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Sample records for air flow parallel

  1. Flow Regimes of Air-Water Counterflow Through Cross Corrugated Parallel Plates

    SciTech Connect

    de Almeida, V.F.

    2000-06-07

    Heretofore unknown flow regimes of air-water counterflow through a pair of transparent vertical parallel cross corrugated plates were observed via high-speed video. Air flows upward driven by pressure gradient and water, downward driven by gravity. The crimp geometry of the corrugations was drawn from typical corrugated sheets used as filling material in modern structured packed towers. Four regimes were featured, namely, rivulet, bicontinuous, flooding fronts, and flooding waves. It is conceivable that the regimes observed might constitute the basis for understanding how gas and liquid phases contend for available space in the interstices of structured packings in packed towers. Flow regime transitions were expressed in terms of liquid load (liquid superficial velocity) and gas flow factor parameters commonly used in pressure drop and capacity curves. We have carefully examined the range of parameters equivalent to the ill-understood high-liquid-flow operation in packed towers. More importantly, our findings should prove valuable in validating improved first-principles modeling of gas-liquid flows in these industrially important devices.

  2. Parallel flow diffusion battery

    DOEpatents

    Yeh, H.C.; Cheng, Y.S.

    1984-01-01

    A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.

  3. Parallel flow diffusion battery

    DOEpatents

    Yeh, Hsu-Chi; Cheng, Yung-Sung

    1984-08-07

    A parallel flow diffusion battery for determining the mass distribution of an aerosol has a plurality of diffusion cells mounted in parallel to an aerosol stream, each diffusion cell including a stack of mesh wire screens of different density.

  4. Theoretical study of the effect of liquid desiccant mass flow rate on the performance of a cross flow parallel-plate liquid desiccant-air dehumidifier

    NASA Astrophysics Data System (ADS)

    Mohammad, Abdulrahman Th.; Mat, Sohif Bin; Sulaiman, M. Y.; Sopian, K.; Al-abidi, Abduljalil A.

    2013-11-01

    A computer simulation using MATLAB is investigated to predict the distribution of air stream parameters (humidity ratio and temperature) as well as desiccant parameters (temperature and concentration) inside the parallel plate absorber. The present absorber consists of fourteen parallel plates with a surface area per unit volume ratio of 80 m2/m3. Calcium chloride as a liquid desiccant flows through the top of the plates to the bottom while the air flows through the gap between the plates making it a cross flow configuration. The model results show the effect of desiccant mass flow rate on the performance of the dehumidifier (moisture removal and dehumidifier effectiveness). Performance comparisons between present cross-flow dehumidifier and another experimental cross-flow dehumidifier in the literature are carried out. The simulation is expected to help in optimizing of a cross flow dehumidifier.

  5. 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.

  6. Stage-by-Stage and Parallel Flow Path Compressor Modeling for a Variable Cycle Engine, NASA Advanced Air Vehicles Program - Commercial Supersonic Technology Project - AeroServoElasticity

    NASA Technical Reports Server (NTRS)

    Kopasakis, George; Connolly, Joseph W.; Cheng, Larry

    2015-01-01

    This paper covers the development of stage-by-stage and parallel flow path compressor modeling approaches for a Variable Cycle Engine. The stage-by-stage compressor modeling approach is an extension of a technique for lumped volume dynamics and performance characteristic modeling. It was developed to improve the accuracy of axial compressor dynamics over lumped volume dynamics modeling. The stage-by-stage compressor model presented here is formulated into a parallel flow path model that includes both axial and rotational dynamics. This is done to enable the study of compressor and propulsion system dynamic performance under flow distortion conditions. The approaches utilized here are generic and should be applicable for the modeling of any axial flow compressor design accurate time domain simulations. The objective of this work is as follows. Given the parameters describing the conditions of atmospheric disturbances, and utilizing the derived formulations, directly compute the transfer function poles and zeros describing these disturbances for acoustic velocity, temperature, pressure, and density. Time domain simulations of representative atmospheric turbulence can then be developed by utilizing these computed transfer functions together with the disturbance frequencies of interest.

  7. Self-sustained radial oscillating flows between parallel disks

    NASA Astrophysics Data System (ADS)

    Mochizuki, S.; Yang, W.-J.

    1985-05-01

    It is pointed out that radial flow between parallel circular disks is of interest in a number of physical systems such as hydrostatic air bearings, radial diffusers, and VTOL aircraft with centrally located downward-positioned jets. The present investigation is concerned with the problem of instability in radial flow between parallel disks. A time-dependent numerical study and experiments are conducted. Both approaches reveal the nucleation, growth, migration, and decay of annular separation bubbles (i.e. vortex or recirculation zones) in the laminar-flow region. A finite-difference technique is utilized to solve the full unsteady vorticity transport equation in the theoretical procedure, while the flow patterns in the experiments are visualized with the aid of dye-injection, hydrogen-bubble, and paraffin-mist methods. It is found that the separation and reattachment of shear layers in the radial flow through parallel disks are unsteady phenomena. The sequence of nucleation, growth, migration, and decay of the vortices is self-sustained.

  8. Causality and the stability of parallel flow

    NASA Astrophysics Data System (ADS)

    Chimonas, George

    1991-11-01

    The linearized theory of the stability of parallel flow is formulated in terms of causality theory. In this method the properties of the Fourier spectrum—the disturbances with real frequency ω—provide the stability criteria for a system. In particular, if the Fourier spectrum provides a complete cause-and-effect formulation, the flow is assuredly stable. This single restriction leads to the critical-level theorems for parallel flows in both stably and unstably stratified fluids, Howard's semicircle theorem, the Miles-Howard Richardson-number criterion, an extended semicircle theorem for unstable flows, and several other results concerning instabilities in fluids. The causal approach supersedes group-velocity concepts, and resolves the problems of defining upward- and downward-propagating signals in a rapidly varying medium. It also associates a causal behavior to scattering from a discontinuity or an interface. Causality is examined by subdividing the continuous fluid into a set of homogeneous intervals within which propagation and interfacial scattering can be explicitly computed. As the intervals are reduced toward infinitesimal size the solution for the continuous fluid is obtained.

  9. HELENA code with incompressible parallel plasma flow

    NASA Astrophysics Data System (ADS)

    Throumoulopoulos, George; Poulipoulis, George; Konz, Christian; EFDA ITM-TF Team

    2015-11-01

    It has been established that plasma rotation in connection to both zonal and equilibrium flow can play a role in the transitions to the advanced confinement regimes in tokamaks, as the L-H transition and the formation of Internal Transport Barriers. For incompressible rotation the equilibrium is governed by a generalized Grad-Shafranov (GGS) equation and a decoupled Bernoulli-type equation for the pressure. For parallel flow the GGS equation can be transformed to one identical in form with the usual Grad-Shafranov equation. In the present study on the basis of the latter equation we have extended HELENA, an equilibrium fixed boundary solver integrated in the ITM-TF modeling infrastructure. The extended code solves the GGS equation for a variety of the two free-surface-function terms involved for arbitrary Afvén Mach functions. We have constructed diverted-boundary equilibria pertinent to ITER and examined their characteristics, in particular as concerns the impact of rotation. It turns out that the rotation affects noticeably the pressure and toroidal current density with the impact on the current density being stronger in the parallel direction than in the toroidal one. Also, the linear stability of the equilibria constructed is examined This work has been carried out within the framework of the EUROfuion Consortium and has received funding from the National Programme for the Controlled Thermonuclear Fusion, Hellenic Republic.

  10. 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.

  11. Receptivity in parallel flows: An adjoint approach

    NASA Technical Reports Server (NTRS)

    Hill, D. Christopher

    1993-01-01

    Linear receptivity studies in parallel flows are aimed at understanding how external forcing couples to the natural unstable motions which a flow can support. The vibrating ribbon problem models the original Schubauer and Skramstad boundary layer experiment and represents the classic boundary layer receptivity problem. The process by which disturbances are initiated in convectively-unstable jets and shear layers has also received attention. Gaster was the first to handle the boundary layer analysis with the recognition that spatial modes, rather than temporal modes, were relevant when studying convectively-unstable flows that are driven by a time-harmonic source. The amplitude of the least stable spatial mode, far downstream of the source, is related to the source strength by a coupling coefficient. The determination of this coefficient is at the heart of this type of linear receptivity study. The first objective of the present study was to determine whether the various wave number derivative factors, appearing in the coupling coefficients for linear receptivity problems, could be reexpressed in a simpler form involving adjoint eigensolutions. Secondly, it was hoped that the general nature of this simplification could be shown; indeed, a rather elegant characterization of the receptivity properties of spatial instabilities does emerge. The analysis is quite distinct from the usual Fourier-inversion procedures, although a detailed knowledge of the spectrum of the Orr-Sommerfeld equation is still required. Since the cylinder wake analysis proved very useful in addressing control considerations, the final objective was to provide a foundation upon which boundary layer control theory may be developed.

  12. Application of a parallel DSMC method to hypersonic rarefied flows

    SciTech Connect

    Wilmoth, R.G. )

    1991-01-01

    This paper describes a method for doing direct simulation Monte Carlo (DSMC) calculations using parallel processing and presents some results of applying the method to several hypersonic, rarefied flow problems. The performance and efficiency of the parallel method are discussed. The applications described are the flow in a channel and the flow about a flat plate at incidence. The results show significant advantages of parallel processing over conventional scalar processing and demonstrate the scalability of the method to large problems. 8 refs.

  13. Evaporation of stationary alcohol layer in minichannel under air flow

    NASA Astrophysics Data System (ADS)

    Afanasyev, Ilya; Orlova, Evgenija; Feoktistov, Dmitriy

    2015-01-01

    This paper presents experimental investigation of effect of the gas flow rate moving parallel to the stationary liquid layer on the evaporation rate under the conditions of formation of a stable plane "liquid-gas" interface. The average evaporation flow rate of liquid layer (ethanol) by the gas flow (air) has been calculated using two independent methods. Obtained results have been compared with previously published data.

  14. Parallel finite element simulation of large ram-air parachutes

    NASA Astrophysics Data System (ADS)

    Kalro, V.; Aliabadi, S.; Garrard, W.; Tezduyar, T.; Mittal, S.; Stein, K.

    1997-06-01

    In the near future, large ram-air parachutes are expected to provide the capability of delivering 21 ton payloads from altitudes as high as 25,000 ft. In development and test and evaluation of these parachutes the size of the parachute needed and the deployment stages involved make high-performance computing (HPC) simulations a desirable alternative to costly airdrop tests. Although computational simulations based on realistic, 3D, time-dependent models will continue to be a major computational challenge, advanced finite element simulation techniques recently developed for this purpose and the execution of these techniques on HPC platforms are significant steps in the direction to meet this challenge. In this paper, two approaches for analysis of the inflation and gliding of ram-air parachutes are presented. In one of the approaches the point mass flight mechanics equations are solved with the time-varying drag and lift areas obtained from empirical data. This approach is limited to parachutes with similar configurations to those for which data are available. The other approach is 3D finite element computations based on the Navier-Stokes equations governing the airflow around the parachute canopy and Newtons law of motion governing the 3D dynamics of the canopy, with the forces acting on the canopy calculated from the simulated flow field. At the earlier stages of canopy inflation the parachute is modelled as an expanding box, whereas at the later stages, as it expands, the box transforms to a parafoil and glides. These finite element computations are carried out on the massively parallel supercomputers CRAY T3D and Thinking Machines CM-5, typically with millions of coupled, non-linear finite element equations solved simultaneously at every time step or pseudo-time step of the simulation.

  15. High order parallel numerical schemes for solving incompressible flows

    NASA Technical Reports Server (NTRS)

    Lin, Avi; Milner, Edward J.; Liou, May-Fun; Belch, Richard A.

    1992-01-01

    The use of parallel computers for numerically solving flow fields has gained much importance in recent years. This paper introduces a new high order numerical scheme for computational fluid dynamics (CFD) specifically designed for parallel computational environments. A distributed MIMD system gives the flexibility of treating different elements of the governing equations with totally different numerical schemes in different regions of the flow field. The parallel decomposition of the governing operator to be solved is the primary parallel split. The primary parallel split was studied using a hypercube like architecture having clusters of shared memory processors at each node. The approach is demonstrated using examples of simple steady state incompressible flows. Future studies should investigate the secondary split because, depending on the numerical scheme that each of the processors applies and the nature of the flow in the specific subdomain, it may be possible for a processor to seek better, or higher order, schemes for its particular subcase.

  16. 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.

  17. Neoclassical parallel flow calculation in the presence of external parallel momentum sources in Heliotron J

    NASA Astrophysics Data System (ADS)

    Nishioka, K.; Nakamura, Y.; Nishimura, S.; Lee, H. Y.; Kobayashi, S.; Mizuuchi, T.; Nagasaki, K.; Okada, H.; Minami, T.; Kado, S.; Yamamoto, S.; Ohshima, S.; Konoshima, S.; Sano, F.

    2016-03-01

    A moment approach to calculate neoclassical transport in non-axisymmetric torus plasmas composed of multiple ion species is extended to include the external parallel momentum sources due to unbalanced tangential neutral beam injections (NBIs). The momentum sources that are included in the parallel momentum balance are calculated from the collision operators of background particles with fast ions. This method is applied for the clarification of the physical mechanism of the neoclassical parallel ion flows and the multi-ion species effect on them in Heliotron J NBI plasmas. It is found that parallel ion flow can be determined by the balance between the parallel viscosity and the external momentum source in the region where the external source is much larger than the thermodynamic force driven source in the collisional plasmas. This is because the friction between C6+ and D+ prevents a large difference between C6+ and D+ flow velocities in such plasmas. The C6+ flow velocities, which are measured by the charge exchange recombination spectroscopy system, are numerically evaluated with this method. It is shown that the experimentally measured C6+ impurity flow velocities do not contradict clearly with the neoclassical estimations, and the dependence of parallel flow velocities on the magnetic field ripples is consistent in both results.

  18. Massively Parallel Direct Simulation of Multiphase Flow

    SciTech Connect

    COOK,BENJAMIN K.; PREECE,DALE S.; WILLIAMS,J.R.

    2000-08-10

    The authors understanding of multiphase physics and the associated predictive capability for multi-phase systems are severely limited by current continuum modeling methods and experimental approaches. This research will deliver an unprecedented modeling capability to directly simulate three-dimensional multi-phase systems at the particle-scale. The model solves the fully coupled equations of motion governing the fluid phase and the individual particles comprising the solid phase using a newly discovered, highly efficient coupled numerical method based on the discrete-element method and the Lattice-Boltzmann method. A massively parallel implementation will enable the solution of large, physically realistic systems.

  19. Modeling groundwater flow on massively parallel computers

    SciTech Connect

    Ashby, S.F.; Falgout, R.D.; Fogwell, T.W.; Tompson, A.F.B.

    1994-12-31

    The authors will explore the numerical simulation of groundwater flow in three-dimensional heterogeneous porous media. An interdisciplinary team of mathematicians, computer scientists, hydrologists, and environmental engineers is developing a sophisticated simulation code for use on workstation clusters and MPPs. To date, they have concentrated on modeling flow in the saturated zone (single phase), which requires the solution of a large linear system. they will discuss their implementation of preconditioned conjugate gradient solvers. The preconditioners under consideration include simple diagonal scaling, s-step Jacobi, adaptive Chebyshev polynomial preconditioning, and multigrid. They will present some preliminary numerical results, including simulations of groundwater flow at the LLNL site. They also will demonstrate the code`s scalability.

  20. Annular fuel and air co-flow premixer

    SciTech Connect

    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.

  1. Multichannel quench-flow microreactor chip for parallel reaction monitoring.

    PubMed

    Bula, Wojciech P; Verboom, Willem; Reinhoudt, David N; Gardeniers, Han J G E

    2007-12-01

    This paper describes a multichannel silicon-glass microreactor which has been utilized to investigate the kinetics of a Knoevenagel condensation reaction under different reaction conditions. The reaction is performed on the chip in four parallel channels under identical conditions but with different residence times. A special topology of the reaction coils overcomes the common problem arising from the difference in pressure drop of parallel channels having different length. The parallelization of reaction coils combined with chemical quenching at specific locations results in a considerable reduction in experimental effort and cost. The system was tested and showed good reproducibility in flow properties and reaction kinetic data generation. PMID:18030392

  2. The transition to turbulence in parallel flows: A personal view

    NASA Astrophysics Data System (ADS)

    Pomeau, Yves

    2015-03-01

    This is a discussion of the present understanding of transition to turbulence in parallel flows, based upon the idea that it arises from a subcritical instability. The result is a coupled set of equations, one amplitude equation in the direction of translational invariance of the geometry coupled with the standard Reynolds equation for the average transfer of momentum. It helps to understand a basic feature of the transition in parallel flows, namely that turbulence manifests itself in localised domains growing at a constant speed depending on the Reynolds number.

  3. Heat transfer optimization for air-mist cooling between a stack of parallel plates

    NASA Astrophysics Data System (ADS)

    Issa, Roy J.

    2010-06-01

    A theoretical model is developed to predict the upper limit heat transfer between a stack of parallel plates subject to multiphase cooling by air-mist flow. The model predicts the optimal separation distance between the plates based on the development of the boundary layers for small and large separation distances, and for dilute mist conditions. Simulation results show the optimal separation distance to be strongly dependent on the liquid-to-air mass flow rate loading ratio, and reach a limit for a critical loading. For these dilute spray conditions, complete evaporation of the droplets takes place. Simulation results also show the optimal separation distance decreases with the increase in the mist flow rate. The proposed theoretical model shall lead to a better understanding of the design of fins spacing in heat exchangers where multiphase spray cooling is used.

  4. Numerical simulation of supersonic wake flow with parallel computers

    SciTech Connect

    Wong, C.C.; Soetrisno, M.

    1995-07-01

    Simulating a supersonic wake flow field behind a conical body is a computing intensive task. It requires a large number of computational cells to capture the dominant flow physics and a robust numerical algorithm to obtain a reliable solution. High performance parallel computers with unique distributed processing and data storage capability can provide this need. They have larger computational memory and faster computing time than conventional vector computers. We apply the PINCA Navier-Stokes code to simulate a wind-tunnel supersonic wake experiment on Intel Gamma, Intel Paragon, and IBM SP2 parallel computers. These simulations are performed to study the mean flow in the near wake region of a sharp, 7-degree half-angle, adiabatic cone at Mach number 4.3 and freestream Reynolds number of 40,600. Overall the numerical solutions capture the general features of the hypersonic laminar wake flow and compare favorably with the wind tunnel data. With a refined and clustering grid distribution in the recirculation zone, the calculated location of the rear stagnation point is consistent with the 2D axisymmetric and 3D experiments. In this study, we also demonstrate the importance of having a large local memory capacity within a computer node and the effective utilization of the number of computer nodes to achieve good parallel performance when simulating a complex, large-scale wake flow problem.

  5. Parallel flow in hele-shaw cells with ferrofluids

    PubMed

    Miranda; Widom

    2000-02-01

    Parallel flow in a Hele-Shaw cell occurs when two immiscible liquids flow with relative velocity parallel to the interface between them. The interface is unstable due to a Kelvin-Helmholtz type of instability in which fluid flow couples with inertial effects to cause an initial small perturbation to grow. Large amplitude disturbances form stable solitons. We consider the effects of applied magnetic fields when one of the two fluids is a ferrofluid. The dispersion relation governing mode growth is modified so that the magnetic field can destabilize the interface even in the absence of inertial effects. However, the magnetic field does not affect the speed of wave propogation for a given wave number. We note that the magnetic field creates an effective interaction between the solitons. PMID:11046508

  6. Numerical Simulation of Flow Field Within Parallel Plate Plastometer

    NASA Technical Reports Server (NTRS)

    Antar, Basil N.

    2002-01-01

    Parallel Plate Plastometer (PPP) is a device commonly used for measuring the viscosity of high polymers at low rates of shear in the range 10(exp 4) to 10(exp 9) poises. This device is being validated for use in measuring the viscosity of liquid glasses at high temperatures having similar ranges for the viscosity values. PPP instrument consists of two similar parallel plates, both in the range of 1 inch in diameter with the upper plate being movable while the lower one is kept stationary. Load is applied to the upper plate by means of a beam connected to shaft attached to the upper plate. The viscosity of the fluid is deduced from measuring the variation of the plate separation, h, as a function of time when a specified fixed load is applied on the beam. Operating plate speeds measured with the PPP is usually in the range of 10.3 cm/s or lower. The flow field within the PPP can be simulated using the equations of motion of fluid flow for this configuration. With flow speeds in the range quoted above the flow field between the two plates is certainly incompressible and laminar. Such flows can be easily simulated using numerical modeling with computational fluid dynamics (CFD) codes. We present below the mathematical model used to simulate this flow field and also the solutions obtained for the flow using a commercially available finite element CFD code.

  7. Numerical simulation of polymer flows: A parallel computing approach

    SciTech Connect

    Aggarwal, R.; Keunings, R.; Roux, F.X.

    1993-12-31

    We present a parallel algorithm for the numerical simulation of viscoelastic fluids on distributed memory computers. The algorithm has been implemented within a general-purpose commercial finite element package used in polymer processing applications. Results obtained on the Intel iPSC/860 computer demonstrate high parallel efficiency in complex flow problems. However, since the computational load is unknown a priori, load balancing is a challenging issue. We have developed an adaptive allocation strategy which dynamically reallocates the work load to the processors based upon the history of the computational procedure. We compare the results obtained with the adaptive and static scheduling schemes.

  8. PArallel Reacting Multiphase FLOw Computational Fluid Dynamic Analysis

    2002-06-01

    PARMFLO is a parallel multiphase reacting flow computational fluid dynamics (CFD) code. It can perform steady or unsteady simulations in three space dimensions. It is intended for use in engineering CFD analysis of industrial flow system components. Its parallel processing capabilities allow it to be applied to problems that use at least an order of magnitude more computational cells than the number that can be used on a typical single processor workstation (about 106 cellsmore » in parallel processing mode versus about io cells in serial processing mode). Alternately, by spreading the work of a CFD problem that could be run on a single workstation over a group of computers on a network, it can bring the runtime down by an order of magnitude or more (typically from many days to less than one day). The software was implemented using the industry standard Message-Passing Interface (MPI) and domain decomposition in one spatial direction. The phases of a flow problem may include an ideal gas mixture with an arbitrary number of chemical species, and dispersed droplet and particle phases. Regions of porous media may also be included within the domain. The porous media may be packed beds, foams, or monolith catalyst supports. With these features, the code is especially suited to analysis of mixing of reactants in the inlet chamber of catalytic reactors coupled to computation of product yields that result from the flow of the mixture through the catalyst coaled support structure.« less

  9. PArallel Reacting Multiphase FLOw Computational Fluid Dynamic Analysis

    SciTech Connect

    Lottes, Steven A.

    2002-06-01

    PARMFLO is a parallel multiphase reacting flow computational fluid dynamics (CFD) code. It can perform steady or unsteady simulations in three space dimensions. It is intended for use in engineering CFD analysis of industrial flow system components. Its parallel processing capabilities allow it to be applied to problems that use at least an order of magnitude more computational cells than the number that can be used on a typical single processor workstation (about 106 cells in parallel processing mode versus about io cells in serial processing mode). Alternately, by spreading the work of a CFD problem that could be run on a single workstation over a group of computers on a network, it can bring the runtime down by an order of magnitude or more (typically from many days to less than one day). The software was implemented using the industry standard Message-Passing Interface (MPI) and domain decomposition in one spatial direction. The phases of a flow problem may include an ideal gas mixture with an arbitrary number of chemical species, and dispersed droplet and particle phases. Regions of porous media may also be included within the domain. The porous media may be packed beds, foams, or monolith catalyst supports. With these features, the code is especially suited to analysis of mixing of reactants in the inlet chamber of catalytic reactors coupled to computation of product yields that result from the flow of the mixture through the catalyst coaled support structure.

  10. Simulator Of Rain In Flowing Air

    NASA Technical Reports Server (NTRS)

    Clayton, Richard M.; Cho, Young I.; Shakkottai, Parthasarathy; Back, Lloyd H.

    1989-01-01

    Report describes relatively inexpensive apparatus that creates simulated precipitation from drizzle to heavy rain in flowing air. Small, positive-displacement pump and water-injecting device positioned at low-airspeed end of converging section of wind tunnel 10 in. in diameter. Drops injected by array entrained in flow of air as it accelerates toward narrower outlet, 15 in. downstream. Outlet 5 in. in diameter.

  11. Rivulet Flow In Vertical Parallel-Wall Channel

    SciTech Connect

    D. M. McEligot; G. E. Mc Creery; P. Meakin

    2006-04-01

    In comparison with studies of rivulet flow over external surfaces, rivulet flow confined by two surfaces has received almost no attention. Fully-developed rivulet flow in vertical parallel-wall channels was characterized, both experimentally and analytically for flows intermediate between a lower flow limit of drop flow and an upper limit where the rivulets meander. Although this regime is the most simple rivulet flow regime, it does not appear to have been previously investigated in detail. Experiments were performed that measured rivulet widths for aperture spacing ranging from 0.152 mm to 0.914 mm. The results were compared with a simple steadystate analytical model for laminar flow. The model divides the rivulet cross-section into an inner region, which is dominated by viscous and gravitational forces and where essentially all flow is assumed to occur, and an outer region, dominated by capillary forces, where the geometry is determined by the contact angle between the fluid and the wall. Calculations using the model provided excellent agreement with data for inner rivulet widths and good agreement with measurements of outer rivulet widths.

  12. Heavy Impurity Entrainment in the Parallel Flows of CSDX

    NASA Astrophysics Data System (ADS)

    Gosselin, Jordan; Thakur, Saikat; Tynan, George

    2014-10-01

    The lifetime of the plasma facing components (PFCs) in a tokamak, governed primarily by material erosion and redeposition, has been identified as a crucial research topic. While some work has been done that shows evidence of the entrainment of impurities in linear machines and in tokamaks, detailed controlled studies of entrainment in plasma flows are harder to come by. Recently, experiments in CSDX have shown increasing parallel ion velocity positively correlated with increasing magnetic field. In an effort to study the effects of the background flow on impurity transport, a laser blow off apparatus was installed on the Controlled Shear Decorelation eXperiment (a 3m long linear helicon source operated plasma machine). Results are shown for parallel entrainment of Bismuth impurities in a relatively light background Ar plasma (5.2 mass ratio).

  13. Modeling of supersonic combustor flows using parallel computing

    NASA Technical Reports Server (NTRS)

    Riggins, D.; Underwood, M.; Mcmillin, B.; Reeves, L.; Lu, E. J.-L.

    1992-01-01

    While current 3D CFD codes and modeling techniques have been shown capable of furnishing engineering data for complex scramjet flowfields, the usefulness of such efforts is primarily limited by solutions' CPU time requirements, and secondarily by memory requirements. Attention is presently given to the use of parallel computing capabilities for engineering CFD tools for the analysis of supersonic reacting flows, and to an illustrative incompressible CFD problem using up to 16 iPSC/2 processors with single-domain decomposition.

  14. Flow invariant droplet formation for stable parallel microreactors

    PubMed Central

    Riche, Carson T.; Roberts, Emily J.; Gupta, Malancha; Brutchey, Richard L.; Malmstadt, Noah

    2016-01-01

    The translation of batch chemistries onto continuous flow platforms requires addressing the issues of consistent fluidic behaviour, channel fouling and high-throughput processing. Droplet microfluidic technologies reduce channel fouling and provide an improved level of control over heat and mass transfer to control reaction kinetics. However, in conventional geometries, the droplet size is sensitive to changes in flow rates. Here we report a three-dimensional droplet generating device that exhibits flow invariant behaviour and is robust to fluctuations in flow rate. In addition, the droplet generator is capable of producing droplet volumes spanning four orders of magnitude. We apply this device in a parallel network to synthesize platinum nanoparticles using an ionic liquid solvent, demonstrate reproducible synthesis after recycling the ionic liquid, and double the reaction yield compared with an analogous batch synthesis. PMID:26902825

  15. Flow invariant droplet formation for stable parallel microreactors

    NASA Astrophysics Data System (ADS)

    Riche, Carson T.; Roberts, Emily J.; Gupta, Malancha; Brutchey, Richard L.; Malmstadt, Noah

    2016-02-01

    The translation of batch chemistries onto continuous flow platforms requires addressing the issues of consistent fluidic behaviour, channel fouling and high-throughput processing. Droplet microfluidic technologies reduce channel fouling and provide an improved level of control over heat and mass transfer to control reaction kinetics. However, in conventional geometries, the droplet size is sensitive to changes in flow rates. Here we report a three-dimensional droplet generating device that exhibits flow invariant behaviour and is robust to fluctuations in flow rate. In addition, the droplet generator is capable of producing droplet volumes spanning four orders of magnitude. We apply this device in a parallel network to synthesize platinum nanoparticles using an ionic liquid solvent, demonstrate reproducible synthesis after recycling the ionic liquid, and double the reaction yield compared with an analogous batch synthesis.

  16. Relativistic radiative transfer and relativistic plane-parallel flows

    NASA Astrophysics Data System (ADS)

    Fukue, Jun

    2015-04-01

    Relativistic radiative transfer and relativistic plane-parallel flows accelerated from their base like accretion disk winds are numerically examined under the special relativistic treatment. We first solve the relativistic transfer equation iteratively, using a given velocity field, and obtain specific intensities as well as moment quantities. Using the obtained flux, we then solve the hydrodynamical equation, and obtain the new velocity field and the mass-loss rate as an eigen value. We repeat these double-iteration processes until both the intensity and velocity profiles converge. Under this double iteration, we solve the relativistic radiative transfer equation and relativistic flows in the vertical direction, simultaneously. The flows are gradually accelerated, as the optical depth decreases towards the surface. The mass-loss rate dot{J} is roughly expressed in terms of the optical depth τb and terminal speed βs of the flow as dot{J} ˜ 10 τ_b β _s^{-3/4}.

  17. Flow invariant droplet formation for stable parallel microreactors.

    PubMed

    Riche, Carson T; Roberts, Emily J; Gupta, Malancha; Brutchey, Richard L; Malmstadt, Noah

    2016-01-01

    The translation of batch chemistries onto continuous flow platforms requires addressing the issues of consistent fluidic behaviour, channel fouling and high-throughput processing. Droplet microfluidic technologies reduce channel fouling and provide an improved level of control over heat and mass transfer to control reaction kinetics. However, in conventional geometries, the droplet size is sensitive to changes in flow rates. Here we report a three-dimensional droplet generating device that exhibits flow invariant behaviour and is robust to fluctuations in flow rate. In addition, the droplet generator is capable of producing droplet volumes spanning four orders of magnitude. We apply this device in a parallel network to synthesize platinum nanoparticles using an ionic liquid solvent, demonstrate reproducible synthesis after recycling the ionic liquid, and double the reaction yield compared with an analogous batch synthesis. PMID:26902825

  18. Air flow cued spatial learning in mice.

    PubMed

    Bouchekioua, Youcef; Mimura, Masaru; Watanabe, Shigeru

    2015-01-01

    Spatial learning experiments in rodents typically employ visual cues that are associated with a goal place, even though it is now well established that they have poor visual acuity. We assessed here the possibility of spatial learning in mice based on an air flow cue in a dry version of the Morris water maze task. A miniature fan was placed at each of the four cardinal points of the circular maze, but only one blew air towards the centre of the maze. The three other fans were blowing towards their own box. The mice were able to learn the task only if the spatial relationship between the air flow cue and the position of the goal place was kept constant across trials. A change of this spatial relationship resulted in an increase in the time to find the goal place. We report here the first evidence of spatial learning relying on an air flow cue. PMID:25257773

  19. Reduced description of exact coherent states in parallel shear flows.

    PubMed

    Beaume, Cédric; Chini, Gregory P; Julien, Keith; Knobloch, Edgar

    2015-04-01

    A reduced description of exact coherent structures in the transition regime of plane parallel shear flows is developed, based on the Reynolds number scaling of streamwise-averaged (mean) and streamwise-varying (fluctuation) velocities observed in numerical simulations. The resulting system is characterized by an effective unit Reynolds number mean equation coupled to linear equations for the fluctuations, regularized by formally higher-order diffusion. Stationary coherent states are computed by solving the resulting equations simultaneously using a robust numerical algorithm developed for this purpose. The algorithm determines self-consistently the amplitude of the fluctuations for which the associated mean flow is just such that the fluctuations neither grow nor decay. The procedure is used to compute exact coherent states of a flow introduced by Drazin and Reid [Hydrodynamic Stability (Cambridge University Press, Cambridge, UK, 1981)] and studied by Waleffe [Phys. Fluids 9, 883 (1997)]: a linearly stable, plane parallel shear flow confined between stationary stress-free walls and driven by a sinusoidal body force. Numerical continuation of the lower-branch states to lower Reynolds numbers reveals the presence of a saddle node; the saddle node allows access to upper-branch states that are, like the lower-branch states, self-consistently described by the reduced equations. Both lower- and upper-branch states are characterized in detail. PMID:25974583

  20. Reduced description of exact coherent states in parallel shear flows

    NASA Astrophysics Data System (ADS)

    Beaume, Cédric; Chini, Gregory P.; Julien, Keith; Knobloch, Edgar

    2015-04-01

    A reduced description of exact coherent structures in the transition regime of plane parallel shear flows is developed, based on the Reynolds number scaling of streamwise-averaged (mean) and streamwise-varying (fluctuation) velocities observed in numerical simulations. The resulting system is characterized by an effective unit Reynolds number mean equation coupled to linear equations for the fluctuations, regularized by formally higher-order diffusion. Stationary coherent states are computed by solving the resulting equations simultaneously using a robust numerical algorithm developed for this purpose. The algorithm determines self-consistently the amplitude of the fluctuations for which the associated mean flow is just such that the fluctuations neither grow nor decay. The procedure is used to compute exact coherent states of a flow introduced by Drazin and Reid [Hydrodynamic Stability (Cambridge University Press, Cambridge, UK, 1981)] and studied by Waleffe [Phys. Fluids 9, 883 (1997), 10.1063/1.869185]: a linearly stable, plane parallel shear flow confined between stationary stress-free walls and driven by a sinusoidal body force. Numerical continuation of the lower-branch states to lower Reynolds numbers reveals the presence of a saddle node; the saddle node allows access to upper-branch states that are, like the lower-branch states, self-consistently described by the reduced equations. Both lower- and upper-branch states are characterized in detail.

  1. Parallel Continuous Flow: A Parallel Suffix Tree Construction Tool for Whole Genomes

    PubMed Central

    Farreras, Montse

    2014-01-01

    Abstract The construction of suffix trees for very long sequences is essential for many applications, and it plays a central role in the bioinformatic domain. With the advent of modern sequencing technologies, biological sequence databases have grown dramatically. Also the methodologies required to analyze these data have become more complex everyday, requiring fast queries to multiple genomes. In this article, we present parallel continuous flow (PCF), a parallel suffix tree construction method that is suitable for very long genomes. We tested our method for the suffix tree construction of the entire human genome, about 3GB. We showed that PCF can scale gracefully as the size of the input genome grows. Our method can work with an efficiency of 90% with 36 processors and 55% with 172 processors. We can index the human genome in 7 minutes using 172 processes. PMID:24597675

  2. Air flow through poppet valves

    NASA Technical Reports Server (NTRS)

    Lewis, G W; Nutting, E M

    1920-01-01

    Report discusses the comparative continuous flow characteristics of single and double poppet valves. The experimental data presented affords a direct comparison of valves, single and in pairs of different sizes, tested in a cylinder designed in accordance with current practice in aviation engines.

  3. Predicting the stability of a compressible periodic parallel jet flow

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey H.

    1996-01-01

    It is known that mixing enhancement in compressible free shear layer flows with high convective Mach numbers is difficult. One design strategy to get around this is to use multiple nozzles. Extrapolating this design concept in a one dimensional manner, one arrives at an array of parallel rectangular nozzles where the smaller dimension is omega and the longer dimension, b, is taken to be infinite. In this paper, the feasibility of predicting the stability of this type of compressible periodic parallel jet flow is discussed. The problem is treated using Floquet-Bloch theory. Numerical solutions to this eigenvalue problem are presented. For the case presented, the interjet spacing, s, was selected so that s/omega =2.23. Typical plots of the eigenvalue and stability curves are presented. Results obtained for a range of convective Mach numbers from 3 to 5 show growth rates omega(sub i)=kc(sub i)/2 range from 0.25 to 0.29. These results indicate that coherent two-dimensional structures can occur without difficulty in multiple parallel periodic jet nozzles and that shear layer mixing should occur with this type of nozzle design.

  4. Algorithms for parallel flow solvers on message passing architectures

    NASA Technical Reports Server (NTRS)

    Vanderwijngaart, Rob F.

