ = O(1), We = ρ Q u c /σ = O(10), Ca = μ U/σ = O(1)). Impingement speed and viscosity were previously shown to be critical parameters in correlating <span class="hlt">air</span> entrainment data with three qualitatively different <span class="hlt">regimes</span> of hydrodynamic assist identified (Marston et al. in Exp Fluids 42(3):483-488, 2007a). The interaction of the impinging curtain with the pre-existing film also led to a significant hysteretic effect throughout the <span class="hlt">flow</span> rate-substrate speed parameter space. For the first time, results considering the influence of surfactants are presented in attempt to elucidate the relative importance of surface tension in this inertia-dominated system. The results show quantitative and qualitative differences to previous results with much more complex hysteretic behaviour which has only been reported previously for rough surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhRvE..94e3104L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhRvE..94e3104L"><span>Hydrodynamic interaction of swimming organisms in an inertial <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Gaojin; Ostace, Anca; Ardekani, Arezoo M.</p> <p>2016-11-01</p> <p>We numerically investigate the hydrodynamic interaction of swimming organisms at small to intermediate Reynolds number <span class="hlt">regimes</span>, i.e., Re˜O (0.1 -100 ) , where inertial effects are important. The hydrodynamic interaction of swimming organisms in this <span class="hlt">regime</span> is significantly different from the Stokes <span class="hlt">regime</span> for microorganisms, as well as the high Reynolds number <span class="hlt">flows</span> for fish and birds, which involves strong <span class="hlt">flow</span> separation and detached vortex structures. Using an archetypal swimmer model, called a "squirmer," we find that the inertial effects change the contact time and dispersion dynamics of a pair of pusher swimmers, and trigger hydrodynamic attraction for two pullers. These results are potentially important in investigating predator-prey interactions, sexual reproduction, and the encounter rate of marine organisms such as copepods, ctenophora, and larvae.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930090144','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930090144"><span>Comparison of Calculated and Experimental Temperatures and Coolant Pressure Losses for a Cascade of Small <span class="hlt">Air</span>-Cooled Turbine Rotor Blades</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stepka, Francis S</p> <p>1958-01-01</p> <p>Average spanwise blade temperatures and cooling-<span class="hlt">air</span> pressure losses through a small (1.4-in, span, 0.7-in, chord) <span class="hlt">air</span>-cooled turbine blade were calculated and are compared with experimental nonrotating cascade data. Two methods of calculating the blade spanwise metal temperature distributions are presented. The method which considered the effect of the length-to-diameter ratio of the coolant passage on the blade-to-coolant heat-transfer coefficient and assumed constant coolant properties based on the coolant bulk temperature gave the best agreement with experimental data. The agreement obtained was within 3 percent at the midspan and tip regions of the blade. At the root region of the blade, the agreement was within 3 percent for coolant <span class="hlt">flows</span> within the turbulent <span class="hlt">flow</span> <span class="hlt">regime</span> and within 10 percent for coolant <span class="hlt">flows</span> in the laminar <span class="hlt">regime</span>. The calculated and measured cooling-<span class="hlt">air</span> pressure losses through the blade agreed within 5 percent. Calculated spanwise blade temperatures for assumed turboprop engine operating conditions of 2000 F turbine-inlet gas temperature and flight conditions of 300 knots at a 30,000-foot altitude agreed well with those obtained by the extrapolation of correlated experimental data of a static cascade investigation of these blades.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25057511','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25057511"><span>Simulation analysis of <span class="hlt">air</span> <span class="hlt">flow</span> and turbulence statistics in a rib grit roughened duct.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vogiatzis, I I; Denizopoulou, A C; Ntinas, G K; Fragos, V P</p> <p>2014-01-01</p> <p>The implementation of variable artificial roughness patterns on a surface is an effective technique to enhance the rate of heat transfer to fluid <span class="hlt">flow</span> in the ducts of solar <span class="hlt">air</span> heaters. Different geometries of roughness elements investigated have demonstrated the pivotal role that vortices and associated turbulence have on the heat transfer characteristics of solar <span class="hlt">air</span> heater ducts by increasing the convective heat transfer coefficient. In this paper we investigate the two-dimensional, turbulent, unsteady <span class="hlt">flow</span> around rectangular ribs of variable aspect ratios by directly solving the transient Navier-Stokes and continuity equations using the finite elements method. <span class="hlt">Flow</span> characteristics and several aspects of turbulent <span class="hlt">flow</span> are presented and discussed including velocity components and statistics of turbulence. The results reveal the impact that different rib lengths have on the computed mean quantities and turbulence statistics of the <span class="hlt">flow</span>. The computed turbulence parameters show a clear tendency to diminish downstream with increasing rib length. Furthermore, the applied numerical method is capable of capturing small-scale <span class="hlt">flow</span> structures resulting from the direct solution of Navier-Stokes and continuity equations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=285944','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=285944"><span>Interrelationships of petiole <span class="hlt">air</span> canal architecture, water depth and convective <span class="hlt">air</span> <span class="hlt">flow</span> in Nymphaea odorata (Nymphaeaceae)</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Premise of the study--Nymphaea odorata grows in water up to 2 m deep, producing fewer, larger leaves in deeper water. This species has a convective <span class="hlt">flow</span> system that moves gases from younger leaves through submerged parts to older leaves, aerating submerged parts. Petiole <span class="hlt">air</span> canals are in the conv...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21669836','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21669836"><span>How kelp produce blade shapes suited to different <span class="hlt">flow</span> <span class="hlt">regimes</span>: A new wrinkle.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Koehl, M A R; Silk, W K; Liang, H; Mahadevan, L</p> <p>2008-12-01</p> <p>Many species of macroalgae have flat, strap-like blades in habitats exposed to rapidly <span class="hlt">flowing</span> water, but have wide, ruffled "undulate" blades at protected sites. We used the giant bull kelp, Nereocystis luetkeana, to investigate how these ecomorphological differences are produced. The undulate blades of N. luetkeana from sites with low <span class="hlt">flow</span> remain spread out and flutter erratically in moving water, thereby not only enhancing interception of light, but also increasing drag. In contrast, strap-like blades of kelp from habitats with rapid <span class="hlt">flow</span> collapse into streamlined bundles and flutter at low amplitude in <span class="hlt">flowing</span> water, thus reducing both drag and interception of light. Transplant experiments in the field revealed that shape of the blade in N. luetkeana is a plastic trait. Laboratory experiments in which growing blades from different sites were subjected to tensile forces that mimicked the hydrodynamic drag experienced by blades in different <span class="hlt">flow</span> <span class="hlt">regimes</span> showed that change in shape is induced by mechanical stress. During growth experiments in the field and laboratory, we mapped the spatial distribution of growth in both undulate and strap-like blades to determine how these different morphologies were produced. The highest growth rates occur near the proximal ends of N. luetkeana blades of both morphologies, but the rates of transverse growth of narrow, strap-like blades are lower than those of wide, undulate blades. If rates of longitudinal growth at the edges of a blade exceed the rate of longitudinal growth along the midline of the blade, ruffles along the edges of the blade are produced by elastic buckling. In contrast, flat blades are produced when rates of longitudinal growth are similar across the width of a blade. Because ruffles are the result of elastic buckling, a compliant undulate N. luetkeana blade can easily be pushed into different configurations (e.g., the wavelengths of the ruffles along the edges of the blade can change, and the whole blade can</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AtmEn..43...64L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AtmEn..43...64L"><span>The development of effects-based <span class="hlt">air</span> quality management <span class="hlt">regimes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Longhurst, J. W. S.; Irwin, J. G.; Chatterton, T. J.; Hayes, E. T.; Leksmono, N. S.; Symons, J. K.</p> <p></p> <p>This paper considers the evolution of attempts to control and manage <span class="hlt">air</span> pollution, principally but not exclusively focussing upon the challenge of managing <span class="hlt">air</span> pollution in urban environments. The development and implementation of a range of <span class="hlt">air</span> pollution control measures are considered. Initially the measures implemented primarily addressed point sources, a small number of fuel types and a limited number of pollutants. The adequacy of such a source-control approach is assessed within the context of a changing and challenging <span class="hlt">air</span> pollution climate. An assessment of <span class="hlt">air</span> quality management in the United Kingdom over a 50-year timeframe exemplifies the range of issues and challenges in contemporary <span class="hlt">air</span> quality management. The need for new approaches is explored and the development and implementation of an effects-based, risk management system for <span class="hlt">air</span> quality regulation is evaluated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CTM....16..275P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CTM....16..275P"><span>Chaotic dynamics in premixed hydrogen/<span class="hlt">air</span> channel <span class="hlt">flow</span> combustion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pizza, Gianmarco; Frouzakis, Christos E.; Mantzaras, John</p> <p>2012-04-01</p> <p>The complex oscillatory behaviour observed in fuel-lean premixed hydrogen/<span class="hlt">air</span> atmospheric pressure flames in an open planar channel with prescribed wall temperature is investigated by means of direct numerical simulations, employing detailed chemistry descriptions and species transport, and nonlinear dynamics analysis. As the inflow velocity is varied, the sequence of transitions includes harmonic single frequency oscillations, intermittency, mixed mode oscillations, and finally a period-doubling cascade leading to chaotic dynamics. The observed modes are described and characterised by means of phase-space portraits and next amplitude maps. It is shown that the interplay of chemistry, transport, and wall-bounded developing <span class="hlt">flow</span> leads to considerably richer dynamics compared to fuel-lean hydrogen/<span class="hlt">air</span> continuously stirred tank reactor studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvE..95f3112G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvE..95f3112G"><span>Instability evolution of the viscous elliptic liquid jet in the Rayleigh <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gu, Shibo; Wang, Lipo; Hung, David L. S.</p> <p>2017-06-01</p> <p>For jet <span class="hlt">flow</span> emanating from noncircular orifices, an unbalanced surface tension force leads to capillary instability, which is independent of influence from the ambient <span class="hlt">air</span> in the Rayleigh <span class="hlt">regime</span>. In the present article, the dynamic behavior of incompressible elliptical jets in the Rayleigh <span class="hlt">regime</span> is investigated. Theoretically, with the consideration of the fluid viscosity, the solution of the Cosserat equation consists of a particular solution and a complementary solution. For the complementary solution the wave number of disturbance modes has two complex conjugate roots, which are responsible for the jet breakup. To match the nonzero particular solution, a spatial wave needs to be introduced, which is independent of external perturbations. Physically, such a spatial wave is interpreted as the axis-switching phenomenon. The predicted features of the axis-switching wavelength and the damping effect from the fluid viscosity have been successfully verified by experimental results. Moreover, the dispersion relations from the present theory suggest that the growth rate of spatial instability is influenced by orifice eccentricity, the Weber number, and the Ohnesorge number.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28709223','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28709223"><span>Instability evolution of the viscous elliptic liquid jet in the Rayleigh <span class="hlt">regime</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gu, Shibo; Wang, Lipo; Hung, David L S</p> <p>2017-06-01</p> <p>For jet <span class="hlt">flow</span> emanating from noncircular orifices, an unbalanced surface tension force leads to capillary instability, which is independent of influence from the ambient <span class="hlt">air</span> in the Rayleigh <span class="hlt">regime</span>. In the present article, the dynamic behavior of incompressible elliptical jets in the Rayleigh <span class="hlt">regime</span> is investigated. Theoretically, with the consideration of the fluid viscosity, the solution of the Cosserat equation consists of a particular solution and a complementary solution. For the complementary solution the wave number of disturbance modes has two complex conjugate roots, which are responsible for the jet breakup. To match the nonzero particular solution, a spatial wave needs to be introduced, which is independent of external perturbations. Physically, such a spatial wave is interpreted as the axis-switching phenomenon. The predicted features of the axis-switching wavelength and the damping effect from the fluid viscosity have been successfully verified by experimental results. Moreover, the dispersion relations from the present theory suggest that the growth rate of spatial instability is influenced by orifice eccentricity, the Weber number, and the Ohnesorge number.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980027689','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980027689"><span>Decentralized and Tactical <span class="hlt">Air</span> Traffic <span class="hlt">Flow</span> Management</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Odoni, Amedeo R.; Bertsimas, Dimitris</p> <p>1997-01-01</p> <p>This project dealt with the following topics: 1. Review and description of the existing <span class="hlt">air</span> traffic <span class="hlt">flow</span> management system (ATFM) and identification of aspects with potential for improvement. 2. Identification and review of existing models and simulations dealing with all system segments (enroute, terminal area, ground) 3. Formulation of concepts for overall decentralization of the ATFM system, ranging from moderate decentralization to full decentralization 4. Specification of the modifications to the ATFM system required to accommodate each of the alternative concepts. 5. Identification of issues that need to be addressed with regard to: determination of the way the ATFM system would be operating; types of <span class="hlt">flow</span> management strategies that would be used; and estimation of the effectiveness of ATFM with regard to reducing delay and re-routing costs. 6. Concept evaluation through identification of criteria and methodologies for accommodating the interests of stakeholders and of approaches to optimization of operational procedures for all segments of the ATFM system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDR28005F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDR28005F"><span>Turbulence Modulation and Particle Segregation in a Turbulent Channel <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fong, Kee Onn; Toloui, Mostafa; Amili, Omid; Hong, Jiarong; Coletti, Filippo</p> <p>2016-11-01</p> <p>Particle-laden <span class="hlt">flows</span> are ubiquitous in biological, environmental, and engineering <span class="hlt">flows</span>, but our understanding of the mechanism by which particles modulate turbulence is incomplete. Simulations involve a wide range of scales, and shall be corroborated by measurements that reconstruct the motion of both the continuous and dispersed phases. We present experimental observations on the interaction between inertial particles and turbulent <span class="hlt">flow</span> through a vertical channel in two-way coupled <span class="hlt">regime</span>. The working fluid is <span class="hlt">air</span> laden with size-selected glass particles, which we investigate by planar particle image velocimetry and digital inline holography. Unlike most previous experiments, we focus on a <span class="hlt">regime</span> in which particle segregation and turbulence modulation are both strong. PIV shows that turbulence modulation is especially pronounced near the wall, where particles accumulate by turbophoresis. The segregation, however, is much weaker than what suggested by one-way coupled simulations. Results from digital holography confirm the trends in particle concentration and velocities, and additionally provide information on the three-dimensional clustering. The findings are compared to previous investigations and discussed in the context of modeling strategies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982gatu.conf.....C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982gatu.conf.....C"><span>Semi-empirical analysis of liquid fuel distribution downstream of a plain orifice injector under cross-stream <span class="hlt">air</span> <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, M.-H.; Jiang, H.-K.; Chin, J.-S.</p> <p>1982-04-01</p> <p>An improved flat-fan spray model is used for the semi-empirical analysis of liquid fuel distribution downstream of a plain orifice injector under cross-stream <span class="hlt">air</span> <span class="hlt">flow</span>. The model assumes that, due to the aerodynamic force of the high-velocity cross <span class="hlt">air</span> <span class="hlt">flow</span>, the injected fuel immediately forms a flat-fan liquid sheet perpendicular to the cross <span class="hlt">flow</span>. Once the droplets have been formed, the trajectories of individual droplets determine fuel distribution downstream. Comparison with test data shows that the proposed model accurately predicts liquid fuel distribution at any point downstream of a plain orifice injector under high-velocity, low-temperature uniform cross-stream <span class="hlt">air</span> <span class="hlt">flow</span> over a wide range of conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Geomo.294...40M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Geomo.294...40M"><span>Residence times and alluvial architecture of a sediment superslug in response to different <span class="hlt">flow</span> <span class="hlt">regimes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moody, John A.</p> <p>2017-10-01</p> <p>A superslug was deposited in a basin in the Colorado Front Range Mountains as a consequence of an extreme flood following a wildfire disturbance in 1996. The subsequent evolution of this superslug was measured by repeat topographic surveys (31 surveys from 1996 through 2014) of 18 cross sections approximately uniformly spaced over 1500 m immediately above the basin outlet. These surveys allowed the identification within the superslug of chronostratigraphic units deposited and eroded by different geomorphic processes in response to different <span class="hlt">flow</span> <span class="hlt">regimes</span>. Over the time period of the study, the superslug went through aggradation, incision, and stabilization phases that were controlled by a shift in geomorphic processes from generally short-duration, episodic, large-magnitude floods that deposited new chronostratigraphic units to long-duration processes that eroded units. These phases were not contemporaneous at each channel cross section, which resulted in a complex response that preserved different chronostratigraphic units at each channel cross section having, in general, two dominant types of alluvial architecture-laminar and fragmented. Age and transit-time distributions for these two alluvial architectures evolved with time since the extreme flood. Because of the complex shape of the distributions they were best modeled by two-parameter Weibull functions. The Weibull scale parameter approximated the median age of the distributions, and the Weibull shape parameter generally had a linear relation that increased with time since the extreme flood. Additional results indicated that deposition of new chronostratigraphic units can be represented by a power-law frequency distribution, and that the erosion of units decreases with depth of burial to a limiting depth. These relations can be used to model other situations with different <span class="hlt">flow</span> <span class="hlt">regimes</span> where vertical aggradation and incision are dominant processes, to predict the residence time of possible contaminated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25019884','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25019884"><span>Production of microbubbles from axisymmetric <span class="hlt">flow</span> focusing in the jetting <span class="hlt">regime</span> for moderate Reynolds numbers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vega, E J; Acero, A J; Montanero, J M; Herrada, M A; Gañán-Calvo, A M</p> <p>2014-06-01</p> <p>We analyze both experimentally and numerically the formation of microbubbles in the jetting <span class="hlt">regime</span> reached when a moderately viscous liquid stream focuses a gaseous meniscus inside a converging micronozzle. If the total (stagnation) pressure of the injected gas current is fixed upstream, then there are certain conditions on which a quasisteady gas meniscus forms. The meniscus tip is sharpened by the liquid stream down to the gas molecular scale. On the other side, monodisperse collections of microbubbles can be steadily produced in the jetting <span class="hlt">regime</span> if the feeding capillary is appropriately located inside the nozzle. In this case, the microbubble size depends on the feeding capillary position. The numerical simulations for an imposed gas <span class="hlt">flow</span> rate show that a recirculation cell appears in the gaseous meniscus for low enough values of that parameter. The experiments allow one to conclude that the bubble pinch-off comprises two phases: (i) a stretching motion of the precursor jet where the neck radius versus the time before the pinch essentially follows a potential law, and (ii) a final stage where a very thin and slender gaseous thread forms and eventually breaks apart into a number of micron-sized bubbles. Because of the difference between the free surface and core velocities, the gaseous jet breakage differs substantially from that of liquid capillary jets and gives rise to bubbles with diameters much larger than those expected from the Rayleigh-type capillary instability. The dependency of the bubble diameter upon the <span class="hlt">flow</span>-rate ratio agrees with the scaling law derived by A. M. Gañán-Calvo [Phys. Rev. E 69, 027301 (2004)], although a slight influence of the Reynolds number can be observed in our experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950044396&hterms=Shifting+identities&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DShifting%2Bidentities','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950044396&hterms=Shifting+identities&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DShifting%2Bidentities"><span>Interactions between gravity waves and cold <span class="hlt">air</span> outflows in a stably stratified uniform <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, Yuh-Lang; Wang, Ting-An; Weglarz, Ronald P.