    1995-01-01

    The purpose of this project has been to identify and test suitable technologies for implementation of fluid flow solvers -- possibly coupled with structures and heat equation solvers -- on MIMD parallel computers. In the course of this investigation much attention has been paid to efficient domain decomposition strategies for ADI-type algorithms. Multi-partitioning derives its efficiency from the assignment of several blocks of grid points to each processor in the parallel computer. A coarse-grain parallelism is obtained, and a near-perfect load balance results. In uni-partitioning every processor receives responsibility for exactly one block of grid points instead of several. This necessitates fine-grain pipelined program execution in order to obtain a reasonable load balance. Although fine-grain parallelism is less desirable on many systems, especially high-latency networks of workstations, uni-partition methods are still in wide use in production codes for flow problems. Consequently, it remains important to achieve good efficiency with this technique that has essentially been superseded by multi-partitioning for parallel ADI-type algorithms. Another reason for the concentration on improving the performance of pipeline methods is their applicability in other types of flow solver kernels with stronger implied data dependence. Analytical expressions can be derived for the size of the dynamic load imbalance incurred in traditional pipelines. From these it can be determined what is the optimal first-processor retardation that leads to the shortest total completion time for the pipeline process. Theoretical predictions of pipeline performance with and without optimization match experimental observations on the iPSC/860 very well. Analysis of pipeline performance also highlights the effect of uncareful grid partitioning in flow solvers that employ pipeline algorithms. If grid blocks at boundaries are not at least as large in the wall-normal direction as those

  5. Toward parallel, adaptive mesh refinement for chemically reacting flow simulations

    SciTech Connect

    Devine, K.D.; Shadid, J.N.; Salinger, A.G. Hutchinson, S.A.; Hennigan, G.L.

    1997-12-01

    Adaptive numerical methods offer greater efficiency than traditional numerical methods by concentrating computational effort in regions of the problem domain where the solution is difficult to obtain. In this paper, the authors describe progress toward adding mesh refinement to MPSalsa, a computer program developed at Sandia National laboratories to solve coupled three-dimensional fluid flow and detailed reaction chemistry systems for modeling chemically reacting flow on large-scale parallel computers. Data structures that support refinement and dynamic load-balancing are discussed. Results using uniform refinement with mesh sequencing to improve convergence to steady-state solutions are also presented. Three examples are presented: a lid driven cavity, a thermal convection flow, and a tilted chemical vapor deposition reactor.

  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...

  7. Domain decomposition methods for the parallel computation of reacting flows

    NASA Astrophysics Data System (ADS)

    Keyes, David E.

    1989-05-01

    Domain decomposition is a natural route to parallel computing for partial differential equation solvers. In this procedure, subdomains of which the original domain of definition is comprised are assigned to independent processors at the price of periodic coordination between processors to compute global parameters and maintain the requisite degree of continuity of the solution at the subdomain interfaces. In the domain-decomposed solution of steady multidimensional systems of PDEs by finite difference methods using a pseudo-transient version of Newton iteration, the only portion of the computation which generally stands in the way of efficient parallelization is the solution of the large, sparse linear systems arising at each Newton step. For some Jacobian matrices drawn from an actual two-dimensional reacting flow problem, we make comparisons between relaxation-based linear solvers and also preconditioned iterative methods of Conjugate Gradient and Chebyshev type, focusing attention on both iteration count and global inner product count. The generalized minimum residual method with block-ILU preconditioning is judged the best serial method among those considered, and parallel numerical experiments on the Encore Multimax demostrate for it approximately 10-fold speedup on 16 processsors. The three special features of reacting flow models in relation to these linear systems are: the possibly large number of degrees of freedom per gridpoint, the dominance of dense intra-point source-term coupling over inter-point convective-diffusive coupling throughout significant portions of the flow-field and strong nonlinearities which restrict the time step to small values (independent of linear algebraic considerations) throughout significant portions of the iteration history. Though these features are exploited to advantage herein, many aspects of the paper are applicable to the modeling of general convective-diffusive systems.

  8. PIV investigation of the intake flow in a parallel valves diesel engine cylinder

    NASA Astrophysics Data System (ADS)

    Alfredsson, P. Henrik; Rabault, Jean; Vernet, Julie A.; Lindgren, Björn

    2015-11-01

    The flow of air (gas) inside the cylinder of internal combustion engines prior to compression may have a large influence on the combustion process. The structure of the in-cylinder flow, which can be swirl or tumble dominated, is to a large extent controlled by the design of the intake ports. In this study the admission flow generated by a parallel valves diesel engine cylinder head was investigated in a steady flow test bench through planar and stereo PIV measurements in both the swirl and tumble planes. By combining several sets of measurements a full three-dimensional, three-component reconstruction of the mean flow field was made. The flow out of the valves has a radial jet character, making the air hit the cylinder wall before flowing down along the cylinder wall. This leads to the formation of a recirculation bubble in the tumble plane. In the swirl plane complex jet dominated structures are found just below the valves giving rise to a counter-rotating vortex pair, where the strongest vortex becomes predominant giving rise to a single coherent swirling structure away from the cylinder head. Variations of the location and strength of the swirling structure may give rise to cycle-to-cycle variations and its stability was analysed by tracking the vortex centre. Supported by SSF, Swedish Foundation for Strategic Research and Scania CV AB.

  9. Domain decomposition methods for the parallel computation of reacting flows

    NASA Technical Reports Server (NTRS)

    Keyes, David E.

    1988-01-01

    Domain decomposition is a natural route to parallel computing for partial differential equation solvers. Subdomains of which the original domain of definition is comprised are assigned to independent processors at the price of periodic coordination between processors to compute global parameters and maintain the requisite degree of continuity of the solution at the subdomain interfaces. In the domain-decomposed solution of steady multidimensional systems of PDEs by finite difference methods using a pseudo-transient version of Newton iteration, the only portion of the computation which generally stands in the way of efficient parallelization is the solution of the large, sparse linear systems arising at each Newton step. For some Jacobian matrices drawn from an actual two-dimensional reacting flow problem, comparisons are made between relaxation-based linear solvers and also preconditioned iterative methods of Conjugate Gradient and Chebyshev type, focusing attention on both iteration count and global inner product count. The generalized minimum residual method with block-ILU preconditioning is judged the best serial method among those considered, and parallel numerical experiments on the Encore Multimax demonstrate for it approximately 10-fold speedup on 16 processors.

  10. Massively parallel simulations of multiphase flows using Lattice Boltzmann methods

    NASA Astrophysics Data System (ADS)

    Ahrenholz, Benjamin

    2010-03-01

    In the last two decades the lattice Boltzmann method (LBM) has matured as an alternative and efficient numerical scheme for the simulation of fluid flows and transport problems. Unlike conventional numerical schemes based on discretizations of macroscopic continuum equations, the LBM is based on microscopic models and mesoscopic kinetic equations. The fundamental idea of the LBM is to construct simplified kinetic models that incorporate the essential physics of microscopic or mesoscopic processes so that the macroscopic averaged properties obey the desired macroscopic equations. Especially applications involving interfacial dynamics, complex and/or changing boundaries and complicated constitutive relationships which can be derived from a microscopic picture are suitable for the LBM. In this talk a modified and optimized version of a Gunstensen color model is presented to describe the dynamics of the fluid/fluid interface where the flow field is based on a multi-relaxation-time model. Based on that modeling approach validation studies of contact line motion are shown. Due to the fact that the LB method generally needs only nearest neighbor information, the algorithm is an ideal candidate for parallelization. Hence, it is possible to perform efficient simulations in complex geometries at a large scale by massively parallel computations. Here, the results of drainage and imbibition (Degree of Freedom > 2E11) in natural porous media gained from microtomography methods are presented. Those fully resolved pore scale simulations are essential for a better understanding of the physical processes in porous media and therefore important for the determination of constitutive relationships.

  11. Implementation of Parallel Computing Technology to Vortex Flow

    NASA Technical Reports Server (NTRS)

    Dacles-Mariani, Jennifer

    1999-01-01

    Mainframe supercomputers such as the Cray C90 was invaluable in obtaining large scale computations using several millions of grid points to resolve salient features of a tip vortex flow over a lifting wing. However, real flight configurations require tracking not only of the flow over several lifting wings but its growth and decay in the near- and intermediate- wake regions, not to mention the interaction of these vortices with each other. Resolving and tracking the evolution and interaction of these vortices shed from complex bodies is computationally intensive. Parallel computing technology is an attractive option in solving these flows. In planetary science vortical flows are also important in studying how planets and protoplanets form when cosmic dust and gases become gravitationally unstable and eventually form planets or protoplanets. The current paradigm for the formation of planetary systems maintains that the planets accreted from the nebula of gas and dust left over from the formation of the Sun. Traditional theory also indicate that such a preplanetary nebula took the form of flattened disk. The coagulation of dust led to the settling of aggregates toward the midplane of the disk, where they grew further into asteroid-like planetesimals. Some of the issues still remaining in this process are the onset of gravitational instability, the role of turbulence in the damping of particles and radial effects. In this study the focus will be with the role of turbulence and the radial effects.

  12. Parallel strip waveguide for ultrasonic flow measurement in harsh environments.

    PubMed

    Laws, Michael; Ramadas, Sivaram N; Lynnworth, Lawrence C; Dixon, Steve

    2015-04-01

    Wetted ultrasonic transit time flow meters typically consist of one or more pairs of transducers, containing piezoelectric elements, which alternate between transmitting and detecting an ultrasonic pulse. Typical piezoelectric materials and the adhesives used to attach the piezoelectric element in such devices can be damaged by hostile environments, such as extreme temperature, potentially limiting possible applications of ultrasonic flow measurement techniques. We have investigated a design for a flow meter with an integrated thermal buffer waveguide consisting of five parallel stainless steel strips. These, in addition to thermal protection, may function as a transducer array, with the possibility of steering the emitted field. Because the buffer strips used in the transducer assembly are thin, one might expect Lamb-like guided waves to propagate along it. However, the finite width of the strips has a significant effect on the propagation characteristics of the guided waves. In this work, the effect of the waveguide's small rectangular cross-section has been studied. Additionally, we have examined the effect of thermal gradients on the average sound speed and dispersion characteristics of such strip waveguides. We also suggest modifications to the plate geometry, which can alter both the frequency content and the shape of the transmitted pulse, potentially giving a better signal to use in flow measurement. PMID:25881347

  13. Columbia University flow instability experimental program: Volume 3. Single tube parallel flow tests

    SciTech Connect

    Dougherty, T.; Maciuca, C.; McAssey, E.V. Jr.; Reddy, D.G.; Yang, B.W.

    1990-06-01

    The coolant in the Savannah River Site (SRS) production nuclear reactor assemblies is circulated as a subcooled liquid under normal operating conditions. This coolant is evenly distributed throughout multiple annular flow channels with a uniform pressure profile across each coolant flow channel. During the postulated Loss of Coolant Accident (LOCA), which is initiated by a hypothetical guillotine pipe break, the coolant flow through the reactor assemblies is significantly reduced. The flow reduction and accompanying power reduction (after shutdown is initiated) occur in the first 1--2 seconds of the LOCA. This portion of the LOCA is referred to as the Flow Instability phase. A series of down flow experiments have been conducted on three different size single tubes. The objective of these experiments was to determine the effect of a parallel flow path on the occurrence of flow instability. In all cases, it has been shown that the point of flow instability (OFI) determined under controlled flow operation does not change when operating in a controlled pressure drop mode (parallel path operation).

  14. Nitric oxide flow tagging in unseeded air.

    PubMed

    Dam, N; Klein-Douwel, R J; Sijtsema, N M; Meulen, J J

    2001-01-01

    A scheme for molecular tagging velocimetry is presented that can be used in air flows without any kind of seeding. The method is based on the local and instantaneous creation of nitric oxide (NO) molecules from N(2) and O(2) in the waist region of a focused ArF excimer laser beam. This NO distribution is advected by the flow and can be visualized any time later by laser-induced fluorescence in the gamma bands. The creation of NO is confirmed by use of an excitation spectrum. Two examples of the application of the new scheme for air-flow velocimetry are given in which single laser pulses are used for creation and visualization of NO. PMID:18033499

  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...

  16. 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...

  17. Parallel magnetic resonance imaging of gas-liquid flows

    NASA Astrophysics Data System (ADS)

    Mueller, Christoph; Penn, Alexander; Pruessmann, Klaas P.

    2015-03-01

    Gas-liquids flows are commonly encountered in nature and industry. Experimental measurements of gas-liquid flows are challenging since such systems can be visually opaque and highly dynamic. Here we report the implementation of advanced magnetic resonance imaging (MRI) strategies allowing us to probe the dynamics (voidage and velocity measurements) of gas-liquid flows with ultra-fast acquisition speeds. Specifically, parallel MRI which exploits the spatial encoding capabilities of multiple receiver coils was implemented. To this end a tailored, 16 channels MR receive array was constructed and employed in the MR acquisition. A magnetic susceptibility matched gas-liquid system was set-up and used to probe the motion, splitting and coalescence of bubbles. The temporal and spatial resolution of our acquired data was 5 ms and 3.5 mm x 3.5 mm, respectively. The total field of view was 200 mm x 200 mm. We will conclude with an outlook of further possible advances in MRI that have the potential to reduce substantially the acquisition time, providing flexible gains in temporal and spatial resolution.

  18. Exact coherent states in purely elastic parallel shear flows

    NASA Astrophysics Data System (ADS)

    Searle, Toby; Morozov, Alexander

    2014-11-01

    Parallel shear flows provide a model system for the understanding of the transition to and structure of incompressible Newtonian turbulence. The turbulent attractor is often thought of as structured by a series of exact solutions to the Navier-Stokes equations, where a turbulent flow ``pinballs'' between these solutions in phase space. The most intuitive mechanism for the appearance of these structures was formulated by F. Waleffe and is known as ``the self-sustaining process.'' A novel form of turbulence has been discovered in polymeric fluids where the Reynold's number is low, Re < 1 , and the Weissenberg number (characterising the fluid elasticity) is large. Using an analogy with the Newtonian self-sustaining process, we attempt to construct the purely elastic counterpart for plane Couette flow of polymer solutions. By introducing a forcing term to the coupled Navier-Stokes and Oldroyd-B equations, we observe the formation of purely elastic streaks and consider their linear stability. We find that there exists a previously unrecognised purely elastic analogue of the Kelvin-Helmholtz instability that gives rise to the streamwise waviness of Newtonian coherent structures. We discuss how this instability might close the cycle and lead to a sustained purely elastic coherent structure. SUPA, School of Physics and Astronomy, University of Edinburgh, Mayfield Road, Edinburgh, EH9 3JZ, UK.

  19. JOSEPHINE: A parallel SPH code for free-surface flows

    NASA Astrophysics Data System (ADS)

    Cherfils, J. M.; Pinon, G.; Rivoalen, E.

    2012-07-01

    JOSEPHINE is a parallel Smoothed Particle Hydrodynamics program, designed to solve unsteady free-surface flows. The adopted numerical scheme is efficient and has been validated on a first case, where a liquid drop is stretched over the time. Boundary conditions can also be modelled, as it is demonstrated in a second case: the collapse of a water column. Results show good agreement with both reference numerical solutions and experiments. The use of parallelism allows significant reduction of the computational time, even more with large number of particles. JOSEPHINE has been written so that any untrained developers can handle it easily and implement new features. Catalogue identifier: AELV_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AELV_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 5139 No. of bytes in distributed program, including test data, etc.: 22 833 Distribution format: tar.gz Programming language: Fortran 90 and OpenMPI Computer: All shared or distributed memory parallel processors, tested on a Xeon W3520, 2.67 GHz. Operating system: Any system with a Fortran 90 compiler and MPI, tested on Debian Linux. Has the code been vectorised or parallelised?: The code has been parallelised but has not been explicitly vectorised. RAM: Dependent upon the number of particles. Classification: 4.12 Nature of problem:JOSEPHINE is designed to solve unsteady incompressible flows with a free-surface and large deformations. Solution method:JOSEPHINE is an implementation of Smoothed Particle Hydrodynamics. SPH is a Lagrangian mesh free particle method, thus, no explicit tracking procedure is required to catch the free surface. Incompressibility is satisfied using a weakly compressible model. Boundary conditions at walls are enforced by means of the ghost particles

  20. PARALLEL EVALUATION OF AIR- AND OXYGEN-ACTIVATED SLUDGE

    EPA Science Inventory

    To provide data on the relative merits of air and oxygen in the activated sludge process, two 1900-cu m/day (0.5-mgd) activated sludge pilot plant, one air and one oxygen system, were operated side-by-side at the Joint Water Pollution Control Plant, Carson, California. Both of th...

  1. Review of air flow measurement techniques

    SciTech Connect

    McWilliams, Jennifer

    2002-12-01

    Airflow measurement techniques are necessary to determine the most basic of indoor air quality questions: ''Is there enough fresh air to provide a healthy environment for the occupants of the building?'' This paper outlines airflow measurement techniques, but it does not make recommendations for techniques that should be used. The airflows that will be discussed are those within a room or zone, those between rooms or zones, such as through doorways (open or closed) or passive vents, those between the building and outdoors, and those through mechanical air distribution systems. Techniques that are highlighted include particle streak velocimetry, hot wire anemometry, fan pressurization (measuring flow at a given pressure), tracer gas, acoustic methods for leak size determination, the Delta Q test to determine duct leakage flows, and flow hood measurements. Because tracer gas techniques are widely used to measure airflow, this topic is broken down into sections as follows: decay, pulse injection, constant injection, constant concentration, passive sampling, and single and multiple gas measurements for multiple zones.

  2. 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.

  3. 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... Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method used... during the test. Overall measurement accuracy must be ± 2 percent of the maximum engine value for...

  4. 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... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method... during the test. Overall measurement accuracy must be ± 2 percent of the maximum engine value for...

  5. 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... Emission Test Procedures § 89.414 Air flow measurement specifications. (a) The air flow measurement method... during the test. Overall measurement accuracy must be ± 2 percent of the maximum engine value for...

  6. 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...

  7. Parallel Computation of Unsteady Flows on a Network of Workstations

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Parallel computation of unsteady flows requires significant computational resources. The utilization of a network of workstations seems an efficient solution to the problem where large problems can be treated at a reasonable cost. This approach requires the solution of several problems: 1) the partitioning and distribution of the problem over a network of workstation, 2) efficient communication tools, 3) managing the system efficiently for a given problem. Of course, there is the question of the efficiency of any given numerical algorithm to such a computing system. NPARC code was chosen as a sample for the application. For the explicit version of the NPARC code both two- and three-dimensional problems were studied. Again both steady and unsteady problems were investigated. The issues studied as a part of the research program were: 1) how to distribute the data between the workstations, 2) how to compute and how to communicate at each node efficiently, 3) how to balance the load distribution. In the following, a summary of these activities is presented. Details of the work have been presented and published as referenced.

  8. Parallel DNS of electro-magnetic flow control

    NASA Astrophysics Data System (ADS)

    Du, Yiqing

    The first part of this thesis deals with incompressible weakly conducting fluid such as sea water. It involves solving the Navier-Stokes equations with Lorentz force as an extra body force. The proper modeling of Lorentz force is investigated, and different electro-magnetic tile configurations are considered and several issues are addressed concerning boundary conditions; the Motz problem; edge effects; and substrate effects. After the validation of the mathematical formulation and simulation by comparing simulation results against experimental data with a single Lorentz force actuator, we perform DNS studies of turbulent channel flow with multi-tile configurations embedded in one channel wall. Simulations of a specific multi-tile configuration and pulsing pattern proposed by researchers of Princeton University reveal a spanwise coherent structure resembling a traveling wave. To model this excitation, we impose a transverse traveling wave that decays exponentially in the wall normal direction in accord with the spanwise Lorentz force. Systematic simulations reveal that for certain combinations of frequency, wavelength and force magnitude, substantial (≥20%) drag reduction can be obtained. This is the first time that such result is obtained as it is based on a fundamental new mechanism not explored in the past. The second part of this thesis considers a single-fluid-two-temperature model of a fully ionized plasma flow. We derive the governing equations and cast them into a conservative formulation. The problem is solved in a discontinuous Galerkin formulation. We adopt the characteristic approach which involves deriving an approximate Riemann solver. A convergence test is performed for a two-dimensional magnetohydrostatic problem. We also obtain some preliminary results for a two-temperature plasma flow past a cylinder. We use spectral/hp element method in all the simulations carried out in this work. Both an old version of the code called PRISM (structured

  9. Parallelized CCHE2D flow model with CUDA Fortran on Graphics Process Units

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This paper presents the CCHE2D implicit flow model parallelized using CUDA Fortran programming technique on Graphics Processing Units (GPUs). A parallelized implicit Alternating Direction Implicit (ADI) solver using Parallel Cyclic Reduction (PCR) algorithm on GPU is developed and tested. This solve...

  10. Flow distribution in parallel connected manifolds for evacuated tubular solar collectors

    NASA Astrophysics Data System (ADS)

    McPhedran, R. C.; Mackey, D. J. M.; McKenzie, D. R.; Collins, R. E.

    A model is presented for predicting the flow distribution in solar collector manifolds in which risers are connected in parallel between headers. Both frictional and Bernoulli effects are considered. The distributions resulting from flow in the manifold in which header streams are parallel and opposed are calculated and compared with experiment. Parallel flow gives a more uniform distribution. The outlet header is found to be more critical in balancing the flow distribution than the inlet header. Conditions under which thermosiphon effects are important and flow reversal in risers may occur are discussed with reference to experiment.

  11. Adapting high-level language programs for parallel processing using data flow

    NASA Technical Reports Server (NTRS)

    Standley, Hilda M.

    1988-01-01

    EASY-FLOW, a very high-level data flow language, is introduced for the purpose of adapting programs written in a conventional high-level language to a parallel environment. The level of parallelism provided is of the large-grained variety in which parallel activities take place between subprograms or processes. A program written in EASY-FLOW is a set of subprogram calls as units, structured by iteration, branching, and distribution constructs. A data flow graph may be deduced from an EASY-FLOW program.

  12. Decentralized and Tactical Air Traffic Flow Management

    NASA Technical Reports Server (NTRS)

    Bertsimas, Dimitris; Odoni, Amedeo R.

    1997-01-01

    This project dealt with the following topics: 1. Review and description of the existing air traffic flow 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 flow 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.

  13. 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.

  14. Dynamic Flow Management Problems in Air Transportation

    NASA Technical Reports Server (NTRS)

    Patterson, Sarah Stock

    1997-01-01

    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 air 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 Air Traffic Flow 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 Air Traffic Flow 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 flow problem with certain side constraints. Using Lagrangian relaxation, we generate aggregate flows that are decomposed into a collection of flight paths using a randomized rounding heuristic. This collection of paths is used in a packing integer

  15. Investigation of the Behavior of Parallel Two-Dimensional Air Jets

    NASA Technical Reports Server (NTRS)

    Corrsin, Stanley

    1944-01-01

    An investigation was made of the flow downstream from a "two-dimensional" grid formed of parallel rods. In both two and three dimensional jet fields there is a critical range of grid density below which the downstream flow is stable and above which it is unstable. The flow can be completely stabilized by means of an adequate lateral contraction beginning immediately after the grid or by use of a fine-mesh damping screen parallel to the grid plane and within a definite range of positions downstream from the grid.

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

    NASA Astrophysics Data System (ADS)

    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.

  17. A Parallel Implicit Adaptive Mesh Refinement Algorithm for Predicting Unsteady Fully-Compressible Reactive Flows

    NASA Astrophysics Data System (ADS)

    Northrup, Scott A.

    A new parallel implicit adaptive mesh refinement (AMR) algorithm is developed for the prediction of unsteady behaviour of laminar flames. The scheme is applied to the solution of the system of partial-differential equations governing time-dependent, two- and three-dimensional, compressible laminar flows for reactive thermally perfect gaseous mixtures. A high-resolution finite-volume spatial discretization procedure is used to solve the conservation form of these equations on body-fitted multi-block hexahedral meshes. A local preconditioning technique is used to remove numerical stiffness and maintain solution accuracy for low-Mach-number, nearly incompressible flows. A flexible block-based octree data structure has been developed and is used to facilitate automatic solution-directed mesh adaptation according to physics-based refinement criteria. The data structure also enables an efficient and scalable parallel implementation via domain decomposition. The parallel implicit formulation makes use of a dual-time-stepping like approach with an implicit second-order backward discretization of the physical time, in which a Jacobian-free inexact Newton method with a preconditioned generalized minimal residual (GMRES) algorithm is used to solve the system of nonlinear algebraic equations arising from the temporal and spatial discretization procedures. An additive Schwarz global preconditioner is used in conjunction with block incomplete LU type local preconditioners for each sub-domain. The Schwarz preconditioning and block-based data structure readily allow efficient and scalable parallel implementations of the implicit AMR approach on distributed-memory multi-processor architectures. The scheme was applied to solutions of steady and unsteady laminar diffusion and premixed methane-air combustion and was found to accurately predict key flame characteristics. For a premixed flame under terrestrial gravity, the scheme accurately predicted the frequency of the natural

  18. Indoor air flow and pollutant removal in a room with desk-top ventilation

    SciTech Connect

    Faulkner, D.; Fisk, W.J.; Sullivan, D.P.

    1993-04-01

    In a furnished experimental facility with three workstations separated by partitions, we studied indoor air flow patterns and tobacco smoke removal efficiency of a desk-top task ventilation system. The task ventilation system permits occupant control of the temperature, flow rate and direction of air supplied through two desk-mounted supply nozzles. In the configuration evaluated, air exited the ventilated space through a ceiling-mounted return grill. To study indoor air flow patterns, we measured the age of air at multiple indoor locations using the tracer gas step-up procedure. To study the intra-room transport of tobacco smoke particles and the efficiency of panicle removal by ventilation, a cigarette was smoked mechanically in one workstation and particle concentrations were measured at multiple indoor locations including the exhaust airstream. Test variables included the direction of air supply from the nozzles, supply nozzle area, supply flow rate and temperature, percent recirculation of chamber air, and internal heatloads. With nozzles pointed toward the occupants, 100% outside air supplied at the desk-top, and air supply rates of approximately 40 L/s per workstation, the age of air at the breathing level of ventilated workstations was approximately 30% less than the age of air that would occur throughout the test space with perfectly mixed indoor air. With smaller air supply rates and/or air supplied parallel to the edges of the desk, ages of air at breathing locations were not significantly lower than the age with perfect mixing. Indoor tobacco smoke particle concentrations at specific locations were generally within 12% of the average measured indoor concentration and concentrations of particles in the exhaust airstream were not significantly different from concentration of particles at breathing locations.

  19. Influence of equilibrium shear flow in the parallel magnetic direction on edge localized mode crash

    NASA Astrophysics Data System (ADS)

    Luo, Y.; Chen, S. Y.; Huang, J.; Xiong, Y. Y.; Tang, C. J.

    2016-04-01

    The influence of the parallel shear flow on the evolution of peeling-ballooning (P-B) modes is studied with the BOUT++ four-field code in this paper. The parallel shear flow has different effects in linear simulation and nonlinear simulation. In the linear simulations, the growth rate of edge localized mode (ELM) can be increased by Kelvin-Helmholtz term, which can be caused by the parallel shear flow. In the nonlinear simulations, the results accord with the linear simulations in the linear phase. However, the ELM size is reduced by the parallel shear flow in the beginning of the turbulence phase, which is recognized as the P-B filaments' structure. Then during the turbulence phase, the ELM size is decreased by the shear flow.

  20. Massively Parallel Dantzig-Wolfe Decomposition Applied to Traffic Flow Scheduling

    NASA Technical Reports Server (NTRS)

    Rios, Joseph Lucio; Ross, Kevin

    2009-01-01

    Optimal scheduling of air traffic over the entire National Airspace System is a computationally difficult task. To speed computation, Dantzig-Wolfe decomposition is applied to a known linear integer programming approach for assigning delays to flights. The optimization model is proven to have the block-angular structure necessary for Dantzig-Wolfe decomposition. The subproblems for this decomposition are solved in parallel via independent computation threads. Experimental evidence suggests that as the number of subproblems/threads increases (and their respective sizes decrease), the solution quality, convergence, and runtime improve. A demonstration of this is provided by using one flight per subproblem, which is the finest possible decomposition. This results in thousands of subproblems and associated computation threads. This massively parallel approach is compared to one with few threads and to standard (non-decomposed) approaches in terms of solution quality and runtime. Since this method generally provides a non-integral (relaxed) solution to the original optimization problem, two heuristics are developed to generate an integral solution. Dantzig-Wolfe followed by these heuristics can provide a near-optimal (sometimes optimal) solution to the original problem hundreds of times faster than standard (non-decomposed) approaches. In addition, when massive decomposition is employed, the solution is shown to be more likely integral, which obviates the need for an integerization step. These results indicate that nationwide, real-time, high fidelity, optimal traffic flow scheduling is achievable for (at least) 3 hour planning horizons.

  1. Femtosecond laser flow tagging in non-air flows

    NASA Astrophysics Data System (ADS)

    Zhang, Yibin; Calvert, Nathan

    2015-11-01

    The Femtosecond Laser Electronic Excitation Tagging (FLEET) [Michael, J. B. et al., Applied optics, 50(26), 2011] method is studied in nitrogen-containing gaseous flows. The underlying mechanism behind the FLEET process is the dissociation of molecular nitrogen into atomic nitrogen, which produces long-lived florescence as the nitrogen atoms recombine. Spectra and images of the resulting tagged line provide insight into the effects of different atmospheric gases on the FLEET process. The ionization cross-section, conductivity and energy states of the gaseous particles are each brought into consideration. These experiments demonstrate the feasibility for long-lived flow tagging on the order of hundreds of microseconds in non-air environments. Of particular interest are the enhancement of the FLEET signal with the addition of argon gas, and the non-monotonic quenching effect of oxygen on the length, duration and intensity of the resulting signal and spectra. FLEET is characterized in number of different atmospheric gases, including that simulating Mar's atmospheric composition.

  2. A Study on the Air flow outside Ambient Vaporizer Fin

    NASA Astrophysics Data System (ADS)

    Oh, G.; Lee, T.; Jeong, H.; Chung, H.

    2015-09-01

    In this study, we interpreted Fog's Fluid that appear in the Ambient Vaporizer and predict the point of change Air to Fog. We interpreted using Analysis working fluid was applied to LNG and Air. We predict air flow when there is chill of LNG in the air Temperature and that makes fog. Also, we interpreted based on Summer and Winter criteria in the air temperature respectively. Finally, we can check the speed of the fog when fog excreted.

  3. PARALLEL EVALUATION OF CONSTANT AND DIURNAL FLOW TREATMENT SYSTEMS

    EPA Science Inventory

    Pilot plant studies were performed to evaluate the effects of an imposed diurnal flow pattern on a conventional activated sludge treatment plant. These results were compared against data generated on a similar system treating a constant flow. Effects on primary clarifier and fina...

  4. Resistance of a plate in parallel flow at low Reynolds numbers

    NASA Technical Reports Server (NTRS)

    Janour, Zbynek

    1951-01-01

    The present paper gives the results of measurements of the resistance of a plate placed parallel to the flow in the range of Reynolds numbers from 10 to 2300; in this range the resistance deviates from the formula of Blasius. The lower limit of validity of the Blasius formula is determined and also the increase in resistance at the edges parallel to the flow in the case of a plate of finite width.

  5. 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...

  6. 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...

  7. 40 CFR 1065.225 - Intake-air flow meter.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 34 2012-07-01 2012-07-01 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...

  8. 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...

  9. 40 CFR 1065.225 - Intake-air flow meter.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 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...

  10. Particle displacement tracking applied to air flows

    NASA Technical Reports Server (NTRS)

    Wernet, Mark P.

    1991-01-01

    Electronic Particle Image Velocimeter (PIV) techniques offer many advantages over conventional photographic PIV methods such as fast turn around times and simplified data reduction. A new all electronic PIV technique was developed which can measure high speed gas velocities. The Particle Displacement Tracking (PDT) technique employs a single cw laser, small seed particles (1 micron), and a single intensified, gated CCD array frame camera to provide a simple and fast method of obtaining two-dimensional velocity vector maps with unambiguous direction determination. Use of a single CCD camera eliminates registration difficulties encountered when multiple cameras are used to obtain velocity magnitude and direction information. An 80386 PC equipped with a large memory buffer frame-grabber board provides all of the data acquisition and data reduction operations. No array processors of other numerical processing hardware are required. Full video resolution (640x480 pixel) is maintained in the acquired images, providing high resolution video frames of the recorded particle images. The time between data acquisition to display of the velocity vector map is less than 40 sec. The new electronic PDT technique is demonstrated on an air nozzle flow with velocities less than 150 m/s.

  11. Parallel Three-Dimensional Computation of Fluid Dynamics and Fluid-Structure Interactions of Ram-Air Parachutes

    NASA Technical Reports Server (NTRS)

    Tezduyar, Tayfun E.

    1998-01-01

    This is a final report as far as our work at University of Minnesota is concerned. The report describes our research progress and accomplishments in development of high performance computing methods and tools for 3D finite element computation of aerodynamic characteristics and fluid-structure interactions (FSI) arising in airdrop systems, namely ram-air parachutes and round parachutes. This class of simulations involves complex geometries, flexible structural components, deforming fluid domains, and unsteady flow patterns. The key components of our simulation toolkit are a stabilized finite element flow solver, a nonlinear structural dynamics solver, an automatic mesh moving scheme, and an interface between the fluid and structural solvers; all of these have been developed within a parallel message-passing paradigm.

  12. Numerical investigation of transient heat and mass transfer in a parallel-flow liquid-desiccant absorber

    NASA Astrophysics Data System (ADS)

    Diaz, Gerardo

    2010-12-01

    Liquid desiccant systems have received significant attention as a way to reduce latent loads. Tests of liquid desiccant systems in humid climates have shown significant reductions in energy consumption. As moisture in the air is absorbed at the dehumidifier, the temperature of the liquid desiccant increases due to the addition of heat from the enthalpy of condensation of the water vapor. Thus, the coupled effects of heat and mass transfer are relevant for these applications. A two-dimensional mathematical model of the transient heat and mass transfer for an absorber where a thin film of liquid desiccant flows down its walls and dehumidifies the air in parallel-flow configuration is developed and the dynamics of the modeled system are analyzed.

  13. Integrated turbine-compressor provides air flow for cooling

    NASA Technical Reports Server (NTRS)

    Ferri, A.

    1970-01-01

    Modified supersonic turbine cycle provides cooling air to surrounding structures. Simplified mechanical design assures correct balance of air flow, allows direct issue of cool air to the structure, and assists in matching turbine work output to work input required by the compressor.

  14. An analysis of pressure driven cross-flow through a long slot connecting two parallel channels

    SciTech Connect

    Shadday, M.A. Jr.

    1992-12-31

    Cross-flow between two parallel channels that were connected by a long narrow slot has been measured. The data was presented primarily in terms of transverse resistance coefficients. This data has been analyzed with momentum balances applied to both the axial and transverse components of the slot flow. The importance of wall friction to the slot flow and the necessity of calculating the axial component of the slot flow is demonstrated.

  15. Research on Air Flow Measurement and Optimization of Control Algorithm in Air Disinfection System

    NASA Astrophysics Data System (ADS)

    Bing-jie, Li; Jia-hong, Zhao; Xu, Wang; Amuer, Mohamode; Zhi-liang, Wang

    2013-01-01

    As the air flow control system has the characteristics of delay and uncertainty, this research designed and achieved a practical air flow control system by using the hydrodynamic theory and the modern control theory. Firstly, the mathematical model of the air flow distribution of the system is analyzed from the hydrodynamics perspective. Then the model of the system is transformed into a lumped parameter state space expression by using the Galerkin method. Finally, the air flow is distributed more evenly through the estimation of the system state and optimal control. The simulation results show that this algorithm has good robustness and anti-interference ability

  16. Air Traffic and Operational Data on Selected US Airports with Parallel Runways

    NASA Technical Reports Server (NTRS)

    Doyle, Thomas M.; McGee, Frank G.

    1998-01-01

    This report presents information on a number of airports in the country with parallel runways and focuses on those that have at least one pair of parallel runways closer than 4300 ft. Information contained in the report describes the airport's current operational activity as obtained through contact with the facility and from FAA air traffic tower activity data for FY 1997. The primary reason for this document is to provide a single source of information for research to determine airports where Airborne Information for Lateral Spacing (AILS) technology may be applicable.

  17. Experimental study on corrugated cross-flow air-cooled plate heat exchangers

    SciTech Connect

    Kim, Minsung; Baik, Young-Jin; Park, Seong-Ryong; Ra, Ho-Sang; Lim, Hyug

    2010-11-15

    Experimental study on cross-flow air-cooled plate heat exchangers (PHEs) was performed. The two prototype PHEs were manufactured in a stack of single-wave plates and double-wave plates in parallel. Cooling air flows through the PHEs in a crosswise direction against internal cooling water. The heat exchanger aims to substitute open-loop cooling towers with closed-loop water circulation, which guarantees cleanliness and compactness. In this study, the prototype PHEs were tested in a laboratory scale experiments. From the tests, double-wave PHE shows approximately 50% enhanced heat transfer performance compared to single-wave PHE. However, double-wave PHE costs 30% additional pressure drop. For commercialization, a wide channel design for air flow would be essential for reliable performance. (author)

  18. MEDUSA - An overset grid flow solver for network-based parallel computer systems

    NASA Technical Reports Server (NTRS)

    Smith, Merritt H.; Pallis, Jani M.

    1993-01-01

    Continuing improvement in processing speed has made it feasible to solve the Reynolds-Averaged Navier-Stokes equations for simple three-dimensional flows on advanced workstations. Combining multiple workstations into a network-based heterogeneous parallel computer allows the application of programming principles learned on MIMD (Multiple Instruction Multiple Data) distributed memory parallel computers to the solution of larger problems. An overset-grid flow solution code has been developed which uses a cluster of workstations as a network-based parallel computer. Inter-process communication is provided by the Parallel Virtual Machine (PVM) software. Solution speed equivalent to one-third of a Cray-YMP processor has been achieved from a cluster of nine commonly used engineering workstation processors. Load imbalance and communication overhead are the principal impediments to parallel efficiency in this application.

  19. Three-dimensional freezing of flowing water in a tube cooled by air flow

    NASA Astrophysics Data System (ADS)

    Sugawara, M.; Komatsu, Y.; Beer, H.

    2015-05-01

    The 3-D freezing of flowing water in a copper tube cooled by air flow is investigated by means of a numerical analysis. The air flows normal to the tube axis. Several parameters as inlet water mean velocity w m , inlet water temperature T iℓ t , air flow temperature T a and air flow velocity u a are selected in the calculations to adapt it to a winter season actually encountered. The numerical results present the development of the ice layer mean thickness and its 3-D morphologies as well as the critical ice layer thickness in the tube choked by the ice layer.

  20. Parallel Magnetic Flow Electromagnet for Movable Coil Control-rod Driving Mechanism

    SciTech Connect

    Jige, Zhang

    2006-07-01

    The parallel magnetic flow electromagnet can effectively relax the saturation, which easily takes place in the single magnetic flow electromagnet, and accordingly can improve the drive capacity of the movable coil electromagnet drive mechanism for a mobile reactor control rod. (authors)

  1. Collective Interaction of a Compressible Periodic Parallel Jet Flow

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    1997-01-01

    A linear instability model for multiple spatially periodic supersonic rectangular jets is solved using Floquet-Bloch theory. The disturbance environment is investigated using a two dimensional perturbation of a mean flow. For all cases large temporal growth rates are found. This work is motivated by an increase in mixing found in experimental measurements of spatially periodic supersonic rectangular jets with phase-locked screech. The results obtained in this paper suggests that phase-locked screech or edge tones may produce correlated spatially periodic jet flow downstream of the nozzles which creates a large span wise multi-nozzle region where a disturbance can propagate. The large temporal growth rates for eddies obtained by model calculation herein are related to the increased mixing since eddies are the primary mechanism that transfer energy from the mean flow to the large turbulent structures. Calculations of growth rates are presented for a range of Mach numbers and nozzle spacings corresponding to experimental test conditions where screech synchronized phase locking was observed. The model may be of significant scientific and engineering value in the quest to understand and construct supersonic mixer-ejector nozzles which provide increased mixing and reduced noise.

  2. Air Force Space Command satellite orbit predictor using parallel virtual machines

    NASA Astrophysics Data System (ADS)

    Brewer, Susan K.

    1993-12-01

    Parallel computing is the wave of the future. As the need for computational power increases, one processor is no longer sufficient to achieve the speed necessary to solve today's complex problems. The Air Force Space Command (AFSPACEOM) tracks approximately 8000 satellites daily; the model used by the AFSPACECOM, SGP4, (Simplified General Perturbation Model Four), has been the operational model since 1976. This thesis contains a detailed discussion of the mathematical theory of the SGP4 model. The tracking of a satellite requires extensive calculations. The satellite can be tracked more efficiently with parallel processing techniques. The principles developed are applicable to a Naval ship tracking multiple incoming threats; the increase in the speed of processing incoming data would result in personnel being informed faster and thus allow more time for better decisions during combat. Three parallel algorithms applied to SGP4 for implementations on a Parallel Virtual Machine (PVM) are developed. PVM is a small software package that allows a network of computer workstations to appear as a single large distributed-memory parallel computer. This thesis contains a description of several algorithms for the implementation on PVM to track satellites, the optimal number of workstations, and methods of distributing data.

  3. Estimating water flow through a hillslope using the massively parallel processor

    NASA Technical Reports Server (NTRS)

    Devaney, Judy E.; Camillo, P. J.; Gurney, R. J.

    1988-01-01

    A new two-dimensional model of water flow in a hillslope has been implemented on the Massively Parallel Processor at the Goddard Space Flight Center. Flow in the soil both in the saturated and unsaturated zones, evaporation and overland flow are all modelled, and the rainfall rates are allowed to vary spatially. Previous models of this type had always been very limited computationally. This model takes less than a minute to model all the components of the hillslope water flow for a day. The model can now be used in sensitivity studies to specify which measurements should be taken and how accurate they should be to describe such flows for environmental studies.

  4. A massively parallel computational approach to coupled thermoelastic/porous gas flow problems

    NASA Technical Reports Server (NTRS)

    Shia, David; Mcmanus, Hugh L.

    1995-01-01

    A new computational scheme for coupled thermoelastic/porous gas flow problems is presented. Heat transfer, gas flow, and dynamic thermoelastic governing equations are expressed in fully explicit form, and solved on a massively parallel computer. The transpiration cooling problem is used as an example problem. The numerical solutions have been verified by comparison to available analytical solutions. Transient temperature, pressure, and stress distributions have been obtained. Small spatial oscillations in pressure and stress have been observed, which would be impractical to predict with previously available schemes. Comparisons between serial and massively parallel versions of the scheme have also been made. The results indicate that for small scale problems the serial and parallel versions use practically the same amount of CPU time. However, as the problem size increases the parallel version becomes more efficient than the serial version.

  5. Distribution of air-water mixtures in parallel vertical channels as an effect of the header geometry

    SciTech Connect

    Marchitto, Annalisa; Fossa, Marco; Guglielmini, Giovanni

    2009-07-15

    Uneven phase distribution in heat exchangers is a cause of severe reductions in thermal performances of refrigeration equipment. To date, no general design rules are available to avoid phase separation in manifolds with several outlet channels, and even predicting the phase and mass distribution in parallel channels is a demanding task. In the present paper, measurements of two-phase air-water distributions are reported with reference to a horizontal header supplying 16 vertical upward channels. The effects of the operating conditions, the header geometry and the inlet port nozzle were investigated in the ranges of liquid and gas superficial velocities of 0.2-1.2 and 1.5-16.5 m/s, respectively. Among the fitting devices used, the insertion of a co-axial, multi-hole distributor inside the header confirmed the possibility of greatly improving the liquid and gas flow distribution by the proper selection of position, diameter and number of the flow openings between the supplying distributor and the system of parallel channels connected to the header. (author)

  6. Position paper -- Tank ventilation system design air flow rates

    SciTech Connect

    Goolsby, G.K.

    1995-01-04

    The purpose of this paper is to document a project position on required ventilation system design air flow rates for the waste storage tanks currently being designed by project W-236A, the Multi-Function Waste Tank Facility (MWTF). The Title 1 design primary tank heat removal system consists of two systems: a primary tank vapor space ventilation system; and an annulus ventilation system. At the conclusion of Title 1 design, air flow rates for the primary and annulus ventilation systems were 960 scfm and 4,400 scfm, respectively, per tank. These design flow rates were capable of removing 1,250,000 Btu/hr from each tank. However, recently completed and ongoing studies have resulted in a design change to reduce the extreme case heat load to 700,000 Btu/hr. This revision of the extreme case heat load, coupled with results of scale model evaporative testing performed by WHC Thermal Hydraulics, allow for a reduction of the design air flow rates for both primary and annulus ventilation systems. Based on the preceding discussion, ICF Kaiser Hanford Co. concludes that the design should incorporate the following design air flow rates: Primary ventilation system--500 scfm maximum and Annulus ventilation system--1,100 scfm maximum. In addition, the minimum air flow rates in the primary and annulus ventilation systems will be investigated during Title 2 design. The results of the Title 2 investigation will determine the range of available temperature control using variable air flows to both ventilation systems.

  7. Parallel computing simulation of fluid flow in the unsaturated zone of Yucca Mountain, Nevada.

    PubMed

    Zhang, Keni; Wu, Yu-Shu; Bodvarsson, G S

    2003-01-01

    This paper presents the application of parallel computing techniques to large-scale modeling of fluid flow in the unsaturated zone (UZ) at Yucca Mountain, Nevada. In this study, parallel computing techniques, as implemented into the TOUGH2 code, are applied in large-scale numerical simulations on a distributed-memory parallel computer. The modeling study has been conducted using an over-1-million-cell three-dimensional numerical model, which incorporates a wide variety of field data for the highly heterogeneous fractured formation at Yucca Mountain. The objective of this study is to analyze the impact of various surface infiltration scenarios (under current and possible future climates) on flow through the UZ system, using various hydrogeological conceptual models with refined grids. The results indicate that the 1-million-cell models produce better resolution results and reveal some flow patterns that cannot be obtained using coarse-grid modeling models. PMID:12714301

  8. Study on Minor Losses Around the Thermoacoustic Parallel Stack in the Oscillatory Flow Conditions

    NASA Astrophysics Data System (ADS)

    Yiyi, Mao; Xiujuan, Xie; Shaoqi, Yang; Qing, Li

    Minor losses around the thermoacoustic parallel stack in the oscillatory flow conditions are amongthe main factors that influencethe efficiency ofthermoacoustic systems. In this paper, a two-dimension model of a thermoacoustic parallel stack in a thermoacoustic system driven by double loudspeakers is setup. The characteristicsof the vortex structure at the end of the parallel stack under different pressure amplitude are analyzed. Meanwhile based on the principle of the two-microphone method and the above simulation result, the minor loss coefficient of oscillatory flow through a sudden area change is analyzed. The result shows that the vortex structuresget larger with the increase of pressure amplitude. Furthermore, the real part of the minor loss coefficient exponentially increases with the ratio of hydraulic radius and displacement amplitude of the oscillatory flow. A close agreement between simulation and experimental result is found, thus providing support for the validly of the model.

  9. Massively parallel computing simulation of fluid flow in the unsaturated zone of Yucca Mountain, Nevada

    SciTech Connect

    Zhang, Keni; Wu, Yu-Shu; Bodvarsson, G.S.

    2001-08-31

    This paper presents the application of parallel computing techniques to large-scale modeling of fluid flow in the unsaturated zone (UZ) at Yucca Mountain, Nevada. In this study, parallel computing techniques, as implemented into the TOUGH2 code, are applied in large-scale numerical simulations on a distributed-memory parallel computer. The modeling study has been conducted using an over-one-million-cell three-dimensional numerical model, which incorporates a wide variety of field data for the highly heterogeneous fractured formation at Yucca Mountain. The objective of this study is to analyze the impact of various surface infiltration scenarios (under current and possible future climates) on flow through the UZ system, using various hydrogeological conceptual models with refined grids. The results indicate that the one-million-cell models produce better resolution results and reveal some flow patterns that cannot be obtained using coarse-grid modeling models.

  10. 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

  11. Two-phase flow instability and dryout in parallel channels in natural circulation

    SciTech Connect

    Duffey, R.B.; Rohatgi, U.S.; Hughes, E.D.

    1993-06-01

    The unique feature of parallel channel flows is that the pressure drop or driving head for the flow is maintained constant across any given channel by the flow in all the others, or by having a large downcomer or bypass in a natural circulation loop. This boundary condition is common in all heat exchangers, reactor cores and boilers, it is well known that the two-phase flow in parallel channels can exhibit both so-called static and dynamic instability. This leads to the question of the separability of the flow and pressure drop boundary conditions in the study of stability and dryout. For the areas of practical interest, the flow can be considered as incompressible. The dynamic instability is characterized by density (kinematic) or continuity waves, and the static instability by inertial (pressure drop) or manometric escalations. The static has been considered to be the zero-frequency or lowest mode of the dynamic case. We briefly review the status of the existing literature on both parallel channel static and dynamic instability, and the latest developments in theory and experiment. The difference between the two derivations lies in the retention of the time-dependent terms in the conservation equations. The effects and impact of design options are also discussed. Since dryout in parallel systems follows instability, it has been traditional to determine the dryout power for a parallel channel by testing a single channel with a given (inlet) flow boundary condition without particular regard for the pressure drop. Thus all modern dryout correlations are based on constant or fixed flow tests, a so-called hard inlet, and subchannel and multiple bundle effects are corrected for separately. We review the thinking that lead to this approach, and suggest that for all multiple channel and natural circulation systems close attention should be paid to the actual (untested) pressure drop conditions. A conceptual formulation is suggested as a basis for discussion.

  12. Experimental Studies of Active and Passive Flow Control Techniques Applied in a Twin Air-Intake

    PubMed Central

    Joshi, Shrey; Jindal, Aman; Maurya, Shivam P.; Jain, Anuj

    2013-01-01

    The flow control in twin air-intakes is necessary to improve the performance characteristics, since the flow traveling through curved and diffused paths becomes complex, especially after merging. The paper presents a comparison between two well-known techniques of flow 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 air-intake duct in different combinations to establish their effectiveness in improving the performance characteristics. The VGJ is designed to insert flow 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 flow pattern drastically as compared to vane-type VG. While the VGJ is directed perpendicular to the side walls of the air-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 air-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

  13. A parallel computational framework for integrated surface-subsurface flow and transport simulations

    NASA Astrophysics Data System (ADS)

    Park, Y.; Hwang, H.; Sudicky, E. A.

    2010-12-01

    HydroGeoSphere is a 3D control-volume finite element hydrologic model describing fully-integrated surface and subsurface water flow and solute and thermal energy transport. Because the model solves tighly-coupled highly-nonlinear partial differential equations, often applied at regional and continental scales (for example, to analyze the impact of climate change on water resources), high performance computing (HPC) is essential. The target parallelization includes the composition of the Jacobian matrix for the iterative linearization method and the sparse-matrix solver, a preconditioned Bi-CGSTAB. The matrix assembly is parallelized by using a coarse-grained scheme in that the local matrix compositions can be performed independently. The preconditioned Bi-CGSTAB algorithm performs a number of LU substitutions, matrix-vector multiplications, and inner products, where the parallelization of the LU substitution is not trivial. The parallelization of the solver is achieved by partitioning the domain into equal-size subdomains, with an efficient reordering scheme. The computational flow of the Bi-CGSTAB solver is also modified to reduce the parallelization overhead and to be suitable for parallel architectures. The parallelized model is tested on several benchmark simulations which include linear and nonlinear flow problems involving various domain sizes and degrees of hydrologic complexities. The performance is evaluated in terms of computational robustness and efficiency, using standard scaling performance measures. The results of simulation profiling indicate that the efficiency becomes higher with an increasing number of nodes/elements in the mesh, for increasingly nonlinear transient simulations, and with domains of irregular geometry. These characteristics are promising for the large-scale analysis water resources problems involved integrated surface/subsurface flow regimes.

  14. ANTI-PARALLEL EUV FLOWS OBSERVED ALONG ACTIVE REGION FILAMENT THREADS WITH HI-C

    SciTech Connect

    Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane; Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Korreck, Kelly; Weber, Mark; Kobayashi, Ken; Platt, Simon; Mitchell, Nick; DePontieu, Bart; Title, Alan; DeForest, Craig; Kuzin, Sergey

    2013-09-20

    Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of 'counter-steaming' flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193 Å). In this work, we present observations of an AR filament observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent filament threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s{sup –1}) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all filaments and are currently not observed in EUV due to current instrument spatial resolution.

  15. Anti-parallel EUV Flows Observed along Active Region Filament Threads with Hi-C

    NASA Astrophysics Data System (ADS)

    Alexander, Caroline E.; Walsh, Robert W.; Régnier, Stéphane; Cirtain, Jonathan; Winebarger, Amy R.; Golub, Leon; Kobayashi, Ken; Platt, Simon; Mitchell, Nick; Korreck, Kelly; DePontieu, Bart; DeForest, Craig; Weber, Mark; Title, Alan; Kuzin, Sergey

    2013-09-01

    Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Previous observations of these flows primarily come from Hα and cool extreme-ultraviolet (EUV) lines (e.g., 304 Å) where estimates of the size of the prominence threads has been limited by the resolution of the available instrumentation. Evidence of "counter-steaming" flows has previously been inferred from these cool plasma observations, but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193 Å). In this work, we present observations of an AR filament observed with the High-resolution Coronal Imager (Hi-C) that exhibits anti-parallel flows along adjacent filament threads. Complementary data from the Solar Dynamics Observatory (SDO)/Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic Imager are presented. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70-80 km s-1) and gives an indication of the resolvable thickness of the individual strands (0.''8 ± 0.''1). The temperature of the plasma flows was estimated to be log T (K) = 5.45 ± 0.10 using Emission Measure loci analysis. We find that SDO/AIA cannot clearly observe these anti-parallel flows or measure their velocity or thread width due to its larger pixel size. We suggest that anti-parallel/counter-streaming flows are likely commonplace within all filaments and are currently not observed in EUV due to current instrument spatial resolution.

  16. Supersonic Air Flow due to Solid-Liquid Impact

    NASA Astrophysics Data System (ADS)

    Gekle, Stephan; Peters, Ivo R.; Gordillo, José Manuel; van der Meer, Devaraj; Lohse, Detlef

    2010-01-01

    A solid object impacting on liquid creates a liquid jet due to the collapse of the impact cavity. Using visualization experiments with smoke particles and multiscale simulations, we show that in addition, a high-speed air jet is pushed out of the cavity. Despite an impact velocity of only 1m/s, this air jet attains supersonic speeds already when the cavity is slightly larger than 1 mm in diameter. The structure of the air flow closely resembles that of compressible flow through a nozzle—with the key difference that here the “nozzle” is a liquid cavity shrinking rapidly in time.

  17. Computational and experimental study of spin coater air flow

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoguang; Liang, Faqiu; Haji-Sheikh, A.; Ghariban, N.

    1998-06-01

    An extensive 2- and 3-D analysis of air flow in a POLARISTM 2200 Microlithography Cluster spin coater was conducted using FLUENTTM Computational Fluid Dynamics (CFD) software. To supplement this analysis, direct measurement of air flow velocity was also performed using a DantecTM Hot Wire Anemometer. Velocity measurements were made along two major planes across the entire flow field in the spin coater at various operating conditions. It was found that the flow velocity at the spin coater inlet is much lower than previously assumed and quite nonuniform. Based on this observation, a pressure boundary condition rather than a velocity boundary condition was used for subsequent CFD analysis. A comparison between calculated results and experimental data shows that the 3D model accurately predicts the air flow field in the spin coater. An added advantage of this approach is that the CFD model can be easily generated from the mechanical design database and used to analyze the effect of design changes. The modeled and measured results show that the flow pattern in the spin bowl is affected by interactions between the spinning wafer, exhaust flow, and the gap between the spin head and surrounding baffle. Different operating conditions such as spin speed, inlet pressure, and exhaust pressure were found to generate substantially different flow patterns. It was also found that backflow of air could be generated under certain conditions.

  18. Low-noise flow valve for air ducts

    NASA Technical Reports Server (NTRS)

    Gallo, E. A.

    1970-01-01

    Valve assembly controls air flow from feeder into main duct, with minimum of turbulence, friction, pressure differential, and noise. Valve consists of damper, deflector, and spring. Streamlining of damper and deflector merges flow smoothly, while spring keeps damper and deflector in contact and eliminates valve chatter and damping vibrations.

  19. Stage-by-Stage and Parallel Flow Path Compressor Modeling for a Variable Cycle Engine

    NASA Technical Reports Server (NTRS)

    Kopasakis, George; Connolly, Joseph W.; Cheng, Larry

    2015-01-01

    This paper covers the development of stage-by-stage and parallel flow path compressor modeling approaches for a Variable Cycle Engine. The stage-by-stage compressor modeling approach is an extension of a technique for lumped volume dynamics and performance characteristic modeling. It was developed to improve the accuracy of axial compressor dynamics over lumped volume dynamics modeling. The stage-by-stage compressor model presented here is formulated into a parallel flow path model that includes both axial and rotational dynamics. This is done to enable the study of compressor and propulsion system dynamic performance under flow distortion conditions. The approaches utilized here are generic and should be applicable for the modeling of any axial flow compressor design.

  20. Low power, constant-flow air pump systems

    SciTech Connect

    Polito, M.D.; Albert, B.

    1994-01-01

    A rugged, yet small and lightweight constant-flow air pump system has been designed. Flow control is achieved using a novel approach which is three times more power efficient than previous designs. The resultant savings in battery size and weight makes these pumps ideal for sampling air on balloon platforms. The pump package includes meteorological sensors and an onboard computer that stores time and sensor data and turns the constant-flow pump circuit on/off. Some applications of these systems are also presented in this report.

  1. Visualization of the air flow behind the automotive benchmark vent

    NASA Astrophysics Data System (ADS)

    Pech, Ondrej; Jedelsky, Jan; Caletka, Petr; Jicha, Miroslav

    2015-05-01

    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 flow behind the ventilation outlet. The article deals with the visualization of air flow 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 air flow axis were investigated.

  2. Eliminating primary air axial flow fan stall at the D. B. Wilson station

    SciTech Connect

    Studley, B.C. ); Schmidt, E. ); Foreman, J.D. )

    1990-01-01

    Having originally chosen two axial flow primary air fans operating in parallel to deliver pulverized coal to this 440 Mw facility because of their high efficiencies and precise flow control, a program for first controlling and then eliminating fan stall was undertaken. An axial flow fan stalls when air flow separation occurs around the blades. This results in heavy turbulence with the fan no longer operating on its normal performance curve and consequently a rapid decrease in both pressure and flow is experienced. In addition, this condition results in high vibration which over time can be destructive to the fan. The immediate effect is obviously a sudden decrease in fuel flow followed b y both steam flow and electrical output. Although fan stall is a potential drawback of axial flow fans, the program implemented, which is described in this paper, has been successful at first controlling and recently eliminating fan stall all together. This was possible through an extensive test program and finally the installation of anti-stall rings on both fans. The net result of this operating improvement has been improved availability, reliability and capacity, in addition to higher fan discharge pressures as the anti-stall rings have modified the pressure-versus-volume curves of the fan similar to the characteristics of a cof a centrifugal fan.

  3. Parallel numerical modeling of two-phase flow during CO2 storage in saline aquifers

    NASA Astrophysics Data System (ADS)

    Wang, Wenqing; Zehner, Björn; Böttcher, Norbert; Görke, Uwe-Jens; Kolditz, Olaf

    2013-04-01

    Numerical modeling of CO2 storage processes in saline aquifers is computationally expensive due to the complexity and nonlinearity of the observed physical processes (e.g., two-phase flow) , and the large size of real reservoir site that also exhibits a heterogeneous distribution of material properties. The modeling of the physical process in the storage sites with a high degree of accuracy requires a fine discretization of the considered domain. Naturally, this leads to the requirement of extremely high computational resources. This work focuses on the parallel simulation of the two-phase flow in CO2 storage sites. The Galerkin finite element method is used to solve the governing equations. Based on the overlapped domain decomposition approach, the PETSc package is employed to parallelize the global equation assembly and the linear solver, respectively. A numerical model based on the real test site Ketzin in Germany is adopted for parallel modeling. The model domain is discretized with more than four million tetrahedral elements. The parallel simulations are carried out on super computers with different number of cores. The obtained speedup shows a good scalability of the current parallel finite element approach of the two-phase flow modeling in geological CO2 storage applications.

  4. Influence of the initial conditions on axisymmetric jets in a parallel flow

    NASA Astrophysics Data System (ADS)

    Navoznov, O. I.; Pavelev, A. A.

    1980-07-01

    The paper deals with an experimental investigation of the flow in the initial portion of axisymmetric helium, air, and Freon-12 jets in turbulent mixing layers. Measurements of the mean and pulsation velocities and temperature are presented, along with flow pattern photographs.

  5. Parallel heat flux and flow acceleration in open field line plasmas with magnetic trapping

    SciTech Connect

    Guo, Zehua; Tang, Xian-Zhu; McDevitt, Chris

    2014-10-15

    The magnetic field strength modulation in a tokamak scrape-off layer (SOL) provides both flux expansion next to the divertor plates and magnetic trapping in a large portion of the SOL. Previously, we have focused on a flux expander with long mean-free-path, motivated by the high temperature and low density edge anticipated for an absorbing boundary enabled by liquid lithium surfaces. Here, the effects of magnetic trapping and a marginal collisionality on parallel heat flux and parallel flow acceleration are examined. The various transport mechanisms are captured by kinetic simulations in a simple but representative mirror-expander geometry. The observed parallel flow acceleration is interpreted and elucidated with a modified Chew-Goldberger-Low model that retains temperature anisotropy and finite collisionality.

  6. Elasto-Aerodynamics-Driven Triboelectric Nanogenerator for Scavenging Air-Flow Energy.

    PubMed

    Wang, Shuhua; Mu, Xiaojing; Wang, Xue; Gu, Alex Yuandong; Wang, Zhong Lin; Yang, Ya

    2015-10-27

    Efficient scavenging the kinetic energy from air-flow 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 air-flow 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 air-flow energy to sustainably power a human body temperature sensor. PMID:26343789

  7. Formation of parallel two-phase flow in nanochannel and application to solvent extraction

    NASA Astrophysics Data System (ADS)

    Kazoe, Yutaka; Ugajin, Takuya; Ohta, Ryoichi; Mawatari, Kazuma; Kitamori, Takehiko; The University of Tokyo Team

    2015-11-01

    Micro chemical systems have realized high-throughput analysis in ultra small volumes. Our group has established unit operations such as extraction, separation and reaction, and a concept of integration of chemical processes using parallel multi-phase flows in microchannels. Recently, the research field has been extended to 10-1000 nm space (extended-nanospace). Exploiting extended-nanospace, we developed ultra high performance chemical operations such as aL-chromatography and single molecule immunoassay. However, formation of parallel multi-phase flow in nanochannels has been difficult. The challenge is to control liquid-liquid/gas-liquid interfaces in 100 nm-scale. For this purpose, this study developed a partial surface modification method of nanochannel and verified formation of parallel two-phase flow. We achieved partial hydrophobic modification using focused ion beam (FIB). Using this method, formation of parallel water/dodecane two-phase flow in a nanochannel of 1500 nm width and 890 nm depth was succeeded. Solvent extraction of lipid, which is a basic separation in bioanalysis, was achieved in 25 fL volume much smaller than single cell. This study will greatly contribute to develop novel nanofluidic devices for chemical analysis and chemical synthesis. This work was supported by Japan Science and Technology Agency, Core Research for Evolutional Science and Technology.

  8. Computation of flow and heat transfer in rotating cavities with peripheral flow of cooling air.

    PubMed

    Kiliç, M

    2001-05-01

    Numerical solutions of the Navier-Stokes equations have been used to model the flow and the heat transfer that occurs in the internal cooling-air systems of gas turbines. Computations are performed to study the effect of gap ratio, Reynolds number and the mass flow rate on the flow and the heat transfer structure inside isothermal and heated rotating cavities with peripheral flow of cooling air. Computations are compared with some of the recent experimental work on flow and heat transfer in rotating-cavities. The agreement between the computed and the available experimental data is reasonably good. PMID:11460668

  9. Trench-parallel flow beneath the nazca plate from seismic anisotropy.

    PubMed

    Russo, R M; Silver, P G

    1994-02-25

    Shear-wave splitting of S and SKS phases reveals the anisotropy and strain field of the mantle beneath the subducting Nazca plate, Cocos plate, and the Caribbean region. These observations can be used to test models of mantle flow. Two-dimensional entrained mantle flow beneath the subducting Nazca slab is not consistent with the data. Rather, there is evidence for horizontal trench-parallel flow in the mantle beneath the Nazca plate along much of the Andean subduction zone. Trench-parallel flow is attributale utable to retrograde motion of the slab, the decoupling of the slab and underlying mantle, and a partial barrier to flow at depth, resulting in lateral mantle flow beneath the slab. Such flow facilitates the transfer of material from the shrinking mantle reservoir beneath the Pacific basin to the growing mantle reservoir beneath the Atlantic basin. Trenchparallel flow may explain the eastward motions of the Caribbean and Scotia sea plates, the anomalously shallow bathymetry of the eastern Nazca plate, the long-wavelength geoid high over western South America, and it may contribute to the high elevation and intense deformation of the central Andes. PMID:17831621

  10. 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.

  11. Equipment for Measuring Air Flow, Air Temperature, Relative Humidity, and Carbon Dioxide in Schools. Technical Bulletin.

    ERIC Educational Resources Information Center

    Jacobs, Bruce W.

    Information on equipment and techniques that school facility personnel may use to evaluate IAQ conditions are discussed. Focus is placed on the IAQ parameters of air flow, air temperature, relative humidity, as well as carbon dioxide and the equipment used to measure these factors. Reasons for measurement and for when the measurement of these…

  12. Optical Feedback Interferometry for Velocity Measurement of Parallel Liquid-Liquid Flows in a Microchannel.

    PubMed

    Ramírez-Miquet, Evelio E; Perchoux, Julien; Loubière, Karine; Tronche, Clément; Prat, Laurent; Sotolongo-Costa, Oscar

    2016-01-01

    Optical feedback interferometry (OFI) is a compact sensing technique with recent implementation for flow measurements in microchannels. We propose implementing OFI for the analysis at the microscale of multiphase flows starting with the case of parallel flows of two immiscible fluids. The velocity profiles in each phase were measured and the interface location estimated for several operating conditions. To the authors knowledge, this sensing technique is applied here for the first time to multiphase flows. Theoretical profiles issued from a model based on the Couette viscous flow approximation reproduce fairly well the experimental results. The sensing system and the analysis presented here provide a new tool for studying more complex interactions between immiscible fluids (such as liquid droplets flowing in a microchannel). PMID:27527178

  13. Cross-flow versus counterflow air-stripping towers

    SciTech Connect

    Little, J.C.; Marinas, B.J.

    1997-07-01

    Mass-transfer and pressure-drop packing performance correlations are used together with tower design equations and detailed cost models to compare the effectiveness of cross-flow and counterflow air stripping towers over a wide range of contaminant volatility. Cross-flow towers are shown to offer a significant economic advantage over counterflow towers when stripping low volatility organic contaminants primarily due to savings in energy costs. These savings increase as contaminant volatility decreases and as water flow rate increases. A further advantage of the cross-flow configuration is that it extends the feasible operating range for air stripping as cross-flow towers can accommodate higher air-to-water flow ratios than conventional counterflow towers. Finally it is shown that the optimized least-cost design for both counterflow and cross-flow towers varies with Henry`s law constant, water flow rate, and percent removal, but that the optimum is virtually insensitive to other cost and operating variables. This greatly simplifies the tower design procedure.

  14. 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.

  15. A parallel expert system for the control of a robotic air vehicle

    NASA Technical Reports Server (NTRS)

    Shakley, Donald; Lamont, Gary B.

    1988-01-01

    Expert systems can be used to govern the intelligent control of vehicles, for example the Robotic Air Vehicle (RAV). Due to the nature of the RAV system the associated expert system needs to perform in a demanding real-time environment. The use of a parallel processing capability to support the associated expert system's computational requirement is critical in this application. Thus, algorithms for parallel real-time expert systems must be designed, analyzed, and synthesized. The design process incorporates a consideration of the rule-set/face-set size along with representation issues. These issues are looked at in reference to information movement and various inference mechanisms. Also examined is the process involved with transporting the RAV expert system functions from the TI Explorer, where they are implemented in the Automated Reasoning Tool (ART), to the iPSC Hypercube, where the system is synthesized using Concurrent Common LISP (CCLISP). The transformation process for the ART to CCLISP conversion is described. The performance characteristics of the parallel implementation of these expert systems on the iPSC Hypercube are compared to the TI Explorer implementation.

  16. Parallel flow accumulation algorithms for graphical processing units with application to RUSLE model

    NASA Astrophysics Data System (ADS)

    Sten, Johan; Lilja, Harri; Hyväluoma, Jari; Westerholm, Jan; Aspnäs, Mats

    2016-04-01

    Digital elevation models (DEMs) are widely used in the modeling of surface hydrology, which typically includes the determination of flow directions and flow accumulation. The use of high-resolution DEMs increases the accuracy of flow accumulation computation, but as a drawback, the computational time may become excessively long if large areas are analyzed. In this paper we investigate the use of graphical processing units (GPUs) for efficient flow accumulation calculations. We present two new parallel flow accumulation algorithms based on dependency transfer and topological sorting and compare them to previously published flow transfer and indegree-based algorithms. We benchmark the GPU implementations against industry standards, ArcGIS and SAGA. With the flow-transfer D8 flow routing model and binary input data, a speed up of 19 is achieved compared to ArcGIS and 15 compared to SAGA. We show that on GPUs the topological sort-based flow accumulation algorithm leads on average to a speedup by a factor of 7 over the flow-transfer algorithm. Thus a total speed up of the order of 100 is achieved. We test the algorithms by applying them to the Revised Universal Soil Loss Equation (RUSLE) erosion model. For this purpose we present parallel versions of the slope, LS factor and RUSLE algorithms and show that the RUSLE erosion results for an area of 12 km x 24 km containing 72 million cells can be calculated in less than a second. Since flow accumulation is needed in many hydrological models, the developed algorithms may find use in many other applications than RUSLE modeling. The algorithm based on topological sorting is particularly promising for dynamic hydrological models where flow accumulations are repeatedly computed over an unchanged DEM.

  17. Single and two-phase flow fluid dynamics in parallel helical coils

    NASA Astrophysics Data System (ADS)

    De Salve, M.; Orio, M.; Panella, B.

    2014-04-01

    The design of helical coiled steam generators requires the knowledge of the single and two-phase fluid dynamics. The present work reports the results of an experimental campaign on single-phase and two phase pressure drops and void fraction in three parallel helicoidal pipes, in which the total water flow rate is splitted by means of a branch. With this test configuration the distribution of the water flow rate in the helicoidal pipes and the phenomena of the instability of the two-phase flow have been experimentally investigated.

  18. Rotordynamic coefficients and leakage flow of parallel grooved seals and smooth seals

    NASA Technical Reports Server (NTRS)

    Nordmann, R.; Dietzen, F. J.; Janson, W.; Frei, A.; Florjancic, S.

    1987-01-01

    Based on Childs finite length solution for annular plain seals an extension of the bulk flow theory is derived to calculate the rotordynamic coefficients and the leakage flow of seals with parallel grooves in the stator. Hirs turbulent lubricant equations are modified to account for the different friction factors in circumferential and axial direction. Furthermore an average groove depth is introduced to consider the additional circumferential flow in the grooves. Theoretical and experimental results are compared for the smooth constant clearance seal and the corresponding seal with parallel grooves. Compared to the smooth seal the direct and cross-coupled stiffness coefficients as well as the direct damping coefficients are lower in the grooved seal configuration. Leakage is reduced by the grooving pattern.

  19. Optical Air Flow Measurements in Flight

    NASA Technical Reports Server (NTRS)

    Bogue, Rodney K.; Jentink, Henk W.

    2004-01-01

    This document has been written to assist the flight-test engineer and researcher in using optical flow measurements in flight applications. The emphasis is on describing tradeoffs in system design to provide desired measurement performance as currently understood. Optical system components are discussed with examples that illustrate the issues. The document concludes with descriptions of optical measurement systems designed for a variety of applications including aeronautics research, airspeed measurement, and turbulence hazard detection. Theoretical discussion is minimized, but numerous references are provided to supply ample opportunity for the reader to understand the theoretical underpinning of optical concepts.

  20. Massively parallel simulation of flow and transport in variably saturated porous and fractured media

    SciTech Connect

    Wu, Yu-Shu; Zhang, Keni; Pruess, Karsten

    2002-01-15

    This paper describes a massively parallel simulation method and its application for modeling multiphase flow and multicomponent transport in porous and fractured reservoirs. The parallel-computing method has been implemented into the TOUGH2 code and its numerical performance is tested on a Cray T3E-900 and IBM SP. The efficiency and robustness of the parallel-computing algorithm are demonstrated by completing two simulations with more than one million gridblocks, using site-specific data obtained from a site-characterization study. The first application involves the development of a three-dimensional numerical model for flow in the unsaturated zone of Yucca Mountain, Nevada. The second application is the study of tracer/radionuclide transport through fracture-matrix rocks for the same site. The parallel-computing technique enhances modeling capabilities by achieving several-orders-of-magnitude speedup for large-scale and high resolution modeling studies. The resulting modeling results provide many new insights into flow and transport processes that could not be obtained from simulations using the single-CPU simulator.

  1. Parallel pulse processing and data acquisition for high speed, low error flow cytometry

    SciTech Connect

    van den Engh, Gerrit J.; Stokdijk, Willem

    1992-01-01

    A digitally synchronized parallel pulse processing and data acquisition system for a flow cytometer has multiple parallel input channels with independent pulse digitization and FIFO storage buffer. A trigger circuit controls the pulse digitization on all channels. After an event has been stored in each FIFO, a bus controller moves the oldest entry from each FIFO buffer onto a common data bus. The trigger circuit generates an ID number for each FIFO entry, which is checked by an error detection circuit. The system has high speed and low error rate.

  2. Data flow analysis of a highly parallel processor for a level 1 pixel trigger

    SciTech Connect

    Cancelo, G.; Gottschalk, Erik Edward; Pavlicek, V.; Wang, M.; Wu, J.

    2003-01-01

    The present work describes the architecture and data flow analysis of a highly parallel processor for the Level 1 Pixel Trigger for the BTeV experiment at Fermilab. First the Level 1 Trigger system is described. Then the major components are analyzed by resorting to mathematical modeling. Also, behavioral simulations are used to confirm the models. Results from modeling and simulations are fed back into the system in order to improve the architecture, eliminate bottlenecks, allocate sufficient buffering between processes and obtain other important design parameters. An interesting feature of the current analysis is that the models can be extended to a large class of architectures and parallel systems.

  3. Parallel pulse processing and data acquisition for high speed, low error flow cytometry

    DOEpatents

    Engh, G.J. van den; Stokdijk, W.

    1992-09-22

    A digitally synchronized parallel pulse processing and data acquisition system for a flow cytometer has multiple parallel input channels with independent pulse digitization and FIFO storage buffer. A trigger circuit controls the pulse digitization on all channels. After an event has been stored in each FIFO, a bus controller moves the oldest entry from each FIFO buffer onto a common data bus. The trigger circuit generates an ID number for each FIFO entry, which is checked by an error detection circuit. The system has high speed and low error rate. 17 figs.