</p> <p>1993-01-01</p> <p>Interactions between gravity waves and cold <span class="hlt">air</span> outflows in a stably stratified uniform <span class="hlt">flow</span> forced by various combinations of prescribed heat sinks and sources are studied using a hydrostatic two-dimensional nonlinear numerical model. The formation time for the development of a stagnation point or reversed <span class="hlt">flow</span> at the surface is not always directly proportional to the Froude number when wave reflections exist from upper levels. A density current is able to form by the wave-otuflow interaction, even though the Froude number is greater than a critical value. This is the result of the wave-outflow interaction shifting the <span class="hlt">flow</span> response to a different location in the characteristic parameter space. A density current is able to form or be destroyed due to the wave-outflow interaction between a traveling gravity wave and cold <span class="hlt">air</span> outflow. This is proved by performing experiments with a steady-state heat sink and an additional transient heat source. In a quiescent fluid, a region of cold <span class="hlt">air</span>, convergence, and upward motion is formed after the collision between two outflows produced by two prescribed heat sinks. After the collision, the individual cold <span class="hlt">air</span> outflows lose their own identity and merge into a single, stationary, cold <span class="hlt">air</span> outflow region. Gravity waves tend to suppress this new stationary cold <span class="hlt">air</span> outflow after the collision. The region of upward motion associated with the collision is confined to a very shallow layer. In a moving airstream, a density current produced by a heat sink may be suppressed or enhanced nonlinearly by an adjacent heat sink due to the wave-outflow interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDM18004V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDM18004V"><span>Toward the Experimental Characterization of an Unmanned <span class="hlt">Air</span> System <span class="hlt">Flow</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Velarde, John-Michael; Connors, Jacob; Glauser, Mark</p> <p>2017-11-01</p> <p>The velocity <span class="hlt">flow</span> field around a small unmanned <span class="hlt">air</span> system (sUAS) is investigated in a series of experiments at Syracuse University. Experiments are conducted in the 2'x2' sub-sonic wind tunnel at Syracuse University and the Indoor <span class="hlt">Flow</span> Lab. The goal of these experiments is to gain a better understanding of the rich, turbulent <span class="hlt">flow</span> field that a sUAS creates. Comparison to large, multi-rotor manned vehicles is done to gain a better understanding of the <span class="hlt">flow</span> physics that could be occurring with the sUAS. Regions of investigation include the downwash, above the vehicle, and far downstream. Characterization of the <span class="hlt">flow</span> is performed using hotwire anemometry. Investigation of several locations around the sUAS show that dominant frequencies exist within the <span class="hlt">flow</span> field. Analysis of the <span class="hlt">flow</span> field using power spectral density will be presented as well as looking at which parameters have an effect on these dominant frequencies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JAP...112l4905T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JAP...112l4905T"><span>Dependence of charge transfer phenomena during solid-<span class="hlt">air</span> two-phase <span class="hlt">flow</span> on particle disperser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tanoue, Ken-ichiro; Suedomi, Yuuki; Honda, Hirotaka; Furutani, Satoshi; Nishimura, Tatsuo; Masuda, Hiroaki</p> <p>2012-12-01</p> <p>An experimental investigation of the tribo-electrification of particles has been conducted during solid-<span class="hlt">air</span> two-phase turbulent <span class="hlt">flow</span>. The current induced in a metal plate by the impact of polymethylmethacrylate (PMMA) particles in a high-speed <span class="hlt">air</span> <span class="hlt">flow</span> was measured for two different plate materials. The results indicated that the contact potential difference between the particles and a stainless steel plate was positive, while for a nickel plate it was negative. These results agreed with theoretical contact charge transfer even if not only the particle size but also the kind of metal plate was changed. The specific charge of the PMMA particles during solid-<span class="hlt">air</span> two-phase <span class="hlt">flow</span> using an ejector, a stainless steel branch pipe, and a stainless steel straight pipe was measured using a Faraday cage. Although the charge was negative in the ejector, the particles had a positive specific charge at the outlet of the branch pipe, and this positive charge increased in the straight pipe. The charge decay along the <span class="hlt">flow</span> direction could be reproduced by the charging and relaxation theory. However, the proportional coefficients in the theory changed with the particle size and <span class="hlt">air</span> velocity. Therefore, an unexpected charge transfer occurred between the ejector and the branch pipe, which could not be explained solely by the contact potential difference. In the ejector, an electrical current in <span class="hlt">air</span> might have been produced by self-discharge of particles with excess charge between the nickel diffuser in the ejector and the stainless steel nozzle or the stainless steel pipe due to a reversal in the contact potential difference between the PMMA and the stainless steel. The sign of the current depended on the particle size, possibly because the position where the particles impacted depended on their size. When dual coaxial glass pipes were used as a particle disperser, the specific charge of the PMMA particles became more positive along the particle <span class="hlt">flow</span> direction due to the contact</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860057973&hterms=Rotary+air+engine&qs=N%3D0%26Ntk%3DTitle%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRotary%2Bair%2Bengine','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860057973&hterms=Rotary+air+engine&qs=N%3D0%26Ntk%3DTitle%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRotary%2Bair%2Bengine"><span>Fluid <span class="hlt">flow</span> and fuel-<span class="hlt">air</span> mixing in a motored two-dimensional Wankel rotary engine</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shih, T. I.-P.; Nguyen, H. L.; Stegeman, J.</p> <p>1986-01-01</p> <p>The implicit-factored method of Beam and Warming was employed to obtain numerical solutions to the conservation equations of mass, species, momentum, and energy to study the unsteady, multidimensional <span class="hlt">flow</span> and mixing of fuel and <span class="hlt">air</span> inside the combustion chambers of a two-dimensional Wankel rotary engine under motored conditions. The effects of the following engine design and operating parameters on fluid <span class="hlt">flow</span> and fuel-<span class="hlt">air</span> mixing during the intake and compression cycles were studied: engine speed, angle of gaseous fuel injection during compression cycle, and speed of the fuel leaving fuel injector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1986jpha.confS....S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1986jpha.confS....S"><span>Fluid <span class="hlt">flow</span> and fuel-<span class="hlt">air</span> mixing in a motored two-dimensional Wankel rotary engine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shih, T. I.-P.; Nguyen, H. L.; Stegeman, J.</p> <p>1986-06-01</p> <p>The implicit-factored method of Beam and Warming was employed to obtain numerical solutions to the conservation equations of mass, species, momentum, and energy to study the unsteady, multidimensional <span class="hlt">flow</span> and mixing of fuel and <span class="hlt">air</span> inside the combustion chambers of a two-dimensional Wankel rotary engine under motored conditions. The effects of the following engine design and operating parameters on fluid <span class="hlt">flow</span> and fuel-<span class="hlt">air</span> mixing during the intake and compression cycles were studied: engine speed, angle of gaseous fuel injection during compression cycle, and speed of the fuel leaving fuel injector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/sir/2016/5041/sir20165041.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/sir/2016/5041/sir20165041.pdf"><span>A method for characterizing late-season low-<span class="hlt">flow</span> <span class="hlt">regime</span> in the upper Grand Ronde River Basin, Oregon</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Kelly, Valerie J.; White, Seth</p> <p>2016-04-19</p> <p>This report describes a method for estimating ecologically relevant low-<span class="hlt">flow</span> metrics that quantify late‑season streamflow <span class="hlt">regime</span> for ungaged sites in the upper Grande Ronde River Basin, Oregon. The analysis presented here focuses on sites sampled by the Columbia River Inter‑Tribal Fish Commission as part of their efforts to monitor habitat restoration to benefit spring Chinook salmon recovery in the basin. Streamflow data were provided by the U.S. Geological Survey and the Oregon Water Resources Department. Specific guidance was provided for selection of streamgages, development of probabilistic frequency distributions for annual 7-day low-<span class="hlt">flow</span> events, and regionalization of the frequency curves based on multivariate analysis of watershed characteristics. Evaluation of the uncertainty associated with the various components of this protocol indicates that the results are reliable for the intended purpose of hydrologic classification to support ecological analysis of factors contributing to juvenile salmon success. They should not be considered suitable for more standard water-resource evaluations that require greater precision, especially those focused on management and forecasting of extreme low-<span class="hlt">flow</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1170705','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1170705"><span>Define and Quantify the Physics of <span class="hlt">Air</span> <span class="hlt">Flow</span>, Pressure Drop and Aerosol Collection in Nuclear Grade HEPA Filters</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Moore, Murray E.</p> <p></p> <p>Objective: Develop a set of peer-review and verified analytical methods to adjust HEPA filter performance to different <span class="hlt">flow</span> rates, temperatures and altitudes. Experimental testing will measure HEPA filter <span class="hlt">flow</span> rate, pressure drop and efficiency to verify the analytical approach. Nuclear facilities utilize HEPA (High Efficiency Particulate <span class="hlt">Air</span>) filters to purify <span class="hlt">air</span> <span class="hlt">flow</span> for workspace ventilation. However, the ASME AG-1 technical standard (Code on Nuclear <span class="hlt">Air</span> and Gas Treatment) does not adequately describe <span class="hlt">air</span> <span class="hlt">flow</span> measurement units for HEPA filter systems. Specifically, the AG-1 standard does not differentiate between volumetric <span class="hlt">air</span> <span class="hlt">flow</span> in ACFM (actual cubic feet per minute)compared to massmore » <span class="hlt">flow</span> measured in SCFM (standard cubic feet per minute). More importantly, the AG-1 standard has an overall deficiency for using HEPA filter devices at different <span class="hlt">air</span> <span class="hlt">flow</span> rates, temperatures, and altitudes. Technical Approach: The collection efficiency and pressure drops of 18 different HEPA filters will be measured over a range of <span class="hlt">flow</span> rates, temperatures and altitudes. The experimental results will be compared to analytical scoping calculations. Three manufacturers have allocated six HEPA filters each for this effort. The 18 filters will be tested at two different <span class="hlt">flow</span> rates, two different temperatures and two different altitudes. The 36 total tests will be conducted at two different facilities: the ATI Test facilities (Baltimore MD) and the Los Alamos National Laboratory (Los Alamos NM). The Radiation Protection RP-SVS group at Los Alamos has an aerosol wind tunnel that was originally designed to evaluate small <span class="hlt">air</span> samplers. In 2010, modifications were started to convert the wind tunnel for HEPA filter testing. (Extensive changes were necessary for the required aerosol generators, HEPA test fixtures, temperature control devices and measurement capabilities.) To this date, none of these modification activities have been funded through a specific DOE or NNSA program</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/of/2012/1114/pdf/ofr2012-1114_report_508.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/of/2012/1114/pdf/ofr2012-1114_report_508.pdf"><span>Biological assessment of environmental <span class="hlt">flows</span> for Oklahoma</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Fisher, William L.; Seilheimer, Titus S.; Taylor, Jason M.</p> <p>2012-01-01</p> <p>Large-scale patterns in fish assemblage structure and functional groups are influenced by alterations in streamflow <span class="hlt">regime</span>. In this study, we defined an objective threshold for alteration for Oklahoma streams using a combination of the expected range of 27 <span class="hlt">flow</span> indices and a discriminant analysis to predict <span class="hlt">flow</span> <span class="hlt">regime</span> group. We found that fish functional groups in reference <span class="hlt">flow</span> conditions had species that were more intolerant to <span class="hlt">flow</span> alterations and preferences for stream habitat and faster <span class="hlt">flowing</span> water. In contrast, altered sites had more tolerant species that preferred lentic habitat and slower water velocity. Ordination graphs of the presence and functional groups of species revealed an underlying geographical pattern roughly conforming to ecoregions, although there was separation between reference and altered sites within the larger geographical framework. Additionally, we found that reservoir construction and operation significantly altered fish assemblages in two different systems, Bird Creek in central Oklahoma and the Kiamichi River in southeastern Oklahoma. The Bird Creek <span class="hlt">flow</span> <span class="hlt">regime</span> shifted from a historically intermittent stream to one with stable perennial <span class="hlt">flows</span>, and changes in fish assemblage structure covaried with changes in all five components of the <span class="hlt">flow</span> <span class="hlt">regime</span>. In contrast, the Kiamichi River <span class="hlt">flow</span> <span class="hlt">regime</span> did not change significantly for most <span class="hlt">flow</span> components despite shifts in fish assemblage structure; however, most of the species associated with shifts in assemblage structure in the Kiamichi River system were characteristic of lentic environments and were likely related more to proximity of reservoirs in the drainage system than changes in <span class="hlt">flow</span>. The spatial patterns in fish assemblage response to <span class="hlt">flow</span> alteration, combined with different temporal responses of hydrology and fish assemblage structure at sites downstream of reservoirs, indicate that interactions between <span class="hlt">flow</span> <span class="hlt">regime</span> and aquatic biota vary depending on ecological setting. This</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhFl...22l3101J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhFl...22l3101J"><span>Mixing of passive tracers in the decay Batchelor <span class="hlt">regime</span> of a channel <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jun, Yonggun; Steinberg, Victor</p> <p>2010-12-01</p> <p>We report detailed quantitative studies of passive scalar mixing in a curvilinear channel <span class="hlt">flow</span>, where elastic turbulence in a dilute polymer solution of high molecular weight polyacrylamide in a high viscosity water-sugar solvent was achieved. For quantitative investigation of mixing, a detailed study of the profiles of mean longitudinal and radial components of the velocity in the channel as a function of Wi was carried out. Besides, a maximum of the average value as well as a rms of the longitudinal velocity was used to determine the threshold of the elastic instability in the channel <span class="hlt">flow</span>. The rms of the radial derivatives of the longitudinal and radial velocity components was utilized to define the control parameters of the problem, the Weissenberg Wiloc and the Péclet Pe numbers. The main result of these studies is the quantitative test of the theoretical prediction about the value of the mixing length in the decay Batchelor <span class="hlt">regime</span>. The experiment shows large quantitative discrepancy, more than 200 times in the value of the coefficient C, which appears in the theoretical expression for the mixing length, but with the predicted scaling relation. There are two possible reasons to this discrepancy. First is the assumption made in the theory about the δ-correlated velocity field, which is in odds with the experimental observations. Second, and probably a more relevant suggestion for the significantly increased mixing length and thus reduced mixing efficiency, is the observed jets, the rare, localized, and vigorous ejection of the scalar trapped near the wall, which protrudes into the peripheral region as well as the bulk. They are first found in the recent numerical calculations and then observed in the experiment reported. The jets definitely strongly reduce the mixing efficiency in particular in the peripheral region and so can lead to considerable increase of the mixing length. We hope that this result will initiate further numerical calculations of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3821326','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3821326"><span>Practical Strategies for Stable Operation of HFF-QCM in Continuous <span class="hlt">Air</span> <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wessels, Alexander; Klöckner, Bernhard; Siering, Carsten; Waldvogel, Siegfried R.