  4. Experimental Studies of the Interaction Between a Parallel Shear Flow and a Directionally-Solidifying Front

    NASA Technical Reports Server (NTRS)

    Zhang, Meng; Maxworthy, Tony

    1999-01-01

    It has long been recognized that flow in the melt can have a profound influence on the dynamics of a solidifying interface and hence the quality of the solid material. In particular, flow affects the heat and mass transfer, and causes spatial and temporal variations in the flow and melt composition. This results in a crystal with nonuniform physical properties. Flow can be generated by buoyancy, expansion or contraction upon phase change, and thermo-soluto capillary effects. In general, these flows can not be avoided and can have an adverse effect on the stability of the crystal structures. This motivates crystal growth experiments in a microgravity environment, where buoyancy-driven convection is significantly suppressed. However, transient accelerations (g-jitter) caused by the acceleration of the spacecraft can affect the melt, while convection generated from the effects other than buoyancy remain important. Rather than bemoan the presence of convection as a source of interfacial instability, Hurle in the 1960s suggested that flow in the melt, either forced or natural convection, might be used to stabilize the interface. Delves considered the imposition of both a parabolic velocity profile and a Blasius boundary layer flow over the interface. He concluded that fast stirring could stabilize the interface to perturbations whose wave vector is in the direction of the fluid velocity. Forth and Wheeler considered the effect of the asymptotic suction boundary layer profile. They showed that the effect of the shear flow was to generate travelling waves parallel to the flow with a speed proportional to the Reynolds number. There have been few quantitative, experimental works reporting on the coupling effect of fluid flow and morphological instabilities. Huang studied plane Couette flow over cells and dendrites. It was found that this flow could greatly enhance the planar stability and even induce the cell-planar transition. A rotating impeller was buried inside the

  5. Parallelization of Lower-Upper Symmetric Gauss-Seidel Method for Chemically Reacting Flow

    NASA Technical Reports Server (NTRS)

    Yoon, Seokkwan; Jost, Gabriele; Chang, Sherry

    2005-01-01

    Development of technologies for exploration of the solar system has revived an interest in computational simulation of chemically reacting flows since planetary probe vehicles exhibit non-equilibrium phenomena during the atmospheric entry of a planet or a moon as well as the reentry to the Earth. Stability in combustion is essential for new propulsion systems. Numerical solution of real-gas flows often increases computational work by an order-of-magnitude compared to perfect gas flow partly because of the increased complexity of equations to solve. Recently, as part of Project Columbia, NASA has integrated a cluster of interconnected SGI Altix systems to provide a ten-fold increase in current supercomputing capacity that includes an SGI Origin system. Both the new and existing machines are based on cache coherent non-uniform memory access architecture. Lower-Upper Symmetric Gauss-Seidel (LU-SGS) relaxation method has been implemented into both perfect and real gas flow codes including Real-Gas Aerodynamic Simulator (RGAS). However, the vectorized RGAS code runs inefficiently on cache-based shared-memory machines such as SGI system. Parallelization of a Gauss-Seidel method is nontrivial due to its sequential nature. The LU-SGS method has been vectorized on an oblique plane in INS3D-LU code that has been one of the base codes for NAS Parallel benchmarks. The oblique plane has been called a hyperplane by computer scientists. It is straightforward to parallelize a Gauss-Seidel method by partitioning the hyperplanes once they are formed. Another way of parallelization is to schedule processors like a pipeline using software. Both hyperplane and pipeline methods have been implemented using openMP directives. The present paper reports the performance of the parallelized RGAS code on SGI Origin and Altix systems.

  6. Air flow management in an internal combustion engine through the use of electronically controlled air jets

    SciTech Connect

    Swain, M.R.

    1988-12-27

    This patent describes a means for producing an air/fuel mixture in the valve pocket and means for directing the air/fuel mixture past the intake valve into the combustion chamber, the improvement comprising a device for generating a swirling flow of the air/fuel mixture in the combustion chamber to thereby obtain greater combustion stability. The device has a nozzle positioned within the valve pocket and directed at an acute angle toward the intake valve comprising at least one opening for receiving air, connected to a first pathway, and at least one opening for expelling air, connected, to a second pathway joined to the first pathway and extending to the expulsion opening. The device also includes a means for controlling the flow of air through the pathway and out the expulsion opening comprising: (i) a stopper having sides complementary in shape to the pair of opposed arcuate walls movable from an open position allowing air through the pathway to a closed position, wherein the sides of the stopper are in a sealed relationship with the opposed arcaute sides of the junction thereby preventing the flow of air through the second pathway and out of the expulsion opening; and (ii) an electronic computer which determines the size and duration of the pathway opening.

  7. Entropy Generation During Fluid Flow Between Two Parallel Plates With Moving Bottom Plate

    NASA Astrophysics Data System (ADS)

    Erbay, Latife B.; Ercan, Mehmet S.; Sülüs, Birsen; Yalçÿn, M. M.

    2003-12-01

    Two dimensional numerical analysis of entropy generation during transient convective heat transfer for laminar flow between two parallel plates has been investigated. The fluid is incompressible and Newtonian and the flow is the hydrodynamically and thermally developing. The plates are held at constant equal temperatures higher than that of the fluid. The bottom plate moves in either parallel or in inverse direction to the flow. The governing equations of the transient convective heat transfer are written in two-dimensional Cartesian coordinates and solved by the finite volume method with SIMPLE algorithm. The solutions are carried for Reynolds numbers of 102, 5x102 and 103 and Prandtl number of 1. After the flow field and the temperature distributions are obtained, the entropy values and the sites initiating the entropy generation are investigated. The results have indicated that the number of the entropy generation has its highest value at the highest Reynolds and Br/Ω values, which is obtained at counter motion of the lower plate. The lowest average number of the entropy generation on the bottom plate is obtained in parallel motion. The corners of the channel plates at the entrance play the role of active sites where the generation of entropy is triggered.

  8. Airway blood flow response to dry air hyperventilation in sheep

    SciTech Connect

    Parsons, G.H.; Baile, E.M.; Pare, P.D.

    1986-03-01

    Airway blood flow (Qaw) may be important in conditioning inspired air. To determine the effect of eucapneic dry air hyperventilation (hv) on Qaw in sheep the authors studied 7 anesthetized open-chest sheep after 25 min. of warm dry air hv. During each period of hv the authors have recorded vascular pressures, cardiac output (CO), and tracheal mucosal and inspired air temperature. Using a modification of the reference flow technique radiolabelled microspheres were injected into the left atrium to make separate measurements after humid air and dry air hv. In 4 animals a snare around the left main pulmonary artery was used following microsphere injection to prevent recirculation (entry into L lung of microspheres from the pulmonary artery). Qaw to the trachea and L lung as measured and Qaw for the R lung was estimated. After the final injection the sheep were killed and bronchi (Br) and lungs removed. Qaw (trachea plus L lung plus R lung) in 4 sheep increased from a mean of 30.8 to 67.0 ml/min. Airway mucosal temp. decreased from 39/sup 0/ to 33/sup 0/C. The authors conclude that dry air hv cools airway mucosa and increases Qaw in sheep.

  9. The impact of traffic-flow patterns on air quality in urban street canyons.

    PubMed

    Thaker, Prashant; Gokhale, Sharad

    2016-01-01

    We investigated the effect of different urban traffic-flow patterns on pollutant dispersion in different winds in a real asymmetric street canyon. Free-flow traffic causes more turbulence in the canyon facilitating more dispersion and a reduction in pedestrian level concentration. The comparison of with and without a vehicle-induced-turbulence revealed that when winds were perpendicular, the free-flow traffic reduced the concentration by 73% on the windward side with a minor increase of 17% on the leeward side, whereas for parallel winds, it reduced the concentration by 51% and 29%. The congested-flow traffic increased the concentrations on the leeward side by 47% when winds were perpendicular posing a higher risk to health, whereas reduced it by 17-42% for parallel winds. The urban air quality and public health can, therefore, be improved by improving the traffic-flow patterns in street canyons as vehicle-induced turbulence has been shown to contribute significantly to dispersion. PMID:26412198

  10. Numerical and physical instabilities in massively parallel LES of reacting flows

    NASA Astrophysics Data System (ADS)

    Poinsot, Thierry

    LES of reacting flows is rapidly becoming mature and providing levels of precision which can not be reached with any RANS (Reynolds Averaged) technique. In addition to the multiple subgrid scale models required for such LES and to the questions raised by the required numerical accurcay of LES solvers, various issues related the reliability, mesh independence and repetitivity of LES must still be addressed, especially when LES is used on massively parallel machines. This talk discusses some of these issues: (1) the existence of non physical waves (known as `wiggles' by most LES practitioners) in LES, (2) the effects of mesh size on LES of reacting flows, (3) the growth of rounding errors in LES on massively parallel machines and more generally (4) the ability to qualify a LES code as `bug free' and `accurate'. Examples range from academic cases (minimum non-reacting turbulent channel) to applied configurations (a sector of an helicopter combustion chamber).

  11. Adaptive finite element simulation of flow and transport applications on parallel computers

    NASA Astrophysics Data System (ADS)

    Kirk, Benjamin Shelton

    The subject of this work is the adaptive finite element simulation of problems arising in flow and transport applications on parallel computers. Of particular interest are new contributions to adaptive mesh refinement (AMR) in this parallel high-performance context, including novel work on data structures, treatment of constraints in a parallel setting, generality and extensibility via object-oriented programming, and the design/implementation of a flexible software framework. This technology and software capability then enables more robust, reliable treatment of multiscale--multiphysics problems and specific studies of fine scale interaction such as those in biological chemotaxis (Chapter 4) and high-speed shock physics for compressible flows (Chapter 5). The work begins by presenting an overview of key concepts and data structures employed in AMR simulations. Of particular interest is how these concepts are applied in the physics-independent software framework which is developed here and is the basis for all the numerical simulations performed in this work. This open-source software framework has been adopted by a number of researchers in the U.S. and abroad for use in a wide range of applications. The dynamic nature of adaptive simulations pose particular issues for efficient implementation on distributed-memory parallel architectures. Communication cost, computational load balance, and memory requirements must all be considered when developing adaptive software for this class of machines. Specific extensions to the adaptive data structures to enable implementation on parallel computers is therefore considered in detail. The libMesh framework for performing adaptive finite element simulations on parallel computers is developed to provide a concrete implementation of the above ideas. This physics-independent framework is applied to two distinct flow and transport applications classes in the subsequent application studies to illustrate the flexibility of the

  12. Parallel traffic flow simulation of freeway networks: Phase 2. Final report 1994--1995

    SciTech Connect

    Chronopoulos, A.

    1997-07-01

    Explicit and implicit numerical methods for solving simple macroscopic traffic flow continuum models have been studied and efficiently implemented in traffic simulation codes in the past. The authors have already studied and implemented explicit methods for solving the high-order flow conservation traffic model. Implicit methods allow much larger time step size than explicit methods, for the same accuracy. However, at each time step a nonlinear system must be solved. They use the Newton method coupled with a linear iterative (Orthomin). They accelerate the convergence of Orthomin with parallel incomplete LU factorization preconditionings. The authors implemented this implicit method on a 16 processor nCUBE2 parallel computer and obtained significant execution time speedup.

  13. 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.

  14. Parallel evolution of local adaptation and reproductive isolation in the face of gene flow.

    PubMed

    Butlin, Roger K; Saura, Maria; Charrier, Grégory; Jackson, Benjamin; André, Carl; Caballero, Armando; Coyne, Jerry A; Galindo, Juan; Grahame, John W; Hollander, Johan; Kemppainen, Petri; Martínez-Fernández, Mónica; Panova, Marina; Quesada, Humberto; Johannesson, Kerstin; Rolán-Alvarez, Emilio

    2014-04-01

    Parallel evolution of similar phenotypes provides strong evidence for the operation of natural selection. Where these phenotypes contribute to reproductive isolation, they further support a role for divergent, habitat-associated selection in speciation. However, the observation of pairs of divergent ecotypes currently occupying contrasting habitats in distinct geographical regions is not sufficient to infer parallel origins. Here we show striking parallel phenotypic divergence between populations of the rocky-shore gastropod, Littorina saxatilis, occupying contrasting habitats exposed to either wave action or crab predation. This divergence is associated with barriers to gene exchange but, nevertheless, genetic variation is more strongly structured by geography than by ecotype. Using approximate Bayesian analysis of sequence data and amplified fragment length polymorphism markers, we show that the ecotypes are likely to have arisen in the face of continuous gene flow and that the demographic separation of ecotypes has occurred in parallel at both regional and local scales. Parameter estimates suggest a long delay between colonization of a locality and ecotype formation, perhaps because the postglacial spread of crab populations was slower than the spread of snails. Adaptive differentiation may not be fully genetically independent despite being demographically parallel. These results provide new insight into a major model of ecologically driven speciation. PMID:24299519

  15. PARALLEL EVOLUTION OF LOCAL ADAPTATION AND REPRODUCTIVE ISOLATION IN THE FACE OF GENE FLOW

    PubMed Central

    Butlin, Roger K; Saura, Maria; Charrier, Grégory; Jackson, Benjamin; André, Carl; Caballero, Armando; Coyne, Jerry A; Galindo, Juan; Grahame, John W; Hollander, Johan; Kemppainen, Petri; Martínez-Fernández, Mónica; Panova, Marina; Quesada, Humberto; Johannesson, Kerstin; Rolán-Alvarez, Emilio

    2014-01-01

    Parallel evolution of similar phenotypes provides strong evidence for the operation of natural selection. Where these phenotypes contribute to reproductive isolation, they further support a role for divergent, habitat-associated selection in speciation. However, the observation of pairs of divergent ecotypes currently occupying contrasting habitats in distinct geographical regions is not sufficient to infer parallel origins. Here we show striking parallel phenotypic divergence between populations of the rocky-shore gastropod, Littorina saxatilis, occupying contrasting habitats exposed to either wave action or crab predation. This divergence is associated with barriers to gene exchange but, nevertheless, genetic variation is more strongly structured by geography than by ecotype. Using approximate Bayesian analysis of sequence data and amplified fragment length polymorphism markers, we show that the ecotypes are likely to have arisen in the face of continuous gene flow and that the demographic separation of ecotypes has occurred in parallel at both regional and local scales. Parameter estimates suggest a long delay between colonization of a locality and ecotype formation, perhaps because the postglacial spread of crab populations was slower than the spread of snails. Adaptive differentiation may not be fully genetically independent despite being demographically parallel. These results provide new insight into a major model of ecologically driven speciation. PMID:24299519

  16. Glow Discharge Characteristics in Transverse Supersonic Air Flow

    NASA Astrophysics Data System (ADS)

    Timerkaev, B. A.; Zalyaliev, B. R.; Saifutdinov, A. I.

    2014-11-01

    A low pressure glow discharge in a transverse supersonic gas flow of air at pressures of the order 1 torr has been experimentally studied for the case where the flow only partially fills the inter electrode gap. It is shown that the space region with supersonic gas flow has a higher concentration of gas particles and, therefore, works as a charged particle generator. The near electrode regions of glow discharge are concentrated specifically in this region. This structure of glow discharge is promising for plasma deposition of coatings under ultralow pressures

  17. Split-flow regeneration in absorptive air separation

    DOEpatents

    Weimer, Robert F.

    1987-01-01

    A chemical absorptive separation of air 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 flow, reduced energy demand and reduced capital costs.

  18. The Wells turbine in an oscillating air flow

    SciTech Connect

    Raghunathan, S.; Ombaka,

    1984-08-01

    An experimental study of the performance of a 0.2 m diameter Wells self rectifying air turbine with NACA 0021 blades is presented. Experiments were conducted in an oscillating flowrig. The effects of Reynolds number and Strouhal number on the performance of the turbine were investigated. Finally comparison between the results with the predictions from uni-directional flow tests are made.

  19. Split-flow regeneration in absorptive air separation

    DOEpatents

    Weimer, R.F.

    1987-11-24

    A chemical absorptive separation of air 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 flow, reduced energy demand and reduced capital costs. 4 figs.

  20. 30 CFR 57.22213 - Air flow (III mines).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Air flow (III mines). 57.22213 Section 57.22213 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...

  1. 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 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...

  2. 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 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...

  3. 30 CFR 57.22213 - Air flow (III mines).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Air flow (III mines). 57.22213 Section 57.22213 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...

  4. 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 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...

  5. High performance parallel computing of flows in complex geometries: I. Methods

    NASA Astrophysics Data System (ADS)

    Gourdain, N.; Gicquel, L.; Montagnac, M.; Vermorel, O.; Gazaix, M.; Staffelbach, G.; Garcia, M.; Boussuge, J.-F.; Poinsot, T.

    2009-01-01

    Efficient numerical tools coupled with high-performance computers, have become a key element of the design process in the fields of energy supply and transportation. However flow phenomena that occur in complex systems such as gas turbines and aircrafts are still not understood mainly because of the models that are needed. In fact, most computational fluid dynamics (CFD) predictions as found today in industry focus on a reduced or simplified version of the real system (such as a periodic sector) and are usually solved with a steady-state assumption. This paper shows how to overcome such barriers and how such a new challenge can be addressed by developing flow solvers running on high-end computing platforms, using thousands of computing cores. Parallel strategies used by modern flow solvers are discussed with particular emphases on mesh-partitioning, load balancing and communication. Two examples are used to illustrate these concepts: a multi-block structured code and an unstructured code. Parallel computing strategies used with both flow solvers are detailed and compared. This comparison indicates that mesh-partitioning and load balancing are more straightforward with unstructured grids than with multi-block structured meshes. However, the mesh-partitioning stage can be challenging for unstructured grids, mainly due to memory limitations of the newly developed massively parallel architectures. Finally, detailed investigations show that the impact of mesh-partitioning on the numerical CFD solutions, due to rounding errors and block splitting, may be of importance and should be accurately addressed before qualifying massively parallel CFD tools for a routine industrial use.

  6. Analytical solution to the equations for parallel-flow four-channel heat exchangers

    SciTech Connect

    Malinowski, L.

    2000-04-01

    Assuming that the thermophysical parameters of the fluids are independent on temperature, the stationary temperature field in a parallel-flow multi-channel heat exchanger can be described by a set of linear differential equations of the first order with constant coefficients. A compact analytical solution to this set is presented for the case of four-channel exchangers and simple eigenvalues of the coefficient matrix of the set.

  7. Arc-parallel flow in the mantle wedge beneath Costa Rica and Nicaragua.

    PubMed

    Hoernle, Kaj; Abt, David L; Fischer, Karen M; Nichols, Holly; Hauff, Folkmar; Abers, Geoffrey A; van den Bogaard, Paul; Heydolph, Ken; Alvarado, Guillermo; Protti, Marino; Strauch, Wilfried

    2008-02-28

    Resolving flow geometry in the mantle wedge is central to understanding the thermal and chemical structure of subduction zones, subducting plate dehydration, and melting that leads to arc volcanism, which can threaten large populations and alter climate through gas and particle emission. Here we show that isotope geochemistry and seismic velocity anisotropy provide strong evidence for trench-parallel flow in the mantle wedge beneath Costa Rica and Nicaragua. This finding contradicts classical models, which predict trench-normal flow owing to the overlying wedge mantle being dragged downwards by the subducting plate. The isotopic signature of central Costa Rican volcanic rocks is not consistent with its derivation from the mantle wedge or eroded fore-arc complexes but instead from seamounts of the Galapagos hotspot track on the subducting Cocos plate. This isotopic signature decreases continuously from central Costa Rica to northwestern Nicaragua. As the age of the isotopic signature beneath Costa Rica can be constrained and its transport distance is known, minimum northwestward flow rates can be estimated (63-190 mm yr(-1)) and are comparable to the magnitude of subducting Cocos plate motion (approximately 85 mm yr(-1)). Trench-parallel flow needs to be taken into account in models evaluating thermal and chemical structure and melt generation in subduction zones. PMID:18223639

  8. A parallelized multidomain compact solver for incompressible turbulent flows in cylindrical geometries

    NASA Astrophysics Data System (ADS)

    Oguic, Romain; Viazzo, Stéphane; Poncet, Sébastien

    2015-11-01

    We present an efficient parallelized multidomain algorithm for solving the 3D Navier-Stokes equations in cylindrical geometries. The numerical method is based on fourth-order compact schemes in the two non-homogeneous directions and Fourier series expansion in the azimuthal direction. The temporal scheme is a second-order semi-implicit projection scheme leading to the solution of five Helmholtz/Poisson equations. To handle the singularity appearing at the axis in cylindrical coordinates, while being able to have a thinner or conversely a coarser mesh in this zone, parity conditions are imposed at r = 0 for each flow variable and azimuthal Fourier mode. To simulate flows in irregularly shaped cylindrical geometries and benefit from a hybrid OpenMP/MPI parallelization, an accurate perfectly free-divergence multidomain method based on the influence matrix technique is proposed. First, the accuracy of the present solver is checked by comparison with analytical solutions and the scalability is then evaluated. Simulations using the present code are then compared to reliable experimental and numerical results of the literature showing good quantitative agreements in the cases of the axisymmetric and 3D unsteady vortex breakdowns in a cylinder and turbulent pipe flow. Finally to show the capability of the algorithm to deal with more complex flows relevant of turbomachineries, the turbulent flow inside a simplified stage of High-Pressure compressor is considered.

  9. Scalable High Performance Computing: Direct and Large-Eddy Turbulent Flow Simulations Using Massively Parallel Computers

    NASA Technical Reports Server (NTRS)

    Morgan, Philip E.

    2004-01-01

    This final report contains reports of research related to the tasks "Scalable High Performance Computing: Direct and Lark-Eddy Turbulent FLow Simulations Using Massively Parallel Computers" and "Devleop High-Performance Time-Domain Computational Electromagnetics Capability for RCS Prediction, Wave Propagation in Dispersive Media, and Dual-Use Applications. The discussion of Scalable High Performance Computing reports on three objectives: validate, access scalability, and apply two parallel flow solvers for three-dimensional Navier-Stokes flows; develop and validate a high-order parallel solver for Direct Numerical Simulations (DNS) and Large Eddy Simulation (LES) problems; and Investigate and develop a high-order Reynolds averaged Navier-Stokes turbulence model. The discussion of High-Performance Time-Domain Computational Electromagnetics reports on five objectives: enhancement of an electromagnetics code (CHARGE) to be able to effectively model antenna problems; utilize lessons learned in high-order/spectral solution of swirling 3D jets to apply to solving electromagnetics project; transition a high-order fluids code, FDL3DI, to be able to solve Maxwell's Equations using compact-differencing; develop and demonstrate improved radiation absorbing boundary conditions for high-order CEM; and extend high-order CEM solver to address variable material properties. The report also contains a review of work done by the systems engineer.

  10. Flow distribution in parallel microfluidic networks and its effect on concentration gradient.

    PubMed

    Guermonprez, Cyprien; Michelin, Sébastien; Baroud, Charles N

    2015-09-01

    The architecture of microfluidic networks can significantly impact the flow distribution within its different branches and thereby influence tracer transport within the network. In this paper, we study the flow rate distribution within a network of parallel microfluidic channels with a single input and single output, using a combination of theoretical modeling and microfluidic experiments. Within the ladder network, the flow rate distribution follows a U-shaped profile, with the highest flow rate occurring in the initial and final branches. The contrast with the central branches is controlled by a single dimensionless parameter, namely, the ratio of hydrodynamic resistance between the distribution channel and the side branches. This contrast in flow rates decreases when the resistance of the side branches increases relative to the resistance of the distribution channel. When the inlet flow is composed of two parallel streams, one of which transporting a diffusing species, a concentration variation is produced within the side branches of the network. The shape of this concentration gradient is fully determined by two dimensionless parameters: the ratio of resistances, which determines the flow rate distribution, and the Péclet number, which characterizes the relative speed of diffusion and advection. Depending on the values of these two control parameters, different distribution profiles can be obtained ranging from a flat profile to a step distribution of solute, with well-distributed gradients between these two limits. Our experimental results are in agreement with our numerical model predictions, based on a simplified 2D advection-diffusion problem. Finally, two possible applications of this work are presented: the first one combines the present design with self-digitization principle to encapsulate the controlled concentration in nanoliter chambers, while the second one extends the present design to create a continuous concentration gradient within an open flow

  11. A stagnation pressure probe for droplet-laden air flow

    NASA Technical Reports Server (NTRS)

    Murthy, S. N. B.; Leonardo, M.; Ehresman, C. M.

    1985-01-01

    It is often of interest in a droplet-laden gas flow to obtain the stagnation pressure of both the gas phase and the mixture. A flow-decelerating probe (TPF), with separate, purged ports for the gas phase and the mixture and with a bleed for accumulating liquid at the closed end, has been developed. Measurements obtained utilizing the TPF in a nearly isothermal air-water droplet mixture flow in a smooth circular pipe under various conditions of flow velocity, pressure, liquid concentration and droplet size are presented and compared with data obtained under identical conditions with a conventional, gas phase stagnation pressure probe (CSP). The data obtained with the CSP and TPF probes are analyzed to determine the applicability of the two probes in relation to the multi-phase characteristics of the flow and the geometry of the probe.

  12. Oscillatory flow at the end of parallel-plate stacks: phenomenological and similarity analysis

    NASA Astrophysics Data System (ADS)

    Mao, Xiaoan; Jaworski, Artur J.

    2010-10-01

    This paper addresses the physics of the oscillatory flow in the vicinity of a series of parallel plates forming geometrically identical channels. This type of flow is particularly relevant to thermoacoustic engines and refrigerators, where a reciprocating flow is responsible for the desirable energy transfer, but it is also of interest to general fluid mechanics of oscillatory flows past bluff bodies. In this paper, the physics of an acoustically induced flow past a series of plates in an isothermal condition is studied in detail using the data provided by PIV imaging. Particular attention is given to the analysis of the wake flow during the ejection part of the flow cycle, where either closed recirculating vortices or alternating vortex shedding can be observed. This is followed by a similarity analysis of the governing Navier-Stokes equations in order to derive the similarity criteria governing the wake flow behaviour. To this end, similarity numbers including two types of Reynolds number, the Keulegan-Carpenter number and a non-dimensional stack configuration parameter, d/h, are considered and their influence on the phenomena are discussed.

  13. Accelerating groundwater flow simulation in MODFLOW using JASMIN-based parallel computing.

    PubMed

    Cheng, Tangpei; Mo, Zeyao; Shao, Jingli

    2014-01-01

    To accelerate the groundwater flow simulation process, this paper reports our work on developing an efficient parallel simulator through rebuilding the well-known software MODFLOW on JASMIN (J Adaptive Structured Meshes applications Infrastructure). The rebuilding process is achieved by designing patch-based data structure and parallel algorithms as well as adding slight modifications to the compute flow and subroutines in MODFLOW. Both the memory requirements and computing efforts are distributed among all processors; and to reduce communication cost, data transfers are batched and conveniently handled by adding ghost nodes to each patch. To further improve performance, constant-head/inactive cells are tagged and neglected during the linear solving process and an efficient load balancing strategy is presented. The accuracy and efficiency are demonstrated through modeling three scenarios: The first application is a field flow problem located at Yanming Lake in China to help design reasonable quantity of groundwater exploitation. Desirable numerical accuracy and significant performance enhancement are obtained. Typically, the tagged program with load balancing strategy running on 40 cores is six times faster than the fastest MICCG-based MODFLOW program. The second test is simulating flow in a highly heterogeneous aquifer. The AMG-based JASMIN program running on 40 cores is nine times faster than the GMG-based MODFLOW program. The third test is a simplified transient flow problem with the order of tens of millions of cells to examine the scalability. Compared to 32 cores, parallel efficiency of 77 and 68% are obtained on 512 and 1024 cores, respectively, which indicates impressive scalability. PMID:23600445

  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. Air Flow in a Separating Laminar Boundary Layer

    NASA Technical Reports Server (NTRS)

    Schubauer, G B

    1936-01-01

    The speed distribution in a laminar boundary layer on the surface of an elliptic cylinder, of major and minor axes 11.78 and 3.98 inches, respectively, has been determined by means of a hot-wire anemometer. The direction of the impinging air stream was parallel to the major axis. Special attention was given to the region of separation and to the exact location of the point of separation. An approximate method, developed by K. Pohlhausen for computing the speed distribution, the thickness of the layer, and the point of separation, is described in detail; and speed-distribution curves calculated by this method are presented for comparison with experiment.

  16. Flow over a Modern Ram-Air Parachute Canopy

    NASA Astrophysics Data System (ADS)

    Mohammadi, Mohammad; Johari, Hamid

    2010-11-01

    The flow field on the central section of a modern ram-air parachute canopy was examined numerically using a finite-volume flow solver coupled with the one equation Spalart-Allmaras turbulence model. Ram-air parachutes are used for guided airdrop applications, and the canopy resembles a wing with an open leading edge for inflation. The canopy surfaces were assumed to be impermeable and rigid. The flow field consisted of a vortex inside the leading edge opening which effectively closed off the canopy and diverted the flow around the leading edge. The flow experienced a rather bluff leading edge in contrast to the smooth leading of an airfoil, leading to a separation bubble on the lower lip of the canopy. The flow inside the canopy was stagnant beyond the halfway point. The section lift coefficient increased linearly with the angle of attack up to 8.5 and the lift curve slope was about 8% smaller than the baseline airfoil. The leading edge opening had a major effect on the drag prior to stall; the drag is at least twice the baseline airfoil drag. The minimum drag of the section occurs over the angle of attack range of 3 -- 7 .

  17. Scalability of preconditioners as a strategy for parallel computation of compressible fluid flow

    SciTech Connect

    Hansen, G.A.

    1996-05-01

    Parallel implementations of a Newton-Krylov-Schwarz algorithm are used to solve a model problem representing low Mach number compressible fluid flow over a backward-facing step. The Mach number is specifically selected to result in a numerically {open_quote}stiff{close_quotes} matrix problem, based on an implicit finite volume discretization of the compressible 2D Navier-Stokes/energy equations using primitive variables. Newton`s method is used to linearize the discrete system, and a preconditioned Krylov projection technique is used to solve the resulting linear system. Domain decomposition enables the development of a global preconditioner via the parallel construction of contributions derived from subdomains. Formation of the global preconditioner is based upon additive and multiplicative Schwarz algorithms, with and without subdomain overlap. The degree of parallelism of this technique is further enhanced with the use of a matrix-free approximation for the Jacobian used in the Krylov technique (in this case, GMRES(k)). Of paramount interest to this study is the implementation and optimization of these techniques on parallel shared-memory hardware, namely the Cray C90 and SGI Challenge architectures. These architectures were chosen as representative and commonly available to researchers interested in the solution of problems of this type. The Newton-Krylov-Schwarz solution technique is increasingly being investigated for computational fluid dynamics (CFD) applications due to the advantages of full coupling of all variables and equations, rapid non-linear convergence, and moderate memory requirements. A parallel version of this method that scales effectively on the above architectures would be extremely attractive to practitioners, resulting in efficient, cost-effective, parallel solutions exhibiting the benefits of the solution technique.

  18. Properties of a constricted-tube air-flow levitator

    NASA Technical Reports Server (NTRS)

    Rush, J. E.; Stephens, W. K.; Ethridge, E. C.

    1982-01-01

    The properties of a constricted-tube gas flow levitator first developed by Berge et al. (1981) have been investigated experimentally in order to predict its behavior in a gravity-free environment and at elevated temperatures. The levitator consists of a constricted (quartz) tube fed at one end by a source of heated air or gas. A spherical sample is positioned by the air stream on the downstream side of the constriction, where it can be melted and resolidified without touching the tube. It is shown experimentally that the kinematic viscosity is the important fluid parameter for operation in thermal equilibrium at high temperatures. If air is heated from room temperature to 1200 C, the kinematic viscosity increases by a factor of 14. To maintain a given value of the Reynolds number, the flow rate would have to be increased by the same factor for a specific geometry of tube and sample. Thus, to maintain stable equilibrium, the flow rate should be increased as the air or other gas is heated. The other stability problem discussed is associated with changes in the shape of a cylindrical sample as it melts.

  19. Turbulent heat transfer in parallel flow boundary layers with streamwise step changes in surface conditions

    SciTech Connect

    Lindberg, W.R.; Lee, R.C.; Smathers, L.B. )

    1989-11-01

    This paper examines the convective heat/mass transfer behavior of a turbulent boundary layer with parallel streamlines. The most notable example of such flow is an atmospheric boundary layer with a steady mean wind in the absence of topography. The classic, two-dimensional problem involves the surface boundary condition of a finite-length step change in temperature/concentration in the streamwise direction of an atmospheric flow. In the literature on geophysical evapotranspiration, this problem is known as Sutton's problem (cf. Sutton, 1934, and Brutsaert, 1984). This flow situation is equally applicable to heat/mass transfer in solar ponds, ground solar collectors, and heated roadways, as examples. The present note revisits the Sutton problem, with the can Driest eddy diffusivity model, and expands the types of boundary conditions that are examined to include surface changes in temperature/concentration and fluxes. The parallel streamline condition allows for Graetz-type solutions, with boundary conditions at the surface and in the far flow field. The predicted results are presented as a series of power law correlations of the relevant nondimensional parameters.

  20. Air Flow and Pressure Drop Measurements Across Porous Oxides

    NASA Technical Reports Server (NTRS)

    Fox, Dennis S.; Cuy, Michael D.; Werner, Roger A.

    2008-01-01

    This report summarizes the results of air flow 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 air flow 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 flow 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 air flow versus processing parameters and the resulting porosity size and distribution.

  1. Anti-parallel filament flows and bright dots observed in the EUV with Hi-C

    NASA Astrophysics Data System (ADS)

    Alexander, C. E.; Regnier, S.; Walsh, R. W.; Winebarger, A. R.; Cirtain, J. W.

    2013-12-01

    The Hi-C instrument imaged the million degree corona at the highest spatial and temporal resolution to date. The instrument imaged a complicated active region which contained several interesting features. Scientists at UCLan in the UK, in collaboration with other members of the Hi-C science team, studied two of these festures: anti-parallel filament flows and bright EUV dots. Plasma flows within prominences/filaments have been observed for many years and hold valuable clues concerning the mass and energy balance within these structures. Evidence of ';counter-steaming' flows has previously been inferred from these cool plasma observations but now, for the first time, these flows have been directly imaged along fundamental filament threads within the million degree corona (at 193 Å). We present observations of an active region filament observed with Hi-C that exhibits anti-parallel flows along adjacent filament threads. The ultra-high spatial and temporal resolution of Hi-C allow the anti-parallel flow velocities to be measured (70 - 80 km/s) and gives an indication of the resolvable thickness of the individual strands (0.8' × 0.1'). The temperature distribution of the plasma flows was estimated to be log T(K) = 5.45 × 0.10 using EM loci analysis. Short-lived, small brightenings sparkling at the edge of the active region, calle EUV Bright Dots (EBDs) were also investigated. EBDs have a characteristic duration of 25 s with a characteristic length of 680 km. These brightenings are not fully resolved by the SDO/AIA instrument at the same wavelength, but can however be identified with respect to the Hi-C location of the EBDs. In addition, EBDs are seen in other chromospheric/coronal channels of SDO/AIA suggesting a temperature between 0.5 and 1.5 MK. Based on a potential field extrapolation from an SDO/HMI magnetogram, the EBDs appear at the footpoints of large-scale trans-equatorial coronal loops. The Hi-C observations provide the first evidence of small-scale EUV

  2. Parallel Computation of Flow in Heterogeneous Media Modelled by Mixed Finite Elements

    NASA Astrophysics Data System (ADS)

    Cliffe, K. A.; Graham, I. G.; Scheichl, R.; Stals, L.

    2000-11-01

    In this paper we describe a fast parallel method for solving highly ill-conditioned saddle-point systems arising from mixed finite element simulations of stochastic partial differential equations (PDEs) modelling flow in heterogeneous media. Each realisation of these stochastic PDEs requires the solution of the linear first-order velocity-pressure system comprising Darcy's law coupled with an incompressibility constraint. The chief difficulty is that the permeability may be highly variable, especially when the statistical model has a large variance and a small correlation length. For reasonable accuracy, the discretisation has to be extremely fine. We solve these problems by first reducing the saddle-point formulation to a symmetric positive definite (SPD) problem using a suitable basis for the space of divergence-free velocities. The reduced problem is solved using parallel conjugate gradients preconditioned with an algebraically determined additive Schwarz domain decomposition preconditioner. The result is a solver which exhibits a good degree of robustness with respect to the mesh size as well as to the variance and to physically relevant values of the correlation length of the underlying permeability field. Numerical experiments exhibit almost optimal levels of parallel efficiency. The domain decomposition solver (DOUG, http://www.maths.bath.ac.uk/~parsoft) used here not only is applicable to this problem but can be used to solve general unstructured finite element systems on a wide range of parallel architectures.

  3. Parallel finite element simulations of incompressible viscous fluid flow by domain decomposition with Lagrange multipliers

    NASA Astrophysics Data System (ADS)

    Rivera, Christian A.; Heniche, Mourad; Glowinski, Roland; Tanguy, Philippe A.

    2010-07-01

    A parallel approach to solve three-dimensional viscous incompressible fluid flow problems using discontinuous pressure finite elements and a Lagrange multiplier technique is presented. The strategy is based on non-overlapping domain decomposition methods, and Lagrange multipliers are used to enforce continuity at the boundaries between subdomains. The novelty of the work is the coupled approach for solving the velocity-pressure-Lagrange multiplier algebraic system of the discrete Navier-Stokes equations by a distributed memory parallel ILU (0) preconditioned Krylov method. A penalty function on the interface constraints equations is introduced to avoid the failure of the ILU factorization algorithm. To ensure portability of the code, a message based memory distributed model with MPI is employed. The method has been tested over different benchmark cases such as the lid-driven cavity and pipe flow with unstructured tetrahedral grids. It is found that the partition algorithm and the order of the physical variables are central to parallelization performance. A speed-up in the range of 5-13 is obtained with 16 processors. Finally, the algorithm is tested over an industrial case using up to 128 processors. In considering the literature, the obtained speed-ups on distributed and shared memory computers are found very competitive.

  4. Trench-parallel flow and seismic anisotropy in the Mariana and Andean subduction systems.

    PubMed

    Kneller, Erik A; van Keken, Peter E

    2007-12-20

    Shear-wave splitting measurements above the mantle wedge of the Mariana and southern Andean subduction zones show trench-parallel seismically fast directions close to the trench and abrupt rotations to trench-perpendicular anisotropy in the back arc. These patterns of seismic anisotropy may be caused by three-dimensional flow associated with along-strike variations in slab geometry. The Mariana and Andean subduction systems are associated with the largest along-strike variations of slab geometry observed on Earth and are ideal for testing the link between slab geometry and solid-state creep processes in the mantle. Here we show, with fully three-dimensional non-newtonian subduction zone models, that the strong curvature of the Mariana slab and the transition to shallow slab dip in the Southern Andes give rise to strong trench-parallel stretching in the warm-arc and warm-back-arc mantle and to abrupt rotations in stretching directions that are accompanied by strong trench-parallel stretching. These models show that the patterns of shear-wave splitting observed in the Mariana and southern Andean systems may be caused by significant three-dimensional flow induced by along-strike variations in slab geometry. PMID:18097407

  5. Experimental modelling of transverse oscillations in aquaculture netting parallel to the flow — Sounds baffling

    NASA Astrophysics Data System (ADS)

    Johnson, Andrew; Balash, Cheslav

    2015-06-01

    Numerous studies have been undertaken to improve the viability, durability and suitability of materials and methods used for aquaculture enclosures. While many of the previous studies considered macro-deformation of nets, there is a paucity of information on netting micro-deformation. When aquaculture pens are towed, industry operators have observed the motion described as "baffling" — the transverse oscillation of the net planes parallel and near parallel to the flow. The difficulty to observe and assess baffling motion in a controlled experimental environment is to sufficiently reproduce netting boundary conditions and the flow environment experienced at sea. The focus of the present study was to develop and assess experimental methods for visualisation and quantification of these transverse oscillations. Four net-rig configurations with varied boundary conditions and model-netting properties were tested in a flume tank. While the Reynolds number was not equivalent to full-scale, usage of the pliable and fine mesh model netting that enabled baffling to develop at low flow velocities was deemed to be of a larger relevance to this initial study. Baffling was observed in the testing frame that constrained the net sheet on the leading edge, similarly to a flag attachment onto a pole. Baffling motion increased the hydrodynamic drag of the net by 35%-58% when compared to the previously developed formula for taut net sheets aligned parallel to the flow. Furthermore, it was found that the drag due to baffling decreased with the increasing velocity over the studied Reynolds numbers (below 200); and the drag coefficient was non-linear for Reynolds numbers below 120. It is hypothesised that baffling motion is initially propagated by vortex shedding of the netting twine which causes the netting to oscillate; there after the restoring force causes unstable pressure differences on each side of the netting which excites the amplitude of the netting oscillations.

  6. A study of turbulent flow between parallel plates by a statistical method

    NASA Technical Reports Server (NTRS)

    Srinivasan, R.; Giddens, D. P.; Bangert, L. H.; Wu, J. C.

    1976-01-01

    Turbulent Couette flow between parallel plates was studied from a statistical mechanics approach utilizing a model equation, similar to the Boltzmann equation of kinetic theory, which was proposed by Lundgren from the velocity distribution of fluid elements. Solutions to this equation are obtained numerically, employing the discrete ordinate method and finite differences. Two types of boundary conditions on the distribution function are considered, and the results of the calculations are compared to available experimental data. The research establishes that Lundgren's equation provides a very good description of turbulence for the flow situation considered and that it offers an analytical tool for further study of more complex turbulent flows. The present work also indicates that modelling of the boundary conditions is an area where further study is required.

  7. Using ion flows parallel and perpendicular to gravity to modify dust acoustic waves

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Fisher, R.

    2008-11-01

    Recent studies of dust acoustic waves have shown that the dust kinetic temperature can play an important role in determining the resulting dispersion relation [M. Rosenberg, et al., Phys. Plasmas, 15, 073701 (2008)]. In these studies, it is believed that ion flows play a dominant role in determining both the kinetic temperature of the charged microparticles as well as providing the source of energy for triggering the waves. In this presentation, results will be presented on the effects of ion flow on spatial structure and velocity distribution of dust acoustic waves. Here, the waves will be formed in dusty plasmas consisting of 3 ± 1 micron diameter silica microspheres. Two separate electrodes will be used to modify the ion flow in the plasma -- one parallel to the direction of gravity and one perpendicular to the direction of gravity. Particle image velocimetry (PIV) techniques will be used to observe the particles and to measure their velocity distributions.

  8. Bio-inspired multi-mode optic flow sensors for micro air vehicles

    NASA Astrophysics Data System (ADS)

    Park, Seokjun; Choi, Jaehyuk; Cho, Jihyun; Yoon, Euisik

    2013-06-01

    Monitoring wide-field surrounding information is essential for vision-based autonomous navigation in micro-air-vehicles (MAV). Our image-cube (iCube) module, which consists of multiple sensors that are facing different angles in 3-D space, can be applied to the wide-field of view optic flows estimation (μ-Compound eyes) and to attitude control (μ- Ocelli) in the Micro Autonomous Systems and Technology (MAST) platforms. In this paper, we report an analog/digital (A/D) mixed-mode optic-flow sensor, which generates both optic flows and normal images in different modes for μ- Compound eyes and μ-Ocelli applications. The sensor employs a time-stamp based optic flow algorithm which is modified from the conventional EMD (Elementary Motion Detector) algorithm to give an optimum partitioning of hardware blocks in analog and digital domains as well as adequate allocation of pixel-level, column-parallel, and chip-level signal processing. Temporal filtering, which may require huge hardware resources if implemented in digital domain, is remained in a pixel-level analog processing unit. The rest of the blocks, including feature detection and timestamp latching, are implemented using digital circuits in a column-parallel processing unit. Finally, time-stamp information is decoded into velocity from look-up tables, multiplications, and simple subtraction circuits in a chip-level processing unit, thus significantly reducing core digital processing power consumption. In the normal image mode, the sensor generates 8-b digital images using single slope ADCs in the column unit. In the optic flow mode, the sensor estimates 8-b 1-D optic flows from the integrated mixed-mode algorithm core and 2-D optic flows with an external timestamp processing, respectively.

  9. Flow regime classification in air magnetic fluid two-phase flow

    NASA Astrophysics Data System (ADS)

    Kuwahara, T.; DeVuyst, F.; Yamaguchi, H.

    2008-05-01

    A new experimental/numerical technique of classification of flow regimes (flow patterns) in air-magnetic fluid two-phase flow is proposed in the present paper. The proposed technique utilizes the electromagnetic induction to obtain time-series signals of the electromotive force, allowing us to make a non-contact measurement. Firstly, an experiment is carried out to obtain the time-series signals in a vertical upward air-magnetic fluid two-phase flow. The signals obtained are first treated using two kinds of wavelet transforms. The data sets treated are then used as input vectors for an artificial neural network (ANN) with supervised training. In the present study, flow regimes are classified into bubbly, slug, churn and annular flows, which are generally the main flow regimes. To validate the flow regimes, a visualization experiment is also performed with a glycerin solution that has roughly the same physical properties, i.e., kinetic viscosity and surface tension, as a magnetic fluid used in the present study. The flow regimes from the visualization are used as targets in an ANN and also used in the estimation of the accuracy of the present method. As a result, ANNs using radial basis functions are shown to be the most appropriate for the present classification of flow regimes, leading to small classification errors.

  10. Flow regime classification in air-magnetic fluid two-phase flow.

    PubMed

    Kuwahara, T; De Vuyst, F; Yamaguchi, H

    2008-05-21

    A new experimental/numerical technique of classification of flow regimes (flow patterns) in air-magnetic fluid two-phase flow is proposed in the present paper. The proposed technique utilizes the electromagnetic induction to obtain time-series signals of the electromotive force, allowing us to make a non-contact measurement. Firstly, an experiment is carried out to obtain the time-series signals in a vertical upward air-magnetic fluid two-phase flow. The signals obtained are first treated using two kinds of wavelet transforms. The data sets treated are then used as input vectors for an artificial neural network (ANN) with supervised training. In the present study, flow regimes are classified into bubbly, slug, churn and annular flows, which are generally the main flow regimes. To validate the flow regimes, a visualization experiment is also performed with a glycerin solution that has roughly the same physical properties, i.e., kinetic viscosity and surface tension, as a magnetic fluid used in the present study. The flow regimes from the visualization are used as targets in an ANN and also used in the estimation of the accuracy of the present method. As a result, ANNs using radial basis functions are shown to be the most appropriate for the present classification of flow regimes, leading to small classification errors. PMID:21694270

  11. A parallel-architecture parametric equalizer for air-coupled capacitive ultrasonic transducers.

    PubMed

    McSweeney, Sean G; Wright, William M D

    2012-01-01

    Parametric equalization is rarely applied to ultrasonic transducer systems, for which it could be used on either the transmitter or the receiver to achieve a desired response. An optimized equalizer with both bump and cut capabilities would be advantageous for ultrasonic systems in applications in which variations in the transducer performance or the properties of the propagating medium produce a less-than-desirable signal. Compensation for non-ideal transducer response could be achieved using equalization on a device-by-device basis. Additionally, calibration of ultrasonic systems in the field could be obtained by offline optimization of equalization coefficients. In this work, a parametric equalizer for ultrasonic applications has been developed using multiple bi-quadratic filter elements arranged in a novel parallel arrangement to increase the flexibility of the equalization. The equalizer was implemented on a programmable system-on-chip (PSOC) using a small number of parallel 4th-order infinite impulse response switchedcapacitor band-pass filters. Because of the interdependency of the required coefficients for the switched capacitors, particle swarm optimization (PSO) was used to determine the optimum values. The response of a through-transmission system using air-coupled capacitive ultrasonic transducers was then equalized to idealized Hamming function or brick-wall frequencydomain responses. In each case, there was excellent agreement between the equalized signals and the theoretical model, and the fidelity of the time-domain response was maintained. The bandwidth and center frequency response of the system were significantly improved. It was also shown that the equalizer could be used on either the transmitter or the receiver, and the system could compensate for the effects of transmitterreceiver misalignment. PMID:22293739

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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 flow system that moves gases from younger leaves through submerged parts to older leaves, aerating submerged parts. Petiole air canals are in the conv...

  13. Character of energy flow in air shower core

    NASA Technical Reports Server (NTRS)

    Mizushima, K.; Asakimori, K.; Maeda, T.; Kameda, T.; Misaki, Y.

    1985-01-01

    Energy per charged particle near the core of air showers was measured by 9 energy flow 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 flow: (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.

  14. DEVELOPMENT OF A LOW PRESSURE, AIR ATOMIZED OIL BURNER WITH HIGH ATOMIZER AIR FLOW

    SciTech Connect

    BUTCHER,T.A.

    1998-01-01

    This report describes technical advances made to the concept of a low pressure, air atomized oil burner for home heating applications. Currently all oil burners on the market are of the pressure atomized, retention head type. These burners have a lower firing rate limit of about 0.5 gallons per hour of oil, due to reliability problems related to small flow passage sizes. High pressure air atomized burners have been shown to be one route to avoid this problem but air compressor cost and reliability have practically eliminated this approach. With the low pressure air atomized burner the air required for atomization can be provided by a fan at 5--8 inches of water pressure. A burner using this concept, termed the Fan-Atomized Burner or FAB has been developed and is currently being commercialized. In the head of the FAB, the combustion air is divided into three parts, much like a conventional retention head burner. This report describes development work on a new concept in which 100% of the air from the fan goes through the atomizer. The primary advantage of this approach is a great simplification of the head design. A nozzle specifically sized for this concept was built and is described in the report. Basic flow pressure tests, cold air velocity profiles, and atomization performance have been measured. A burner head/flame tube has been developed which promotes a torroidal recirculation zone near the nozzle for flame stability. The burner head has been tested in several furnace and boiler applications over the tiring rate range 0.2 to 0.28 gallons per hour. In all cases the burner can operate with very low excess air levels (under 10%) without producing smoke. Flue gas NO{sub x} concentration varied from 42 to 62 ppm at 3% 0{sub 2}. The concept is seen as having significant potential and planned development efforts are discussed.

  15. Effects of air flow directions on composting process temperature profile

    SciTech Connect

    Kulcu, Recep; Yaldiz, Osman

    2008-07-01

    In this study, chicken manure mixed with carnation wastes was composted by using three different air flow directions: R1-sucking (downward), R2-blowing (upward) and R3-mixed. The aim was to find out the most appropriate air flow 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 temperature 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.

  16. Vision and air flow combine to streamline flying honeybees

    PubMed Central

    Taylor, Gavin J.; Luu, Tien; Ball, David; Srinivasan, Mandyam V.

    2013-01-01

    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 flow, is also strongly modulated by the presence of air flow simulating a head wind. The Johnston's organs in the antennae were found to play a role in the measurement of the air 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

  17. Parallel CFD Algorithms for Aerodynamical Flow Solvers on Unstructured Meshes. Parts 1 and 2

    NASA Technical Reports Server (NTRS)

    Barth, Timothy J.; Kwak, Dochan (Technical Monitor)

    1995-01-01

    The Advisory Group for Aerospace Research and Development (AGARD) has requested my participation in the lecture series entitled Parallel Computing in Computational Fluid Dynamics to be held at the von Karman Institute in Brussels, Belgium on May 15-19, 1995. In addition, a request has been made from the US Coordinator for AGARD at the Pentagon for NASA Ames to hold a repetition of the lecture series on October 16-20, 1995. I have been asked to be a local coordinator for the Ames event. All AGARD lecture series events have attendance limited to NATO allied countries. A brief of the lecture series is provided in the attached enclosure. Specifically, I have been asked to give two lectures of approximately 75 minutes each on the subject of parallel solution techniques for the fluid flow equations on unstructured meshes. The title of my lectures is "Parallel CFD Algorithms for Aerodynamical Flow Solvers on Unstructured Meshes" (Parts I-II). The contents of these lectures will be largely review in nature and will draw upon previously published work in this area. Topics of my lectures will include: (1) Mesh partitioning algorithms. Recursive techniques based on coordinate bisection, Cuthill-McKee level structures, and spectral bisection. (2) Newton's method for large scale CFD problems. Size and complexity estimates for Newton's method, modifications for insuring global convergence. (3) Techniques for constructing the Jacobian matrix. Analytic and numerical techniques for Jacobian matrix-vector products, constructing the transposed matrix, extensions to optimization and homotopy theories. (4) Iterative solution algorithms. Practical experience with GIVIRES and BICG-STAB matrix solvers. (5) Parallel matrix preconditioning. Incomplete Lower-Upper (ILU) factorization, domain-decomposed ILU, approximate Schur complement strategies.

  18. Numerical characterization of the hydrodynamics and thermal behavior of air flow in flexible air distribution system

    NASA Astrophysics Data System (ADS)

    Gharehdaghi, Samad; Moujaes, Samir

    2013-10-01

    Flexible duct air distribution systems are used in a large percentage of residential and small commercial buildings in the United States . Very few empirical or predictive data are available though to help provide the HVAC design engineer with reliable information . Moreover, because of the ducts flexibility, the shapes of these ducts offer a different set of operating fluid flow and thermal conditions from traditional smooth metal ducts. Hence, both the flow field and heat transfer through this kind of ducts are much more complex and merit to be analyzed from a numerical predictive approach. The aim of this research paper is to compute some of the hydrodynamic and heat transfer characteristics of the air flow inside these ducts over a range of Re numbers commonly used in the flow conditions of these air distribution systems. The information resulting from this CFD simulation, where a κ-ɛ turbulent model is used to predict the flow conditions, provide pressure drop and average convective heat transfer coefficients that exist in these ducts and was compared to previously found data. Circulation zones in the depressions of these ducts are found to exist which are suspected of influencing the pressured drop and heat transfer coefficients as compared to smooth ducts. The results show that fully developed conditions exist much earlier with regard to the inlet for both hydrodynamic and thermal entrance regions than what would be expected in smooth ducts under the same turbulent conditions.

  19. Development of an air flow thermal balance calorimeter

    NASA Technical Reports Server (NTRS)

    Sherfey, J. M.

    1972-01-01

    An air flow 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.

  20. Electron concentration distribution in a glow discharge in air flow

    NASA Astrophysics Data System (ADS)

    Mukhamedzianov, R. B.; Gaisin, F. M.; Sabitov, R. A.

    1989-04-01

    Electron concentration distributions in a glow discharge in longitudinal and vortex air flows 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.

  1. Methods of Visually Determining the Air Flow Around Airplanes

    NASA Technical Reports Server (NTRS)

    Gough, Melvin N; Johnson, Ernest

    1932-01-01

    This report describes methods used by the National Advisory Committee for Aeronautics to study visually the air flow 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.

  2. Managing parallel cryogenic flows to the thermal intercepts in the Cornell ERL

    NASA Astrophysics Data System (ADS)

    Eichhorn, R.; Holmes, A.; Markham, S.; Sabol, D.; Smith, E.

    2014-01-01

    The proposed Cornell Energy Recovery Linac (ERL) is based on superconducting 1.3 GHz cavities operated in continuous wave mode. It presents a number of interesting cryogenic challenges, as approximately 30 cryomodules share a common vacuum space and common cryogenic distribution lines forming two 300 meter long half-linacs. Within each module, are a number of concentrated heat loads which must be intercepted at 80K and 6.5K. It is necessary to provide convective cooling by helium gas via many parallel channels to intercept these large individual loads (average up to 200W at 80K, but some as high as 400W), and we discuss the design choices made to ensure no flow instabilities. We limit the control complexity by using a single control valve for each coolant stream within each cryomodule. These streams are subdivided into parallel paths using a length of smaller diameter tubing in the cold part to limit the variation in mass flow with heat load for each path. A model describing these flows at 80 K and 5 K under different operation regimes will be derived and presented and parameters for stability will be discussed.

  3. An improved parallel SPH approach to solve 3D transient generalized Newtonian free surface flows

    NASA Astrophysics Data System (ADS)

    Ren, Jinlian; Jiang, Tao; Lu, Weigang; Li, Gang

    2016-08-01

    In this paper, a corrected parallel smoothed particle hydrodynamics (C-SPH) method is proposed to simulate the 3D generalized Newtonian free surface flows with low Reynolds number, especially the 3D viscous jets buckling problems are investigated. The proposed C-SPH method is achieved by coupling an improved SPH method based on the incompressible condition with the traditional SPH (TSPH), that is, the improved SPH with diffusive term and first-order Kernel gradient correction scheme is used in the interior of the fluid domain, and the TSPH is used near the free surface. Thus the C-SPH method possesses the advantages of two methods. Meanwhile, an effective and convenient boundary treatment is presented to deal with 3D multiple-boundary problem, and the MPI parallelization technique with a dynamic cells neighbor particle searching method is considered to improve the computational efficiency. The validity and the merits of the C-SPH are first verified by solving several benchmarks and compared with other results. Then the viscous jet folding/coiling based on the Cross model is simulated by the C-SPH method and compared with other experimental or numerical results. Specially, the influences of macroscopic parameters on the flow are discussed. All the numerical results agree well with available data, and show that the C-SPH method has higher accuracy and better stability for solving 3D moving free surface flows over other particle methods.

  4. Heat transfer and flow analysis of nanofluid flow between parallel plates in presence of variable magnetic field using HPM

    NASA Astrophysics Data System (ADS)

    Hatami, M.; Jing, Dengwei; Song, Dongxing; Sheikholeslami, M.; Ganji, D. D.

    2015-12-01

    In this study, effect of variable magnetic field on nanofluid flow and heat transfer analysis between two parallel disks is investigated. By using the appropriate transformation for the velocity, temperature and concentration, the basic equations governing the flow, heat and mass transfer were reduced to a set of ordinary differential equations. These equations subjected to the associated boundary conditions were solved analytically using Homotopy perturbation method. The analytical investigation is carried out for different governing parameters namely: squeeze number, suction parameter, Hartmann number, Brownian motion parameter, thermophrotic parameter and Lewis number. Results show that Nusselt number has direct relationship with Brownian motion parameter and thermophrotic parameter but it is a decreasing function of squeeze number, suction parameter, Hartmann number and Lewis number.

  5. On the impact of entrapped air in infiltration under ponding conditions. Part a: Preferential air flow path effects on infiltration

    NASA Astrophysics Data System (ADS)

    Mizrahi, Guy; Weisbrod, Noam; Furman, Alex

    2015-04-01

    Entrapped air effects on infiltration under ponding conditions could be important for massive infiltration of managed aquifer recharge (MAR) or soil aquifer treatment (SAT) of treated wastewater. Earlier studies found that under ponding conditions, air is being entrapped and compressed until it reaches a pressure which will enable the air to escape (unstable air flow). They also found that entrapped air could reduce infiltration by 70-90%. Most studies have dealt with entrapped air effects when soil surface topography is flat. The objective of this study is to investigate, under ponding conditions, the effects of: (1) irregular surface topography on preferential air flow path development (stable air flow); (2) preferential air flow path on infiltration; and (3) hydraulic head on infiltration when air is trapped. Column experiments were used to investigate these particular effects. A 140 cm deep and 30 cm wide column packed with silica sand was used under two boundary conditions: in the first, air can only escape vertically upward through the soil surface; in the second, air is free to escape through 20 ports installed along the column perimeter. The surface was flooded with 13 liters of water, with ponding depth decreasing with time. Two soil surface conditions were tested: flat surface and irregular surface (high and low surface zones). Additionally, Helle-show experiments were conducted in order to obtain a visual observation of preferential air flow path development. The measurements were carried out using a tension meter, air pressure transducers, TDR and video cameras. It was found that in irregular surfaces, stable air flow through preferential paths was developed in the high altitude zones. Flat surface topography caused unstable air flow through random paths. Comparison between irregular and flat surface topography showed that the entrapped air pressure was lower and the infiltration rate was about 40% higher in the irregular surface topography than in the

  6. High performance parallel computing of flows in complex geometries: II. Applications

    NASA Astrophysics Data System (ADS)

    Gourdain, N.; Gicquel, L.; Staffelbach, G.; Vermorel, O.; Duchaine, F.; Boussuge, J.-F.; Poinsot, T.

    2009-01-01

    Present regulations in terms of pollutant emissions, noise and economical constraints, require new approaches and designs in the fields of energy supply and transportation. It is now well established that the next breakthrough will come from a better understanding of unsteady flow effects and by considering the entire system and not only isolated components. However, these aspects are still not well taken into account by the numerical approaches or understood whatever the design stage considered. The main challenge is essentially due to the computational requirements inferred by such complex systems if it is to be simulated by use of supercomputers. This paper shows how new challenges can be addressed by using parallel computing platforms for distinct elements of a more complex systems as encountered in aeronautical applications. Based on numerical simulations performed with modern aerodynamic and reactive flow solvers, this work underlines the interest of high-performance computing for solving flow in complex industrial configurations such as aircrafts, combustion chambers and turbomachines. Performance indicators related to parallel computing efficiency are presented, showing that establishing fair criterions is a difficult task for complex industrial applications. Examples of numerical simulations performed in industrial systems are also described with a particular interest for the computational time and the potential design improvements obtained with high-fidelity and multi-physics computing methods. These simulations use either unsteady Reynolds-averaged Navier-Stokes methods or large eddy simulation and deal with turbulent unsteady flows, such as coupled flow phenomena (thermo-acoustic instabilities, buffet, etc). Some examples of the difficulties with grid generation and data analysis are also presented when dealing with these complex industrial applications.

  7. A lightweight, flow-based toolkit for parallel and distributed bioinformatics pipelines

    PubMed Central

    2011-01-01

    Background Bioinformatic analyses typically proceed as chains of data-processing tasks. A pipeline, or 'workflow', is a well-defined protocol, with a specific structure defined by the topology of data-flow interdependencies, and a particular functionality arising from the data transformations applied at each step. In computer science, the dataflow programming (DFP) paradigm defines software systems constructed in this manner, as networks of message-passing components. Thus, bioinformatic workflows can be naturally mapped onto DFP concepts. Results To enable the flexible creation and execution of bioinformatics dataflows, we have written a modular framework for parallel pipelines in Python ('PaPy'). A PaPy workflow is created from re-usable components connected by data-pipes into a directed acyclic graph, which together define nested higher-order map functions. The successive functional transformations of input data are evaluated on flexibly pooled compute resources, either local or remote. Input items are processed in batches of adjustable size, all flowing one to tune the trade-off between parallelism and lazy-evaluation (memory consumption). An add-on module ('NuBio') facilitates the creation of bioinformatics workflows by providing domain specific data-containers (e.g., for biomolecular sequences, alignments, structures) and functionality (e.g., to parse/write standard file formats). Conclusions PaPy offers a modular framework for the creation and deployment of parallel and distributed data-processing workflows. Pipelines derive their functionality from user-written, data-coupled components, so PaPy also can be viewed as a lightweight toolkit for extensible, flow-based bioinformatics data-processing. The simplicity and flexibility of distributed PaPy pipelines may help users bridge the gap between traditional desktop/workstation and grid computing. PaPy is freely distributed as open-source Python code at http://muralab.org/PaPy, and includes extensive

  8. Wave Number Selection for Incompressible Parallel Jet Flows Periodic in Space

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    1997-01-01

    The temporal instability of a spatially periodic parallel flow of an incompressible inviscid fluid for various jet velocity profiles is studied numerically using Floquet Analysis. The transition matrix at the end of a period is evaluated by direct numerical integration. For verification, a method based on approximating a continuous function by a series of step functions was used. Unstable solutions were found only over a limited range of wave numbers and have a band type structure. The results obtained are analogous to the behavior observed in systems exhibiting complexity at the edge of order and chaos.

  9. Analysis and identification of subsynchronous vibration for a high pressure parallel flow centrifugal compressor

    NASA Technical Reports Server (NTRS)

    Kirk, R. G.; Nicholas, J. C.; Donald, G. H.; Murphy, R. C.

    1980-01-01

    The summary of a complete analytical design evaluation of an existing parallel flow compressor is presented and a field vibration problem that manifested itself as a subsynchronous vibration that tracked at approximately 2/3 of compressor speed is reviewed. The comparison of predicted and observed peak response speeds, frequency spectrum content, and the performance of the bearing-seal systems are presented as the events of the field problem are reviewed. Conclusions and recommendations are made as to the degree of accuracy of the analytical techniques used to evaluate the compressor design.

  10. Experimental study of static flow instability in subcooled flow boiling in parallel channels

    SciTech Connect

    Siman-Tov, M.; Felde, D.K.; McDuffee, J.L.; Yoder, G.L.

    1995-12-31

    Experimental data for static flow instability or flow excursion (FE) at conditions applicable to the Advanced Neutron Source Reactor are very limited. A series of FE tests with light water flowing vertically upward was completed covering a local exit heat flux range of 0.7--18 MW/m{sup 2}, exit velocity range of 2.8--28.4 m/s, exit pressure range of 0.117--1.7 MPa, and inlet temperature range of 40-- 50{degrees}C. Most of the tests were performed in a ``stiff`` (constant flow) system where the instability threshold was detected through the minimum of the pressure-drop curve. A few tests were also conducted using as ``soft`` (constant pressure drop) a system as possible to secure a true FE phenomenon (actual secondary burnout). True critical heat flux experiments under similar conditions were also conducted using a stiff system. The FE data reported in this study considerably extend the velocity range of data presently available worldwide, most of which were obtained at velocities below 10 m/s. The Saha and Zuber correlation had the best fit with the data out of the three correlations compared. However, a modification was necessary to take into account the demonstrated dependence of the St and Nu numbers on subcooling levels, especially in the low subcooling regime. Comparison of Thermal Hydraulic Test Loop (THTL) data, as well as extensive data from other investigators, led to a proposed modification to the Saha and Zuber correlation for onset of significant void, applied to FE prediction. The mean and standard deviation of the THTL data were 0.95 and 15%, respectively, when comparing the THTL data with the original Saha and Zuber correlation, and 0.93 and 10% when comparing them with the modification. Comparison with the worldwide database showed a mean and standard deviation of 1.37 and 53%, respectively, for the original Saha and Zuber correlation and 1.0 and 27% for the modification.

  11. Flow over a Ram-Air Parachute Canopy

    NASA Astrophysics Data System (ADS)

    Eslambolchi, Ali; Johari, Hamid

    2012-11-01

    The flow field over a full-scale, ram-air personnel parachute canopy was investigated numerically using a finite-volume flow solver coupled with the Spalart-Allmaras turbulence model. Ram-air parachute canopies resemble wings with arc-anhedral, surface protuberances, and an open leading edge for inflation. The rectangular planform canopy had an aspect ratio of 2.2 and was assumed to be rigid and impermeable. The chord-based Reynolds number was 3.2 million. Results indicate that the oncoming flow barely penetrates the canopy opening, and creates a large separation bubble below the lower lip of canopy. A thick boundary layer exists over the entire lower surface of the canopy. The flow over the upper surface of the canopy remains attached for an extended fraction of the chord. Lift increases linearly with angle of attack up to about 12 degrees. To assess the capability of lifting-line theory in predicting the forces on the canopy, the lift and drag data from a two-dimensional simulation of the canopy profile were extended using finite-wing expressions and compared with the forces from the present simulations. The finite-wing predicted lift and drag trends compare poorly against the full-span simulation, and the maximum lift-to-drag ratio is over-predicted by 36%. Sponsored by the US Army NRDEC.

  12. Thermistor based, low velocity isothermal, air flow sensor

    NASA Astrophysics Data System (ADS)

    Cabrita, Admésio A. C. M.; Mendes, Ricardo; Quintela, Divo A.

    2016-03-01

    The semiconductor thermistor technology is applied as a flow sensor to measure low isothermal air velocities (<2 ms-1). The sensor is subjected to heating and cooling cycles controlled by a multifunctional timer. In the heating stage, the alternating current of a main AC power supply source guarantees a uniform thermistor temperature distribution. The conditioning circuit assures an adequate increase of the sensors temperature and avoids the thermal disturbance of the flow. The power supply interruption reduces the consumption from the source and extends the sensors life time. In the cooling stage, the resistance variation of the flow sensor is recorded by the measuring chain. The resistive sensor parameters proposed vary significantly and feature a high sensitivity to the flow velocity. With the aid of a computer, the data transfer, storage and analysis provides a great advantage over the traditional local anemometer readings. The data acquisition chain has a good repeatability and low standard uncertainties. The proposed method measures isothermal air mean velocities from 0.1 ms-1 to 2 ms-1 with a standard uncertainty error less than 4%.

  13. A parallel overset-curvilinear-immersed boundary framework for simulating complex 3D incompressible flows

    PubMed Central

    Borazjani, Iman; Ge, Liang; Le, Trung; Sotiropoulos, Fotis

    2013-01-01

    We develop an overset-curvilinear immersed boundary (overset-CURVIB) method in a general non-inertial frame of reference to simulate a wide range of challenging biological flow problems. The method incorporates overset-curvilinear grids to efficiently handle multi-connected geometries and increase the resolution locally near immersed boundaries. Complex bodies undergoing arbitrarily large deformations may be embedded within the overset-curvilinear background grid and treated as sharp interfaces using the curvilinear immersed boundary (CURVIB) method (Ge and Sotiropoulos, Journal of Computational Physics, 2007). The incompressible flow equations are formulated in a general non-inertial frame of reference to enhance the overall versatility and efficiency of the numerical approach. Efficient search algorithms to identify areas requiring blanking, donor cells, and interpolation coefficients for constructing the boundary conditions at grid interfaces of the overset grid are developed and implemented using efficient parallel computing communication strategies to transfer information among sub-domains. The governing equations are discretized using a second-order accurate finite-volume approach and integrated in time via an efficient fractional-step method. Various strategies for ensuring globally conservative interpolation at grid interfaces suitable for incompressible flow fractional step methods are implemented and evaluated. The method is verified and validated against experimental data, and its capabilities are demonstrated by simulating the flow past multiple aquatic swimmers and the systolic flow in an anatomic left ventricle with a mechanical heart valve implanted in the aortic position. PMID:23833331

  14. Slip effects on squeezing flow of nanofluid between two parallel disks

    NASA Astrophysics Data System (ADS)

    Das, K.; Jana, S.; Acharya, N.

    2016-02-01

    In this study, the influence of temperature and wall slip conditions on the unsteady flow of a viscous, incompressible and electrically conducting nanofluid squeezed between two parallel disks in the presence of an applied magnetic field is investigated numerically. Using the similarity transformation, the governing coupled partial differential equations are transformed into similarity non-linear ordinary differential equations which are solved numerically using the Nachtsheim and Swigert shooting iteration technique together with the sixth order Runge-Kutta integration scheme. The effects of various emerging parameters on the flow characteristics are determined and discussed in detail. To check the reliability of the method, the numerical results for the skin friction coefficient and Nusselt number in the absence of slip conditions are compared with the results reported by the predecessors and an excellent agreement is observed between the two sets of results.

  15. Instability of plane-parallel flow of incompressible liquid over a saturated porous medium

    NASA Astrophysics Data System (ADS)

    Lyubimova, T. P.; Lyubimov, D. V.; Baydina, D. T.; Kolchanova, E. A.; Tsiberkin, K. B.

    2016-07-01

    The linear stability of plane-parallel flow of an incompressible viscous fluid over a saturated porous layer is studied to model the instability of water flow in a river over aquatic plants. The saturated porous layer is bounded from below by a rigid plate and the pure fluid layer has a free, undeformable upper boundary. A small inclination of the layers is imposed to simulate the riverbed slope. The layers are inclined at a small angle to the horizon. The problem is studied within two models: the Brinkman model with the boundary conditions by Ochoa-Tapia and Whitaker at the interface, and the Darcy-Forchheimer model with the conditions by Beavers and Joseph. The neutral curves and critical Reynolds numbers are calculated for various porous layer permeabilities and relative thicknesses of the porous layer. The results obtained within the two models are compared and analyzed.

  16. Instability of plane-parallel flow of incompressible liquid over a saturated porous medium.

    PubMed

    Lyubimova, T P; Lyubimov, D V; Baydina, D T; Kolchanova, E A; Tsiberkin, K B

    2016-07-01

    The linear stability of plane-parallel flow of an incompressible viscous fluid over a saturated porous layer is studied to model the instability of water flow in a river over aquatic plants. The saturated porous layer is bounded from below by a rigid plate and the pure fluid layer has a free, undeformable upper boundary. A small inclination of the layers is imposed to simulate the riverbed slope. The layers are inclined at a small angle to the horizon. The problem is studied within two models: the Brinkman model with the boundary conditions by Ochoa-Tapia and Whitaker at the interface, and the Darcy-Forchheimer model with the conditions by Beavers and Joseph. The neutral curves and critical Reynolds numbers are calculated for various porous layer permeabilities and relative thicknesses of the porous layer. The results obtained within the two models are compared and analyzed. PMID:27575214

  17. Ion kinetic instabilities and turbulence of a parallel shearing flow of a plasma with hot ions

    NASA Astrophysics Data System (ADS)

    Mykhaylenko, Volodymyr St.; Mykhaylenko, Volodymyr; Lee, Hae June

    2015-11-01

    The results of the analytical and numerical investigations of the shear flow driven ion kinetic instabilities, excited due to the inverse ion Landau damping in the parallel shearing flow of plasmas with comparable ion and electron temperatures, that is the case relevant to a tokamak and space plasma, are presented. The levels of turbulence and the turbulent heating rates of ions and ion turbulent viscosity, resulted from the development of the electrostatic ion-temperature gradient and electromagnetic drift-Alfven turbulence, are determined and their consequences are discussed. This work was funded by National R&D Program through the National Research Foundation of Korea.Grants NRF-2014M1A7A1A03029878, NRF-2013R1A1A2005758.

  18. Parallel solution of high-order numerical schemes for solving incompressible flows

    NASA Technical Reports Server (NTRS)

    Milner, Edward J.; Lin, Avi; Liou, May-Fun; Blech, Richard A.

    1993-01-01

    A new parallel numerical scheme for solving incompressible steady-state flows is presented. The algorithm uses a finite-difference approach to solving the Navier-Stokes equations. The algorithms are scalable and expandable. They may be used with only two processors or with as many processors as are available. The code is general and expandable. Any size grid may be used. Four processors of the NASA LeRC Hypercluster were used to solve for steady-state flow in a driven square cavity. The Hypercluster was configured in a distributed-memory, hypercube-like architecture. By using a 50-by-50 finite-difference solution grid, an efficiency of 74 percent (a speedup of 2.96) was obtained.

  19. Spontaneous Hot Flow Anomalies at Quasi-Parallel Shocks: 2. Hybrid Simulations

    NASA Technical Reports Server (NTRS)

    Omidi, N.; Zhang, H.; Sibeck, D.; Turner, D.