</p> <p>2013-01-01</p> <p>Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to-noise ratio. It was possible to reduce the noise in frequency in a continuous <span class="hlt">air</span> <span class="hlt">flow</span> of 7.5 m/s to 0.4 Hz [i.e., σ(τ) = 2 × 10−9] by elucidating the major source of noise. The <span class="hlt">air</span> <span class="hlt">flow</span> in the vicinity of the quartz was analyzed to reduce turbulences. Furthermore, we found a dependency between the acceleration sensitivity and mechanical stress induced by an internal thermal gradient. By reducing this gradient, we achieved reduction of the sensitivity to acceleration by more than one decade. Hence, the resulting sensor is more robust to environmental conditions such as temperature, acceleration and <span class="hlt">air</span> <span class="hlt">flow</span>. PMID:24021970</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24021970','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24021970"><span>Practical strategies for stable operation of HFF-QCM in continuous <span class="hlt">air</span> <span class="hlt">flow</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wessels, Alexander; Klöckner, Bernhard; Siering, Carsten; Waldvogel, Siegfried R</p> <p>2013-09-09</p> <p>Currently there are a few fields of application using quartz crystal microbalances (QCM). Because of environmental conditions and insufficient resolution of the microbalance, chemical sensing of volatile organic compounds in an open system was as yet not possible. In this study we present strategies on how to use 195 MHz fundamental quartz resonators for a mobile sensor platform to detect airborne analytes. Commonly the use of devices with a resonant frequency of about 10 MHz is standard. By increasing the frequency to 195 MHz the frequency shift increases by a factor of almost 400. Unfortunately, such kinds of quartz crystals tend to exhibit some challenges to obtain a reasonable signal-to-noise ratio. It was possible to reduce the noise in frequency in a continuous <span class="hlt">air</span> <span class="hlt">flow</span> of 7.5 m/s to 0.4 Hz [i.e., σ(τ) = 2 × 10-9] by elucidating the major source of noise. The <span class="hlt">air</span> <span class="hlt">flow</span> in the vicinity of the quartz was analyzed to reduce turbulences. Furthermore, we found a dependency between the acceleration sensitivity and mechanical stress induced by an internal thermal gradient. By reducing this gradient, we achieved reduction of the sensitivity to acceleration by more than one decade. Hence, the resulting sensor is more robust to environmental conditions such as temperature, acceleration and <span class="hlt">air</span> <span class="hlt">flow</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28402293','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28402293"><span>Influence of relative <span class="hlt">air</span>/water <span class="hlt">flow</span> velocity on oxygen mass transfer in gravity sewers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carrera, Lucie; Springer, Fanny; Lipeme-Kouyi, Gislain; Buffiere, Pierre</p> <p>2017-04-01</p> <p>Problems related to hydrogen sulfide may be serious for both network stakeholders and the public in terms of health, sustainability of the sewer structure and urban comfort. H 2 S emission models are generally theoretical and simplified in terms of environmental conditions. Although <span class="hlt">air</span> transport characteristics in sewers must play a role in the fate of hydrogen sulfide, only a limited number of studies have investigated this issue. The aim of this study was to better understand H 2 S liquid to gas transfer by highlighting the link between the mass transfer coefficient and the turbulence in the <span class="hlt">air</span> <span class="hlt">flow</span> and the water <span class="hlt">flow</span>. For experimental safety reasons, O 2 was taken as a model compound. The oxygen mass transfer coefficients were obtained using a mass balance in plug <span class="hlt">flow</span>. The mass transfer coefficient was not impacted by the range of the interface <span class="hlt">air-flow</span> velocity values tested (0.55-2.28 m·s -1 ) or the water velocity values (0.06-0.55 m·s -1 ). Using the ratio between k L,O 2 to k L,H 2 S , the H 2 S mass transfer behavior in a gravity pipe in the same hydraulic conditions can be predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017IJCFD..31..435W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017IJCFD..31..435W"><span>Numerical simulation for the <span class="hlt">air</span> entrainment of aerated <span class="hlt">flow</span> with an improved multiphase SPH model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wan, Hang; Li, Ran; Pu, Xunchi; Zhang, Hongwei; Feng, Jingjie</p> <p>2017-11-01</p> <p>Aerated <span class="hlt">flow</span> is a complex hydraulic phenomenon that exists widely in the field of environmental hydraulics. It is generally characterised by large deformation and violent fragmentation of the free surface. Compared to Euler methods (volume of fluid (VOF) method or rigid-lid hypothesis method), the existing single-phase Smooth Particle Hydrodynamics (SPH) method has performed well for solving particle motion. A lack of research on interphase interaction and <span class="hlt">air</span> concentration, however, has affected the application of SPH model. In our study, an improved multiphase SPH model is presented to simulate aeration <span class="hlt">flows</span>. A drag force was included in the momentum equation to ensure accuracy of the <span class="hlt">air</span> particle slip velocity. Furthermore, a calculation method for <span class="hlt">air</span> concentration is developed to analyse the <span class="hlt">air</span> entrainment characteristics. Two studies were used to simulate the hydraulic and <span class="hlt">air</span> entrainment characteristics. And, compared with the experimental results, the simulation results agree with the experimental results well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23571516','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23571516"><span>Relationship between spontaneous expiratory <span class="hlt">flow</span>-volume curve pattern and <span class="hlt">air-flow</span> obstruction in elderly COPD patients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nozoe, Masafumi; Mase, Kyoshi; Murakami, Shigefumi; Okada, Makoto; Ogino, Tomoyuki; Matsushita, Kazuhiro; Takashima, Sachie; Yamamoto, Noriyasu; Fukuda, Yoshihiro; Domen, Kazuhisa</p> <p>2013-10-01</p> <p>Assessment of the degree of <span class="hlt">air-flow</span> obstruction is important for determining the treatment strategy in COPD patients. However, in some elderly COPD patients, measuring FVC is impossible because of cognitive dysfunction or severe dyspnea. In such patients a simple test of airways obstruction requiring only a short run of tidal breathing would be useful. We studied whether the spontaneous expiratory <span class="hlt">flow</span>-volume (SEFV) curve pattern reflects the degree of <span class="hlt">air-flow</span> obstruction in elderly COPD patients. In 34 elderly subjects (mean ± SD age 80 ± 7 y) with stable COPD (percent-of-predicted FEV(1) 39.0 ± 18.5%), and 12 age-matched healthy subjects, we measured FVC and recorded <span class="hlt">flow</span>-volume curves during quiet breathing. We studied the SEFV curve patterns (concavity/convexity), spirometry results, breathing patterns, and demographics. The SEFV curve concavity/convexity prediction accuracy was examined by calculating the receiver operating characteristic curves, cutoff values, area under the curve, sensitivity, and specificity. Fourteen subjects with COPD had a concave SEFV curve. All the healthy subjects had convex SEFV curves. The COPD subjects who had concave SEFV curves often had very severe airway obstruction. The percent-of-predicted FEV(1)% (32.4%) was the most powerful SEFV curve concavity predictor (area under the curve 0.92, 95% CI 0.83-1.00), and had the highest sensitivity (0.93) and specificity (0.88). Concavity of the SEFV curve obtained during tidal breathing may be a useful test for determining the presence of very severe obstruction in elderly patients unable to perform a satisfactory FVC maneuver.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920071659&hterms=mixture+experimental+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmixture%2Bexperimental%2Bdesign','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920071659&hterms=mixture+experimental+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmixture%2Bexperimental%2Bdesign"><span>Definition of two-phase <span class="hlt">flow</span> behaviors for spacecraft design</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reinarts, Thomas R.; Best, Frederick R.; Miller, Katherine M.; Hill, Wayne S.</p> <p>1991-01-01</p> <p>Data for complete models of two-phase <span class="hlt">flow</span> in microgravity are taken from in-flight experiments and applied to an adiabatic <span class="hlt">flow-regime</span> analysis to study the feasibility of two-phase systems for spacecraft. The data are taken from five in-flight experiments by Hill et al. (1990) in which a two-phase pump circulates a freon mixture and vapor and liquid <span class="hlt">flow</span> streams are measured. Adiabatic <span class="hlt">flow</span> <span class="hlt">regimes</span> are analyzed based on the experimental superficial velocities of liquid and vapor, and comparisons are made with the results of two-phase <span class="hlt">flow</span> <span class="hlt">regimes</span> at 1 g. A motion analyzer records the <span class="hlt">flow</span> characteristics at a rate of 1000 frames/sec, and stratified <span class="hlt">flow</span> <span class="hlt">regimes</span> are reported at 1 g. The <span class="hlt">flow</span> <span class="hlt">regimes</span> observed under microgravitational conditions are primarily annular and include slug and bubbly-slug <span class="hlt">regimes</span>. The present data are of interest to the design and analysis of two-phase thermal-management systems for use in space missions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3522942','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3522942"><span>Novel <span class="hlt">Air</span> <span class="hlt">Flow</span> Meter for an Automobile Engine Using a Si Sensor with Porous Si Thermal Isolation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Hourdakis, Emmanouel; Sarafis, Panagiotis; Nassiopoulou, Androula G.</p> <p>2012-01-01</p> <p>An <span class="hlt">air</span> <span class="hlt">flow</span> meter for measuring the intake <span class="hlt">air</span> of an automobile engine is presented. It is based on a miniaturized silicon thermal mass <span class="hlt">flow</span> sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the sensor active elements are integrated. The sensor is mounted on one side of a printed circuit board (PCB), on the other side of which the readout and control electronics of the meter are mounted. The PCB is fixed on a housing containing a semi-cylindrical <span class="hlt">flow</span> tube, in the middle of which the sensor is situated. An important advantage of the present <span class="hlt">air</span> <span class="hlt">flow</span> meter is that it detects with equal sensitivity both forward and reverse <span class="hlt">flows</span>. Two prototypes were fabricated, a laboratory prototype for <span class="hlt">flow</span> calibration using mass <span class="hlt">flow</span> controllers and a final demonstrator with the housing mounted in an automobile engine inlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube of a truck. It shows an almost linear response in a large <span class="hlt">flow</span> range between –6,500 kg/h and +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered in an automobile engine. PMID:23202189</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23202189','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23202189"><span>Novel <span class="hlt">air</span> <span class="hlt">flow</span> meter for an automobile engine using a Si sensor with porous Si thermal isolation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hourdakis, Emmanouel; Sarafis, Panagiotis; Nassiopoulou, Androula G</p> <p>2012-11-02</p> <p>An <span class="hlt">air</span> <span class="hlt">flow</span> meter for measuring the intake <span class="hlt">air</span> of an automobile engine is presented. It is based on a miniaturized silicon thermal mass <span class="hlt">flow</span> sensor using a thick porous Si (Po-Si) layer for local thermal isolation from the Si substrate, on which the sensor active elements are integrated. The sensor is mounted on one side of a printed circuit board (PCB), on the other side of which the readout and control electronics of the meter are mounted. The PCB is fixed on a housing containing a semi-cylindrical <span class="hlt">flow</span> tube, in the middle of which the sensor is situated. An important advantage of the present <span class="hlt">air</span> <span class="hlt">flow</span> meter is that it detects with equal sensitivity both forward and reverse <span class="hlt">flows</span>. Two prototypes were fabricated, a laboratory prototype for <span class="hlt">flow</span> calibration using mass <span class="hlt">flow</span> controllers and a final demonstrator with the housing mounted in an automobile engine inlet tube. The final demonstrator was tested in real life conditions in the engine inlet tube of a truck. It shows an almost linear response in a large <span class="hlt">flow</span> range between –6,500 kg/h and +6,500 kg/h, which is an order of magnitude larger than the ones usually encountered in an automobile engine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..DFD.GA002C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..DFD.GA002C"><span><span class="hlt">Air</span> Layer Drag Reduction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ceccio, Steven; Elbing, Brian; Winkel, Eric; Dowling, David; Perlin, Marc</p> <p>2008-11-01</p> <p>A set of experiments have been conducted at the US Navy's Large Cavitation Channel to investigate skin-friction drag reduction with the injection of <span class="hlt">air</span> into a high Reynolds number turbulent boundary layer. Testing was performed on a 12.9 m long flat-plate test model with the surface hydraulically smooth and fully rough at downstream-distance-based Reynolds numbers to 220 million and at speeds to 20 m/s. Local skin-friction, near-wall bulk void fraction, and near-wall bubble imaging were monitored along the length of the model. The instrument suite was used to access the requirements necessary to achieve <span class="hlt">air</span> layer drag reduction (ALDR). Injection of <span class="hlt">air</span> over a wide range of <span class="hlt">air</span> fluxes showed that three drag reduction <span class="hlt">regimes</span> exist when injecting <span class="hlt">air</span>; (1) bubble drag reduction that has poor downstream persistence, (2) a transitional <span class="hlt">regime</span> with a steep rise in drag reduction, and (3) ALDR <span class="hlt">regime</span> where the drag reduction plateaus at 90% ± 10% over the entire model length with large void fractions in the near-wall region. These investigations revealed several requirements for ALDR including; sufficient volumetric <span class="hlt">air</span> fluxes that increase approximately with the square of the free-stream speed, slightly higher <span class="hlt">air</span> fluxes are needed when the surface tension is reduced, higher <span class="hlt">air</span> fluxes are required for rough surfaces, and the formation of ALDR is sensitive to the inlet condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018E%26ES..121d2025G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018E%26ES..121d2025G"><span>Numerical study of the thermo-<span class="hlt">flow</span> performances of novel finned tubes for <span class="hlt">air</span>-cooled condensers in power plant</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Yonghong; Du, Xiaoze; Yang, Lijun</p> <p>2018-02-01</p> <p><span class="hlt">Air</span>-cooled condenser is the main equipment of the direct dry cooling system in a power plant, which rejects heat of the exhaust steam with the finned tube bundles. Therefore, the thermo-<span class="hlt">flow</span> performances of the finned tubes have an important effect on the optimal operation of the direct dry cooling system. In this paper, the <span class="hlt">flow</span> and heat transfer characteristics of the single row finned tubes with the conventional flat fins and novel jagged fins are investigated by numerical method. The <span class="hlt">flow</span> and temperature fields of cooling <span class="hlt">air</span> for the finned tubes are obtained. Moreover, the variations of the <span class="hlt">flow</span> resistance and average convection heat transfer coefficient under different frontal velocity of <span class="hlt">air</span> and jag number are presented. Finally, the correlating equations of the friction factor and Nusselt number versus the Reynolds number are fitted. The results show that with increasing the frontal velocity of <span class="hlt">air</span>, the heat transfer performances of the finned tubes are enhanced but the pressure drop will increase accordingly, resulting in the average convection heat transfer coefficient and friction factor increasing. Meanwhile, with increasing the number of fin jag, the heat transfer performance is intensified. The present studies provide a reference in optimal designing for the <span class="hlt">air</span>-cooled condenser of direct <span class="hlt">air</span> cooling system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010ExFl...48...17B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010ExFl...48...17B"><span>Performance of a combined three-hole conductivity probe for void fraction and velocity measurement in <span class="hlt">air</span>-water <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Borges, João Eduardo; Pereira, Nuno H. C.; Matos, Jorge; Frizell, Kathleen H.</p> <p>2010-01-01</p> <p>The development of a three-hole pressure probe with back-flushing combined with a conductivity probe, used for measuring simultaneously the magnitude and direction of the velocity vector in complex <span class="hlt">air</span>-water <span class="hlt">flows</span>, is described in this paper. The <span class="hlt">air</span>-water <span class="hlt">flows</span> envisaged in the current work are typically those occurring around the rotors of impulse hydraulic turbines (like the Pelton and Cross-<span class="hlt">Flow</span> turbines), where the <span class="hlt">flow</span> direction is not known prior to the data acquisition. The calibration of both the conductivity and three-hole pressure components of the combined probe in a rig built for the purpose, where the probe was placed in a position similar to that adopted for the <span class="hlt">flow</span> measurements, will be reported. After concluding the calibration procedure, the probe was utilized in the outside region of a Cross-<span class="hlt">Flow</span> turbine rotor. The experimental results obtained in the present study illustrate the satisfactory performance of the combined probe, and are encouraging toward its use for characterizing the velocity field of other complex <span class="hlt">air</span>-water <span class="hlt">flows</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001IJNMF..35..643M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001IJNMF..35..643M"><span>Computation of two-dimensional <span class="hlt">flows</span> past ram-<span class="hlt">air</span> parachutes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mittal, S.; Saxena, P.; Singh, A.</p> <p>2001-03-01</p> <p>Computational results for <span class="hlt">flow</span> past a two-dimensional model of a ram-<span class="hlt">air</span> parachute with leading edge cut are presented. Both laminar (Re=104) and turbulent (Re=106) <span class="hlt">flows</span> are computed. A well-proven stabilized finite element method (FEM), which has been applied to various <span class="hlt">flow</span> problems earlier, is utilized to solve the incompressible Navier-Stokes equations in the primitive variables formulation. The Baldwin-Lomax model is employed for turbulence closure. Turbulent <span class="hlt">flow</span> computations past a Clarck-Y airfoil without a leading edge cut, for =7.5°, result in an attached <span class="hlt">flow</span>. The leading edge cut causes the <span class="hlt">flow</span> to become unsteady and leads to a significant loss in lift and an increase in drag. The <span class="hlt">flow</span> inside the parafoil cell remains almost stagnant, resulting in a high value of pressure, which is responsible for giving the parafoil its shape. The value of the lift-to-drag ratio obtained with the present computations is in good agreement with those reported in the literature. The effect of the size and location of the leading edge cut is studied. It is found that the <span class="hlt">flow</span> on the upper surface of the parafoil is fairly insensitive to the configuration of the cut. However, the <span class="hlt">flow</span> quality on the lower surface improves as the leading edge cut becomes smaller. The lift-to-drag ratio for various configurations of the leading edge cut varies between 3.4 and 5.8. It is observed that even though the time histories of the aerodynamic coefficients from the laminar and turbulent <span class="hlt">flow</span> computations are quite different, their time-averaged values are quite similar. Copyright</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EPJAP..7730803B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EPJAP..7730803B"><span>Negative DC corona discharge current characteristics in a <span class="hlt">flowing</span> two-phase (<span class="hlt">air</span> + suspended smoke particles) fluid</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berendt, Artur; Domaszka, Magdalena; Mizeraczyk, Jerzy</p> <p>2017-04-01</p> <p>The electrical characteristics of a steady-state negative DC corona discharge in a two-phase fluid (<span class="hlt">air</span> with suspended cigarette smoke particles) <span class="hlt">flowing</span> along a chamber with a needle-to-plate electrode arrangement were experimentally investigated. The two-phase <span class="hlt">flow</span> was transverse in respect to the needle-to-plate axis. The velocity of the transverse two-phase <span class="hlt">flow</span> was limited to 0.8 m/s, typical of the electrostatic precipitators. We found that three discharge current modes of the negative corona exist in the two-phase (<span class="hlt">air</span> + smoke particles) fluid: the Trichel pulses mode, the "Trichel pulses superimposed on DC component" mode and the DC component mode, similarly as in the corona discharge in <span class="hlt">air</span> (a single-phase fluid). The shape of Trichel pulses in the <span class="hlt">air</span> + suspended particles fluid is similar to that in <span class="hlt">air</span>. However, the Trichel pulse amplitudes are higher than those in "pure" <span class="hlt">air</span> while their repetition frequency is lower. As a net consequence of that the averaged corona discharge current in the two-phase fluid is lower than in "pure" <span class="hlt">air</span>. It was also found that the average discharge current decreases with increasing suspended particle concentration. The calculations showed that the dependence of the average negative corona current (which is a macroscopic corona discharge parameter) on the particle concentration can be explained by the particle-concentration dependencies of the electric charge of Trichel pulse and the repetition frequency of Trichel pulses, both giving a microscopic insight into the electrical phenomena in the negative corona discharge. Our investigations showed also that the average corona discharge current in the two-phase fluid is almost unaffected by the transverse fluid <span class="hlt">flow</span> up to a velocity of 0.8 m/s. Contribution to the topical issue "The 15th International Symposium on High Pressure Low Temperature Plasma Chemistry (HAKONE XV)", edited by Nicolas Gherardi and Tomáš Hoder</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017WRR....53.9496K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017WRR....53.9496K"><span>Effect of Unsaturated <span class="hlt">Flow</span> Modes on Partitioning Dynamics of Gravity-Driven <span class="hlt">Flow</span> at a Simple Fracture Intersection: Laboratory Study and Three-Dimensional Smoothed Particle Hydrodynamics Simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kordilla, Jannes; Noffz, Torsten; Dentz, Marco; Geyer, Tobias; Tartakovsky, Alexandre M.</p> <p>2017-11-01</p> <p>In this work, we study gravity-driven <span class="hlt">flow</span> of water in the presence of <span class="hlt">air</span> on a synthetic surface intersected by a horizontal fracture and investigate the importance of droplet and rivulet <span class="hlt">flow</span> modes on the partitioning behavior at the fracture intersection. We present laboratory experiments, three-dimensional smoothed particle hydrodynamics (SPH) simulations using a heavily parallelized code, and a theoretical analysis. The <span class="hlt">flow</span>-rate-dependent mode switching from droplets to rivulets is observed in experiments and reproduced by the SPH model, and the transition ranges agree in SPH simulations and laboratory experiments. We show that <span class="hlt">flow</span> modes heavily influence the "bypass" behavior of water <span class="hlt">flowing</span> along a fracture junction. <span class="hlt">Flows</span> favoring the formation of droplets exhibit a much stronger bypass capacity compared to rivulet <span class="hlt">flows</span>, where nearly the whole fluid mass is initially stored within the horizontal fracture. The effect of fluid buffering within the horizontal fracture is presented in terms of dimensionless fracture inflow so that characteristic scaling <span class="hlt">regimes</span> can be recovered. For both cases (rivulets and droplets), the <span class="hlt">flow</span> within the horizontal fracture transitions into a Washburn <span class="hlt">regime</span> until a critical threshold is reached and the bypass efficiency increases. For rivulet <span class="hlt">flows</span>, the initial filling of the horizontal fracture is described by classical plug <span class="hlt">flow</span>. Meanwhile, for droplet <span class="hlt">flows</span>, a size-dependent partitioning behavior is observed, and the filling of the fracture takes longer. For the case of rivulet <span class="hlt">flow</span>, we provide an analytical solution that demonstrates the existence of classical Washburn <span class="hlt">flow</span> within the horizontal fracture.