    2013-01-01

    Motivated by recent THEMIS observations, this paper uses 2.5-D electromagnetic hybrid simulations to investigate the formation of Spontaneous Hot Flow Anomalies (SHFA) upstream of quasi-parallel bow shocks during steady solar wind conditions and in the absence of discontinuities. The results show the formation of a large number of structures along and upstream of the quasi-parallel bow shock. Their outer edges exhibit density and magnetic field enhancements, while their cores exhibit drops in density, magnetic field, solar wind velocity and enhancements in ion temperature. Using virtual spacecraft in the simulation, we show that the signatures of these structures in the time series data are very similar to those of SHFAs seen in THEMIS data and conclude that they correspond to SHFAs. Examination of the simulation data shows that SHFAs form as the result of foreshock cavitons interacting with the bow shock. Foreshock cavitons in turn form due to the nonlinear evolution of ULF waves generated by the interaction of the solar wind with the backstreaming ions. Because foreshock cavitons are an inherent part of the shock dissipation process, the formation of SHFAs is also an inherent part of the dissipation process leading to a highly non-uniform plasma in the quasi-parallel magnetosheath including large scale density and magnetic field cavities.

  20. Spontaneous hot flow anomalies at quasi-parallel shocks: 2. Hybrid simulations

    NASA Astrophysics Data System (ADS)

    Omidi, N.; Zhang, H.; Sibeck, D.; Turner, D.