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.9744S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.9744S"><span>Groundwater Recharge and <span class="hlt">Flow</span> <span class="hlt">Regime</span> revealed by multi-tracers approach in a headwater, North China Plain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sakakibara, Koichi; Tsujimura, Maki; Song, Xianfang; Zhang, Jie</p> <p>2014-05-01</p> <p>Groundwater recharge is a crucial hydrological process for effective water management especially in arid/ semi-arid regions. However, the insufficient number of specific research regarding groundwater recharge process has been reported previously. Intensive field surveys were conducted during rainy season, mid dry season, and end of dry season, in order to clarify comprehensive groundwater recharge and <span class="hlt">flow</span> <span class="hlt">regime</span> of Wangkuai watershed in a headwater, which is a main recharge zone of North China Plain. The groundwater, spring, stream water and lake water were sampled, and inorganic solute constituents and stable isotopes of oxygen 18 and deuterium were determined on all water samples. Also the stream <span class="hlt">flow</span> rate was observed. The solute ion concentrations and stable isotopic compositions show that the most water of this region can be characterized by Ca-HCO3 type and the main water source is precipitation which is affected by altitude effect of stable isotopes. In addition, the river and reservoir of the area seem to recharge the groundwater during rainy season, whereas interaction between surface water and groundwater does not become dominant gradually after the rainy season. The inversion analysis applied in Wangkuai watershed using simple mixing model represents an existing multi-<span class="hlt">flow</span> systems which shows a distinctive tracer signal and <span class="hlt">flow</span> rate. In summary, the groundwater recharged at different locations in the upper stream of Wangkuai reservoir <span class="hlt">flows</span> downward to alluvial fan with a certain amount of mixing together, also the surface water recharges certainly the groundwater in alluvial plain in the rainy season.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRB..122.5766P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRB..122.5766P"><span>Heat <span class="hlt">flow</span>, heat production, and crustal temperatures in the Archaean Bundelkhand craton, north-central India: Implications for thermal <span class="hlt">regime</span> beneath the Indian shield</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Podugu, Nagaraju; Ray, Labani; Singh, S. P.; Roy, Sukanta</p> <p>2017-07-01</p> <p>Heat <span class="hlt">flow</span> and heat production data sets constrain the crustal thermal structure in the 2.5-3.5 Ga Bundelkhand craton, the oldest cratonic core in northern Indian shield, for the first time and allow comparisons with the southern Indian shield. Temperature measurements carried out in 10 boreholes at five sites in the craton, combined with systematic thermal conductivity measurements on major rock types, yield low heat <span class="hlt">flow</span> in the range of 32-41 mW m-2, which is distinct from the generally high heat <span class="hlt">flow</span> reported from other parts of the northern Indian shield. Radioelemental measurements on 243 samples of drill cores and outcrops reveal both large variability and high average heat production for the Neo-Archaean to Palaeo-Proterozoic granites (4.0 ± 2.1 (SD) μW m-3) relative to the Meso-Archaean tonalite-trondhjemite-granodiorite (TTG) gneisses (2.0 ± 1.0 (SD) μW m-3). On the basis of new heat <span class="hlt">flow</span> and heat production data sets combined with available geological and geophysical information, a set of steady state, heat <span class="hlt">flow</span>-crustal heat production models representative of varying crustal scenarios in the craton are envisaged. Mantle heat <span class="hlt">flow</span> and Moho temperatures are found to be in the range of 12-22 mW m-2 and 290-420°C, respectively, not much different from those reported for the similar age Dharwar craton in southern India. This study reveals similar mantle thermal <span class="hlt">regimes</span> across the northern and southern parts of the Indian shield, in spite of varying surface heat <span class="hlt">flow</span> <span class="hlt">regimes</span>, implying that much of the intraprovince and interprovince variations in the Indian shield are explained by variations in upper crustal heat production.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26358048','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26358048"><span>Root-soil <span class="hlt">air</span> gap and resistance to water <span class="hlt">flow</span> at the soil-root interface of Robinia pseudoacacia.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, X P; Zhang, W J; Wang, X Y; Cai, Y J; Chang, J G</p> <p>2015-12-01</p> <p>During periods of water deficit, growing roots may shrink, retaining only partial contact with the soil. In this study, known mathematical models were used to calculate the root-soil <span class="hlt">air</span> gap and water <span class="hlt">flow</span> resistance at the soil-root interface, respectively, of Robinia pseudoacacia L. under different water conditions. Using a digital camera, the root-soil <span class="hlt">air</span> gap of R. pseudoacacia was investigated in a root growth chamber; this root-soil <span class="hlt">air</span> gap and the model-inferred water <span class="hlt">flow</span> resistance at the soil-root interface were compared with predictions based on a separate outdoor experiment. The results indicated progressively greater root shrinkage and loss of root-soil contact with decreasing soil water potential. The average widths of the root-soil <span class="hlt">air</span> gap for R. pseudoacacia in open fields and in the root growth chamber were 0.24 and 0.39 mm, respectively. The resistance to water <span class="hlt">flow</span> at the soil-root interface in both environments increased with decreasing soil water potential. Stepwise regression analysis demonstrated that soil water potential and soil temperature were the best predictors of variation in the root-soil <span class="hlt">air</span> gap. A combination of soil water potential, soil temperature, root-<span class="hlt">air</span> water potential difference and soil-root water potential difference best predicted the resistance to water <span class="hlt">flow</span> at the soil-root interface. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BoLMe.150..381W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BoLMe.150..381W"><span>Numerical Simulations of Laminar <span class="hlt">Air</span>-Water <span class="hlt">Flow</span> of a Non-linear Progressive Wave at Low Wind Speed</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wen, X.; Mobbs, S.</p> <p>2014-03-01</p> <p>A numerical simulation for two-dimensional laminar <span class="hlt">air</span>-water <span class="hlt">flow</span> of a non-linear progressive water wave with large steepness is performed when the background wind speed varies from zero to the wave phase speed. It is revealed that in the water the difference between the analytical solution of potential <span class="hlt">flow</span> and numerical solution of viscous <span class="hlt">flow</span> is very small, indicating that both solutions of the potential <span class="hlt">flow</span> and viscous <span class="hlt">flow</span> describe the water wave very accurately. In the <span class="hlt">air</span> the solutions of potential and viscous <span class="hlt">flows</span> are very different due to the effects of viscosity. The velocity distribution in the airflow is strongly influenced by the background wind speed and it is found that three wind speeds, , (the maximum orbital velocity of a water wave), and (the wave phase speed), are important in distinguishing different features of the <span class="hlt">flow</span> patterns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..12.2763T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..12.2763T"><span>Evaluating the effects of monthly river <span class="hlt">flow</span> trends on Environmental <span class="hlt">Flow</span> allocation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Torabi Haghighi, Ali; Klove, Bjorn</p> <p>2010-05-01</p> <p>The Natural river <span class="hlt">flow</span> <span class="hlt">regime</span> can be changed by the construction of hydraulic structures such as dams, hydropower plants, pump stations and so on. Due to the new river <span class="hlt">flow</span> <span class="hlt">regime</span>, some parts of water resources must be allocated to environmental <span class="hlt">flow</span> (EF). There are more than 62 hydrological methods which have been proposed for calculating EF, although these methods don't have enough acceptability to be used in practical cases and The so other methods are preferred such as holistic,….. Most hydrological methods do not take basin physiography, climate, location of hydraulic structures, monthly river <span class="hlt">flow</span> <span class="hlt">regime</span>, historical trend of river (annually <span class="hlt">regime</span>), purpose of hydraulic structures and so on, into consideration. In the present work, data from more than 180 rivers from Asia (71 rivers and 16 countries), Europe (79 Rivers and 23 countries), Americas (23 rivers and 10 countries) and Africa (12 rivers and 6 countries) were used to assess EF. The rivers were divided into 5 main groups of regular permanent rivers, semi regular permanent rivers, irregular permanent rivers, seasonal rivers and dry rivers, for each groups EF calculated by some hydrological methods and compared with the natural <span class="hlt">flow</span> <span class="hlt">regime</span>. The results showed that besides the amount of EF, the monthly distribution of <span class="hlt">flow</span> is very important and should be considered in reservoir operation. In seasonal rivers and dry rivers, hydraulic structure construction can be useful for conserving aquatic ecosystems</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NucFu..57h6047X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NucFu..57h6047X"><span>E  ×  B <span class="hlt">flow</span> shear drive of the linear low-n modes of EHO in the QH-mode <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, G. S.; Wan, B. N.; Wang, Y. F.; Wu, X. Q.; Chen, Xi; Peng, Y.-K. Martin; Guo, H. Y.; Burrell, K. H.; Garofalo, A. M.; Osborne, T. H.; Groebner, R. J.; Wang, H. Q.; Chen, R.; Yan, N.; Wang, L.; Ding, S. Y.; Shao, L. M.; Hu, G. H.; Li, Y. L.; Lan, H.; Yang, Q. Q.; Chen, L.; Ye, Y.; Xu, J. C.; Li, J.</p> <p>2017-08-01</p> <p>A new model for the edge harmonic oscillations (EHOs) in the quiescent H-mode <span class="hlt">regime</span> has been developed, which successfully reproduces the recent observations in the DIII-D tokamak. In particular, at high E  ×  B <span class="hlt">flow</span> shear only a few low-n kink modes remain unstable at the plasma edge, consistent with the EHO behavior, while at low E  ×  B <span class="hlt">flow</span> shear, the unstable mode spectrum is significantly broadened, consistent with the low-n broadband electromagnetic turbulence behavior. The model is based on a new mechanism for destabilizing low-n kink/peeling modes by the E  ×  B <span class="hlt">flow</span> shear, which underlies the EHOs, separately from the previously found Kelvin-Helmholtz drive. We find that the differential advection of mode vorticity by sheared E  ×  B <span class="hlt">flows</span> modifies the 2D pattern of mode electrostatic potential perpendicular to the magnetic field lines, which in turn causes a radial expansion of the mode structure, an increase of field line bending away from the mode rational surface, and a reduction of inertial stabilization. This enhances the kink drive as the parallel wavenumber increases significantly away from the rational surface at the plasma edge where the magnetic shear is also strong. This destabilization is also shown to be independent of the sign of the <span class="hlt">flow</span> shear, as observed experimentally, and has not been taken into account in previous pedestal linear stability analyses. Verification of the veracity of this EHO mechanism will require analysis of the nonlinear evolution of low-n kink/peeling modes so destabilized in the linear <span class="hlt">regime</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1635..182O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1635..182O"><span>Internal <span class="hlt">air</span> <span class="hlt">flow</span> analysis of a bladeless micro aerial vehicle hemisphere body using computational fluid dynamic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Othman, M. N. K.; Zuradzman, M. Razlan; Hazry, D.; Khairunizam, Wan; Shahriman, A. B.; Yaacob, S.; Ahmed, S. Faiz; Hussain, Abadalsalam T.</p> <p>2014-12-01</p> <p>This paper explain the analysis of internal <span class="hlt">air</span> <span class="hlt">flow</span> velocity of a bladeless vertical takeoff and landing (VTOL) Micro Aerial Vehicle (MAV) hemisphere body. In mechanical design, before produce a prototype model, several analyses should be done to ensure the product's effectiveness and efficiency. There are two types of analysis method can be done in mechanical design; mathematical modeling and computational fluid dynamic. In this analysis, I used computational fluid dynamic (CFD) by using SolidWorks <span class="hlt">Flow</span> Simulation software. The idea came through to overcome the problem of ordinary quadrotor UAV which has larger size due to using four rotors and the propellers are exposed to environment. The bladeless MAV body is designed to protect all electronic parts, which means it can be used in rainy condition. It also has been made to increase the thrust produced by the ducted propeller compare to exposed propeller. From the analysis result, the <span class="hlt">air</span> <span class="hlt">flow</span> velocity at the ducted area increased to twice the inlet <span class="hlt">air</span>. This means that the duct contribute to the increasing of <span class="hlt">air</span> velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22390748-internal-air-flow-analysis-bladeless-micro-aerial-vehicle-hemisphere-body-using-computational-fluid-dynamic','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22390748-internal-air-flow-analysis-bladeless-micro-aerial-vehicle-hemisphere-body-using-computational-fluid-dynamic"><span>Internal <span class="hlt">air</span> <span class="hlt">flow</span> analysis of a bladeless micro aerial vehicle hemisphere body using computational fluid dynamic</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Othman, M. N. K., E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Zuradzman, M. Razlan, E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my; Hazry, D., E-mail: najibkhir86@gmail.com, E-mail: zuradzman@unimap.edu.my, E-mail: hazry@unimap.edu.my, E-mail: khairunizam@unimap.edu.my, E-mail: shahriman@unimap.edu.my, E-mail: s.yaacob@unimap.edu.my, E-mail: syedfaiz@unimap.edu.my, E-mail: abadal@unimap.edu.my</p> <p>2014-12-04</p> <p>This paper explain the analysis of internal <span class="hlt">air</span> <span class="hlt">flow</span> velocity of a bladeless vertical takeoff and landing (VTOL) Micro Aerial Vehicle (MAV) hemisphere body. In mechanical design, before produce a prototype model, several analyses should be done to ensure the product's effectiveness and efficiency. There are two types of analysis method can be done in mechanical design; mathematical modeling and computational fluid dynamic. In this analysis, I used computational fluid dynamic (CFD) by using SolidWorks <span class="hlt">Flow</span> Simulation software. The idea came through to overcome the problem of ordinary quadrotor UAV which has larger size due to using four rotors andmore » the propellers are exposed to environment. The bladeless MAV body is designed to protect all electronic parts, which means it can be used in rainy condition. It also has been made to increase the thrust produced by the ducted propeller compare to exposed propeller. From the analysis result, the <span class="hlt">air</span> <span class="hlt">flow</span> velocity at the ducted area increased to twice the inlet <span class="hlt">air</span>. This means that the duct contribute to the increasing of <span class="hlt">air</span> velocity.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22486085','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22486085"><span>Life history theory predicts fish assemblage response to hydrologic <span class="hlt">regimes</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mims, Meryl C; Olden, Julian D</p> <p>2012-01-01</p> <p>The hydrologic <span class="hlt">regime</span> is regarded as the primary driver of freshwater ecosystems, structuring the physical habitat template, providing connectivity, framing biotic interactions, and ultimately selecting for specific life histories of aquatic organisms. In the present study, we tested ecological theory predicting directional relationships between major dimensions of the <span class="hlt">flow</span> <span class="hlt">regime</span> and life history composition of fish assemblages in perennial free-<span class="hlt">flowing</span> rivers throughout the continental United States. Using long-term discharge records and fish trait and survey data for 109 stream locations, we found that 11 out of 18 relationships (61%) tested between the three life history strategies (opportunistic, periodic, and equilibrium) and six hydrologic metrics (two each describing <span class="hlt">flow</span> variability, predictability, and seasonality) were statistically significant (P < or = 0.05) according to quantile regression. Our results largely support a priori hypotheses of relationships between specific <span class="hlt">flow</span> indices and relative prevalence of fish life history strategies, with 82% of all significant relationships observed supporting predictions from life history theory. Specifically, we found that (1) opportunistic strategists were positively related to measures of <span class="hlt">flow</span> variability and negatively related to predictability and seasonality, (2) periodic strategists were positively related to high <span class="hlt">flow</span> seasonality and negatively related to variability, and (3) the equilibrium strategists were negatively related to <span class="hlt">flow</span> variability and positively related to predictability. Our study provides important empirical evidence illustrating the value of using life history theory to understand both the patterns and processes by which fish assemblage structure is shaped by adaptation to natural <span class="hlt">regimes</span> of variability, predictability, and seasonality of critical <span class="hlt">flow</span> events over broad biogeographic scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70147793','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70147793"><span>The natural sediment <span class="hlt">regime</span> in rivers: broadening the foundation for ecosystem management</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Wohl, Ellen E.; Bledsoe, Brian P.; Jacobson, Robert B.; Poff, N. LeRoy; Rathburn, Sara L.; Walters, David M.; Wilcox, Andrew C.</p> <p>2015-01-01</p> <p>Water and sediment inputs are fundamental drivers of river ecosystems, but river management tends to emphasize <span class="hlt">flow</span> <span class="hlt">regime</span> at the expense of sediment <span class="hlt">regime</span>. In an effort to frame a more inclusive paradigm for river management, we discuss sediment inputs, transport, and storage within river systems; interactions among water, sediment, and valley context; and the need to broaden the natural <span class="hlt">flow</span> <span class="hlt">regime</span> concept. Explicitly incorporating sediment is challenging, because sediment is supplied, transported, and stored by nonlinear and episodic processes operating at different temporal and spatial scales than water and because sediment <span class="hlt">regimes</span> have been highly altered by humans. Nevertheless, managing for a desired balance between sediment supply and transport capacity is not only tractable, given current geomorphic process knowledge, but also essential because of the importance of sediment <span class="hlt">regimes</span> to aquatic and riparian ecosystems, the physical template of which depends on sediment-driven river structure and function.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28085369','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28085369"><span>Intermediate <span class="hlt">regime</span> and a phase diagram of red blood cell dynamics in a linear <span class="hlt">flow</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Levant, Michael; Steinberg, Victor</p> <p>2016-12-01</p> <p>In this paper we investigate the in vitro dynamics of a single rabbit red blood cell (RBC) in a planar linear <span class="hlt">flow</span> as a function of a shear stress σ and the dynamic viscosity of outer fluid η_{o}. A linear <span class="hlt">flow</span> is a generalization of previous studies dynamics of soft objects including RBC in shear <span class="hlt">flow</span> and is realized in the experiment in a microfluidic four-roll mill device. We verify that the RBC stable orientation dynamics is found in the experiment being the in-shear-plane orientation and the RBC dynamics is characterized by observed three RBC dynamical states, namely tumbling (TU), intermediate (INT), and swinging (SW) [or tank-treading (TT)] on a single RBC. The main results of these studies are the following. (i) We completely characterize the RBC dynamical states and reconstruct their phase diagram in the case of the RBC in-shear-plane orientation in a planar linear <span class="hlt">flow</span> and find it in a good agreement with that obtained in early experiments in a shear <span class="hlt">flow</span> for human RBCs. (ii) The value of the critical shear stress σ_{c} of the TU-TT(SW) transition surprisingly coincides with that found in early experiments in spite of a significant difference in the degree of RBC shape deformations in both the SW and INT states. (iii) We describe the INT <span class="hlt">regime</span>, which is stationary, characterized by strong RBC shape deformations and observed in a wide range of the shear stresses. We argue that our observations cast doubts on the main claim of the recent numerical simulations that the only RBC spheroidal stress-free shape is capable to explain the early experimental data. Finally, we suggest that the amplitude dependence of both θ and the shape deformation parameter D on σ can be used as the quantitative criterion to determine the RBC stress-free shape.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016E%26ES...49g2008N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016E%26ES...49g2008N"><span>Simulation of <span class="hlt">air</span> admission in a propeller hydroturbine during transient events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nicolle, J.; Morissette, J.-F.</p> <p>2016-11-01</p> <p>In this study, multiphysic simulations are carried out in order to model fluid loading and structural stresses on propeller blades during startup and runaway. It is found that <span class="hlt">air</span> admission plays an important role during these transient events and that biphasic simulations are therefore required. At the speed no load <span class="hlt">regime</span>, a large <span class="hlt">air</span> pocket with vertical free surface forms in the centre of the runner displacing the water <span class="hlt">flow</span> near the shroud. This significantly affects the torque developed on the blades and thus structural loading. The resulting pressures are applied to a quasi-static structural model and good agreement is obtained with experimental strain gauge data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70024723','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70024723"><span>Land use and <span class="hlt">flow</span> <span class="hlt">regime</span> effects on phosphorus chemical dynamics in the fluvial sediment of the Winooski River, Vermont</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>McDowell, R.W.; Sharpley, A.N.; Chalmers, A.T.</p> <p>2002-01-01</p> <p>In the last century, fourfold increase in phosphorus (P) loadings to Lake Champlain, Vermont (VT), USA, have led to nuisance levels of algal growth occurring more often. To better understand the transport, storage, and cycling of P within the lake's catchment, we examined the chemistry, bioavailability and processes controlling sediment P release to waters of the Winooski River, VT, the largest tributary to Lake Champlain. Iron-oxide strip P (algal-bioavailable P) of the river sediments adjacent to agricultural land (3.6 mg kg-1) was greater (P < 0.05) than adjacent to forested land (2.4 mg kg-1). When compared among <span class="hlt">flow</span> <span class="hlt">regimes</span>, impoundment (731 mg kg-1) and reservoir sediments (803 mg kg-1) had greater total P concentrations than river sediment (462 mg kg-1). This was attributed to more fines (< 63 ??m) in impoundments and reservoirs (64%) than in river sediments (33%), which also decreased the ability of impoundment sediments to release P to solution and thereby be a sink for P. Although land use and <span class="hlt">flow</span> <span class="hlt">regime</span> influenced whether Winooski River sediments acted as a sink or source of P to Lake Champlain, long-term remedial strategies for the catchment should continue to focus on decreasing P losses in agricultural and urban runoff. ?? 2002 Elsevier Science B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930081237','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930081237"><span>Methods of Visually Determining the <span class="hlt">Air</span> <span class="hlt">Flow</span> Around Airplanes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gough, Melvin N; Johnson, Ernest</p> <p>1932-01-01</p> <p>This report describes methods used by the National Advisory Committee for Aeronautics to study visually the <span class="hlt">air</span> <span class="hlt">flow</span> around airplanes. The use of streamers, oil and exhaust gas streaks, lampblack and kerosene, powdered materials, and kerosene smoke is briefly described. The generation and distribution of smoke from candles and from titanium tetrachloride are described in greater detail because they appear most advantageous for general application. Examples are included showing results of the various methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011BGD.....8.7071F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011BGD.....8.7071F"><span>Biogeography in the <span class="hlt">air</span>: fungal diversity over land and oceans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fröhlich-Nowoisky, J.; Burrows, S. M.; Xie, Z.; Engling, G.; Solomon, P. A.; Fraser, M. P.; Mayol-Bracero, O. L.; Artaxo, P.; Begerow, D.; Conrad, R.; Andreae, M. O.; Després, V. R.; Pöschl, U.</p> <p>2011-07-01</p> <p>Biogenic aerosols are relevant for the Earth system, climate, and public health on local, regional, and global scales. Up to now, however, little is known about the diversity and biogeography of airborne microorganisms. We present the first DNA-based analysis of airborne fungi on global scales, showing pronounced geographic patterns and boundaries. In particular we found that the ratio of species richness between Basidiomycota and Ascomycota is much higher in continental <span class="hlt">air</span> than in marine <span class="hlt">air</span>. This may be an important difference between the "blue ocean" and "green ocean" <span class="hlt">regimes</span> in the formation of clouds and precipitation, for which fungal spores can act as nuclei. Our findings also suggest that <span class="hlt">air</span> <span class="hlt">flow</span> patterns and the global atmospheric circulation are important for the evolution of microbial ecology and for the understanding of global changes in biodiversity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012BGeo....9.1125F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012BGeo....9.1125F"><span>Biogeography in the <span class="hlt">air</span>: fungal diversity over land and oceans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fröhlich-Nowoisky, J.; Burrows, S. M.; Xie, Z.; Engling, G.; Solomon, P. A.; Fraser, M. P.; Mayol-Bracero, O. L.; Artaxo, P.; Begerow, D.; Conrad, R.; Andreae, M. O.; Després, V. R.; Pöschl, U.</p> <p>2012-03-01</p> <p>Biogenic aerosols are relevant for the Earth system, climate, and public health on local, regional, and global scales. Up to now, however, little is known about the diversity and biogeography of airborne microorganisms. We present the first DNA-based analysis of airborne fungi on global scales, showing pronounced geographic patterns and boundaries. In particular we find that the ratio of species richness between Basidiomycota and Ascomycota is much higher in continental <span class="hlt">air</span> than in marine <span class="hlt">air</span>. This may be an important difference between the "blue ocean" and "green ocean" <span class="hlt">regimes</span> in the formation of clouds and precipitation, for which fungal spores can act as nuclei. Our findings also suggest that <span class="hlt">air</span> <span class="hlt">flow</span> patterns and the global atmospheric circulation are important for the understanding of global changes in biodiversity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19482337','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19482337"><span>Thermal effects on bacterial bioaerosols in continuous <span class="hlt">air</span> <span class="hlt">flow</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jung, Jae Hee; Lee, Jung Eun; Kim, Sang Soo</p> <p>2009-08-01</p> <p>Exposure to bacterial bioaerosols can have adverse effects on health, such as infectious diseases, acute toxic effects, and allergies. The search for ways of preventing and curing the harmful effects of bacterial bioaerosols has created a strong demand for the study and development of an efficient method of controlling bioaerosols. We investigated the thermal effects on bacterial bioaerosols of Escherichia coli and Bacillus subtilis by using a thermal electric heating system in continuous <span class="hlt">air</span> <span class="hlt">flow</span>. The bacterial bioaerosols were exposed to a surrounding temperature that ranged from 20 degrees C to 700 degrees C for about 0.3 s. Both E. coli and B. subtilis vegetative cells were rendered more than 99.9% inactive at 160 degrees C and 350 degrees C of wall temperature of the quartz tube, respectively. Although the data on bacterial injury showed that the bacteria tended to sustain greater damage as the surrounding temperature increased, Gram-negative E. coli was highly sensitive to structural injury but Gram-positive B. subtilis was slightly more sensitive to metabolic injury. In addition, the inactivation of E. coli endotoxins was found to range from 9.2% (at 200 degrees C) to 82.0% (at 700 degrees C). However, the particle size distribution and morphology of both bacterial bioaerosols were maintained, despite exposure to a surrounding temperature of 700 degrees C. Our results show that thermal heating in a continuous <span class="hlt">air</span> <span class="hlt">flow</span> can be used with short exposure time to control bacterial bioaerosols by rendering the bacteria and endotoxins to a large extent inactive. This result could also be useful for developing more effective thermal treatment strategies for use in <span class="hlt">air</span> purification or sterilization systems to control bioaerosols.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JThSc..26..214D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JThSc..26..214D"><span>Liquid phase evaporation on the normal shock wave in moist <span class="hlt">air</span> transonic <span class="hlt">flows</span> in nozzles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dykas, Sławomir; Szymański, Artur; Majkut, Mirosław</p> <p>2017-06-01</p> <p>This paper presents a numerical analysis of the atmospheric <span class="hlt">air</span> transonic <span class="hlt">flow</span> through de Laval nozzles. By nature, atmospheric <span class="hlt">air</span> always contains a certain amount of water vapor. The calculations were made using a Laval nozzle with a high expansion rate and a convergent-divergent (CD) "half-nozzle", referred to as a transonic diffuser, with a much slower expansion rate. The calculations were performed using an in-house CFD code. The computational model made it possible to simulate the formation of the liquid phase due to spontaneous condensation of water vapor contained in moist <span class="hlt">air</span>. The transonic <span class="hlt">flow</span> calculations also take account of the presence of a normal shock wave in the nozzle supersonic part to analyze the effect of the liquid phase evaporation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1455212','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1455212"><span>Metal-<span class="hlt">air</span> <span class="hlt">flow</span> batteries using oxygen enriched electrolyte</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Zheng, Jian-ping; Andrei, Petru; Shellikeri, Annadanesh</p> <p></p> <p>A metal <span class="hlt">air</span> <span class="hlt">flow</span> battery includes an electrochemical reaction unit and an oxygen exchange unit. The electrochemical reaction unit includes an anode electrode, a cathode electrode, and an ionic conductive membrane between the anode and the cathode, an anode electrolyte, and a cathode electrolyte. The oxygen exchange unit contacts the cathode electrolyte with oxygen separate from the electrochemical reaction unit. At least one pump is provided for pumping cathode electrolyte between the electrochemical reaction unit and the oxygen exchange unit. A method for producing an electrical current is also disclosed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989SPIE.1021..175L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989SPIE.1021..175L"><span><span class="hlt">Flowing</span> <span class="hlt">Air</span>-Water Cooled Slab Nd: Glass Laser</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, Baida; Cai, Bangwei; Liao, Y.; Xu, Shifa; Xin, Z.</p> <p>1989-03-01</p> <p>A zig-zag optical path slab geometry Nd: glass laser cooled through <span class="hlt">flowing</span> <span class="hlt">air</span>-water is developed by us. Theoretical studies on temperature distribution of slab and rod configurations in the unsteady state clarify the advantages of the slab geometry laser. The slab design and processing are also reported. In our experiments main laser output characteristics, e. g. laser efficiency, polarization, far-field divergence angle as well as resonator misalignment are investigated. The slab phosphate glass laser in combination with a crossed Porro-prism resonator demonstrates a good laser performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1373550','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1373550"><span>Metal-<span class="hlt">air</span> <span class="hlt">flow</span> batteries using oxygen enriched electrolyte</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Zheng, Jian-ping; Andrei, Petru; Shellikeri, Annadanesh; Chen, Xujie</p> <p>2017-08-01</p> <p>A metal <span class="hlt">air</span> <span class="hlt">flow</span> battery includes an electrochemical reaction unit and an oxygen exchange unit. The electrochemical reaction unit includes an anode electrode, a cathode electrode, and an ionic conductive membrane between the anode and the cathode, an anode electrolyte, and a cathode electrolyte. The oxygen exchange unit contacts the cathode electrolyte with oxygen separate from the electrochemical reaction unit. At least one pump is provided for pumping cathode electrolyte between the electrochemical reaction unit and the oxygen exchange unit. A method for producing an electrical current is also disclosed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDR16006V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDR16006V"><span>Effects of lung disease on the three-dimensional structure and <span class="hlt">air</span> <span class="hlt">flow</span> pattern in the human airway tree</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>van de Moortele, Tristan; Nemes, Andras; Wendt, Christine; Coletti, Filippo</p> <p>2016-11-01</p> <p>The morphological features of the airway tree directly affect the <span class="hlt">air</span> <span class="hlt">flow</span> features during breathing, which determines the gas exchange and inhaled particle transport. Lung disease, Chronic Obstructive Pulmonary Disease (COPD) in this study, affects the structural features of the lungs, which in turn negatively affects the <span class="hlt">air</span> <span class="hlt">flow</span> through the airways. Here bronchial tree <span class="hlt">air</span> volume geometries are segmented from Computed Tomography (CT) scans of healthy and diseased subjects. Geometrical analysis of the airway centerlines and corresponding cross-sectional areas provide insight into the specific effects of COPD on the airway structure. These geometries are also used to 3D print anatomically accurate, patient specific <span class="hlt">flow</span> models. Three-component, three-dimensional velocity fields within these models are acquired using Magnetic Resonance Imaging (MRI). The three-dimensional <span class="hlt">flow</span> fields provide insight into the change in <span class="hlt">flow</span> patterns and features. Additionally, particle trajectories are determined using the velocity fields, to identify the fate of therapeutic and harmful inhaled aerosols. Correlation between disease-specific and patient-specific anatomical features with dysfunctional airflow patterns can be achieved by combining geometrical and <span class="hlt">flow</span> analysis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040075664','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040075664"><span>Mechanical Design of a Performance Test Rig for the Turbine <span class="hlt">Air-Flow</span> Task (TAFT)</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Forbes, John C.; Xenofos, George D.; Farrow, John L.; Tyler, Tom; Williams, Robert; Sargent, Scott; Moharos, Jozsef</p> <p>2004-01-01</p> <p>To support development of the Boeing-Rocketdyne RS84 rocket engine, a full-<span class="hlt">flow</span>, reaction turbine geometry was integrated into the NASA-MSFC turbine <span class="hlt">air-flow</span> test facility. A mechanical design was generated which minimized the amount of new hardware while incorporating all test and instrumentation requirements. This paper provides details of the mechanical design for this Turbine <span class="hlt">Air-Flow</span> Task (TAFT) test rig. The mechanical design process utilized for this task included the following basic stages: Conceptual Design. Preliminary Design. Detailed Design. Baseline of Design (including Configuration Control and Drawing Revision). Fabrication. Assembly. During the design process, many lessons were learned that should benefit future test rig design projects. Of primary importance are well-defined requirements early in the design process, a thorough detailed design package, and effective communication with both the customer and the fabrication contractors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1426924-numerical-simulations-mounding-submerging-flows-shear-thinning-jets-impinging-container','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1426924-numerical-simulations-mounding-submerging-flows-shear-thinning-jets-impinging-container"><span>Numerical simulations of mounding and submerging <span class="hlt">flows</span> of shear-thinning jets impinging in a container</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Roberts, Scott A.; Rao, Rekha R.</p> <p>2011-10-01</p> <p>Continuous jets of non-Newtonian fluids impinging on a fluid surface exhibit instabilities from jet buckling and coiling at low Reynolds numbers to delayed die swell, mounding, and <span class="hlt">air</span> entrainment at higher Reynolds numbers. Filling containers with complex fluids is an important process for many industries, where the need for high throughput requires operating at high Reynolds numbers. In this <span class="hlt">regime</span>, <span class="hlt">air</span> entrainment can produce a visually unappealing product, causing a major quality control issue. Just prior to the onset of <span class="hlt">air</span> entrainment, however, there exists an ideal filling <span class="hlt">regime</span> which we term “planar filling,” as it is characterized by amore » relatively flat free surface that maintains its shape over time. In this paper, we create a steady-state, 2-D axisymmetric finite element model to study the transition from planar filling to the onset of <span class="hlt">air</span> entrainment in a container filling process with generalized-Newtonian fluids. We use this model to explore the operating window for Newtonian and shear-thinning (or, more generally, deformation-rate-thinning) fluids, demonstrating that the <span class="hlt">flow</span> behavior is characterized by a balance between inertial, viscous, and gravitational forces, as characterized by the Reynolds and Froude numbers. A scaling analysis suggests that the relevant parameters for calculating these dimensionless numbers are located where the jet impacts the liquid surface, and simulations show that the transition from planar filling to <span class="hlt">air</span> entrainment often occurs when Re ~ O(10). Our study found that the bottom and side surfaces of the container drastically influence this transition to entrainment, stabilizing the <span class="hlt">flow</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19900019500','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19900019500"><span>An investigation of chaotic Kolmogorov <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Platt, N.; Sirovich, L.; Fitzmaurice, N.</p> <p>1990-01-01</p> <p>A two dimensional <span class="hlt">flow</span> governed by the incompressible Navier-Stokes equations with a steady spatially periodic forcing (known as the Kolmogorov <span class="hlt">flow</span>) is numerically simulated. The behavior of the <span class="hlt">flow</span> and its transition states as the Reynolds number (Re) varies is investigated in detail, as well as a number of the <span class="hlt">flow</span> features. A sequence of bifurcations is shown to take place in the <span class="hlt">flow</span> as Re varied. Two main <span class="hlt">regimes</span> of the <span class="hlt">flow</span> were observed: small and large scale structure <span class="hlt">regimes</span> corresponding to different ranges of Re. Each of the <span class="hlt">regimes</span> includes a number of quasiperiodic, chaotic, and relaminarization windows. In addition, each range contains a chaotic window with non-ergodic chaotic attractors. Spatially disordered, but temporally steady states were discovered in large scale structure <span class="hlt">regime</span>. Features of the diverse cases are displayed in terms of the temporal power spectrum, Poincare sections and, where possible, Lyapunov exponents and Kaplan-Yorke dimension.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhFl...28h3303G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhFl...28h3303G"><span>An experimental study of the elastic theory for granular <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Tongtong; Campbell, Charles S.</p> <p>2016-08-01</p> <p>This paper reports annular shear cell measurements granular <span class="hlt">flows</span> with an eye towards experimentally confirming the <span class="hlt">flow</span> <span class="hlt">regimes</span> laid out in the elastic theory of granular <span class="hlt">flow</span>. Tests were carried out on four different kinds of plastic spherical particles under both constant volume <span class="hlt">flows</span> and constant applied stress <span class="hlt">flows</span>. In particular, observations were made of the new <span class="hlt">regime</span> in that model, the elastic-inertial <span class="hlt">regime</span>, and the predicted transitions between the elastic-inertial and both the elastic-quasistatic and pure inertial <span class="hlt">regimes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26950527','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26950527"><span>Installation of a <span class="hlt">flow</span> control device in an inclined <span class="hlt">air</span>-curtain fume hood to control wake-induced exposure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chen, Jia-Kun</p> <p>2016-08-01</p> <p>An inclined plate for <span class="hlt">flow</span> control was installed at the lower edge of the sash of an inclined <span class="hlt">air</span>-curtain fume hood to reduce the effects of the wake around a worker standing in front of the fume hood. <span class="hlt">Flow</span> inside the fume hood is controlled by the inclined <span class="hlt">air</span>-curtain and deflection plates, thereby forming a quad-vortex <span class="hlt">flow</span> structure. Controlling the face velocity of the fume hood resulted in convex, straight, concave, and attachment <span class="hlt">flow</span> profiles in the inclined <span class="hlt">air</span>-curtain. We used the <span class="hlt">flow</span> visualization and conducted a tracer gas test with a mannequin to determine the performance of two sash geometries, namely, the half-cylinder and inclined plate designs. When the half-cylinder design was used, the tracer gas test registered a high leakage concentration at Vf ≦ 57.1 fpm or less. This concentration occurred at the top of the sash opening, which was close to the breathing zone of the mannequin placed in front of the fume hood. When the inclined plate design was used, the containment was good, with concentrations of 0.002-0.004 ppm, at Vf ≦ 63.0 fpm. Results indicate that an inclined plate effectively reduces the leakage concentration induced by recirculation <span class="hlt">flow</span> structures that form in the wake of a worker standing in front of an inclined <span class="hlt">air</span>-curtain fume hood.