    2013-01-01

    Abstract<p label="1">Motivated by recent THEMIS observations, this paper uses 2.5-D electromagnetic hybrid simulations to investigate the formation of Spontaneous Hot <span class="hlt">Flow</span> Anomalies (SHFAs) upstream of quasi-<span class="hlt">parallel</span> bow shocks during steady solar wind conditions and in the absence of discontinuities. The results show the formation of a large number of structures along and upstream of the quasi-<span class="hlt">parallel</span> bow shock. Their outer edges exhibit density and magnetic field enhancements, while their cores exhibit drops in density, magnetic field, solar wind velocity, and enhancements in ion temperature. Using virtual spacecraft in the simulation, we show that the signatures of these structures in the time series data are very similar to those of SHFAs seen in THEMIS data and conclude that they correspond to SHFAs. Examination of the simulation data shows that SHFAs form as the result of foreshock cavitons interacting with the bow shock. Foreshock cavitons in turn form due to the nonlinear evolution of ULF waves generated by the interaction of the solar wind with the backstreaming ions. Because foreshock cavitons are an inherent part of the shock dissipation process, the formation of SHFAs is also an inherent part of the dissipation process leading to a highly nonuniform plasma in the quasi-<span class="hlt">parallel</span> magnetosheath including large-scale density and magnetic field cavities.</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/1995STIN...9614863S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995STIN...9614863S"><span id="translatedtitle">Modeling flue pipes: Subsonic <span class="hlt">flow</span>, lattice Boltzmann, and <span class="hlt">parallel</span> distributed computers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skordos, Panayotis A.</p> <p>1995-01-01</p> <p>The problem of simulating the hydrodynamics and the acoustic waves inside wind musical instruments such as the recorder the organ, and the flute is considered. The problem is attacked by developing suitable local-interaction algorithms and a <span class="hlt">parallel</span> simulation system on a cluster of non-dedicated workstations. Physical measurements of the acoustic signal of various flue pipes show good agreement with the simulations. Previous attempts at this problem have been frustrated because the modeling of acoustic waves requires small integration time steps which make the simulation very compute-intensive. In addition, the simulation of subsonic viscous compressible <span class="hlt">flow</span> at high Reynolds numbers is susceptible to slow-growing numerical instabilities which are triggered by high-frequency acoustic modes. The numerical instabilities are mitigated by employing suitable explicit algorithms: lattice Boltzmann method, compressible finite differences, and fourth-order artificial-viscosity filter. Further, a technique for accurate initial and boundary conditions for the lattice Boltzmann method is developed, and the second-order accuracy of the lattice Boltzmann method is demonstrated. The compute-intensive requirements are handled by developing a <span class="hlt">parallel</span> simulation system on a cluster of non-dedicated workstations. The system achieves 80 percent <span class="hlt">parallel</span> efficiency (speedup/processors) using 20 HP-Apollo workstations. The system is built on UNIX and TCP/IP communication routines, and includes automatic process migration from busy hosts to free hosts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=126363&keyword=ssd&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&CFID=63072004&CFTOKEN=82498633','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=126363&keyword=ssd&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&CFID=63072004&CFTOKEN=82498633"><span id="translatedtitle">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.gpo.gov/fdsys/pkg/CFR-2010-title30-vol1/pdf/CFR-2010-title30-vol1-sec75-152.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol1/pdf/CFR-2010-title30-vol1-sec75-152.pdf"><span id="translatedtitle">30 CFR 75.152 - Tests of <span class="hlt">air</span> <span class="hlt">flow</span>; qualified person.</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>... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Tests of <span class="hlt">air</span> <span class="hlt">flow</span>; qualified person. 75.152....152 Tests of <span class="hlt">air</span> <span class="hlt">flow</span>; qualified person. A person is a qualified person within the meaning of the provisions of Subpart D—Ventilation of this part requiring that tests of <span class="hlt">air</span> <span class="hlt">flow</span> be made by a...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19990024947','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19990024947"><span id="translatedtitle">A <span class="hlt">Parallel</span>, Finite-Volume Algorithm for Large-Eddy Simulation of Turbulent <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>Bui, Trong T.</p> <p>1999-01-01</p> <p>A <span class="hlt">parallel</span>, finite-volume algorithm has been developed for large-eddy simulation (LES) of compressible turbulent <span class="hlt">flows</span>. This algorithm includes piecewise linear least-square reconstruction, trilinear finite-element interpolation, Roe flux-difference splitting, and second-order MacCormack time marching. <span class="hlt">Parallel</span> implementation is done using the message-passing programming model. In this paper, the numerical algorithm is described. To validate the numerical method for turbulence simulation, LES of fully developed turbulent <span class="hlt">flow</span> in a square duct is performed for a Reynolds number of 320 based on the average friction velocity and the hydraulic diameter of the duct. Direct numerical simulation (DNS) results are available for this test case, and the accuracy of this algorithm for turbulence simulations can be ascertained by comparing the LES solutions with the DNS results. The effects of grid resolution, upwind numerical dissipation, and subgrid-scale dissipation on the accuracy of the LES are examined. Comparison with DNS results shows that the standard Roe flux-difference splitting dissipation adversely affects the accuracy of the turbulence simulation. For accurate turbulence simulations, only 3-5 percent of the standard Roe flux-difference splitting dissipation is needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/20444567','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/20444567"><span id="translatedtitle"><span class="hlt">Parallel</span>-plate RF resonator imaging of chemical shift resolved capillary <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>Zhang, Jing; Balcom, Bruce J</p> <p>2010-07-01</p> <p>Magnetic resonance imaging has been introduced to study <span class="hlt">flow</span> in microchannels using pure phase spatial encoding with a microfabricated <span class="hlt">parallel</span>-plate nuclear magnetic resonance (NMR) probe. The NMR probe and pure phase spatial encoding enhance the sensitivity and resolution of the measurement. In this paper, (1)H NMR spectra and images were acquired at 100 MHz. The B(1) magnetic field is homogeneous and the signal-to-noise ratio of 30 microl doped water for a single scan is 8x10(4). The high sensitivity of the probe enables velocity mapping of the fluids in the micro-channel with a spatial resolution of 13x13 microm. The <span class="hlt">parallel</span>-plate probe with pure phase encoding permits the acquisition of NMR spectra; therefore, chemical shift resolved velocity mapping was also undertaken. Results are presented which show separate velocity maps for water and methanol <span class="hlt">flowing</span> through a straight circular micro-channel. Finally, future performance of these techniques for the study of microfluidics is extrapolated and discussed. PMID:20444567</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/7028107','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/7028107"><span id="translatedtitle">Integral manifolding structure for fuel cell core having <span class="hlt">parallel</span> gas <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Herceg, J.E.</p> <p>1983-10-12</p> <p>Disclosed herein are manifolding means for directing the fuel and oxidant gases to <span class="hlt">parallel</span> <span class="hlt">flow</span> passageways in a fuel cell core. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte and interconnect wall consists respectively of anode and cathode materials layered on the opposite sides of electrolyte material, or on the opposite sides of interconnect material. A core wall projects beyond the open ends of the defined core passageways and is disposed approximately midway between and <span class="hlt">parallel</span> to the adjacent overlaying and underlying interconnect walls to define manifold chambers therebetween on opposite sides of the wall. Each electrolyte wall defining the <span class="hlt">flow</span> passageways is shaped to blend into and be connected to this wall in order to redirect the corresponding fuel and oxidant passageways to the respective manifold chambers either above or below this intermediate wall. Inlet and outlet connections are made to these separate manifold chambers respectively, for carrying the fuel and oxidant gases to the core, and for carrying their reaction products away from the core.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/865192','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/865192"><span id="translatedtitle">Integral manifolding structure for fuel cell core having <span class="hlt">parallel</span> gas <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Herceg, Joseph E.</p> <p>1984-01-01</p> <p>Disclosed herein are manifolding means for directing the fuel and oxidant gases to <span class="hlt">parallel</span> <span class="hlt">flow</span> passageways in a fuel cell core. Each core passageway is defined by electrolyte and interconnect walls. Each electrolyte and interconnect wall consists respectively of anode and cathode materials layered on the opposite sides of electrolyte material, or on the opposite sides of interconnect material. A core wall projects beyond the open ends of the defined core passageways and is disposed approximately midway between and <span class="hlt">parallel</span> to the adjacent overlaying and underlying interconnect walls to define manifold chambers therebetween on opposite sides of the wall. Each electrolyte wall defining the <span class="hlt">flow</span> passageways is shaped to blend into and be connected to this wall in order to redirect the corresponding fuel and oxidant passageways to the respective manifold chambers either above or below this intermediate wall. Inlet and outlet connections are made to these separate manifold chambers respectively, for carrying the fuel and oxidant gases to the core, and for carrying their reaction products away from the core.</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 id="translatedtitle"><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 <span class="hlt">parallel</span> to the longitudinal valley axis, possibly influenced by pressure gradient and forced channeling.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1225432','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1225432"><span id="translatedtitle">Analysis of cell flux in the <span class="hlt">parallel</span> plate <span class="hlt">flow</span> chamber: implications for cell capture studies.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Munn, L L; Melder, R J; Jain, R K</p> <p>1994-01-01</p> <p>The <span class="hlt">parallel</span> plate <span class="hlt">flow</span> chamber provides a controlled environment for determinations of the shear stress at which cells in suspension can bind to endothelial cell monolayers. By decreasing the <span class="hlt">flow</span> rate of cell-containing media over the monolayer and assessing the number of cells bound at each wall shear stress, the relationship between shear force and binding efficiency can be determined. The rate of binding should depend on the delivery of cells to the surface as well as the intrinsic cell-surface interactions; thus, only if the cell flux to the surface is known can the resulting binding curves be interpreted correctly. We present the development and validation of a mathematical model based on the sedimentation rate and velocity profile in the chamber for the delivery of cells from a <span class="hlt">flowing</span> suspension to the chamber surface. Our results show that the flux depends on the bulk cell concentration, the distance from the entrance point, and the <span class="hlt">flow</span> rate of the cell-containing medium. The model was then used in a normalization procedure for experiments in which T cells attach to TNF-alpha-stimulated HUVEC monolayers, showing that a threshold for adhesion occurs at a shear stress of about 3 dyn/cm2. Images FIGURE 1 FIGURE 2 PMID:7948702</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150006663','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150006663"><span id="translatedtitle">Interaction of a Rectangular Jet with a Flat-Plate Placed <span class="hlt">Parallel</span> to the <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>Zaman, K. B. M. Q.; Brown, C. A.; Bridges, J. A.</p> <p>2013-01-01</p> <p>An experimental study is carried out addressing the flowfield and radiated noise from the interaction of a large aspect ratio rectangular jet with a flat plate placed <span class="hlt">parallel</span> to but away from the direct path of the jet. Sound pressure level spectra exhibit an increase in the noise levels for both the 'reflected' and 'shielded' sides of the plate relative to the free-jet case. Detailed cross-sectional distributions of flowfield properties obtained by hot-wire anemometry are documented for a low subsonic condition. Corresponding mean Mach number distributions obtained by Pitot-probe surveys are presented for high subsonic conditions. In the latter <span class="hlt">flow</span> regime and for certain relative locations of the plate, a <span class="hlt">flow</span> resonance accompanied by audible tones is encountered. Under the resonant condition the jet cross-section experiences an 'axis-switching' and <span class="hlt">flow</span> visualization indicates the presence of an organized 'vortex street'. The trends of the resonant frequency variation with <span class="hlt">flow</span> parameters exhibit some similarities to, but also marked differences with, corresponding trends of the well-known edgetone phenomenon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010IJCFD..24...37L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010IJCFD..24...37L"><span id="translatedtitle"><span class="hlt">Parallel</span> FEM LES with one-equation subgrid-scale model for incompressible <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>Li, Xian-Xiang; Liu, Chun-Ho; Leung, Dennis Y. C.</p> <p>2010-01-01</p> <p>This article develops a <span class="hlt">parallel</span> large-eddy simulation (LES) with a one-equation subgrid-scale (SGS) model based on the Galerkin finite element method and three-dimensional (3D) brick elements. The governing filtered Navier-Stokes equations were solved by a second-order accurate fractional-step method, which decomposed the implicit velocity-pressure coupling in incompressible <span class="hlt">flow</span> and segregated the solution to the advection and diffusion terms. The transport equation for the SGS turbulent kinetic energy was solved to calculate the SGS processes. This FEM LES model was applied to study the turbulence of the benchmark open channel <span class="hlt">flow</span> at a Reynolds number Reτ = 180 (based on the friction velocity and channel height) using different model constants and grid resolutions. By comparing the turbulence statistics calculated by the current model with those obtained from direct numerical simulation (DNS) and experiments in literature, an optimum set of model constants for the current FEM LES model was established. The budgets of turbulent kinetic energy and vertical Reynolds stress were then analysed for the open channel <span class="hlt">flow</span>. Finally, the <span class="hlt">flow</span> structures were visualised to further reveal some important characteristics. It was demonstrated that the current model with the optimum model constants can predict well the organised structure near the wall and free surface, and can be further applied to other fundamental and engineering applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007APS..DFD.BO003A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007APS..DFD.BO003A"><span id="translatedtitle">Control of High-Speed Spray <span class="hlt">Flows</span> Using a Steady, <span class="hlt">Parallel</span> Control <span class="hlt">Flow</span> Under the Influence of the Coanda Effect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Allen, Dustin; Smith, Barton</p> <p>2007-11-01</p> <p>An experimental demonstration of a jet vectoring technique used in our novel spray device called a Coanda-assisted Spray Manipulation (CSM) nozzle is presented. The CSM makes use of a Coanda-like effect on axisymmetric geometries through the interaction of a high volume-<span class="hlt">flow</span> primary jet <span class="hlt">flowing</span> through the center of a collar and a secondary high-momentum jet <span class="hlt">parallel</span> to the first and adjacent to a convex collar. The control jet attaches to the convex wall and vectors due to the Coanda effect, entraining and vectoring the primary jet, resulting in controllable r-theta directional spraying. Various annular secondary exit holes and curved wall radii were tested over a range of momentum flux ratios to study the effects of these variables on the vectored jet angle. Particle Image Velocimetry (PIV) was used to determine the vectoring angle and the profile of the primary jet in each experiment. The experiments show that the secondary exit hole size and curve wall radius, along with the momentum ratios of the two jets predominantly affect the vectoring angle of the primary jet. Also, the jet profile is largely unchanged with vectoring for high velocity <span class="hlt">flows</span>, which is important for the thermal spray applications for which CSM will be used.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/988956','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/988956"><span id="translatedtitle">Mesoscale Simulations of Particulate <span class="hlt">Flows</span> with <span class="hlt">Parallel</span> Distributed Lagrange Multiplier Technique</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kanarska, Y</p> <p>2010-03-24</p> <p>Fluid particulate <span class="hlt">flows</span> are common phenomena in nature and industry. Modeling of such <span class="hlt">flows</span> at micro and macro levels as well establishing relationships between these approaches are needed to understand properties of the particulate matter. We propose a computational technique based on the direct numerical simulation of the particulate <span class="hlt">flows</span>. The numerical method is based on the distributed Lagrange multiplier technique following the ideas of Glowinski et al. (1999). Each particle is explicitly resolved on an Eulerian grid as a separate domain, using solid volume fractions. The fluid equations are solved through the entire computational domain, however, Lagrange multiplier constrains are applied inside the particle domain such that the fluid within any volume associated with a solid particle moves as an incompressible rigid body. Mutual forces for the fluid-particle interactions are internal to the system. Particles interact with the fluid via fluid dynamic equations, resulting in implicit fluid-rigid-body coupling relations that produce realistic fluid <span class="hlt">flow</span> around the particles (i.e., no-slip boundary conditions). The particle-particle interactions are implemented using explicit force-displacement interactions for frictional inelastic particles similar to the DEM method of Cundall et al. (1979) with some modifications using a volume of an overlapping region as an input to the contact forces. The method is flexible enough to handle arbitrary particle shapes and size distributions. A <span class="hlt">parallel</span> implementation of the method is based on the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) library, which allows handling of large amounts of rigid particles and enables local grid refinement. Accuracy and convergence of the presented method has been tested against known solutions for a falling sphere as well as by examining fluid <span class="hlt">flows</span> through stationary particle beds (periodic and cubic packing). To evaluate code performance and validate particle</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22046893','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22046893"><span id="translatedtitle">Evolution of symmetric reconnection layer in the presence of <span class="hlt">parallel</span> shear <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lu Haoyu; Cao Jinbin</p> <p>2011-07-15</p> <p>The development of the structure of symmetric reconnection layer in the presence of a shear <span class="hlt">flow</span> <span class="hlt">parallel</span> to the antiparallel magnetic field component is studied by using a set of one-dimensional (1D) magnetohydrodynamic (MHD) equations. The Riemann problem is simulated through a second-order conservative TVD (total variation diminishing) scheme, in conjunction with Roe's averages for the Riemann problem. The simulation results indicate that besides the MHD shocks and expansion waves, there exist some new small-scale structures in the reconnection layer. For the case of zero initial guide magnetic field (i.e., B{sub y0} = 0), a pair of intermediate shock and slow shock (SS) is formed in the presence of the <span class="hlt">parallel</span> shear <span class="hlt">flow</span>. The critical velocity of initial shear <span class="hlt">flow</span> V{sub zc} is just the Alfven velocity in the inflow region. As V{sub z{infinity}} increases to the value larger than V{sub zc}, a new slow expansion wave appears in the position of SS in the case V{sub z{infinity}} < V{sub zc}, and one of the current densities drops to zero. As plasma {beta} increases, the out-<span class="hlt">flow</span> region is widened. For B{sub y0} {ne} 0, a pair of SSs and an additional pair of time-dependent intermediate shocks (TDISs) are found to be present. Similar to the case of B{sub y0} = 0, there exists a critical velocity of initial shear <span class="hlt">flow</span> V{sub zc}. The value of V{sub zc} is, however, smaller than the Alfven velocity of the inflow region. As plasma {beta} increases, the velocities of SS and TDIS increase, and the out-<span class="hlt">flow</span> region is widened. However, the velocity of downstream SS increases even faster, making the distance between SS and TDIS smaller. Consequently, the interaction between SS and TDIS in the case of high plasma {beta} influences the property of direction rotation of magnetic field across TDIS. Thereby, a wedge in the hodogram of tangential magnetic field comes into being. When {beta}{yields}{infinity}, TDISs disappear and the guide magnetic field becomes constant.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001SPIE.4183..881M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001SPIE.4183..881M"><span id="translatedtitle">Optical observation of ultrafine droplets and <span class="hlt">air</span> <span class="hlt">flows</span> from newly designed supersonic <span class="hlt">air</span> assist spray nozzles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miyashiro, Seiji S.; Mori, H.; Takechi, H.</p> <p>2001-04-01</p> <p>One of the authors developed a new spray drying nozzle (special quadruplet fluid spray nozzle) for drug manufacturing and it has succeeded in manufacturing fine particles of 2 micrometer diameter of 1/15 ratios to those currently in use. The <span class="hlt">flow</span> visualization results show that the two <span class="hlt">air</span> jets become under-expanded on both edge sides of the nozzle, generate shock and expansion waves alternately on each side and reach the edge tip, where they collide, unite, and spout out while shock and expansion waves are again formed in the mixed jet. When the edge surfaces are supplied with water, the water is extended into thin film by the <span class="hlt">air</span> jet and intensely disturbed. At the nozzle tip it is torn into droplets, which are further atomized afterwards in shock waves. At the spray tip, the friction with ambient <span class="hlt">air</span> shears the droplets furthermore, and they decrease further in size.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AIPC.1084..843B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AIPC.1084..843B"><span id="translatedtitle">Non-equilibrium <span class="hlt">Flows</span> of Reacting <span class="hlt">Air</span> Components 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>Bazilevich, S. S.; Sinitsyn, K. A.; Nagnibeda, E. A.</p> <p>2008-12-01</p> <p>The paper presents the results of the investigation of non-equilibrium <span class="hlt">flows</span> of reacting <span class="hlt">air</span> mixtures in nozzles. State-to-state approach based on the solution of the equations for vibrational level populations of molecules and atomic concentrations coupled to the gas dynamics equations is used. For the 5-component <span class="hlt">air</span> mixture (N2, O2, NO, N, O) non-equilibrium distributions and gasdynamical parameters are calculated for different conditions in a nozzle throat. The influence of various kinetic processes on distributions and gas dynamics parameters is studied. The paper presents the comparison of the results with ones obtained for binary mixtures of molecules and atoms and various models of elementary processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050177239','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050177239"><span id="translatedtitle">LSPRAY: Lagrangian Spray Solver for Applications With <span class="hlt">Parallel</span> Computing and Unstructured Gas-Phase <span class="hlt">Flow</span> Solvers</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raju, Manthena S.</p> <p>1998-01-01</p> <p>Sprays occur in a wide variety of industrial and power applications and in the processing of materials. A liquid spray is a phase <span class="hlt">flow</span> with a gas as the continuous phase and a liquid as the dispersed phase (in the form of droplets or ligaments). Interactions between the two phases, which are coupled through exchanges of mass, momentum, and energy, can occur in different ways at different times and locations involving various thermal, mass, and fluid dynamic factors. An understanding of the <span class="hlt">flow</span>, combustion, and thermal properties of a rapidly vaporizing spray requires careful modeling of the rate-controlling processes associated with the spray's turbulent transport, mixing, chemical kinetics, evaporation, and spreading rates, as well as other phenomena. In an attempt to advance the state-of-the-art in multidimensional numerical methods, we at the NASA Lewis Research Center extended our previous work on sprays to unstructured grids and <span class="hlt">parallel</span> computing. LSPRAY, which was developed by M.S. Raju of Nyma, Inc., is designed to be massively <span class="hlt">parallel</span> and could easily be coupled with any existing gas-phase <span class="hlt">flow</span> and/or Monte Carlo probability density function (PDF) solver. The LSPRAY solver accommodates the use of an unstructured mesh with mixed triangular, quadrilateral, and/or tetrahedral elements in the gas-phase solvers. It is used specifically for fuel sprays within gas turbine combustors, but it has many other uses. The spray model used in LSPRAY provided favorable results when applied to stratified-charge rotary combustion (Wankel) engines and several other confined and unconfined spray flames. The source code will be available with the National Combustion Code (NCC) as a complete package.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SPIE.5396...89N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SPIE.5396...89N"><span id="translatedtitle">A modeling of <span class="hlt">air</span> <span class="hlt">flow</span> in a street canyon</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nuterman, R. B.; Starchenko, Alexander V.</p> <p>2004-02-01</p> <p>Steady plane-<span class="hlt">parallel</span> isothermal turbulent <span class="hlt">flow</span> of a viscous incompressible liquid above a surface with elements of a roughness is considered. Buildings and road with vehicle emissions for a city canyon. Reynolds equations and Boussinesq assumption are used to solve the considered problem. We apply the no-slip boundary conditions on the rigid walls, simple gradient conditions on the upper and outflow boundaries and known distributions of <span class="hlt">flow</span> parameters on inflow boundary. Turbulent parameters are calculated on the basis of "k--ɛ" model of turbulence with near-wall functions approach for energy of turbulence k and dissipation ɛ. A numerical solution of the problem is found with using of finite-volume method and the SIMPLE algorithm. Influence of atmospheric parameters on pollutant dispersion in a street canyon is investigated. Also influences of the geometrical factors of a city street canyon on a pattern of turbulent <span class="hlt">flow</span> and distribution of harmful impurity concentration emitting from urban vehicles are investigated. The adverse meteorological situations resulting in accumulation of the harmful substances in street canyon are shown.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..DFD.GM006T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..DFD.GM006T"><span id="translatedtitle"><span class="hlt">Flow</span> Analysis over Batten Reinforced Wings for Micro <span class="hlt">Air</span> Vehicles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Townsend, Kurtis; Hicks, Travis; Hubner, James P.</p> <p>2008-11-01</p> <p>Flexible membrane wings modify the <span class="hlt">flow</span> separation of low Reynolds number micro <span class="hlt">air</span> vehicles (MAVs). A specific type of fixed-wing geometry is a batten-reinforced configuration in which the membrane is attached to a rigid frame with chordwise battens, allowing the vibration of the membrane at the trailing-edge. In this study, smoke-wire visualization and hot-wire anemometry, both near the trailing-edge and further downstream in the wake, are used to quantify the frequency and energy of these fluctuations for various cell geometries and <span class="hlt">flow</span> angles-of-attack. Improvement in the wake momentum deficit will be analyzed to determine preferred membrane cell geometries for MAV flight conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870018512','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870018512"><span id="translatedtitle">Surface-slip equations for multicomponent, nonequilibrium <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>Gupta, Roop N.; Scott, Carl D.; Moss, James N.; Goglia, Gene</p> <p>1985-01-01</p> <p>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 <span class="hlt">air</span> <span class="hlt">flow</span>, 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 <span class="hlt">flow</span>-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.</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/2016IJCFD..30...79Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJCFD..30...79Z"><span id="translatedtitle">Implementation and efficiency analysis of <span class="hlt">parallel</span> computation using OpenACC: a case study using <span class="hlt">flow</span> field 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, Shanghong; Yuan, Rui; Wu, Yu; Yi, Yujun</p> <p>2016-01-01</p> <p>The Open Accelerator (OpenACC) application programming interface is a relatively new <span class="hlt">parallel</span> computing standard. In this paper, particle-based <span class="hlt">flow</span> field simulations are examined as a case study of OpenACC <span class="hlt">parallel</span> computation. The <span class="hlt">parallel</span> conversion process of the OpenACC standard is explained, and further, the performance of the <span class="hlt">flow</span> field <span class="hlt">parallel</span> model is analysed using different directive configurations and grid schemes. With careful implementation and optimisation of the data transportation in the <span class="hlt">parallel</span> algorithm, a speedup factor of 18.26× is possible. In contrast, a speedup factor of just 11.77× was achieved with the conventional Open Multi-Processing (OpenMP) <span class="hlt">parallel</span> mode on a 20-kernel computer. These results demonstrate that optimised feature settings greatly influence the degree of speedup, and models involving larger numbers of calculations exhibit greater efficiency and higher speedup factors. In addition, the OpenACC <span class="hlt">parallel</span> mode is found to have good portability, making it easy to implement <span class="hlt">parallel</span> computation from the original serial model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1220523','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1220523"><span id="translatedtitle">Laboratory Evaluation of <span class="hlt">Air</span> <span class="hlt">Flow</span> Measurement Methods for Residential HVAC Returns</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Walker, Iain; Stratton, Chris</p> <p>2015-07-01</p> <p>This project improved the accuracy of <span class="hlt">air</span> <span class="hlt">flow</span> measurements used in commissioning California heating and <span class="hlt">air</span> conditioning systems in Title 24 (Building and Appliance Efficiency Standards), thereby improving system performance and efficiency of California residences. The research team at Lawrence Berkeley National Laboratory addressed the issue that typical tools used by contractors in the field to test <span class="hlt">air</span> <span class="hlt">flows</span> may not be accurate enough to measure return <span class="hlt">flows</span> used in Title 24 applications. The team developed guidance on performance of current diagnostics as well as a draft test method for use in future evaluations. The series of tests performed measured <span class="hlt">air</span> <span class="hlt">flow</span> using a range of techniques and devices. The measured <span class="hlt">air</span> <span class="hlt">flows</span> were compared to reference <span class="hlt">air</span> <span class="hlt">flow</span> measurements using inline <span class="hlt">air</span> <span class="hlt">flow</span> meters built into the test apparatus. The experimental results showed that some devices had reasonable results (typical errors of 5 percent or less) but others had much bigger errors (up to 25 percent).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.8689M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8689M"><span id="translatedtitle">Upper <span class="hlt">air</span> teleconnections to Ob River <span class="hlt">flows</span> and tree rings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meko, David; Panyushkina, Irina; Agafonov, Leonid</p> <p>2015-04-01</p> <p>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 <span class="hlt">flows</span>, 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 <span class="hlt">air</span> temperature regime by flooding appears to be an important driver of the tree-ring response. In unraveling the relationship of tree-growth to river <span class="hlt">flows</span>, it is important to identify atmospheric circulation features directly linked to observed time series variations of <span class="hlt">flow</span> and tree growth. In this study we examine statistical links between primary teleconnection modes of Northern Hemisphere upper-<span class="hlt">air</span> (500 mb) circulation, Ob River <span class="hlt">flow</span>, 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 <span class="hlt">air</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AtmEn.141..454A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AtmEn.141..454A&link_type=ABSTRACT"><span id="translatedtitle">Ozone concentrations in <span class="hlt">air</span> <span class="hlt">flowing</span> into New York State</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Aleksic, Nenad; Kent, John; Walcek, Chris</p> <p>2016-09-01</p> <p>Ozone (O3) concentrations measured at Pinnacle State Park (PSPNY), very close to the southern border of New York State, are used to estimate concentrations in <span class="hlt">air</span> <span class="hlt">flowing</span> into New York. On 20% of the ozone season (April-September) afternoons from 2004 to 2015, mid-afternoon 500-m back trajectories calculated from PSPNY cross New York border from the south and spend less than three hours in New York State, in this area of negligible local pollution emissions. One-hour (2p.m.-3p.m.) O3 concentrations during these inflowing conditions were 46 ± 13 ppb, and ranged from a minimum of 15 ppb to a maximum of 84 ppb. On average during 2004-2015, each year experienced 11.8 days with inflowing 1-hr O3 concentrations exceeding 50 ppb, 4.3 days with O3 > 60 ppb, and 1.5 days had O3 > 70 ppb. During the same period, 8-hr average concentrations (10a.m. to 6p.m.) exceeded 50 ppb on 10.0 days per season, while 3.9 days exceeded 60 ppb, and 70 ppb was exceeded 1.2 days per season. Two afternoons of minimal in-state emission influences with high ozone concentrations were analyzed in more detail. Synoptic and back trajectory analysis, including comparison with upwind ozone concentrations, indicated that the two periods were characterized as photo-chemically aged <span class="hlt">air</span> containing high inflowing O3 concentrations most likely heavily influenced by pollution emissions from states upwind of New York including Pennsylvania, Tennessee, West Virginia, and Ohio. These results suggest that New York state-level attempts to comply with National Ambient <span class="hlt">Air</span> Quality Standards by regulating in-state O3 precursor NOx and organic emissions would be very difficult, since <span class="hlt">air</span> frequently enters New York State very close to or in excess of Federal <span class="hlt">Air</span> Quality Standards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/567494','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/567494"><span id="translatedtitle">Massively <span class="hlt">parallel</span> computation of 3D <span class="hlt">flow</span> and reactions in chemical vapor deposition reactors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Salinger, A.G.; Shadid, J.N.; Hutchinson, S.A.; Hennigan, G.L.; Devine, K.D.; Moffat, H.K.</p> <p>1997-12-01</p> <p>Computer modeling of Chemical Vapor Deposition (CVD) reactors can greatly aid in the understanding, design, and optimization of these complex systems. Modeling is particularly attractive in these systems since the costs of experimentally evaluating many design alternatives can be prohibitively expensive, time consuming, and even dangerous, when working with toxic chemicals like Arsine (AsH{sub 3}): until now, predictive modeling has not been possible for most systems since the behavior is three-dimensional and governed by complex reaction mechanisms. In addition, CVD reactors often exhibit large thermal gradients, large changes in physical properties over regions of the domain, and significant thermal diffusion for gas mixtures with widely varying molecular weights. As a result, significant simplifications in the models have been made which erode the accuracy of the models` predictions. In this paper, the authors will demonstrate how the vast computational resources of massively <span class="hlt">parallel</span> computers can be exploited to make possible the analysis of models that include coupled fluid <span class="hlt">flow</span> and detailed chemistry in three-dimensional domains. For the most part, models have either simplified the reaction mechanisms and concentrated on the fluid <span class="hlt">flow</span>, or have simplified the fluid <span class="hlt">flow</span> and concentrated on rigorous reactions. An important CVD research thrust has been in detailed modeling of fluid <span class="hlt">flow</span> and heat transfer in the reactor vessel, treating transport and reaction of chemical species either very simply or as a totally decoupled problem. Using the analogy between heat transfer and mass transfer, and the fact that deposition is often diffusion limited, much can be learned from these calculations; however, the effects of thermal diffusion, the change in physical properties with composition, and the incorporation of surface reaction mechanisms are not included in this model, nor can transitions to three-dimensional <span class="hlt">flows</span> be detected.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhFl...28b2006D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhFl...28b2006D"><span id="translatedtitle">Transient Couette <span class="hlt">flow</span> of a rarefied gas between plane <span class="hlt">parallel</span> walls with different surface properties</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Doi, Toshiyuki</p> <p>2016-02-01</p> <p>Transient Couette <span class="hlt">flow</span> of a rarefied gas between plane <span class="hlt">parallel</span> walls with different surface properties induced by a sudden start-up of one of the walls is studied based on kinetic theory. The linearized Boltzmann equation for a hard sphere molecular gas is analyzed under the assumptions that one wall is a diffuse reflection boundary and the other wall is a Maxwell-type boundary. The initial and boundary value problem is solved numerically by using a modified hybrid scheme of characteristic coordinate and finite difference methods, to describe the discontinuities in the velocity distribution function correctly. The time evolution of the <span class="hlt">flow</span> and the approach to the final time-independent state are studied over a wide range of the mean free paths and the accommodation coefficient of the boundary. In the transient process, the shear force acting on the moving wall depends on which wall moves. In contrast, the shear force acting on the wall at rest is independent of which wall moves; this property is a consequence of the symmetric relation of the Boltzmann equation [S. Takata, "Symmetry of the unsteady linearized Boltzmann equation in a fixed bounded domain," J. Stat. Phys. 140, 985 (2010)]. The speed of approach to the time-independent state is fastest at an intermediate value of the mean free path. The behavior of the gas in the final time-independent state, including the heat <span class="hlt">flow</span> in the isothermal gas, is also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/25171501','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/25171501"><span id="translatedtitle">Redox-magnetohydrodynamics, flat <span class="hlt">flow</span> profile-guided enzyme assay detection: toward multiple, <span class="hlt">parallel</span> analyses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sahore, Vishal; Fritsch, Ingrid</p> <p>2014-10-01</p> <p>A proof-of-concept superparamagnetic microbead-enzyme complex was integrated with microfluidics pumped by redox-magneto-hydrodynamics (MHD) to take advantage of the magnet (0.56 T) beneath the chip and the uniform flat <span class="hlt">flow</span> profile, as a first step toward developing multiple, <span class="hlt">parallel</span> chemical analyses on a chip without the need for independent channels. The superparamagnetic beads were derivatized with alkaline phosphatase (a common enzyme label for biochemical assays) and magnetically immobilized at three different locations on the chip with one directly on the path to the detector and the other two locations adjacent to, but off the path, by a distance >5 times the detector diameter. Electroactive p-aminophenol, enzymatically generated at the bead-enzyme complex from its electroinactive precursor p-aminophenyl phosphate in a solution containing a redox species [Ru(NH3)6](3+/2+) for pumping and Tris buffer, was transported by redox-MHD and detected with square wave voltammetry at a 312 μm diameter gold microdisk stationed 2 mm downstream from the bead-complex on the <span class="hlt">flow</span> path. Oppositely biased pumping electrodes, consisting of 2.5 cm long gold bands and separated by 5.6 mm, flanked the active <span class="hlt">flow</span> region containing the bead-enzyme complex and detection site. The signal from adjacent paths was only 20% of that for the direct path and ≤8% when pumping electrodes were inactive. PMID:25171501</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PhFl...18e3301B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PhFl...18e3301B"><span id="translatedtitle">Hydrodynamic interactions of spherical particles in Poiseuille <span class="hlt">flow</span> between two <span class="hlt">parallel</span> walls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhattacharya, S.; Bławzdziewicz, J.; Wajnryb, E.</p> <p>2006-05-01</p> <p>We study hydrodynamic interactions of spherical particles in incident Poiseuille <span class="hlt">flow</span> in a channel with infinite planar walls. The particles are suspended in a Newtonian fluid, and creeping-<span class="hlt">flow</span> conditions are assumed. Numerical results, obtained using our highly accurate Cartesian-representation algorithm [Physica A 356, 294 (2005)] are presented for a single sphere, two spheres, and arrays of many spheres. We consider the motion of freely suspended particles as well as the forces and torques acting on particles adsorbed at a wall. We find that the pair hydrodynamic interactions in this wall-bounded system have a complex dependence on the lateral interparticle distance due to the combined effects of the dissipation in the gap between the particle surfaces and the backflow associated with the presence of the walls. For immobile particle pairs we have examined the crossover between several far-field asymptotic regimes corresponding to different relations between the particle separation and the distances of the particles from the walls. We have also shown that the cumulative effect of the far-field <span class="hlt">flow</span> substantially influences the force distribution in arrays of immobile spheres, and it affects trajectories of suspended particles. Therefore, the far-field contributions should be included in any reliable algorithm for evaluating many-particle hydrodynamic interactions in the <span class="hlt">parallel</span>-wall geometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhFl...26j4102J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhFl...26j4102J"><span id="translatedtitle"><span class="hlt">Flow</span>-induced vibrations of two tandem circular cylinders in a <span class="hlt">parallel</span>-wall channel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Ren-Jie; Lin, Jian-Zhong; Ku, Xiao-Ke</p> <p>2014-10-01</p> <p><span class="hlt">Flow</span>-induced vibrations of one and two tandem circular cylinders in the <span class="hlt">flow</span> around cylinders in a <span class="hlt">parallel</span>-wall channel are numerically studied by the lattice Boltzmann method. Within a range of Reynolds number Re = [1, 160], the effects of streamwise separation between two cylinders S/D = [1.25, 3], mass ratio M = [0.05, 5], and blockage ratio β = [1/2, 1/8] on the motions of cylinders and fluids are investigated, respectively. For the case of an isolated cylinder, as the mass ratio is 1, no large-amplitude oscillation is observed, and as the mass ratio is 0.1, the cylinder motion translates from the steady regime to the biased periodic vibration with a large oscillation amplitude gradually as Reynolds number is increased from 1 to 160. For the case of two cylinders in tandem, two steady regimes and a variety of distinct oscillation regimes with the corresponding <span class="hlt">flow</span> structures are observed. The critical mass ratio of the two tandem cylinders in the strong coupling regime is about an order of magnitude larger than that of an isolated cylinder. For blockage ratio is more than 1/5, the vibration type of the cylinders is exclusive, while for blockage ratio is less than 1/6, the cylinder oscillation state is bistable. The mechanisms of the observed phenomena are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014PhDT.......297B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014PhDT.......297B"><span id="translatedtitle">Application of <span class="hlt">parallel</span> time-implicit discontinuous Galerkin finite element methods to hypersonic nonequilibrium <span class="hlt">flow</span> problems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhatia, Ankush</p> <p></p> <p>Discontinuous Galerkin (DG) methods are high-order accurate, compact-stencil methods, proven to possess favorable properties for highly efficient <span class="hlt">parallel</span> systems, complex geometries and unstructured meshes. Coding effort is significantly reduced for compact-stencil DG methods in comparison to main stream finite difference and finite volume methods. This work successfully introduces DG methods to thermal ablation and non-equilibrium hypersonic <span class="hlt">flows</span>. In the state-of-the-art hypersonic <span class="hlt">flow</span> codes, surface heating predictions are very sensitive to mesh resolution in the shock. A minor misalignment can cause major changes in the heating predictions. This is due to the lack of high-order accuracy in current streamline methods and numerical errors associated with the shock capturing approach. Shock capturing methods like slope limiter or artificial viscosity, being empirical have errors in the shock region. This work employs r-p adaptivity to accurately capture the shock with p = 0 elements (first order accuracy). Smooth <span class="hlt">flow</span> regions are captured using p greater than 0. This method is stable. Implicit methods are developed for solution advancement with high CFL numbers. Error in the shock is reduced by redistributing the elements (outside of the shock) to within the shock (r adaptivity). Inviscid and viscous hypersonic <span class="hlt">flow</span> problems, with same accuracy as in h-p adaptivity method, are simulated with one-third elements. This methodology requires no a priori knowledge of the shock's location, and is suitable for detached shock problems. r-p adaptivity method has allowed for successful prediction of surface heating rate for hypersonic <span class="hlt">flow</span> over cylinder. Additionally, good comparisons are made, for non-equilibrium hypersonic <span class="hlt">flows</span>, to the published results. This tool is also used to determine the effect of micro-second pulsed sinusoidal Dielectric Barrier Discharge (DBD) plasma actuators on the surface heating reduction for hypersonic <span class="hlt">flow</span> over cylinder. A significant</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002PhDT.......200S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002PhDT.......200S"><span id="translatedtitle"><span class="hlt">Parallel</span> methods for the computation of unsteady separated <span class="hlt">flows</span> around complex geometries</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Souliez, Frederic Jean</p> <p></p> <p>A numerical investigation of separated <span class="hlt">flows</span> is made using unstructured meshes around complex geometries. The <span class="hlt">flow</span> data in the wake of a 60-degree vertex angle cone are analyzed for various versions of our finite volume solver, including a generic version without turbulence model, and a Large Eddy Simulation model with different sub-grid scale constant values. While the primary emphasis is on the comparison of the results against experimental data, the solution is also used as a benchmark tool for an aeroacoustic post-processing utility combined with the Ffowcs Williams-Hawkings (FW-H) equation. A concurrent study is performed of the <span class="hlt">flow</span> around two 4-wheel landing gear models, with the difference residing in the addition of two additional support struts. These unsteady calculations are used to provide aerodynamic and aeroacoustic data. The impact of the two configurations on the forces as well as on the acoustic near- and far-field is evaluated with the help of the above-mentioned aeroacoustic program. For both the cone and landing gear runs, <span class="hlt">parallel</span> versions of the <span class="hlt">flow</span> solver and of the FW-H utility are used via the implementation of the Message Passing Interface (MPI) library, resulting in very good scaling performance. The speed-up results for these cases are described for different platforms including inexpensive Beowulf-class clusters, which are the computing workhorse for the present numerical investigation. Furthermore, the analysis of the <span class="hlt">flow</span> around a Bell 214 Super Transport (ST) fuselage is presented. A mesh sensitivity analysis is compared against experimental and numerical results collected by the helicopter manufacturer. Parameters such as surface pressure coefficient, lift and drag are evaluated resulting from both steady-state and time-accurate simulations. Various flight conditions are tested, with a slightly negative angle of attack, a large positive angle of attack and a positive yaw angle, all of which resulting in massive <span class="hlt">flow</span> separation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820010304','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820010304"><span id="translatedtitle">Comparison of two <span class="hlt">parallel</span>/series <span class="hlt">flow</span> turbofan propulsion concepts for supersonic V/STOL</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Luidens, R. W.; Turney, G. E.; Allen, J.</p> <p>1981-01-01</p> <p>The thrust, specific fuel consumption, and relative merits of the tandem fan and the dual reverse <span class="hlt">flow</span> front fan propulsion systems for a supersonic V/STOL aircraft are discussed. Consideration is given to: fan pressure ratio, fan <span class="hlt">air</span> burning, and variable core supercharging. The special propulsion system components required are described, namely: the deflecting front inlet/nozzle, the aft subsonic inlet, the reverse pitch fan, the variable core supercharger and the low pressure forward burner. The potential benefits for these unconventional systems are indicated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995PhDT........53S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995PhDT........53S"><span id="translatedtitle">Modeling Flue Pipes: Subsonic <span class="hlt">Flow</span>, Lattice Boltzmann, and <span class="hlt">Parallel</span> Distributed Computers.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Skordos, Panayotis A.</p> <p>1995-01-01</p> <p>The problem of simulating the hydrodynamics and the acoustic waves inside wind musical instruments such as the recorder, the organ, and the flute is considered. The problem is attacked by developing suitable local-interaction algorithms and a <span class="hlt">parallel</span> simulation system on a cluster of non-dedicated workstations. Physical measurements of the acoustic signal of various flue pipes show good agreement with the simulations. Previous attempts at this problem have been frustrated because the modeling of acoustic waves requires small integration time steps which make the simulation very compute-intensive. In addition, the simulation of subsonic viscous compressible <span class="hlt">flow</span> at high Reynolds numbers is susceptible to slow-growing numerical instabilities which are triggered by high-frequency acoustic modes. The numerical instabilities are mitigated by employing suitable explicit algorithms: lattice Boltzmann method, compressible finite differences, and fourth-order artificial -viscosity filter. Further, a technique for accurate initial and boundary conditions for the lattice Boltzmann method is developed, and the second-order accuracy of the lattice Boltzmann method is demonstrated. The compute-intensive requirements are handled by developing a <span class="hlt">parallel</span> simulation system on a cluster of non-dedicated workstations. The system achieves 80% <span class="hlt">parallel</span> efficiency (speedup/processors) using 20 HP-Apollo workstations. The system is built on UNIX and TCP/IP communication routines, and includes automatic process migration from busy hosts to free hosts. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139-4307. Ph. 617 -253-5668; Fax 617-253-1690.).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19780013469','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19780013469"><span id="translatedtitle">Experimental study of the laminar-turbulent transition of a concave wall in a <span class="hlt">parallel</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>Bippes, H.</p> <p>1978-01-01</p> <p>The instability of the laminar boundary layer <span class="hlt">flow</span> along a concave wall was studied. Observations of these three-dimensional boundary layer phenomena were made using the hydrogen-bubble visualization technique. With the application of stereo-photogrammetric methods in the <span class="hlt">air</span>-water system it was possible to investigate the <span class="hlt">flow</span> processes qualitatively and quantitatively. In the case of a concave wall of sufficient curvature, a primary instability occurs first in the form of Goertler vortices with wave lengths depending upon the boundary layer thickness and the wall curvature. At the onset the amplification rate is in agreement with the linear theory. Later, during the non-linear amplification stage, periodic spanwise vorticity concentrations develop in the low velocity region between the longitudinal vortices. Then a meandering motion of the longitudinal vortex streets subsequently ensues, leading to turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000004185','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000004185"><span id="translatedtitle">Large-Scale <span class="hlt">Parallel</span> Viscous <span class="hlt">Flow</span> Computations using an Unstructured Multigrid Algorithm</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mavriplis, Dimitri J.</p> <p>1999-01-01</p> <p>The development and testing of a <span class="hlt">parallel</span> unstructured agglomeration multigrid algorithm for steady-state aerodynamic <span class="hlt">flows</span> is discussed. The agglomeration multigrid strategy uses a graph algorithm to construct the coarse multigrid levels from the given fine grid, similar to an algebraic multigrid approach, but operates directly on the non-linear system using the FAS (Full Approximation Scheme) approach. The scalability and convergence rate of the multigrid algorithm are examined on the SGI Origin 2000 and the Cray T3E. An argument is given which indicates that the asymptotic scalability of the multigrid algorithm should be similar to that of its underlying single grid smoothing scheme. For medium size problems involving several million grid points, near perfect scalability is obtained for the single grid algorithm, while only a slight drop-off in <span class="hlt">parallel</span> efficiency is observed for the multigrid V- and W-cycles, using up to 128 processors on the SGI Origin 2000, and up to 512 processors on the Cray T3E. For a large problem using 25 million grid points, good scalability is observed for the multigrid algorithm using up to 1450 processors on a Cray T3E, even when the coarsest grid level contains fewer points than the total number of processors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3702567','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3702567"><span id="translatedtitle"><span class="hlt">Parallel</span> generation of uniform fine droplets at hundreds of kilohertz in a <span class="hlt">flow</span>-focusing module</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bardin, David; Kendall, Michael R.; Dayton, Paul A.; Lee, Abraham P.</p> <p>2013-01-01</p> <p>Droplet-based microfluidic systems enable a variety of biomedical applications from point-of-care diagnostics with third world implications, to targeted therapeutics alongside medical ultrasound, to molecular screening and genetic testing. Though these systems maintain the key advantage of precise control of the size and composition of the droplet as compared to conventional methods of production, the low rates at which droplets are produced limits translation beyond the laboratory setting. As well, previous attempts to scale up shear-based microfluidic systems focused on increasing the volumetric throughput and formed large droplets, negating many practical applications of emulsions such as site-specific therapeutics. We present the operation of a <span class="hlt">parallel</span> module with eight <span class="hlt">flow</span>-focusing orifices in the dripping regime of droplet formation for the generation of uniform fine droplets at rates in the hundreds of kilohertz. Elevating the capillary number to access dripping, generation of monodisperse droplets of liquid perfluoropentane in the <span class="hlt">parallel</span> module exceeded 3.69 × 105 droplets per second, or 1.33 × 109 droplets per hour, at a mean diameter of 9.8 μm. Our microfluidic method offers a novel means to amass uniform fine droplets in practical amounts, for instance, to satisfy clinical needs, with the potential for modification to form massive amounts of more complex droplets. PMID:24404032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26646022','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26646022"><span id="translatedtitle"><span class="hlt">Parallel</span>, open-channel lateral <span class="hlt">flow</span> (immuno) assay substrate based on capillary-channeled polymer films.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Lynn X; Jiang, Liuwei; Willett, Daniel R; Marcus, R Kenneth</p> <p>2016-02-01</p> <p>Presented here is a novel implementation of polypropylene capillary-channeled polymer (C-CP) films, functionalized for bioaffinity separations and implemented as a platform for lateral <span class="hlt">flow</span> (immuno) assays. The <span class="hlt">parallel</span> ∼80 μm × 80 μm channels pass test solutions down the 30 mm film length via spontaneous wicking action, setting up the possibility for immobilizing different capture agents in the respective channels. The base-film modification process is divided into two steps: ultraviolet light treatment to improve hydrophillicity of the polypropylene substrate and the physical adsorption of a functionalized lipid tethered ligand (LTL) as a selective capture agent. The entire modification procedure is performed under ambient conditions in an aqueous solution without extreme pH conditions. In this demonstration, physical adsorption of a biotinylated-LTL onto the UV-treated PP surface selectively captures Texas Red-labeled streptavidin (SAv-TR) in the presence of enhanced green fluorescence protein (EGFP), which passes without retention in less than 5 s. In addition to the fluorescence imaging of the protein solutes, matrix assisted laser desorption/ionization-mass spectrometry (MALDI-MS) was used to confirm the formation of the LTL-SAv conjugates on the channel surface as well as to demonstrate an alternative means of probing the capture step. The present effort sets the groundwork for further development of C-CP films as a <span class="hlt">parallel</span>, multi-analyte LFA platform; a format that to-date has not been described. PMID:26646022</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/978354','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/978354"><span id="translatedtitle">A <span class="hlt">Parallel</span> Reconstructed Discontinuous Galerkin Method for the Compressible <span class="hlt">Flows</span> on Aritrary Grids</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hong Luo; Amjad Ali; Robert Nourgaliev; Vincent A. Mousseau</p> <p>2010-01-01</p> <p>A reconstruction-based discontinuous Galerkin method is presented for the solution of the compressible Navier-Stokes equations on arbitrary grids. In this method, an in-cell reconstruction is used to obtain a higher-order polynomial representation of the underlying discontinuous Galerkin polynomial solution and an inter-cell reconstruction is used to obtain a continuous polynomial solution on the union of two neighboring, interface-sharing cells. The in-cell reconstruction is designed to enhance the accuracy of the discontinuous Galerkin method by increasing the order of the underlying polynomial solution. The inter-cell reconstruction is devised to remove an interface discontinuity of the solution and its derivatives and thus to provide a simple, accurate, consistent, and robust approximation to the viscous and heat fluxes in the Navier-Stokes equations. A <span class="hlt">parallel</span> strategy is also devised for the resulting reconstruction discontinuous Galerkin method, which is based on domain partitioning and Single Program Multiple Data (SPMD) <span class="hlt">parallel</span> programming model. The RDG method is used to compute a variety of compressible <span class="hlt">flow</span> problems on arbitrary meshes to demonstrate its accuracy, efficiency, robustness, and versatility. The numerical results demonstrate that this RDG method is third-order accurate at a cost slightly higher than its underlying second-order DG method, at the same time providing a better performance than the third order DG method, in terms of both computing costs and storage requirements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10357','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10357"><span id="translatedtitle">Large-Scale Eigenvalue Calculations for Stability Analysis of Steady <span class="hlt">Flows</span> on Massively <span class="hlt">Parallel</span> Computers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lehoucq, Richard B.; Salinger, Andrew G.</p> <p>1999-08-01</p> <p>We present an approach for determining the linear stability of steady states of PDEs on massively <span class="hlt">parallel</span> computers. Linearizing the transient behavior around a steady state leads to a generalized eigenvalue problem. The eigenvalues with largest real part are calculated using Arnoldi's iteration driven by a novel implementation of the Cayley transformation to recast the problem as an ordinary eigenvalue problem. The Cayley transformation requires the solution of a linear system at each Arnoldi iteration, which must be done iteratively for the algorithm to scale with problem size. A representative model problem of 3D incompressible <span class="hlt">flow</span> and heat transfer in a rotating disk reactor is used to analyze the effect of algorithmic parameters on the performance of the eigenvalue algorithm. Successful calculations of leading eigenvalues for matrix systems of order up to 4 million were performed, identifying the critical Grashof number for a Hopf bifurcation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JCoPh.281..970L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JCoPh.281..970L"><span id="translatedtitle"><span class="hlt">Parallel</span> domain decomposition method with non-blocking communication for <span class="hlt">flow</span> through porous media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lemmer, Andreas; Hilfer, Rudolf</p> <p>2015-01-01</p> <p>This paper introduces a domain decomposition method for numerically solving the Stokes equation for very large, complex geometries. Examples arise from realistic porous media. The computational method is based on the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm which uses a finite-differences approach for discretizing the underlying equations. It achieves comparable speed and efficiency as lattice Boltzmann methods. The domain decomposition method splits a large three-dimensional region into slices that can be processed in <span class="hlt">parallel</span> on multi-processor computation environments with only minimal communication between the computation nodes. With this method, the <span class="hlt">flow</span> through a porous medium with grid sizes up to 20483 voxel has been calculated.</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/cgi-bin/nph-data_query?bibcode=2016ZNatA..71..595Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016ZNatA..71..595Y&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Parallel</span> Plate <span class="hlt">Flow</span> of a Third-Grade Fluid and a Newtonian Fluid With Variable Viscosity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yıldız, Volkan; Pakdemirli, Mehmet; Aksoy, Yiğit</p> <p>2016-07-01</p> <p>Steady-state <span class="hlt">parallel</span> plate <span class="hlt">flow</span> of a third-grade fluid and a Newtonian fluid with temperature-dependent viscosity is considered. Approximate analytical solutions are constructed using the newly developed perturbation-iteration algorithms. Two different perturbation-iteration algorithms are used. The velocity and temperature profiles obtained by the iteration algorithms are contrasted with the numerical solutions as well as with the regular perturbation solutions. It is found that the perturbation-iteration solutions converge better to the numerical solutions than the regular perturbation solutions, in particular when the validity criteria of the regular perturbation solution are not satisfied. The new analytical approach produces promising results in solving complex fluid problems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19900054441&hterms=Ballooning&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBallooning','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19900054441&hterms=Ballooning&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DBallooning"><span id="translatedtitle">Ballooning instability of the earth's plasma sheet region in the presence of <span class="hlt">parallel</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>Lakhina, G. S.; Hameiri, E.; Mond, M.</p> <p>1990-01-01</p> <p>Stability of the plasma sheet and plasma sheet boundary layer against the ballooning mode instability is investigated. The equilibrium state of a two-dimensional plasma sheet configuration with <span class="hlt">parallel</span> sheared <span class="hlt">flow</span> is modeled. This equilibrium is shown to be ballooning unstable when delta-W is not positive definite, where delta-W is the potential energy. The eigenmode structure of the ballooning mode is found by imposing the boundary conditions that the waves are totally reflected from the ionosphere, and that no waves are coming in from infinity. The eigenmode structure of the unstable balloning modes is highly oscillatory, extending beyond about 100 R(E). The ballooning modes are thus a possible candidate for explaining the MHD waves and other dynamical events observed in the magnetotail by ISEE 3 and other spacecraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/791136','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/791136"><span id="translatedtitle"><span class="hlt">Parallel</span> Computations of Natural Convection <span class="hlt">Flow</span> in a Tall Cavity Using an Explicit Finite Element Method</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dunn, T.A.; McCallen, R.C.