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AtmRe.171..107K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AtmRe.171..107K"><span>Observational and numerical study of the Vardaris wind <span class="hlt">regime</span> in northern Greece</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Koletsis, I.; Giannaros, T. M.; Lagouvardos, K.; Kotroni, V.</p> <p>2016-05-01</p> <p>The Axios Valley, located in central-northern Greece, is surrounded by complex topography that plays a significant role in the modification of wind <span class="hlt">flow</span>, both in terms of speed and direction. The characteristic wind <span class="hlt">regime</span> of this valley is Vardaris, a northwesterly wind that prevails in this region, especially during the cold period of the year. Vardaris is well known for its consistent direction and high intensity, as well as for the effective advection of cold and dry <span class="hlt">air</span>, often resulting to significant damages in local infrastructures and agriculture. A field campaign under the name AXIOS took place during the period from November 2007 through May 2008 in order to examine this particular wind <span class="hlt">flow</span>. The analysis of the in situ observational data, which was funded by the research program THESPIA-KRIPIS, showed that topography plays a key role in intensifying Vardaris, generating gusts that approximated 30 m s- 1 during the experimental period. The <span class="hlt">air</span> temperature and humidity fields were also found to be significantly influenced. In addition to the observational study, an intense Vardaris episode was simulated with the Weather Research and Forecasting (WRF) model at high horizontal resolution. Results revealed that the model was able to reproduce the favorable environmental conditions that lead to Vardaris occurrence, providing a useful insight on the physical mechanisms explaining its structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016HMT....52.2593M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016HMT....52.2593M"><span>Experimental investigation of head resistance reduction in bubbly Couette-Taylor <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Maryami, R.; Javadpoor, M.; Farahat, S.</p> <p>2016-12-01</p> <p>Small bubble experiments are carried out in a circulating vertical Couette-Taylor <span class="hlt">flow</span> system to investigate the effect of <span class="hlt">air</span> bubbles on head resistance. In the system with inner rotating cylinder and circulating <span class="hlt">flow</span>, <span class="hlt">flow</span> is combined with circumferential and axial <span class="hlt">flow</span>. Moreover, the variation range of rotational Reynolds number is 7 × 103 ≤ {Re}_{ω } ≤ 70 × 103 and small bubbles are dispersed into fully turbulent <span class="hlt">flow</span> which consists of Taylor vortices. The modification of head resistance is examined by measuring the pressure difference between two certain holes along the cylinders axis. The results show that head resistance is decreased in the presence of small bubbles and a head resistance reduction greater than 60 % is achieved in low {Re}_{ω } s and in all {Re}_{ax} s changing from 299.15 to 396.27. The effect of <span class="hlt">air</span> bubbles on vortices could be possible reason for head resistance reduction. Since Taylor vortices are stable in this <span class="hlt">regime</span>, bubbles decrease the momentum transfer by elongating vortices along the axis of cylinders and decreasing their numbers. The positive effect of <span class="hlt">air</span> bubbles on head resistance reduction is diminished when {Re}_{ω } is increased. Moreover, in certain ranges of {Re}_{ω }, small bubbles enhance head resistance when {Re}_{ax} is increased. It is predicted that negative effect of small bubbles on head resistance reduction is due to <span class="hlt">flow</span> turbulence enhancement when {Re}_{ω } and {Re}_{ax} are increased.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005ASAJ..118Q1918L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..118Q1918L"><span><span class="hlt">Air</span> <span class="hlt">flow</span> measurement techniques applied to noise reduction of a centrifugal blower</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Laage, John W.; Armstrong, Ashli J.; Eilers, Daniel J.; Olsen, Michael G.; Mann, J. Adin</p> <p>2005-09-01</p> <p>The <span class="hlt">air</span> <span class="hlt">flow</span> in a centrifugal blower was studied using a variety of <span class="hlt">flow</span> and sound measurement techniques. The <span class="hlt">flow</span> measurement techniques employed included Particle Image Velocimetry (PIV), pitot tubes, and a five hole spherical probe. PIV was used to measure instantaneous and ensemble-averaged velocity fields over large area of the outlet duct as a function of fan position, allowing for the visualization of the <span class="hlt">flow</span> as it leave the fan blades and progressed downstream. The results from the <span class="hlt">flow</span> measurements were reviewed along side the results of the sound measurements with the goal of identifying sources of noise and inefficiencies in <span class="hlt">flow</span> performance. The radiated sound power was divided into broadband and tone noise and measures of the <span class="hlt">flow</span>. The changes in the tone and broadband sound were compared to changes in <span class="hlt">flow</span> quantities such as the turbulent kinetic energy and Reynolds stress. Results for each method will be presented to demonstrate the strengths of each <span class="hlt">flow</span> measurement technique as well as their limitations. Finally, the role that each played in identifying noise sources is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70035391','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70035391"><span>Theory, methods and tools for determining environmental <span class="hlt">flows</span> for riparian vegetation: Riparian vegetation-<span class="hlt">flow</span> response guilds</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Merritt, D.M.; Scott, M.L.; Leroy, Poff N.; Auble, G.T.; Lytle, D.A.</p> <p>2010-01-01</p> <p>Riparian vegetation composition, structure and abundance are governed to a large degree by river <span class="hlt">flow</span> <span class="hlt">regime</span> and <span class="hlt">flow</span>-mediated fluvial processes. Streamflow <span class="hlt">regime</span> exerts selective pressures on riparian vegetation, resulting in adaptations (trait syndromes) to specific <span class="hlt">flow</span> attributes. Widespread modification of <span class="hlt">flow</span> <span class="hlt">regimes</span> by humans has resulted in extensive alteration of riparian vegetation communities. Some of the negative effects of altered <span class="hlt">flow</span> <span class="hlt">regimes</span> on vegetation may be reversed by restoring components of the natural <span class="hlt">flow</span> <span class="hlt">regime</span>. 2. Models have been developed that quantitatively relate components of the <span class="hlt">flow</span> <span class="hlt">regime</span> to attributes of riparian vegetation at the individual, population and community levels. Predictive models range from simple statistical relationships, to more complex stochastic matrix population models and dynamic simulation models. Of the dozens of predictive models reviewed here, most treat one or a few species, have many simplifying assumptions such as stable channel form, and do not specify the time-scale of response. In many cases, these models are very effective in developing alternative streamflow management plans for specific river reaches or segments but are not directly transferable to other rivers or other regions. 3. A primary goal in riparian ecology is to develop general frameworks for prediction of vegetation response to changing environmental conditions. The development of riparian vegetation-<span class="hlt">flow</span> response guilds offers a framework for transferring information from rivers where <span class="hlt">flow</span> standards have been developed to maintain desirable vegetation attributes, to rivers with little or no existing information. 4. We propose to organise riparian plants into non-phylogenetic groupings of species with shared traits that are related to components of hydrologic <span class="hlt">regime</span>: life history, reproductive strategy, morphology, adaptations to fluvial disturbance and adaptations to water availability. Plants from any river or region may be grouped</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4897587','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4897587"><span>Combined Influence of Hall Current and Soret Effect on Chemically Reacting Magnetomicropolar Fluid <span class="hlt">Flow</span> from Radiative Rotating Vertical Surface with Variable Suction in Slip-<span class="hlt">Flow</span> <span class="hlt">Regime</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jain, Preeti</p> <p>2014-01-01</p> <p>An analysis study is presented to study the effects of Hall current and Soret effect on unsteady hydromagnetic natural convection of a micropolar fluid in a rotating frame of reference with slip-<span class="hlt">flow</span> <span class="hlt">regime</span>. A uniform magnetic field acts perpendicularly to the porous surface which absorbs the micropolar fluid with variable suction velocity. The effects of heat absorption, chemical reaction, and thermal radiation are discussed and for this Rosseland approximation is used to describe the radiative heat flux in energy equation. The entire system rotates with uniform angular velocity Ω about an axis normal to the plate. The nonlinear coupled partial differential equations are solved by perturbation techniques. In order to get physical insight, the numerical results of translational velocity, microrotation, fluid temperature, and species concentration for different physical parameters entering into the analysis are discussed and explained graphically. Also, the results of the skin-friction coefficient, the couple stress coefficient, Nusselt number, and Sherwood number are discussed with the help of figures for various values of <span class="hlt">flow</span> pertinent <span class="hlt">flow</span> parameters. PMID:27350957</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3233893','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3233893"><span>Effect of cold <span class="hlt">air</span> inhalation and isometric exercise on coronary blood <span class="hlt">flow</span> and myocardial function in humans</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Muller, Matthew D.; Gao, Zhaohui; Drew, Rachel C.; Herr, Michael D.; Leuenberger, Urs A.</p> <p>2011-01-01</p> <p>The effects of cold <span class="hlt">air</span> inhalation and isometric exercise on coronary blood <span class="hlt">flow</span> are currently unknown, despite the fact that both cold <span class="hlt">air</span> and acute exertion trigger angina in clinical populations. In this study, we used transthoracic Doppler echocardiography to measure coronary blood <span class="hlt">flow</span> velocity (CBV; left anterior descending coronary artery) and myocardial function during cold <span class="hlt">air</span> inhalation and handgrip exercise. Ten young healthy subjects underwent the following protocols: 5 min of inhaling cold <span class="hlt">air</span> (cold <span class="hlt">air</span> protocol), 5 min of inhaling thermoneutral <span class="hlt">air</span> (sham protocol), 2 min of isometric handgrip at 30% of maximal voluntary contraction (grip protocol), and 5 min of isometric handgrip at 30% maximal voluntary contraction while breathing cold <span class="hlt">air</span> (cold + grip protocol). Heart rate, blood pressure, inspired <span class="hlt">air</span> temperature, CBV, myocardial function (tissue Doppler imaging), O2 saturation, and pulmonary function were measured. The rate-pressure product (RPP) was used as an index of myocardial O2 demand, whereas CBV was used as an index of myocardial O2 supply. Compared with the sham protocol, the cold <span class="hlt">air</span> protocol caused a significantly higher RPP, but there was a significant reduction in CBV. The cold + grip protocol caused a significantly greater increase in RPP compared with the grip protocol (P = 0.045), but the increase in CBV was significantly less (P = 0.039). However, myocardial function was not impaired during the cold + grip protocol relative to the grip protocol alone. Collectively, these data indicate that there is a supply-demand mismatch in the coronary vascular bed when cold ambient <span class="hlt">air</span> is breathed during acute exertion but myocardial function is preserved, suggesting an adequate redistribution of blood <span class="hlt">flow</span>. PMID:21940852</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26180842','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26180842"><span>A Novel Biobjective Risk-Based Model for Stochastic <span class="hlt">Air</span> Traffic Network <span class="hlt">Flow</span> Optimization Problem.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cai, Kaiquan; Jia, Yaoguang; Zhu, Yanbo; Xiao, Mingming</p> <p>2015-01-01</p> <p>Network-wide <span class="hlt">air</span> traffic <span class="hlt">flow</span> management (ATFM) is an effective way to alleviate demand-capacity imbalances globally and thereafter reduce airspace congestion and flight delays. The conventional ATFM models assume the capacities of airports or airspace sectors are all predetermined. However, the capacity uncertainties due to the dynamics of convective weather may make the deterministic ATFM measures impractical. This paper investigates the stochastic <span class="hlt">air</span> traffic network <span class="hlt">flow</span> optimization (SATNFO) problem, which is formulated as a weighted biobjective 0-1 integer programming model. In order to evaluate the effect of capacity uncertainties on ATFM, the operational risk is modeled via probabilistic risk assessment and introduced as an extra objective in SATNFO problem. Computation experiments using real-world <span class="hlt">air</span> traffic network data associated with simulated weather data show that presented model has far less constraints compared to stochastic model with nonanticipative constraints, which means our proposed model reduces the computation complexity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......275C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......275C"><span>Constitutive model development for <span class="hlt">flows</span> of granular materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chialvo, Sebastian</p> <p></p> <p>Granular <span class="hlt">flows</span> are ubiquitous in both natural and industrial processes. When com- posed of dry, noncohesive particles, they manifest three different <span class="hlt">flow</span> <span class="hlt">regimes</span>---commonly referred to as the quasistatic, inertial, and intermediate <span class="hlt">regimes</span>---each of which exhibits its own dependences on solids volume fraction, shear rate, and particle-level properties. The differences in these <span class="hlt">regimes</span> can be attributed to microscale phenomena, with quasistatic <span class="hlt">flows</span> being dominated by enduring, frictional contacts between grains, inertial <span class="hlt">flows</span> by grain collisions, and intermediate <span class="hlt">flows</span> by a combination of the two. Existing constitutive models for the solids-phase stress tend to focus on one or two <span class="hlt">regimes</span> at a time, with a limited degree of success; the same is true of models for wall-boundary conditions for granular <span class="hlt">flows</span>. Moreover, these models tend not to be based on detailed particle-level <span class="hlt">flow</span> data, either from experiment or simulation. Clearly, a comprehensive modeling framework is lacking. The work in this thesis aims to address these issues by proposing continuum models constructed on the basis of discrete element method (DEM) simulations of granular shear <span class="hlt">flows</span>. Specifically, we propose (a) a constitutive stress model that bridges the three dense <span class="hlt">flow</span> <span class="hlt">regimes</span>, (b) an modified kinetic-theory model that covers both the dense and dilute ends of the inertial <span class="hlt">regime</span>, and (c) a boundary-condition model for dense, wall-bounded <span class="hlt">flows</span>. These models facilitate the modeling of a wide range of <span class="hlt">flow</span> systems of practical interest and provide ideas for further model development and refinement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70190127','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70190127"><span>Residence times and alluvial architecture of a sediment superslug in response to different <span class="hlt">flow</span> <span class="hlt">regimes</span></span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Moody, John A.</p> <p>2017-01-01</p> <p>A superslug was deposited in a basin in the Colorado Front Range Mountains as a consequence of an extreme flood following a wildfire disturbance in 1996. The subsequent evolution of this superslug was measured by repeat topographic surveys (31 surveys from 1996 through 2014) of 18 cross sections approximately uniformly spaced over 1500 m immediately above the basin outlet. These surveys allowed the identification within the superslug of chronostratigraphic units deposited and eroded by different geomorphic processes in response to different <span class="hlt">flow</span> <span class="hlt">regimes</span>.Over the time period of the study, the superslug went through aggradation, incision, and stabilization phases that were controlled by a shift in geomorphic processes from generally short-duration, episodic, large-magnitude floods that deposited new chronostratigraphic units to long-duration processes that eroded units. These phases were not contemporaneous at each channel cross section, which resulted in a complex response that preserved different chronostratigraphic units at each channel cross section having, in general, two dominant types of alluvial architecture—laminar and fragmented. Age and transit-time distributions for these two alluvial architectures evolved with time since the extreme flood. Because of the complex shape of the distributions they were best modeled by two-parameter Weibull functions. The Weibull scale parameter approximated the median age of the distributions, and the Weibull shape parameter generally had a linear relation that increased with time since the extreme flood. Additional results indicated that deposition of new chronostratigraphic units can be represented by a power-law frequency distribution, and that the erosion of units decreases with depth of burial to a limiting depth. These relations can be used to model other situations with different <span class="hlt">flow</span> <span class="hlt">regimes</span> where vertical aggradation and incision are dominant processes, to predict the residence time of possible contaminated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA286807','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA286807"><span>Demonstration of Split-<span class="hlt">Flow</span> Ventilation and Recirculation as <span class="hlt">Flow</span>- Reduction Methods in an <span class="hlt">Air</span> Force Paint Spray Booth. Volume 1</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1994-07-27</p> <p>of the split-<span class="hlt">flow</span> and recirculation modifications in typical <span class="hlt">Air</span> Force painting operations; itwas a proof-of- concept study only. It is recognized...recirculating ventilation. 4 To Implement this <span class="hlt">flow</span>-reduction concept , it must first be established that recirculation does not cause an accumulation of toxic...ventilation concept . The concentration gradient is determined by height and direction of paint application. If the concentration in the top portion is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1347226-assessment-melcor-condensation-models-presence-noncondensable-gas-natural-convection-flow-regime','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1347226-assessment-melcor-condensation-models-presence-noncondensable-gas-natural-convection-flow-regime"><span>Assessment of MELCOR condensation models with the presence of noncondensable gas in natural convection <span class="hlt">flow</span> <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Yoon, Dhongik S; Jo, HangJin; Corradini, Michael L</p> <p>2017-04-01</p> <p>Condensation of steam vapor is an important mode of energy removal from the reactor containment. The presence of noncondensable gas complicates the process and makes it difficult to model. MELCOR, one of the more widely used system codes for containment analyses, uses the heat and mass transfer analogy to model condensation heat transfer. To investigate previously reported nodalization-dependence in natural convection <span class="hlt">flow</span> <span class="hlt">regime</span>, MELCOR condensation model as well as other models are studied. The nodalization-dependence issue is resolved by using physical length from the actual geometry rather than node size of each control volume as the characteristic length scale formore » MELCOR containment analyses. At the transition to turbulent natural convection <span class="hlt">regime</span>, the McAdams correlation for convective heat transfer produces a better prediction compared to the original MELCOR model. The McAdams correlation is implemented in MELCOR and the prediction is validated against a set of experiments on a scaled AP600 containment. The MELCOR with our implemented model produces improved predictions. For steam molar fractions in the gas mixture greater than about 0.58, the predictions are within the uncertainty margin of the measurements. The simulation results still underestimate the heat transfer from the gas-steam mixture, implying that conservative predictions are provided.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1347226','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1347226"><span>Assessment of MELCOR condensation models with the presence of noncondensable gas in natural convection <span class="hlt">flow</span> <span class="hlt">regime</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Yoon, Dhongik S; Jo, HangJin; Corradini, Michael L</p> <p></p> <p>Condensation of steam vapor is an important mode of energy removal from the reactor containment. The presence of noncondensable gas complicates the process and makes it difficult to model. MELCOR, one of the more widely used system codes for containment analyses, uses the heat and mass transfer analogy to model condensation heat transfer. To investigate previously reported nodalization-dependence in natural convection <span class="hlt">flow</span> <span class="hlt">regime</span>, MELCOR condensation model as well as other models are studied. The nodalization-dependence issue is resolved by using physical length from the actual geometry rather than node size of each control volume as the characteristic length scale formore » MELCOR containment analyses. At the transition to turbulent natural convection <span class="hlt">regime</span>, the McAdams correlation for convective heat transfer produces a better prediction compared to the original MELCOR model. The McAdams correlation is implemented in MELCOR and the prediction is validated against a set of experiments on a scaled AP600 containment. The MELCOR with our implemented model produces improved predictions. For steam molar fractions in the gas mixture greater than about 0.58, the predictions are within the uncertainty margin of the measurements. The simulation results still underestimate the heat transfer from the gas-steam mixture, implying that conservative predictions are provided.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880059266&hterms=job+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Djob%2Banalysis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880059266&hterms=job+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Djob%2Banalysis"><span>Comparison of Space Shuttle Hot Gas Manifold analysis to <span class="hlt">air</span> <span class="hlt">flow</span> data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mcconnaughey, P. K.</p> <p>1988-01-01</p> <p>This paper summarizes several recent analyses of the Space Shuttle Main Engine Hot Gas Manifold and compares predicted <span class="hlt">flow</span> environments to <span class="hlt">air</span> <span class="hlt">flow</span> data. Codes used in these analyses include INS3D, PAGE, PHOENICS, and VAST. Both laminar (Re = 250, M = 0.30) and turbulent (Re = 1.9 million, M = 0.30) results are discussed, with the latter being compared to data for system losses, outer wall static pressures, and manifold exit Mach number profiles. Comparison of predicted results for the turbulent case to <span class="hlt">air</span> <span class="hlt">flow</span> data shows that the analysis using INS3D predicted system losses within 1 percent error, while the PHOENICS, PAGE, and VAST codes erred by 31, 35, and 47 percent, respectively. The INS3D, PHOENICS, and PAGE codes did a reasonable job of predicting outer wall static pressure, while the PHOENICS code predicted exit Mach number profiles with acceptable accuracy. INS3D was approximately an order of magnitude more efficient than the other codes in terms of code speed and memory requirements. In general, it is seen that complex internal <span class="hlt">flows</span> in manifold-like geometries can be predicted with a limited degree of confidence, and further development is necessary to improve both efficiency and accuracy of codes if they are to be used as design tools for complex three-dimensional geometries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=315727','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=315727"><span>Optimal ranking <span class="hlt">regime</span> analysis of Tree<span class="hlt">Flow</span> dendrohydrological reconstructions</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>The Optimal Ranking <span class="hlt">Regime</span> (ORR) method was used to identify 6-100 year time windows containing significant ranking sequences in 55 western U.S. streamflow reconstructions, and reconstructions of the level of the Great Salt Lake and San Francisco Bay salinity during 1500-2007. The method’s ability t...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989TepVT..27..226M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989TepVT..27..226M"><span>Electron concentration distribution in a glow discharge in <span class="hlt">air</span> <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mukhamedzianov, R. B.; Gaisin, F. M.; Sabitov, R. A.</p> <p>1989-04-01</p> <p>Electron concentration distributions in a glow discharge in longitudinal and vortex <span class="hlt">air</span> <span class="hlt">flows</span> are determined from the attenuation of the electromagnetic wave passing through the plasma using microwave probes. An analysis of the distribution curves obtained indicates that electron concentration decreases in the direction of the anode. This can be explained by charge diffusion toward the chamber walls and electron recombination and sticking within the discharge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910064614&hterms=self+expansion+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dself%2Bexpansion%2Btheory','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910064614&hterms=self+expansion+theory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dself%2Bexpansion%2Btheory"><span>High enthalpy, hypervelocity <span class="hlt">flows</span> of <span class="hlt">air</span> and argon in an expansion tube</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Neely, A. J; Stalker, R. J.; Paull, A.</p> <p>1991-01-01</p> <p>An expansion tube with a free piston driver has been used to generate quasi-steady hypersonic <span class="hlt">flows</span> in argon and <span class="hlt">air</span> at <span class="hlt">flow</span> velocities in excess of 9 km/s. Irregular test <span class="hlt">flow</span> unsteadiness has limited the performance of previous expansion tubes, and it has been found that this can be avoided by attention to the interaction between the test gas accelerating expansion and the contact surface in the primary shock tube. Test section measurements of pitot pressure, static pressure and flat plate heat transfer are reported. An approximate analytical theory has been developed for predicting the velocities achieved in the unsteady expansion of the ionizing or dissociating test gas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018WRR....54.1890W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018WRR....54.1890W"><span>Distribution of Large Wood Within River Corridors in Relation to <span class="hlt">Flow</span> <span class="hlt">Regime</span> in the Semiarid Western US</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wohl, Ellen; Cadol, Daniel; Pfeiffer, Andrew; Jackson, Karen; Laurel, DeAnna</p> <p>2018-03-01</p> <p>The cumulative volume and spatial distribution of large wood (LW) along river corridors (channels and floodplains) reflect interactions between rates and volumes of LW recruitment and channel transport capacity through time. Rivers of the semiarid interior western US can have relatively low-magnitude disturbances associated with annual snowmelt or relatively high-magnitude disturbances associated with episodic rainfall runoff, especially following wildfires. We use characteristics of LW from 25 river segments in four regions of New Mexico and Colorado to analyze wood loads and spatial patterns of wood distribution in relation to disturbance <span class="hlt">regime</span>. High-magnitude disturbances move LW onto floodplains and create longitudinally nonuniform LW distributions with aggregated (closer together than random) LW pieces and abundant LW jams in the floodplain. Sites with low-magnitude disturbances have a greater proportion of LW in the channel and much of this wood is within segregated (farther apart than random) jams. These results imply that river management, which typically focuses on LW within channels, should focus on floodplain as well as in-channel LW in rivers with high-magnitude disturbances. The results also indicate that the proportions of LW loads in channels versus floodplains can differ significantly among rivers with different disturbance <span class="hlt">regimes</span> that are otherwise similar in terms of forest type or drainage area. This is particularly relevant to mountainous regions with elevation-related changes in <span class="hlt">flow</span> and disturbance <span class="hlt">regime</span>. River management that reintroduces LW to river corridors will be most effective if it incorporates the mobility and spatial distribution of LW.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25a3514I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25a3514I"><span>Transport coefficients in high-temperature ionized <span class="hlt">air</span> <span class="hlt">flows</span> with electronic excitation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Istomin, V. A.; Oblapenko, G. P.</p> <p>2018-01-01</p> <p>Transport coefficients are studied in high-temperature ionized <span class="hlt">air</span> mixtures using the modified Chapman-Enskog method. The 11-component mixture N2/N2+/N /N+/O2/O2+/O /O+/N O /N O+/e- , taking into account the rotational and vibrational degrees of freedom of molecules and electronic degrees of freedom of both atomic and molecular species, is considered. Using the PAINeT software package, developed by the authors of the paper, in wide temperature range calculations of the thermal conductivity, thermal diffusion, diffusion, and shear viscosity coefficients for an equilibrium ionized <span class="hlt">air</span> mixture and non-equilibrium <span class="hlt">flow</span> conditions for mixture compositions, characteristic of those in shock tube experiments and re-entry conditions, are performed. For the equilibrium <span class="hlt">air</span> case, the computed transport coefficients are compared to those obtained using simplified kinetic theory algorithms. It is shown that neglecting electronic excitation leads to a significant underestimation of the thermal conductivity coefficient at temperatures higher than 25 000 K. For non-equilibrium test cases, it is shown that the thermal diffusion coefficients of neutral species and the self-diffusion coefficients of all species are strongly affected by the mixture composition, while the thermal conductivity coefficient is most strongly influenced by the degree of ionization of the <span class="hlt">flow</span>. Neglecting electronic excitation causes noticeable underestimation of the thermal conductivity coefficient at temperatures higher than 20 000 K.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AtmEn..45.3352Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AtmEn..45.3352Z"><span>Effect of real-time boundary wind conditions on the <span class="hlt">air</span> <span class="hlt">flow</span> and pollutant dispersion in an urban street canyon—Large eddy simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Yun-Wei; Gu, Zhao-Lin; Cheng, Yan; Lee, Shun-Cheng</p> <p>2011-07-01</p> <p><span class="hlt">Air</span> <span class="hlt">flow</span> and pollutant dispersion characteristics in an urban street canyon are studied under the real-time boundary conditions. A new scheme for realizing real-time boundary conditions in simulations is proposed, to keep the upper boundary wind conditions consistent with the measured time series of wind data. The <span class="hlt">air</span> <span class="hlt">flow</span> structure and its evolution under real-time boundary wind conditions are simulated by using this new scheme. The induced effect of time series of ambient wind conditions on the <span class="hlt">flow</span> structures inside and above the street canyon is investigated. The <span class="hlt">flow</span> shows an obvious intermittent feature in the street canyon and the flapping of the shear layer forms near the roof layer under real-time wind conditions, resulting in the expansion or compression of the <span class="hlt">air</span> mass in the canyon. The simulations of pollutant dispersion show that the pollutants inside and above the street canyon are transported by different dispersion mechanisms, relying on the time series of <span class="hlt">air</span> <span class="hlt">flow</span> structures. Large scale <span class="hlt">air</span> movements in the processes of the <span class="hlt">air</span> mass expansion or compression in the canyon exhibit obvious effects on pollutant dispersion. The simulations of pollutant dispersion also show that the transport of pollutants from the canyon to the upper <span class="hlt">air</span> <span class="hlt">flow</span> is dominated by the shear layer turbulence near the roof level and the expansion or compression of the <span class="hlt">air</span> mass in street canyon under real-time boundary wind conditions. Especially, the expansion of the <span class="hlt">air</span> mass, which features the large scale <span class="hlt">air</span> movement of the <span class="hlt">air</span> mass, makes more contribution to the pollutant dispersion in this study. Comparisons of simulated results under different boundary wind conditions indicate that real-time boundary wind conditions produces better condition for pollutant dispersion than the artificially-designed steady boundary wind conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JFS....25.1213M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JFS....25.1213M"><span>Fluid-elastic instability in tube arrays subjected to <span class="hlt">air</span>-water and steam-water cross-<span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mitra, D.; Dhir, V. K.; Catton, I.</p> <p>2009-10-01</p> <p><span class="hlt">Flow</span> induced vibrations in heat exchanger tubes have led to numerous accidents and economic losses in the past. Efforts have been made to systematically study the cause of these vibrations and develop remedial design criteria for their avoidance. In this research, experiments were systematically carried out with <span class="hlt">air</span>-water and steam-water cross-<span class="hlt">flow</span> over horizontal tubes. A normal square tube array of pitch-to-diameter ratio of 1.4 was used in the experiments. The tubes were suspended from piano wires and strain gauges were used to measure the vibrations. Tubes made of aluminum; stainless steel and brass were systematically tested by maintaining approximately the same stiffness in the tube-wire systems. Instability was clearly seen in single phase and two-phase <span class="hlt">flow</span> and the critical <span class="hlt">flow</span> velocity was found to be proportional to tube mass. The present study shows that fully flexible arrays become unstable at a lower <span class="hlt">flow</span> velocity when compared to a single flexible tube surrounded by rigid tubes. It is also found that tubes are more stable in steam-water <span class="hlt">flow</span> as compared to <span class="hlt">air</span>-water <span class="hlt">flow</span>. Nucleate boiling on the tube surface is also found to have a stabilizing effect on fluid-elastic instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=252972&Lab=NERL&keyword=filters&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=252972&Lab=NERL&keyword=filters&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span><span class="hlt">Air</span> Change Rates and Interzonal <span class="hlt">Flows</span> in Residences, and the Need for Multi-Zone Models for Exposure and Health Analysis</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p><span class="hlt">Air</span> change rates (ACRs) and interzonal <span class="hlt">flows</span> are key determinants of indoor <span class="hlt">air</span> quality (IAQ) and building energy use. This paper characterizes ACRs and interzonal <span class="hlt">flows</span> in 126 houses, and evaluates effects of these parameters on IAQ. ACRs measured using weeklong tracer measureme...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27094269','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27094269"><span>Recent changes (1973-2014 versus 1903-1972) in the <span class="hlt">flow</span> <span class="hlt">regime</span> of the Lower Paraná River and current fluvial pollution warnings in its Delta Biosphere Reserve.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Puig, Alba; Olguín Salinas, Héctor F; Borús, Juan A</p> <p>2016-06-01</p> <p>Alterations in <span class="hlt">flow</span> <span class="hlt">regimes</span> of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of <span class="hlt">flows</span> incoming to the Delta (Paraná-Santa Fe section), <span class="hlt">flow</span> characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental <span class="hlt">Flow</span> Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the "Paraná Delta" Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903-1972) and two more altered periods (1973-1999 wet period and 2000-2014 dry period) were identified. <span class="hlt">Flow</span> duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the <span class="hlt">flow</span> <span class="hlt">regime</span> were the lack of record of the extreme-low-<span class="hlt">flow</span> component, the attenuation of monthly <span class="hlt">flow</span> seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum <span class="hlt">flow</span> dates. These alterations are consistent with the monthly and daily <span class="hlt">flow</span> regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ESPR...2311471P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ESPR...2311471P"><span>Recent changes (1973-2014 versus 1903-1972) in the <span class="hlt">flow</span> <span class="hlt">regime</span> of the Lower Paraná River and current fluvial pollution warnings in its Delta Biosphere Reserve</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Puig, Alba; Olguín Salinas, Héctor F.; Borús, Juan A.</p> <p>2016-06-01</p> <p>Alterations in <span class="hlt">flow</span> <span class="hlt">regimes</span> of large rivers may originate or increase risks to ecosystems and humans. The Paraná River basin (South America) undergoes human pressures (e.g., heavy damming in the upper basin, deforestation, and mixed pollution) that may affect the water quantity and quality of its terminal Delta (Argentina). In this study, after applying univariate and multivariate change-point detection and trend analyses to the daily data series of <span class="hlt">flows</span> incoming to the Delta (Paraná-Santa Fe section), <span class="hlt">flow</span> characteristics were compared by Indicators of Hydrologic Alteration (IHA) and Environmental <span class="hlt">Flow</span> Components (EFC). Some flood characteristics were also compared from hydrometric levels in the middle Delta (San Pedro station). Chemical and microbiological water variables in the main rivers of the "Paraná Delta" Biosphere Reserve were examined during two extreme hydrologic years (October 2008 to July 2010) to detect potential risk factors in association with hydrologic conditions. In the Lower Paraná River, a historical period (1903-1972) and two more altered periods (1973-1999 wet period and 2000-2014 dry period) were identified. <span class="hlt">Flow</span> duration curves evidenced different changes in both altered periods, reflecting the joint effect of climatic variability and human influence. The most evident alterations in the <span class="hlt">flow</span> <span class="hlt">regime</span> were the lack of record of the extreme-low-<span class="hlt">flow</span> component, the attenuation of monthly <span class="hlt">flow</span> seasonality, and the increase in the number of reversals (dry period) and in the variability of maximum and minimum <span class="hlt">flow</span> dates. These alterations are consistent with the monthly and daily <span class="hlt">flow</span> regulation by upstream dams evidenced by available data from the current dry period. In the middle Delta, the marked monthly seasonality in flood days decreased only in the wet period. The proportion between the number of flood days exceeding the evacuation level and that of those exceeding the warning level doubled in the wet period but decreased only slightly</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050186637&hterms=hand+writing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhand%2Bwriting','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050186637&hterms=hand+writing&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dhand%2Bwriting"><span>Graphical User Interface Development for Representing <span class="hlt">Air</span> <span class="hlt">Flow</span> Patterns</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chaudhary, Nilika</p> <p>2004-01-01</p> <p>In the Turbine Branch, scientists carry out experimental and computational work to advance the efficiency and diminish the noise production of jet engine turbines. One way to do this is by decreasing the heat that the turbine blades receive. Most of the experimental work is carried out by taking a single turbine blade and analyzing the <span class="hlt">air</span> <span class="hlt">flow</span> patterns around it, because this data indicates the sections of the turbine blade that are getting too hot. Since the cost of doing turbine blade <span class="hlt">air</span> <span class="hlt">flow</span> experiments is very high, researchers try to do computational work that fits the experimental data. The goal of computational fluid dynamics is for scientists to find a numerical way to predict the complex <span class="hlt">flow</span> patterns around different turbine blades without physically having to perform tests or costly experiments. When visualizing <span class="hlt">flow</span> patterns, scientists need a way to represent the <span class="hlt">flow</span> conditions around a turbine blade. A researcher will assign specific zones that surround the turbine blade. In a two-dimensional view, the zones are usually quadrilaterals. The next step is to assign boundary conditions which define how the <span class="hlt">flow</span> enters or exits one side of a zone. way of setting up computational zones and grids, visualizing <span class="hlt">flow</span> patterns, and storing all the <span class="hlt">flow</span> conditions in a file on the computer for future computation. Such a program is necessary because the only method for creating <span class="hlt">flow</span> pattern graphs is by hand, which is tedious and time-consuming. By using a computer program to create the zones and grids, the graph would be faster to make and easier to edit. Basically, the user would run a program that is an editable graph. The user could click and drag with the mouse to form various zones and grids, then edit the locations of these grids, add <span class="hlt">flow</span> and boundary conditions, and finally save the graph for future use and analysis. My goal this summer is to create a graphical user interface (GUI) that incorporates all of these elements. I am writing the program in</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JMiMi..27g5020T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JMiMi..27g5020T"><span>Liquid-in-gas droplet microfluidics; experimental characterization of droplet morphology, generation frequency, and monodispersity in a <span class="hlt">flow</span>-focusing microfluidic device</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tirandazi, Pooyan; Hidrovo, Carlos H.</p> <p>2017-07-01</p> <p>Microfluidic techniques for production of uniform droplets usually rely on the use of two immiscible liquids (e.g. water-in-oil emulsions). It has been shown recently that a continuous gas <span class="hlt">flow</span> instead of a second liquid carrier can be used as an alternative approach in droplet microfluidics. In this work we experimentally investigate the generation of liquid water droplets within <span class="hlt">air</span> in <span class="hlt">flow</span>-focusing configurations. Over a wide range of <span class="hlt">flow</span> conditions we identify six distinct <span class="hlt">flow</span> <span class="hlt">regimes</span> inside the microchannel: Co-<span class="hlt">flowing</span>, Threading, Plugging, Dripping, Multi-Satellite Formation, and Jetting. <span class="hlt">Flow</span> <span class="hlt">regimes</span> and their transitions are plotted and characterized based on the Weber number (We) of the system. We further investigate the impact of liquid microchannel size on the <span class="hlt">flow</span> maps. Generation frequency, morphology, and monodispersity of the droplets are characterized in more detail in the Dripping <span class="hlt">regime</span>. Generation frequency can be related to the product of the liquid and gas <span class="hlt">flow</span> rates. However, droplet morphology (length and width) is more dependent on the gas <span class="hlt">flow</span> rate. We demonstrate the production of monodisperse droplets (d < 100 µm and σ/d < 5 %) up to kHz formation rates in liquid-gas microfluidic systems for the first time. The results of this work provide practical and useful guidelines for precise, oil-free delivery of ultra-small volumes of fluid which can be integrated in lab-on-a-chip systems for a variety of applications in biochemical research and material synthesis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16822018','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16822018"><span>Transport processes in magnetically confined plasmas in the nonlinear <span class="hlt">regime</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sonnino, Giorgio</p> <p>2006-06-01</p> <p>A field theory approach to transport phenomena in magnetically confined plasmas is presented. The thermodynamic field theory (TFT), previously developed for treating the generic thermodynamic system out of equilibrium, is applied to plasmas physics. Transport phenomena are treated here as the effect of the field linking the thermodynamic forces with their conjugate <span class="hlt">flows</span> combined with statistical mechanics. In particular, the Classical and the Pfirsch-Schluter <span class="hlt">regimes</span> are analyzed by solving the thermodynamic field equations of the TFT in the weak-field approximation. We found that, the TFT does not correct the expressions of the ionic heat fluxes evaluated by the neoclassical theory in these two <span class="hlt">regimes</span>. On the other hand, the fluxes of matter and electronic energy (heat <span class="hlt">flow</span>) is further enhanced in the nonlinear Classical and Pfirsch-Schluter <span class="hlt">regimes</span>. These results seem to be in line with the experimental observations. The complete set of the electronic and ionic transport equations in the nonlinear Banana <span class="hlt">regime</span>, is also reported. A paper showing the comparison between our theoretic results and the experimental observations in the JET machine is currently in preparation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080004478','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080004478"><span><span class="hlt">Air</span>-cooled, hydrogen-<span class="hlt">air</span> fuel cell</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Shelekhin, Alexander B. (Inventor); Bushnell, Calvin L. (Inventor); Pien, Michael S. (Inventor)</p> <p>1999-01-01</p> <p>An <span class="hlt">air</span>-cooled, hydrogen-<span class="hlt">air</span> solid polymer electrolyte (SPE) fuel cell with a membrane electrode assembly operatively associated with a fluid <span class="hlt">flow</span> plate having at least one plate cooling channel extending through the plate and at least one <span class="hlt">air</span> distribution hole extending from a surface of the cathode <span class="hlt">flow</span> field into the plate cooling channel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006AtmRe..80..263C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006AtmRe..80..263C"><span><span class="hlt">Air</span> <span class="hlt">flow</span> analysis in the upper Río Negro Valley (Argentina)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cogliati, M. G.; Mazzeo, N. A.</p> <p>2006-06-01</p> <p>The so called Upper Río Negro Valley in Argentina is one of the most important fruit and vegetable production regions of the country. It comprises the lower valleys of the Limay and Neuquén rivers and the upper Negro river valley. Out of the 41,671 cultivated hectares, 84.6% are cultivated with fruit trees, especially apple, pear and stone fruit trees. Late frosts occurring when trees are sensitive to low temperatures have a significant impact on the regional production. This study presents an analysis of <span class="hlt">air</span> <span class="hlt">flow</span> characteristics in the Upper Río Negro Valley and its relationship with ambient <span class="hlt">air</span> <span class="hlt">flow</span>. To such effect, observations made when synoptic-scale weather patterns were favorable for radiative frosts (light wind and clear sky) or nocturnal temperature inversion in the lower layer were used. In the Negro river valley, both wind channeling and downward horizontal momentum transport from ambient wind were observed; in nighttime, very light wind events occurred, possibly associated with drainage winds from the nearby higher levels of the barda. In the Neuquén river valley, the prevailing effect appeared to be forced channeling, consistent with the results obtained in valleys where the synoptic scale wind crossed the axis of the valley. In the Limay river valley, the <span class="hlt">flow</span> was observed to blow parallel to the longitudinal valley axis, possibly influenced by pressure gradient and forced channeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA020223','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA020223"><span>Aircraft Carrier Turbulence Study for Predicting <span class="hlt">Air</span> <span class="hlt">Flow</span> Dynamics with Increasing Wind-Over-Deck Velocities</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>1968-03-28</p> <p>AD-A020 223 AIRCRAFT CARRIER TURBULENCE STUDY FOR PREDICTING <span class="hlt">AIR</span> <span class="hlt">FLOW</span> DYNAMICS WITH INCREASING WIND-OVER-DECK VELOCITIES S. Frost Naval <span class="hlt">Air</span>...Copy NAVAL <span class="hlt">AIR</span> ENGINEERING CENTERElPILAOUPHBA, PENNSYLVANIA 19112 Q Had-NG7~ CODE IDEN NO. *OOM 28 MARCH 4fe AIRCRAFT CARRIER TUJRBULENCE STUDY FOR...carrier dynamics. Ike- comirendations for future experimental and theoretical studies are give,. DD 1473 EDITIOIN 0F I NOV SS IS O@SOLETE S - ’i02</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25844537','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25844537"><span>Hybridized electromagnetic-triboelectric nanogenerator for scavenging <span class="hlt">air-flow</span> energy to sustainably power temperature sensors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Xue; Wang, Shuhua; Yang, Ya; Wang, Zhong Lin</p> <p>2015-04-28</p> <p>We report a hybridized nanogenerator with dimensions of 6.7 cm × 4.5 cm × 2 cm and a weight of 42.3 g that consists of two triboelectric nanogenerators (TENGs) and two electromagnetic generators (EMGs) for scavenging <span class="hlt">air-flow</span> energy. Under an <span class="hlt">air-flow</span> speed of about 18 m/s, the hybridized nanogenerator can deliver largest output powers of 3.5 mW for one TENG (in correspondence of power per unit mass/volume: 8.8 mW/g and 14.6 kW/m(3)) at a loading resistance of 3 MΩ and 1.8 mW for one EMG (in correspondence of power per unit mass/volume: 0.3 mW/g and 0.4 kW/m(3)) at a loading resistance of 2 kΩ, respectively. The hybridized nanogenerator can be utilized to charge a capacitor of 3300 μF to sustainably power four temperature sensors for realizing self-powered temperature sensor networks. Moreover, a wireless temperature sensor driven by a hybridized nanogenerator charged Li-ion battery can work well to send the temperature data to a receiver/computer at a distance of 1.5 m. This work takes a significant step toward <span class="hlt">air-flow</span> energy harvesting and its potential applications in self-powered wireless sensor networks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/862771','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/862771"><span>Apparatus for monitoring two-phase <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Sheppard, John D.; Tong, Long S.</p> <p>1977-03-01</p> <p>A method and apparatus for monitoring two-phase <span class="hlt">flow</span> is provided that is particularly related to the monitoring of transient two-phase (liquid-vapor) <span class="hlt">flow</span> rates such as may occur during a pressurized water reactor core blow-down. The present invention essentially comprises the use of flanged wire screens or similar devices, such as perforated plates, to produce certain desirable effects in the <span class="hlt">flow</span> <span class="hlt">regime</span> for monitoring purposes. One desirable effect is a measurable and reproducible pressure drop across the screen. The pressure drop can be characterized for various known <span class="hlt">flow</span> rates and then used to monitor nonhomogeneous <span class="hlt">flow</span> <span class="hlt">regimes</span>. Another useful effect of the use of screens or plates in nonhomogeneous <span class="hlt">flow</span> is that such apparatus tends to create a uniformly dispersed <span class="hlt">flow</span> <span class="hlt">regime</span> in the immediate downstream vicinity. This is a desirable effect because it usually increases the accuracy of <span class="hlt">flow</span> rate measurements determined by conventional methods.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/6476778','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/6476778"><span>Geothermal studies at Kirtland <span class="hlt">Air</span> Force Base, Albuquerque, New Mexico</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Riddle, L.; Grant, B.</p> <p></p> <p>Due to an effort by government installations to discontinue use of natural gas, alternative energy sources are being investigated at Kirtland <span class="hlt">Air</span> Force Base, Albuquerque, New Mexico. New Mexico has geologic characteristics favorable for geothermal energy utilization. Local heat <span class="hlt">flow</span> and geochemical studies indicate a normal subsurface temperature <span class="hlt">regime</span>. The alluvial deposits, however, extend to great depths where hot fluids, heated by the normal geothermal gradient, could be encountered. Two potential models for tapping geothermal energy are presented: the basin model and the fault model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120003618','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120003618"><span>Using <span class="hlt">Flow</span> <span class="hlt">Regime</span> Lightning and Sounding Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lambert, Winifred; Short, David; Wolkmer, Matthew; Sharp, David; Spratt, Scott</p> <p>2006-01-01</p> <p>Each morning, the forecasters at the National Weather Service in Melbourne, FL (NWS MLB) produce an experimental cloud-to-ground (CG) lightning threat index map for their county warning area (CWA) that is posted to their web site (http://www.srh.weather.gov/mlb/ghwo/lightning.shtml) . Given the hazardous nature of lightning in East Central Florida, especially during the warm season months of May September, these maps help users factor the threat of lightning, relative to their location, into their daily plans. The maps are color-coded in five levels from Very Low to Extreme, with threat level definitions based on the probability of lightning occurrence and the expected amount of CG activity. On a day in which thunderstorms are expected, there are typically two or more threat levels depicted spatially across the CWA. The locations of relative lightning threat maxima and minima often depend on the position and orientation of the low-level ridge axis, forecast propagation and interaction of sea/lake/outflow boundaries, expected evolution of moisture and stability fields, and other factors that can influence the spatial distribution of thunderstorms over the CWA. The lightning threat index maps are issued for the 24-hour period beginning at 1200 UTC each day with a grid resolution of 5 km x 5 km. Product preparation is performed on the AWIPS Graphical Forecast Editor (GFE), which is the standard NWS platform for graphical editing. Currently, the forecasters create each map manually, starting with a blank map. To improve efficiency of the forecast process, NWS MLB requested that the Applied Meteorology Unit (AMU) create gridded warm season lightning climatologies that could be used as first-guess inputs to initialize lightning threat index maps. The gridded values requested included CG strike densities and frequency of occurrence stratified by synoptic-scale <span class="hlt">flow</span> <span class="hlt">regime</span>. The intent is to improve consistency between forecasters while allowing them to focus on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130012614','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130012614"><span>Using <span class="hlt">Flow</span> <span class="hlt">Regime</span> Lightning and Sounding Climatologies to Initialize Gridded Lightning Threat Forecasts for East Central Florida</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lambert, Winifred; Short, David; Volkmer, Matthew; Sharp, David; Spratt, Scott</p> <p>2007-01-01</p> <p>Each morning, the forecasters at the National Weather Service in Melbourne, FL (NWS MLB) produce an experimental cloud-to-ground (CG) lightning threat index map for their county warning area (CWA) that is posted to their web site (httl://www.srh.weather.gov/mlb/ghwo/lightning.shtml) . Given the hazardous nature of lightning in East Central Florida, especially during the warm season months of May September, these maps help users factor the threat of lightning, relative to their location, into their daily plans. The maps are color-coded in five levels from Very Low to Extreme, with threat level definitions based on the probability of lightning occurrence and the expected amount of CG activity. On a day in which thunderstorms are expected, there are typically two or more threat levels depicted spatially across the CWA. The locations of relative lightning threat maxima and minima often depend on the position and orientation of the low-level ridge axis, forecast propagation and interaction of sea/lake/outflow boundaries, expected evolution of moisture and stability fields, and other factors that can influence the spatial distribution of thunderstorms over the CWA. The lightning threat index maps are issued for the 24-hour period beginning at 1200 UTC each day with a grid resolution of 5 km x 5 km. Product preparation is performed on the AWIPS Graphical Forecast Editor (GFE), which is the standard NWS platform for graphical editing. Until recently, the forecasters created each map manually, starting with a blank map. To improve efficiency of the forecast process, NWS MLB requested that the Applied Meteorology Unit (AMU) create gridded warm season lightning climatologies that could be used as first-guess inputs to initialize lightning threat index maps. The gridded values requested included CG strike densities and frequency of occurrence stratified by synoptic-scale <span class="hlt">flow</span> <span class="hlt">regime</span>. The intent was to improve consistency between forecasters while allowing them to focus on the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A51H0157X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A51H0157X"><span>Extreme Temperature <span class="hlt">Regimes</span> during the Cool Season and their Associated Large-Scale Circulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Z.</p> <p>2015-12-01</p> <p>In the cool season (November-March), extreme temperature events (ETEs) always hit the continental United States (US) and provide significant societal impacts. According to the anomalous amplitudes of the surface <span class="hlt">air</span> temperature (SAT), there are two typical types of ETEs, e.g. cold waves (CWs) and warm waves (WWs). This study used cluster analysis to categorize both CWs and WWs into four distinct <span class="hlt">regimes</span> respectively and investigated their associated large-scale circulations on intra-seasonal time scale. Most of the CW <span class="hlt">regimes</span> have large areal impact over the continental US. However, the distribution of cold SAT anomalies varies apparently in four <span class="hlt">regimes</span>. In the sea level, the four CW <span class="hlt">regimes</span> are characterized by anomalous high pressure over North America (near and to west of cold anomaly) with different extension and orientation. As a result, anomalous northerlies along east flank of anomalous high pressure convey cold <span class="hlt">air</span> into the continental US. To the middle troposphere, the leading two groups feature large-scale and zonally-elongated circulation anomaly pattern, while the other two <span class="hlt">regimes</span> exhibit synoptic wavetrain pattern with meridionally elongated features. As for the WW <span class="hlt">regimes</span>, there are some patterns symmetry and anti-symmetry with respect to CW <span class="hlt">regimes</span>. The WW <span class="hlt">regimes</span> are characterized by anomalous low pressure and southerlies wind over North America. The first and fourth groups are affected by remote forcing emanating from North Pacific, while the others appear mainly locally forced.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930029917&hterms=mixture+experimental+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmixture%2Bexperimental%2Bdesign','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930029917&hterms=mixture+experimental+design&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmixture%2Bexperimental%2Bdesign"><span>Definition of two-phase <span class="hlt">flow</span> behaviors for spacecraft design</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reinarts, Thomas R.; Best, Frederick R.; Miller, Katherine M.; Hill, Wayne S.</p> <p>1991-01-01</p> <p>Two-phase <span class="hlt">flow</span>, thermal management systems are currently being considered as an alternative to conventional, single phase systems for future space missions because of their potential to reduce overall system mass, size, and pumping power requirements. Knowledge of <span class="hlt">flow</span> <span class="hlt">regime</span> transitions, heat transfer characteristics, and pressure drop correlations is necessary to design and develop two-phase systems. A boiling and condensing experiment was built in which R-12 was used as the working fluid. A two-phase pump was used to circulate a freon mixture and allow separate measurements of the vapor and liquid <span class="hlt">flow</span> streams. The experimental package was flown five times aboard the NASA KC-135 aircraft which simulates zero-g conditions by its parabolic flight trajectory. Test conditions included stratified and annual <span class="hlt">flow</span> <span class="hlt">regimes</span> in 1-g which became bubbly, slug, or annular <span class="hlt">flow</span> <span class="hlt">regimes</span> on 0-g. A portion of this work is the analysis of adiabatic <span class="hlt">flow</span> <span class="hlt">regimes</span>. The superficial velocities of liquid and vapor have been obtained from the measured <span class="hlt">flow</span> rates and are presented along with the observed <span class="hlt">flow</span> <span class="hlt">regimes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGC51E1134H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC51E1134H"><span>Analysis of Future Streamflow <span class="hlt">Regimes</span> under Global Change Scenarios in Central Chile for Ecosystem Sustainability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Henriquez Dole, L. E.; Gironas, J. A.; Vicuna, S.</p> <p>2015-12-01</p> <p>Given the critical role of the streamflow <span class="hlt">regime</span> for ecosystem sustainability, modeling long term effects of climate change and land use change on streamflow is important to predict possible impacts in stream ecosystems. Because <span class="hlt">flow</span> duration curves are largely used to characterize the streamflow <span class="hlt">regime</span> and define indices of ecosystem health, they were used to represent and analyze in this study the stream <span class="hlt">regime</span> in the Maipo River Basin in Central Chile. Water and Environmental Assessment and Planning (WEAP) model and the Plant Growth Model (PGM) were used to simulate water distribution, consumption in rural areas and stream <span class="hlt">flows</span> on a weekly basis. Historical data (1990-2014), future land use scenarios (2030/2050) and climate change scenarios were included in the process. Historical data show a declining trend in <span class="hlt">flows</span> mainly by unprecedented climatic conditions, increasing interest among users on future streamflow scenarios. In the future, under an expected decline in water availability coupled with changes in crop water demand, water users will be forced to adapt by changing water allocation rules. Such adaptation actions would in turns affect the streamflow <span class="hlt">regime</span>. Future scenarios for streamflow <span class="hlt">regime</span> show dramatic changes in water availability and temporal distribution. Annual weekly mean <span class="hlt">flows</span> can reduce in 19% in the worst scenario and increase in 3.3% in the best of them, and variability in streamflow increases nearly 90% in all scenarios under evaluation. The occurrence of maximum and minimum monthly <span class="hlt">flows</span> changes, as June instead of July becomes the driest month, and December instead of January becomes the month with maximum <span class="hlt">flows</span>. Overall, results show that under future scenarios streamflow is affected and altered by water allocation rules to satisfy water demands, and thus decisions will need to consider the streamflow <span class="hlt">regime</span> (and habitat) in order to be sustainable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol2/pdf/CFR-2012-title7-vol2-sec28-603.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title7-vol2/pdf/CFR-2012-title7-vol2-sec28-603.pdf"><span>7 CFR 28.603 - Procedures for <span class="hlt">air</span> <span class="hlt">flow</span> tests of micronaire reading.</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2012&page.go=Go">Code of Federal Regulations, 2012 CFR</a></p> <p></p> <p>2012-01-01</p> <p>... 7 Agriculture 2 2012-01-01 2012-01-01 false Procedures for <span class="hlt">air</span> <span class="hlt">flow</span> tests of micronaire reading. 28.603 Section 28.603 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing Practices), DEPARTMENT OF AGRICULTURE COMMODITY STANDARDS AND STANDARD CONTAINER REGULATIONS COTTON...</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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