</p> <p>2000-10-17</p> <p>The Galerkin Finite Element Method was used to predict a natural convection <span class="hlt">flow</span> in an enclosed cavity. The problem considered was a differentially heated, tall (8:1), rectangular cavity with a Rayleigh number of 3.4 x 10{sup 5} and Prandtl number of 0.71. The incompressible Navier-Stokes equations were solved using a Boussinesq approximation for the buoyancy force. The algorithm was developed for efficient use on massively <span class="hlt">parallel</span> computer systems. Emphasis was on time-accurate simulations. It was found that the average temperature and velocity values can be captured with a relatively coarse grid, while the oscillation amplitude and period appear to be grid sensitive and require a refined computation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020004354','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020004354"><span id="translatedtitle">A <span class="hlt">Parallel</span> Multigrid Solver for Viscous <span class="hlt">Flows</span> on Anisotropic Structured Grids</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Prieto, Manuel; Montero, Ruben S.; Llorente, Ignacio M.; Bushnell, Dennis M. (Technical Monitor)</p> <p>2001-01-01</p> <p>This paper presents an efficient <span class="hlt">parallel</span> multigrid solver for speeding up the computation of a 3-D model that treats the <span class="hlt">flow</span> of a viscous fluid over a flat plate. The main interest of this simulation lies in exhibiting some basic difficulties that prevent optimal multigrid efficiencies from being achieved. As the computing platform, we have used Coral, a Beowulf-class system based on Intel Pentium processors and equipped with GigaNet cLAN and switched Fast Ethernet networks. Our study not only examines the scalability of the solver but also includes a performance evaluation of Coral where the investigated solver has been used to compare several of its design choices, namely, the interconnection network (GigaNet versus switched Fast-Ethernet) and the node configuration (dual nodes versus single nodes). As a reference, the performance results have been compared with those obtained with the NAS-MG benchmark.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Geomo.231...53F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Geomo.231...53F"><span id="translatedtitle">Occurrence of <span class="hlt">flow</span> <span class="hlt">parallel</span> and <span class="hlt">flow</span> transverse bedforms in Fehmarn Belt (SW Baltic Sea) related to the local palaeomorphology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feldens, P.; Diesing, M.; Schwarzer, K.; Heinrich, C.; Schlenz, B.</p> <p>2015-02-01</p> <p>This study describes the spatial distribution of <span class="hlt">flow-parallel</span> sand ribbons and <span class="hlt">flow</span>-transverse large and very large subaqueous dunes in the south-western Baltic Sea offshore Fehmarn Island between 13 m and 20 m water depth, based on hydroacoustic and grain size data. The system of sand ribbons and dunes is intermittently active due to currents induced during major inflows of the North Sea water into the Baltic Sea. The sand ribbons are located on a lag deposit on top of glacial till, while the dunes rest on top of drowned Holocene nearshore deposits. The sand ribbons reach heights between 0.4 m and 0.6 m, with widths varying between 60 m and several hundreds of metres. The observed dunes have heights between 0.09 m and 2.35 m, while their wavelengths range from 17 m to 120 m. Offshore Fehmarn Island, the transition from sand ribbons to dunes is most likely linked to a contrast in sediment supply, as reworked drowned nearshore deposits provide sediment available for transport in significantly larger amounts than glacial till. Similar to an earlier approach for river bed states, the dimensionless thickness of sediment available for transport is able to differentiate between the bed states.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005APS..DFD.EL010S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005APS..DFD.EL010S"><span id="translatedtitle"><span class="hlt">Air-flow</span> separation over unsteady breaking 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>Saxena, Gaurav</p> <p>2005-11-01</p> <p>In <span class="hlt">air</span>-sea interaction processes, when considering wind stress over small-scale breaking waves, there are few direct quantitative experimental investigations into the role of <span class="hlt">air-flow</span> separation on the interfacial momentum flux. Reul et. al, (1999), found multiple coherent patches of vorticity downwind of the crest that were strongly influenced by the geometric characteristics of the breaker. However, their breakers were generated by dispersive focusing techniques and, therefore, independent of the wind stress. We present experimental results obtained with particle image velocimetry (PIV) where moderate to strong winds directly generate unsteady small-scale breaking waves, a scenario commonly found in the open ocean. Particular attention has been devoted to capturing the spatio-temporal evolution of the <span class="hlt">air</span>-water interface. Specifically, texture segmentation algorithms typically used for face recognition (Grey Level Co-occurrence Matrix (GLCM) and the Cross-Diagonal Texture Matrix (CDTM)) have been combined to yield robust and accurate estimates of the instantaneous breaker geometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012EPJWC..2501013E&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012EPJWC..2501013E&link_type=ABSTRACT"><span id="translatedtitle">Numerical simulation of <span class="hlt">air</span> <span class="hlt">flow</span> in a model of lungs with mouth cavity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elcner, Jakub; Lizal, Frantisek; Jedelsky, Jan; Jicha, Miroslav</p> <p>2012-04-01</p> <p>The <span class="hlt">air</span> <span class="hlt">flow</span> in a realistic geometry of human lung is simulated with computational <span class="hlt">flow</span> dynamics approach as stationary inspiration. Geometry used for the simulation includes oral cavity, larynx, trachea and bronchial tree up to the seventh generation of branching. Unsteady RANS approach was used for the <span class="hlt">air</span> <span class="hlt">flow</span> simulation. Velocities corresponding to 15, 30 and 60 litres/min of <span class="hlt">flow</span> rate were set as boundary conditions at the inlet to the model. These <span class="hlt">flow</span> rates are frequently used as a representation of typical human activities. Character of <span class="hlt">air</span> <span class="hlt">flow</span> in the model for these different <span class="hlt">flow</span> rates is discussed with respect to future investigation of particle deposition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJWC.11402047C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJWC.11402047C"><span id="translatedtitle">Short-term gas dispersion in idealised urban canopy in street <span class="hlt">parallel</span> with <span class="hlt">flow</span> direction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chaloupecká, Hana; Jaňour, Zbyněk; Nosek, Štěpán</p> <p>2016-03-01</p> <p>Chemical attacks (e.g. Syria 2014-15 chlorine, 2013 sarine or Iraq 2006-7 chlorine) as well as chemical plant disasters (e.g. Spain 2015 nitric oxide, ferric chloride; Texas 2014 methyl mercaptan) threaten mankind. In these crisis situations, gas clouds are released. Dispersion of gas clouds is the issue of interest investigated in this paper. The paper describes wind tunnel experiments of dispersion from ground level point gas source. The source is situated in a model of an idealised urban canopy. The short duration releases of passive contaminant ethane are created by an electromagnetic valve. The gas cloud concentrations are measured in individual places at the height of the human breathing zone within a street <span class="hlt">parallel</span> with <span class="hlt">flow</span> direction by Fast-response Ionisation Detector. The simulations of the gas release for each measurement position are repeated many times under the same experimental set up to obtain representative datasets. These datasets are analysed to compute puff characteristics (arrival, leaving time and duration). The results indicate that the mean value of the dimensionless arrival time can be described as a growing linear function of the dimensionless coordinate in the street <span class="hlt">parallel</span> with <span class="hlt">flow</span> direction where the gas source is situated. The same might be stated about the dimensionless leaving time as well as the dimensionless duration, however these fits are worse. Utilising a linear function, we might also estimate some other statistical characteristics from datasets than the datasets means (medians, trimeans). The datasets of the dimensionless arrival time, the dimensionless leaving time and the dimensionless duration can be fitted by the generalized extreme value distribution (GEV) in all sampling positions except one.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1997JFM...351..139P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997JFM...351..139P"><span id="translatedtitle">Instability of two-layer creeping <span class="hlt">flow</span> in a channel with <span class="hlt">parallel</span>-sided walls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pozrikidis, C.</p> <p>1997-11-01</p> <p>The evolution of the interface between two viscous fluid layers in a two-dimensional horizontal channel confined between two <span class="hlt">parallel</span> walls is considered in the limit of Stokes <span class="hlt">flow</span>. The motion is generated either by the translation of the walls, in a shear-driven or plane-Couette mode, or by an axial pressure gradient, in a plane-Poiseuille mode. Linear stability analysis for infinitesimal perturbations and fluids with matched densities shows that when the viscosities of the fluids are different and the Reynolds number is sufficiently high, the <span class="hlt">flow</span> is unstable. At vanishing Reynolds number, the <span class="hlt">flow</span> is stable when the surface tension has a non-zero value, and neutrally stable when the surface tension vanishes. We investigate the behaviour of the interface subject to finite-amplitude two-dimensional perturbations by solving the equations of Stokes <span class="hlt">flow</span> using a boundary-integral method. Integral equations for the interfacial velocity are formulated for the three modular cases of shear-driven, pressure-driven, and gravity-driven <span class="hlt">flow</span>, and numerical computations are performed for the first two modes. The results show that disturbances of sufficiently large amplitude may cause permanent interfacial deformation in which the interface folds, develops elongated fingers, or supports slowly evolving travelling waves. Smaller amplitude disturbances decay, sometimes after a transient period of interfacial folding. The ratio of the viscosities of the two fluids plays an important role in determining the morphology of the emerging interfacial patterns, but the parabolicity of the unperturbed velocity profile does not affect the character of the motion. Increasing the contrast in the viscosities of the two fluids, while keeping the channel capillary number fixed, destabilizes the interfaces; re-examining the <span class="hlt">flow</span> in terms of an alternative capillary number that is defined with respect to the velocity drop across the more-viscous layer shows that this is a reasonable behaviour</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20050186637&hterms=goal+setting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgoal%2Bsetting','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20050186637&hterms=goal+setting&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dgoal%2Bsetting"><span id="translatedtitle">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://hdl.handle.net/2060/19930002341','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930002341"><span id="translatedtitle">Direct numerical simulation of instabilities in <span class="hlt">parallel</span> <span class="hlt">flow</span> with spherical roughness elements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Deanna, R. G.</p> <p>1992-01-01</p> <p>Results from a direct numerical simulation of laminar <span class="hlt">flow</span> over a flat surface with spherical roughness elements using a spectral-element method are given. The numerical simulation approximates roughness as a cellular pattern of identical spheres protruding from a smooth wall. Periodic boundary conditions on the domain's horizontal faces simulate an infinite array of roughness elements extending in the streamwise and spanwise directions, which implies the <span class="hlt">parallel-flow</span> assumption, and results in a closed domain. A body force, designed to yield the horizontal Blasius velocity in the absence of roughness, sustains the <span class="hlt">flow</span>. Instabilities above a critical Reynolds number reveal negligible oscillations in the recirculation regions behind each sphere and in the free stream, high-amplitude oscillations in the layer directly above the spheres, and a mean profile with an inflection point near the sphere's crest. The inflection point yields an unstable layer above the roughness (where U''(y) is less than 0) and a stable region within the roughness (where U''(y) is greater than 0). Evidently, the instability begins when the low-momentum or wake region behind an element, being the region most affected by disturbances (purely numerical in this case), goes unstable and moves. In compressible <span class="hlt">flow</span> with periodic boundaries, this motion sends disturbances to all regions of the domain. In the unstable layer just above the inflection point, the disturbances grow while being carried downstream with a propagation speed equal to the local mean velocity; they do not grow amid the low energy region near the roughness patch. The most amplified disturbance eventually arrives at the next roughness element downstream, perturbing its wake and inducing a global response at a frequency governed by the streamwise spacing between spheres and the mean velocity of the most amplified layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930081203','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930081203"><span id="translatedtitle">Considerations of <span class="hlt">Air</span> <span class="hlt">Flow</span> in Combustion Chambers of High-Speed Compression-Ignition Engines</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>1932-01-01</p> <p>The <span class="hlt">air</span> <span class="hlt">flow</span> in combustion chambers is divided into three fundamental classes - induced, forced, and residual. A generalized resume is given of the present status of <span class="hlt">air</span> <span class="hlt">flow</span> investigations and of the work done at this and other laboratories to determine the direction and velocity of <span class="hlt">air</span> movement in auxiliary and integral combustion chambers. The effects of <span class="hlt">air</span> <span class="hlt">flow</span> on engine performance are mentioned to show that although <span class="hlt">air</span> <span class="hlt">flow</span> improves the combustion efficiency, considerable induction, friction, and thermal losses must be guarded against.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120015750','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120015750"><span id="translatedtitle">Development of a Robust and Efficient <span class="hlt">Parallel</span> Solver for Unsteady Turbomachinery <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>West, Jeff; Wright, Jeffrey; Thakur, Siddharth; Luke, Ed; Grinstead, Nathan</p> <p>2012-01-01</p> <p>The traditional design and analysis practice for advanced propulsion systems relies heavily on expensive full-scale prototype development and testing. Over the past decade, use of high-fidelity analysis and design tools such as CFD early in the product development cycle has been identified as one way to alleviate testing costs and to develop these devices better, faster and cheaper. In the design of advanced propulsion systems, CFD plays a major role in defining the required performance over the entire flight regime, as well as in testing the sensitivity of the design to the different modes of operation. Increased emphasis is being placed on developing and applying CFD models to simulate the <span class="hlt">flow</span> field environments and performance of advanced propulsion systems. This necessitates the development of next generation computational tools which can be used effectively and reliably in a design environment. The turbomachinery simulation capability presented here is being developed in a computational tool called Loci-STREAM [1]. It integrates proven numerical methods for generalized grids and state-of-the-art physical models in a novel rule-based programming framework called Loci [2] which allows: (a) seamless integration of multidisciplinary physics in a unified manner, and (b) automatic handling of massively <span class="hlt">parallel</span> computing. The objective is to be able to routinely simulate problems involving complex geometries requiring large unstructured grids and complex multidisciplinary physics. An immediate application of interest is simulation of unsteady <span class="hlt">flows</span> in rocket turbopumps, particularly in cryogenic liquid rocket engines. The key components of the overall methodology presented in this paper are the following: (a) high fidelity unsteady simulation capability based on Detached Eddy Simulation (DES) in conjunction with second-order temporal discretization, (b) compliance with Geometric Conservation Law (GCL) in order to maintain conservative property on moving meshes for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995PhDT.......219M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995PhDT.......219M"><span id="translatedtitle">Three-Dimensional <span class="hlt">Parallel</span> Lattice Boltzmann Hydrodynamic Simulations of Turbulent <span class="hlt">Flows</span> in Interstellar Dark Clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Muders, Dirk</p> <p>1995-08-01</p> <p>Exploring the clumpy and filamentary structure of interstellar molecular clouds is one of the key problems of modern astrophysics. So far, we have little knowledge of the physical processes that cause the structure, but turbulence is suspected to be essential. In this thesis I study turbulent <span class="hlt">flows</span> and how they contribute to the structure of interstellar dark clouds. To this end, three-dimensional numerical hydrodynamic simulations are needed since the detailed turbulent spatial and velocity structure cannot be analytically calculated. I employ the ``Lattice Boltzmann Method'', a recently developed numerical method which solves the Boltzmann equation in a discretized phase space. Mesoscopic particle packets move with fixed velocities on a Cartesian lattice and at each time step they exchange mass according to given rules. Because of its mainly local operations the method is well suited for application on <span class="hlt">parallel</span> or clustered computers. As part of my thesis I have developed a <span class="hlt">parallelized</span> ``Lattice Boltzmann Method'' hydrodynamics code. I have improved the numerical stability for Reynolds numbers of up to 104.5 and Mach numbers of up to 0.9 and I have extended the method to include a second miscible fluid phase. The code has been used on the three currently most powerful workstations at the ``Max-Planck-Institut für Radioastronomie'' in Bonn and on the massively <span class="hlt">parallel</span> mainframe CM-5 at the ``Gesellschaft für Mathematik und Datenverarbeitung'' in St. Augustin. The simulations consist of collimated shear <span class="hlt">flows</span> and the motion of molecular clumps through an ambient medium. The dependence of the emerging structure on Reynolds and Mach numbers is studied. The main results are (1) that distinct clumps and filaments appear only at the transition between laminar and fully turbulent <span class="hlt">flow</span> at Reynolds numbers between 500 and 5000 and (2) that subsonic viscous shear <span class="hlt">flows</span> are capable of producing the dark cloud velocity structure. The unexpectedly low Reynolds numbers can</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1175626','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1175626"><span id="translatedtitle">Fuel cell stack with passive <span class="hlt">air</span> supply</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ren, Xiaoming; Gottesfeld, Shimshon</p> <p>2006-01-17</p> <p>A fuel cell stack has a plurality of polymer electrolyte fuel cells (PEFCs) where each PEFC includes a rectangular membrane electrode assembly (MEA) having a fuel <span class="hlt">flow</span> field along a first axis and an <span class="hlt">air</span> <span class="hlt">flow</span> field along a second axis perpendicular to the first axis, where the fuel <span class="hlt">flow</span> field is long relative to the <span class="hlt">air</span> <span class="hlt">flow</span> field. A cathode <span class="hlt">air</span> <span class="hlt">flow</span> field in each PEFC has <span class="hlt">air</span> <span class="hlt">flow</span> channels for <span class="hlt">air</span> <span class="hlt">flow</span> <span class="hlt">parallel</span> to the second axis and that directly open to atmospheric <span class="hlt">air</span> for <span class="hlt">air</span> diffusion within the channels into contact with the MEA.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/20837798','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20837798"><span id="translatedtitle">Dry <span class="hlt">Flowing</span> Abrasive Decontamination Technique for Pipe Systems with Swirling <span class="hlt">Air</span> <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kameo, Yutaka; Nakashima, Mikio; Hirabayashi, Takakuni</p> <p>2003-10-15</p> <p>A dry abrasive decontamination method was developed for removing radioactive corrosion products from surfaces of coolant pipe systems in decommissioning of a nuclear power plant. Erosion behavior of inside surfaces of stainless and carbon steel pipes by a swirling <span class="hlt">air</span> <span class="hlt">flow</span> containing alumina or cast-iron grit abrasive was studied. Erosion depths of the test pipes were approximately proportional to an abrasive concentration in <span class="hlt">air</span> and an exponent of <span class="hlt">flow</span> rate of airstream. The experimental results indicated that the present method could keep satisfactory erosion ability of abrasives even for a large-size pipe. The present method was successfully applied to {sup 60}Co-contaminated specimens sampled from a pipe of the water cleanup system of the Japan Power Demonstration Reactor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008SPIE.7133E..0FW','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008SPIE.7133E..0FW"><span id="translatedtitle">Simulation of <span class="hlt">air</span> gap vibration on aerostatic bearing under <span class="hlt">flow</span>/structure coupled conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Qian; Wu, Jianjin; Li, Dongsheng</p> <p>2008-10-01</p> <p>The vibration of aerostatic bearing <span class="hlt">air</span> gap is one of the main factors, which restricts the precision of nano-processing and nano-measurement. Finite volume method was employed to obtain the <span class="hlt">air</span> gap steady <span class="hlt">flow</span> of different <span class="hlt">air</span> gap thicknesses for the demonstration of vibrations under <span class="hlt">flow</span>/structure coupled conditions. The unsteady <span class="hlt">flow</span> of <span class="hlt">air</span> gap was analyzed numerically by using the <span class="hlt">air</span> gap <span class="hlt">flow</span> & boundary movement control equations to get the pressure distribution on the slide surface and the amplitude of <span class="hlt">air</span> gap for further study on the self-excited vibration of aerostatic bearings. Numerical analyses show that the highest aerostatic bearing amplitude is relative to the difference between load capacity and gravity at the initial moment as <span class="hlt">air</span> gap rises, and the final <span class="hlt">air</span> gap thickness has nothing to do with the initial <span class="hlt">air</span> gap thickness. The results presented a new analytic demonstration for the research on the reduction of aerostatic bearing vibration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013ShWav..23..439B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013ShWav..23..439B"><span id="translatedtitle">Laser ignition of hypersonic <span class="hlt">air</span>-hydrogen <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>Brieschenk, S.; Kleine, H.; O'Byrne, S.</p> <p>2013-09-01</p> <p>An experimental investigation of the behaviour of laser-induced ignition in a hypersonic <span class="hlt">air</span>-hydrogen <span class="hlt">flow</span> is presented. A compression-ramp model with port-hole injection, fuelled with hydrogen gas, is used in the study. The experiments were conducted in the T-ADFA shock tunnel using a <span class="hlt">flow</span> condition with a specific total enthalpy of 2.5 MJ/kg and a freestream velocity of 2 km/s. This study is the first comprehensive laser spark study in a hypersonic <span class="hlt">flow</span> and demonstrates that laser-induced ignition at the fuel-injection site can be effective in terms of hydroxyl production. A semi-empirical method to estimate the conditions in the laser-heated gas kernel is presented in the paper. This method uses blast-wave theory together with an expansion-wave model to estimate the laser-heated gas conditions. The spatially averaged conditions found with this approach are matched to enthalpy curves generated using a standard chemical equilibrium code (NASA CEA). This allows us to account for differences that are introduced due to the idealised description of the blast wave, the isentropic expansion wave as well as thermochemical effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003PhDT........82A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003PhDT........82A"><span id="translatedtitle">Analysis of heat and mass transfer between <span class="hlt">air</span> and falling film desiccant for different <span class="hlt">flow</span> configurations in the presence of ultrafine particles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ali, Ahmad A.</p> <p></p> <p>This work focuses on the enhancement of heat and mass transfer between <span class="hlt">air</span> and falling desiccant film for different <span class="hlt">flow</span> channel configurations. Cu-Ultrafine particles are added to the desiccant film to investigate the enhancement in heat and mass transfer between <span class="hlt">air</span> and desiccant film for dehumidification and cooling processes of the <span class="hlt">air</span> and regeneration of desiccant film. A detailed comparative study between <span class="hlt">parallel</span> and counter <span class="hlt">flow</span> channels is performed using a parametric study to investigate the enhancements in dehumidification, cooling, and regeneration processes in terms of the pertinent parameters. The results reveal that the <span class="hlt">parallel</span> <span class="hlt">flow</span> arrangement provides better dehumidification and cooling for the <span class="hlt">air</span> than the counter <span class="hlt">flow</span> channel for a wide range of parameters. Next, the inclined <span class="hlt">parallel</span> and counter <span class="hlt">flow</span> configurations are investigated using an Alternating Direction Implicit (ADI) and successive over-relaxation methods to discretize the vorticity and stream-function equations, respectively. A parametric study is employed to investigate the inclination angle effects in enhancing the heat and mass transfer in terms of the controlling parameters. It is shown that inclination angle plays a significant role in enhancing the dehumidification, cooling, and regeneration processes. Finally, the enhancements in heat and mass transfer in cross <span class="hlt">flow</span> channel between <span class="hlt">air</span> and desiccant film is examined based on a parametric study to investigate the dehumidification and cooling processes of the <span class="hlt">air</span> in terms of the pertinent controlling parameters. These parameters are <span class="hlt">air</span> and desiccant Reynolds numbers, dimensions of the channel, volume fraction of Cu-ultrafine particles, and thermal dispersion effects. It is found that an increase in the Cu-volume fraction increases dehumidification and cooling capabilities and produce more stable Cu-desiccant film.</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 id="translatedtitle">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>... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) <span class="hlt">Flow</span> conditioning... 40 Protection of Environment 33 2011-07-01 2011-07-01 false Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related...</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('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 id="translatedtitle">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>... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) <span class="hlt">Flow</span> conditioning... 40 Protection of Environment 32 2010-07-01 2010-07-01 false Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related...</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 id="translatedtitle">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>... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) <span class="hlt">Flow</span> conditioning... 40 Protection of Environment 34 2012-07-01 2012-07-01 false Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related...</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 id="translatedtitle">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>... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) <span class="hlt">Flow</span> conditioning... 40 Protection of Environment 34 2013-07-01 2013-07-01 false Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related...</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 id="translatedtitle">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>... meter, a thermal-mass meter, an averaging Pitot tube, or a hot-wire anemometer. (c) <span class="hlt">Flow</span> conditioning... 40 Protection of Environment 33 2014-07-01 2014-07-01 false Dilution <span class="hlt">air</span> and diluted exhaust <span class="hlt">flow</span>...) <span class="hlt">AIR</span> POLLUTION CONTROLS ENGINE-TESTING PROCEDURES Measurement Instruments <span class="hlt">Flow</span>-Related...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H23B1585W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H23B1585W"><span id="translatedtitle">On the impact of entrapped <span class="hlt">air</span> in infiltration under ponding conditions: Part a: Preferential <span class="hlt">air</span> <span class="hlt">flow</span> path effects on infiltration</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weisbord, N.; Mizrahi, G.; Furman, A.</p> <p>2015-12-01</p> <p>Entrapped <span class="hlt">air</span> effects on infiltration under ponding conditions could be important for massive infiltration of managed aquifer recharge or soil aquifer treatment. Earlier studies found that under ponding conditions <span class="hlt">air</span> could reduce infiltration by 70-90%. Most studies have dealt with entrapped <span class="hlt">air</span> effects when soil surface topography is flat. The objective of this study is to investigate the effects of: (1) irregular surface topography on preferential <span class="hlt">air</span> <span class="hlt">flow</span> path development; (2) preferential <span class="hlt">air</span> <span class="hlt">flow</span> path on infiltration; and (3) hydraulic head on infiltration when <span class="hlt">air</span> is trapped. Column experiments were used to investigate these particular effects. A 140 cm deep and 30 cm wide column packed with silica sand was used under two boundary conditions: in the first, <span class="hlt">air</span> can only escape vertically upward through the soil surface; in the second, <span class="hlt">air</span> is free to escape. The surface was flooded with 13 liters of water, with ponding depth decreasing with time. Two soil surface conditions were tested: flat surface and irregular. It was found that in irregular surfaces, stable <span class="hlt">air</span> <span class="hlt">flow</span> through preferential paths was developed in the high altitude zones. Flat surface topography caused unstable <span class="hlt">air</span> <span class="hlt">flow</span> through random paths. Comparison between irregular and flat surface topography showed that the entrapped <span class="hlt">air</span> pressure was lower and the infiltration rate was about 40% higher in the irregular surface topography than in the flat surface topography. No difference of infiltration rate between flat and irregular surface topography was observed when <span class="hlt">air</span> was free to escape along the infiltration path. It was also found that at the first stage of infiltration, higher hydraulic heads caused higher entrapped <span class="hlt">air</span> pressures and lower infiltration rates. In contrast, higher hydraulic head results in higher infiltration rate, when <span class="hlt">air</span> was free to escape. Our results suggest that during ponding conditions: (1) preferential <span class="hlt">air</span> <span class="hlt">flow</span> paths develop at high surface zones of irregular topography</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 id="translatedtitle">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/cgi-bin/nph-data_query?bibcode=2015JGRB..120..976M&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JGRB..120..976M&link_type=ABSTRACT"><span id="translatedtitle">Seismic anisotropy indicates ridge-<span class="hlt">parallel</span> asthenospheric <span class="hlt">flow</span> beneath the Eastern Lau Spreading Center</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Menke, William; Zha, Yang; Webb, Spahr C.; Blackman, Donna K.</p> <p>2015-02-01</p> <p>Seismic anisotropy beneath the Eastern Lau Spreading Center (ELSC) is investigated using both Rayleigh waves and shear waves, using data from the 2009-2010 ELSC ocean bottom seismograph experiment. Phase velocities of Rayleigh waves determined by ambient noise cross correlation are inverted for azimuthally anisotropic phase velocity maps. Splitting of S waves from five intermediate and deep focus earthquakes was determined by waveform analysis. Taken together, Rayleigh wave and S wave data indicate that significant (~2%) anisotropy extends to at least 300 km depth. Both data sets indicate a fast direction aligned within a few degrees of the N10°E striking ELSC and somewhat oblique to the N25°E strike of the neighboring volcanic arc. We therefore describe the fast direction as spreading perpendicular, not convergence perpendicular and interpret it as due to ridge-<span class="hlt">parallel</span> <span class="hlt">flow</span> of the asthenosphere. However, the region arcward (east) of the ELSC has the stronger anisotropy, suggesting that the strongest <span class="hlt">flow</span> gradients may occur in the region between the spreading center and the arc, in contrast to being centered beneath the ELSC. Fluids released from the underlying plate may produce anisotropic hydrous materials, but more importantly lower the viscosity, thus enhancing along-strike <span class="hlt">flow</span>. Both could contribute to an along-strike fast direction signature. Seafloor spreading diminishes south of the seismic array, ceasing altogether south of latitude 25°S (500 km south of the array center), a region dominated by much slower tectonic extension, suggesting that asthenosphere is inflowing from the north to accommodate the increase in asthenospheric volume associated with the seafloor spreading.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/95195','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/95195"><span id="translatedtitle">New sensor for measurement of low <span class="hlt">air</span> <span class="hlt">flow</span> velocity. Phase I final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Hashemian, H.M.; Hashemian, M.; Riggsbee, E.T.</p> <p>1995-08-01</p> <p>The project described here is the Phase I feasibility study of a two-phase program to integrate existing technologies to provide a system for determining <span class="hlt">air</span> <span class="hlt">flow</span> velocity and direction in radiation work areas. Basically, a low <span class="hlt">air</span> <span class="hlt">flow</span> sensor referred to as a thermocouple <span class="hlt">flow</span> sensor has been developed. The sensor uses a thermocouple as its sensing element. The response time of the thermocouple is measured using an existing in-situ method called the Loop Current Step Response (LCSR) test. The response time results are then converted to a <span class="hlt">flow</span> signal using a response time-versus-<span class="hlt">flow</span> correlation. The Phase I effort has shown that a strong correlation exists between the response time of small diameter thermocouples and the ambient <span class="hlt">flow</span> rate. As such, it has been demonstrated that thermocouple <span class="hlt">flow</span> sensors can be used successfully to measure low <span class="hlt">air</span> <span class="hlt">flow</span> rates that can not be measured with conventional <span class="hlt">flow</span> sensors. While the thermocouple <span class="hlt">flow</span> sensor developed in this project was very successful in determining <span class="hlt">air</span> <span class="hlt">flow</span> velocity, determining <span class="hlt">air</span> <span class="hlt">flow</span> direction was beyond the scope of the Phase I project. Nevertheless, work was performed during Phase I to determine how the new <span class="hlt">flow</span> sensor can be used to determine the direction, as well as the velocity, of ambient <span class="hlt">air</span> movements. Basically, it is necessary to use either multiple <span class="hlt">flow</span> sensors or move a single sensor in the monitoring area and make <span class="hlt">flow</span> measurements at various locations sweeping the area from top to bottom and from left to right. The results can then be used with empirical or physical models, or in terms of directional vectors to estimate <span class="hlt">air</span> <span class="hlt">flow</span> patterns. The measurements can be made continuously or periodically to update the <span class="hlt">flow</span> patterns as they change when people and objects are moved in the monitoring area. The potential for using multiple thermocouple <span class="hlt">flow</span> sensors for determining <span class="hlt">air</span> <span class="hlt">flow</span> patterns will be examined in Phase II.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/936676','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/936676"><span id="translatedtitle">Simulation of Large <span class="hlt">Parallel</span> Plasma <span class="hlt">Flows</span> in the Tokamak SOL Driven by Cross-Field Transport Asymmetries</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pigarov, A Y; Krasheninnikov, S I; LaBombard, B; Rognlien, T D</p> <p>2006-06-06</p> <p>Large-Mach-number <span class="hlt">parallel</span> plasma <span class="hlt">flows</span> in the single-null SOL of different tokamaks are simulated with multi-fluid transport code UEDGE. The key role of poloidal asymmetry of cross-field plasma transport as the driving mechanism for such <span class="hlt">flows</span> is discussed. The impact of ballooning-like diffusive and convective transport and plasma <span class="hlt">flows</span> on divertor detachment, material migration, impurity <span class="hlt">flows</span>, and erosion/deposition profiles is studied. The results on well-balanced double null plasma modeling that are indicative of strong asymmetry of cross-field transport are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850013263','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850013263"><span id="translatedtitle">Surface-slip equations for multicomponent nonequilibrium <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>Gupta, R. N.; Scott, C. D.; Moss, J. N.</p> <p>1985-01-01</p> <p>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 <span class="hlt">air</span> <span class="hlt">flow</span>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013PhDT.......186C&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013PhDT.......186C&link_type=ABSTRACT"><span id="translatedtitle">Cloud-based large-scale <span class="hlt">air</span> traffic <span class="hlt">flow</span> optimization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, Yi</p> <p></p> <p>The ever-increasing traffic demand makes the efficient use of airspace an imperative mission, and this paper presents an effort in response to this call. Firstly, a new aggregate model, called Link Transmission Model (LTM), is proposed, which models the nationwide traffic as a network of flight routes identified by origin-destination pairs. The traversal time of a flight route is assumed to be the mode of distribution of historical flight records, and the mode is estimated by using Kernel Density Estimation. As this simplification abstracts away physical trajectory details, the complexity of modeling is drastically decreased, resulting in efficient traffic forecasting. The predicative capability of LTM is validated against recorded traffic data. Secondly, a nationwide traffic <span class="hlt">flow</span> optimization problem with airport and en route capacity constraints is formulated based on LTM. The optimization problem aims at alleviating traffic congestions with minimal global delays. This problem is intractable due to millions of variables. A dual decomposition method is applied to decompose the large-scale problem such that the subproblems are solvable. However, the whole problem is still computational expensive to solve since each subproblem is an smaller integer programming problem that pursues integer solutions. Solving an integer programing problem is known to be far more time-consuming than solving its linear relaxation. In addition, sequential execution on a standalone computer leads to linear runtime increase when the problem size increases. To address the computational efficiency problem, a <span class="hlt">parallel</span> computing framework is designed which accommodates concurrent executions via multithreading programming. The multithreaded version is compared with its monolithic version to show decreased runtime. Finally, an open-source cloud computing framework, Hadoop MapReduce, is employed for better scalability and reliability. This framework is an "off-the-shelf" <span class="hlt">parallel</span> computing model</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1194329','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1194329"><span id="translatedtitle">A Many-Task <span class="hlt">Parallel</span> Approach for Multiscale Simulations of Subsurface <span class="hlt">Flow</span> and Reactive Transport</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Scheibe, Timothy D.; Yang, Xiaofan; Schuchardt, Karen L.; Agarwal, Khushbu; Chase, Jared M.; Palmer, Bruce J.; Tartakovsky, Alexandre M.</p> <p>2014-12-16</p> <p>Continuum-scale models have long been used to study subsurface <span class="hlt">flow</span>, transport, and reactions but lack the ability to resolve processes that are governed by pore-scale mixing. Recently, pore-scale models, which explicitly resolve individual pores and soil grains, have been developed to more accurately model pore-scale phenomena, particularly reaction processes that are controlled by local mixing. However, pore-scale models are prohibitively expensive for modeling application-scale domains. This motivates the use of a hybrid multiscale approach in which continuum- and pore-scale codes are coupled either hierarchically or concurrently within an overall simulation domain (time and space). This approach is naturally suited to an adaptive, loosely-coupled many-task methodology with three potential levels of concurrency. Each individual code (pore- and continuum-scale) can be implemented in <span class="hlt">parallel</span>; multiple semi-independent instances of the pore-scale code are required at each time step providing a second level of concurrency; and Monte Carlo simulations of the overall system to represent uncertainty in material property distributions provide a third level of concurrency. We have developed a hybrid multiscale model of a mixing-controlled reaction in a porous medium wherein the reaction occurs only over a limited portion of the domain. Loose, minimally-invasive coupling of pre-existing <span class="hlt">parallel</span> continuum- and pore-scale codes has been accomplished by an adaptive script-based workflow implemented in the Swift workflow system. We describe here the methods used to create the model system, adaptively control multiple coupled instances of pore- and continuum-scale simulations, and maximize the scalability of the overall system. We present results of numerical experiments conducted on NERSC supercomputing systems; our results demonstrate that loose many-task coupling provides a scalable solution for multiscale subsurface simulations with minimal overhead.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015HMT....51.1691F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015HMT....51.1691F"><span id="translatedtitle">Optimum design of bipolar plates for separate <span class="hlt">air</span> <span class="hlt">flow</span> cooling system of PEM fuel cells stacks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Franco, Alessandro</p> <p>2015-12-01</p> <p>The paper discusses about thermal management of PEM fuel cells. The objective is to define criteria and guidelines for the design of the <span class="hlt">air</span> <span class="hlt">flow</span> cooling system of fuel cells stacks for different combination of power density, bipolar plates material, <span class="hlt">air</span> <span class="hlt">flow</span> rate, operating temperature It is shown that the optimization of the geometry of the channel permits interesting margins for maintaining the use of separate <span class="hlt">air</span> <span class="hlt">flow</span> cooling systems for high power density PEM fuel cells.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22107858','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22107858"><span id="translatedtitle">Gas and liquid measurements in <span class="hlt">air</span>-water bubbly <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhou, X.; Doup, B.; Sun, X.</p> <p>2012-07-01</p> <p>Local measurements of gas- and liquid-phase <span class="hlt">flow</span> parameters are conducted in an <span class="hlt">air</span>-water two-phase <span class="hlt">flow</span> loop. The test section is a vertical pipe with an inner diameter of 50 mm and a height of 3.2 m. The measurements are performed at z/D = 10. The gas-phase measurements are performed using a four-sensor conductivity probe. The data taken from this probe are processed using a signal processing program to yield radial profiles of the void fraction, bubble velocity, and interfacial area concentration. The velocity measurements of the liquid-phase are performed using a state-of-the-art Particle Image Velocimetry (PIV) system. The raw PIV images are acquired using fluorescent particles and an optical filtration device. Image processing is used to remove noise in the raw PIV images. The statistical cross correlation is introduced to determine the axial velocity field and turbulence intensity of the liquid-phase. Measurements are currently being performed at z/D = 32 to provide a more complete data set. These data can be used for computational fluid dynamic model development and validation. (authors)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930081123','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930081123"><span id="translatedtitle">Some Effects of <span class="hlt">Air</span> <span class="hlt">Flow</span> on the Penetration and Distribution of Oil Sprays</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; Beardsley, E G</p> <p>1929-01-01</p> <p>Tests were made to determine the effects of <span class="hlt">air</span> <span class="hlt">flow</span> on the characteristics of fuel sprays from fuel injection valves. Curves and photographs are presented showing the airflow throughout the chamber and the effects of the <span class="hlt">air</span> <span class="hlt">flow</span> on the fuel spray characteristics. It was found that the moving <span class="hlt">air</span> had little effect on the spray penetration except with the 0.006 inch orifice. The moving <span class="hlt">air</span> did, however, affect the oil particles on the outside of the spray cone. After spray cut-off, the <span class="hlt">air</span> <span class="hlt">flow</span> rapidly distributed the atomized fuel throughout the spray chamber.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100030606','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100030606"><span id="translatedtitle">Real-Time Aerodynamic Parameter Estimation without <span class="hlt">Air</span> <span class="hlt">Flow</span> Angle Measurements</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Morelli, Eugene A.</p> <p>2010-01-01</p> <p>A technique for estimating aerodynamic parameters in real time from flight data without <span class="hlt">air</span> <span class="hlt">flow</span> 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 <span class="hlt">air</span> <span class="hlt">flow</span> angle measurements were compared to modeling results computed conventionally using flight data that included <span class="hlt">air</span> <span class="hlt">flow</span> angle measurements. Comparisons demonstrated that the new technique can provide accurate aerodynamic modeling results without <span class="hlt">air</span> <span class="hlt">flow</span> angle measurements, which are often difficult and expensive to obtain. Implications for efficient flight testing and flight safety are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860057114&hterms=flow+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dflow%2Belectric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860057114&hterms=flow+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dflow%2Belectric"><span id="translatedtitle">Transition to unstable ion <span class="hlt">flow</span> in <span class="hlt">parallel</span> electric fields. [in ionosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bergmann, R.; Lotko, W.</p> <p>1986-01-01</p> <p>The stability of ionospheric O(+)-H(+) outflows accelerated by a nonambipolar <span class="hlt">parallel</span> electric field is considered under conditions where the ion motion initially develops adiabatically and the ambient plasma is vertically stratified with an effective temperature that increases with altitude. Such conditions are expected near the bottom of the auroral acceleration region where ion and electron streaming instabilities first develop. It is shown for a particular equilibrium profile that the differentially accelerated ion <span class="hlt">flows</span> become unstable within about 100 km from their entry point in the acceleration region. At O(+)/H(+) density ratios less than about 9, the instability is dominated by a violent H(+)-O(+) two-stream interaction which couples the O(+) and H(+) acoustic modes, and which mediates a transition to nonadiabatic acceleration. At higher altitudes and/or larger O(+)/H(+) density ratios, a much weaker resonant instability exists, which is driven by the relative drift between electrons and O(+) or H(+) ions. The results suggest that the H(+)-O(+) two-stream instability may be a viable mechanism for heating upflowing auroral ions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016CoPhC.200..324N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016CoPhC.200..324N"><span id="translatedtitle">MaMiCo: Software design for <span class="hlt">parallel</span> molecular-continuum <span class="hlt">flow</span> simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Neumann, Philipp; Flohr, Hanno; Arora, Rahul; Jarmatz, Piet; Tchipev, Nikola; Bungartz, Hans-Joachim</p> <p>2016-03-01</p> <p>The macro-micro-coupling tool (MaMiCo) was developed to ease the development of and modularize molecular-continuum simulations, retaining sequential and <span class="hlt">parallel</span> performance. We demonstrate the functionality and performance of MaMiCo by coupling the spatially adaptive Lattice Boltzmann framework waLBerla with four molecular dynamics (MD) codes: the light-weight Lennard-Jones-based implementation SimpleMD, the node-level optimized software ls1 mardyn, and the community codes ESPResSo and LAMMPS. We detail interface implementations to connect each solver with MaMiCo. The coupling for each waLBerla-MD setup is validated in three-dimensional channel <span class="hlt">flow</span> simulations which are solved by means of a state-based coupling method. We provide sequential and strong scaling measurements for the four molecular-continuum simulations. The overhead of MaMiCo is found to come at 10%-20% of the total (MD) runtime. The measurements further show that scalability of the hybrid simulations is reached on up to 500 Intel SandyBridge, and more than 1000 AMD Bulldozer compute cores.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.9500Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.9500Z"><span id="translatedtitle"><span class="hlt">Parallel</span>-dominant and perpendicular-dominant components of the fast bulk <span class="hlt">flow</span>: Comparing with the PSBL beams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, L. Q.; Dai, L.; Baumjohann, W.; Rème, H.; Dunlop, M. W.; Wei, X. H.</p> <p>2015-11-01</p> <p>Utilizing multipoint observations by the Cluster satellites, we investigated the ion distributions of the fast bulk <span class="hlt">flows</span> (FBFs) in the plasma sheet. Simultaneous observation by C1 and C3 revealed that <span class="hlt">parallel</span>-dominant and perpendicular-dominant components of the <span class="hlt">flows</span> coexist and correspond to Bx-dominant and Bz-dominant magnetic field regions within the FBFs, respectively. In both cases, the ions distributions are characterized by a single-beam/crescent shape. In particular, no reflected ions are found within the FBFs. Statistical analysis showed that within the FBFs, the strength of the Bx component is typically less than 5 nT for Bz-dominant regions and above 10 nT for Bx-dominant regions. To distinguish between the <span class="hlt">parallel</span>-dominant component of the FBFs and the field-aligned beams in the plasma sheet boundary layer (PSBL), we further statistically analyzed the tailward <span class="hlt">parallel</span> <span class="hlt">flows</span> (TPF) with positive Bz in the plasma sheet. The results indicated that the FBFs tend to have higher velocity, weaker B, and higher magnetic tilt angle (θMTA) than the TPFs/PSBL beams. Statistically, in the region of B > 30 nT (θMTA > 10°), only PSBL beams can be observed, while in the region of B < 10 nT (θMTA > 30°), the FBFs are dominant. In the intermediate region (10° < θMTA < 30°) of the plasma sheet, the FBFs and the PSBL beams cooccur. These Cluster observations suggest that the X line can produce both perpendicular <span class="hlt">flow</span> in central plasma sheet and <span class="hlt">parallel</span> <span class="hlt">flow</span> in the PSBL. In addition, the <span class="hlt">parallel</span>-dominant component of the FBFs could be an important origin for the PSBL beams.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1128529','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1128529"><span id="translatedtitle">Investigation of Countercurrent Helium-<span class="hlt">Air</span> <span class="hlt">Flows</span> in <span class="hlt">Air</span>-ingress Accidents for VHTRs</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Sun, Xiaodong; Christensen, Richard; Oh, Chang</p> <p>2013-10-03</p> <p>The primary objective of this research is to develop an extensive experimental database for the <span class="hlt">air</span>- ingress phenomenon for the validation of computational fluid dynamics (CFD) analyses. This research is intended to be a separate-effects experimental study. However, the project team will perform a careful scaling analysis prior to designing a scaled-down test facility in order to closely tie this research with the real application. As a reference design in this study, the team will use the 600 MWth gas turbine modular helium reactor (GT-MHR) developed by General Atomic. In the test matrix of the experiments, researchers will vary the temperature and pressure of the helium— along with break size, location, shape, and orientation—to simulate deferent scenarios and to identify potential mitigation strategies. Under support of the Department of Energy, a high-temperature helium test facility has been designed and is currently being constructed at Ohio State University, primarily for high- temperature compact heat exchanger testing for the VHTR program. Once the facility is in operation (expected April 2009), this study will utilize high-temperature helium up to 900°C and 3 MPa for loss-of-coolant accident (LOCA) depressurization and <span class="hlt">air</span>-ingress experiments. The project team will first conduct a scaling study and then design an <span class="hlt">air</span>-ingress test facility. The major parameter to be measured in the experiments is oxygen (or nitrogen) concentration history at various locations following a LOCA scenario. The team will use two measurement techniques: 1) oxygen (or similar type) sensors employed in the <span class="hlt">flow</span> field, which will introduce some undesirable intrusiveness, disturbing the <span class="hlt">flow</span>, and 2) a planar laser-induced fluorescence (PLIF) imaging technique, which has no physical intrusiveness to the <span class="hlt">flow</span> but requires a transparent window or test section that the laser beam can penetrate. The team will construct two test facilities, one for high-temperature helium tests with</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/2012HMT....48.1663H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012HMT....48.1663H"><span id="translatedtitle">Influence mechanism on <span class="hlt">flow</span> and heat transfer characteristics for <span class="hlt">air</span>-cooled steam condenser cells</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>He, Wei Feng; Dai, Yi Ping; Li, Mao Qing; Ma, Qing Zhong</p> <p>2012-09-01</p> <p><span class="hlt">Air</span>-cooled steam condensers (ACSCs) have been extensively utilized to reject waste heat in power industry to save water resources. However, ACSC performance is so sensitive to ambient wind that almost all the <span class="hlt">air</span>-cooled power plants in China are less efficient compared to design conditions. It is shown from previous research that the influence of ambient wind on the cell performance differs from its location in the condenser. As a result, a numerical model including two identical ACSC cells are established, and the different influence on the performance of the cells is demonstrated and analyzed through the computational fluid dynamics method. Despite the great influence from the wind speeds, similar cell performance is obtained for the two cells under both windless and wind speed conditions when the wind <span class="hlt">parallels</span> to the steam duct. Fan volumetric effectiveness which characterizes the fan performance, as well as the exchanger heat transfer rate, drops obviously with the increasing wind speed, and performance difference between the exchanger pair in the same A-frame also rises continuously. Furthermore, different <span class="hlt">flow</span> and heat transfer characteristics of the windward and leeward cell are obtained at different wind angles, and ambient wind enhances the performance of the leeward cell, while that of the windward one changes little.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004PhDT.......241M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004PhDT.......241M"><span id="translatedtitle">Dynamic stochastic optimization models for <span class="hlt">air</span> traffic <span class="hlt">flow</span> management</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mukherjee, Avijit</p> <p></p> <p>This dissertation presents dynamic stochastic optimization models for <span class="hlt">Air</span> Traffic <span class="hlt">Flow</span> Management (ATFM) that enables decisions to adapt to new information on evolving capacities of National Airspace System (NAS) resources. Uncertainty is represented by a set of capacity scenarios, each depicting a particular time-varying capacity profile of NAS resources. We use the concept of a scenario tree in which multiple scenarios are possible initially. Scenarios are eliminated as possibilities in a succession of branching points, until the specific scenario that will be realized on a particular day is known. Thus the scenario tree branching provides updated information on evolving scenarios, and allows ATFM decisions to be re-addressed and revised. First, we propose a dynamic stochastic model for a single airport ground holding problem (SAGHP) that can be used for planning Ground Delay Programs (GDPs) when there is uncertainty about future airport arrival capacities. Ground delays of non-departed flights can be revised based on updated information from scenario tree branching. The problem is formulated so that a wide range of objective functions, including non-linear delay cost functions and functions that reflect equity concerns can be optimized. Furthermore, the model improves on existing practice by ensuring efficient use of available capacity without necessarily exempting long-haul flights. Following this, we present a methodology and optimization models that can be used for decentralized decision making by individual airlines in the GDP planning process, using the solutions from the stochastic dynamic SAGHP. Airlines are allowed to perform cancellations, and re-allocate slots to remaining flights by substitutions. We also present an optimization model that can be used by the FAA, after the airlines perform cancellation and substitutions, to re-utilize vacant arrival slots that are created due to cancellations. Finally, we present three stochastic integer programming</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020050406','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020050406"><span id="translatedtitle"><span class="hlt">Parallelization</span> of the <span class="hlt">Flow</span> Field Dependent Variation Scheme for Solving the Triple Shock/Boundary Layer Interaction Problem</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schunk, Richard Gregory; Chung, T. J.</p> <p>2001-01-01</p> <p>A <span class="hlt">parallelized</span> version of the Flowfield Dependent Variation (FDV) Method is developed to analyze a problem of current research interest, the flowfield resulting from a triple shock/boundary layer interaction. Such flowfields are often encountered in the inlets of high speed <span class="hlt">air</span>-breathing vehicles including the NASA Hyper-X research vehicle. In order to resolve the complex shock structure and to provide adequate resolution for boundary layer computations of the convective heat transfer from surfaces inside the inlet, models containing over 500,000 nodes are needed. Efficient <span class="hlt">parallelization</span> of the computation is essential to achieving results in a timely manner. Results from a <span class="hlt">parallelization</span> scheme, based upon multi-threading, as implemented on multiple processor supercomputers and workstations is presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20000010540&hterms=SCHEME+RESEARCH&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DSCHEME%2BRESEARCH','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20000010540&hterms=SCHEME+RESEARCH&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DSCHEME%2BRESEARCH"><span id="translatedtitle"><span class="hlt">Parallelization</span> of the <span class="hlt">Flow</span> Field Dependent Variation Scheme for Solving the Triple Shock/Boundary Layer Interaction Problem</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schunk, Greg; chung, T. J.</p> <p>1999-01-01</p> <p>A <span class="hlt">parallelized</span> version of the Flowfield Dependent Variation (FDV) Method is developed to analyze a problem of current research interest, the flowfield resulting from a triple shock/boundary layer interaction. Such flowfields are often encountered in the inlets of high speed <span class="hlt">air</span>-breathing vehicles including NASA's Hyper-X. In order to resolve the complex shock structure and to provide adequate resolution for boundary layer computations of the convective heat transfer from surfaces inside the inlet, models containing over 500,000 nodes are needed. Efficient <span class="hlt">parallelization</span> of the computation is essential to obtaining the results in a timely manner. Results from different <span class="hlt">parallelization</span> schemes, based upon multi-threading and message passing, as implemented on multiple processor supercomputers and on distributed workstations are compared.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007SPIE.6795E..0WW','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007SPIE.6795E..0WW"><span id="translatedtitle">Cascade connection serial <span class="hlt">parallel</span> hybrid acquisition synchronization method for DS-FHSS in <span class="hlt">air</span>-ground data link</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Feng; Zhou, Desuo</p> <p>2007-11-01</p> <p>In <span class="hlt">air</span>-ground tactical data link system, a kind of primary anti jamming technology adopted is direct sequence - frequency hopping spread spectrum (DS-FHSS) technology. However, how to implement the quick synchronization of DS-FHSS is an important technology problem, which could influence the whole communication capability of system. Thinking of the application demand of anti jamming technology in actual, a kind of cascade connection serial <span class="hlt">parallel</span> hybrid acquisition synchronization method is given for the DS-FHSS system. The synchronization consists of two stages. The synchronization of FH communication is adopted at the first stage, and the serial <span class="hlt">parallel</span> hybrid structure is adopted for the DS PN code synchronization at the secondary stage. Through calculating the detect probability of the FH synchronization acquisition and the acquisition time of DS code chip synchronization, the contribution to the synchronization capability of system by this method in this paper is analyzed. Finally, through simulating on computer, the performance estimate about this cascade connection serial <span class="hlt">parallel</span> hybrid acquisition synchronization method is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=128826&keyword=Radon&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&CFID=76683263&CFTOKEN=47243165','EPA-EIMS'); return false;" href="http://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=128826&keyword=Radon&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&CFID=76683263&CFTOKEN=47243165"><span id="translatedtitle">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('http://www.osti.gov/scitech/servlets/purl/875029','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/875029"><span id="translatedtitle">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/cgi-bin/nph-data_query?bibcode=2015JThSc..24..583G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JThSc..24..583G&link_type=ABSTRACT"><span id="translatedtitle">Ignition of hydrocarbon-<span class="hlt">air</span> supersonic <span class="hlt">flow</span> by volumetric ionization</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Goldfeld, Marat A.; Pozdnyakov, George A.</p> <p>2015-11-01</p> <p>The paper describes the results of the electron-beam initiation of the combustion in the mixtures of hydrogen, natural gas or kerosene vapors with <span class="hlt">air</span>. Electron beam characteristics were studied in closed volume with immobile gas. The researches included definition of an integrated current of an electronic beam, distribution of a current density and an estimation of average energy of electrons. Possibility of fuel mixtures ignition by means of this approach in the combustor at high velocity at the entrance was demonstrated. Experiments were carried out at Mach numbers of 4 and 5. Process of ignition and combustion under electron beam action was researched. It was revealed that ignition of mixture occurs after completion of electron gun operation. Data obtained have confirmed effectiveness of electron beam application for ignition of hydrogen and natural gas. The numerical simulation of the combustion of mixture in channel was carried out by means of ANSYS CFD 12.0 instrumentation on the basis of Reynolds averaged Navier-Stokes equation using SST/k-ω turbulence model. For combustion modeling, a detailed kinetic scheme with 38 reactions of 8 species was implemented taking into account finite rate chemistry. Computations have shown that the developed model allow to predict ignition of a mixture and flame propagation even at low <span class="hlt">flow</span> temperatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740017837','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740017837"><span id="translatedtitle"><span class="hlt">Flow</span> measurement in base cooling <span class="hlt">air</span> passages of a rotating turbine blade</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liebert, C. H.; Pollack, F. G.</p> <p>1974-01-01</p> <p>The operational performance is decribed of a shaft-mounted system for measuring the <span class="hlt">air</span> mass <span class="hlt">flow</span> rate in the base cooling passages of a rotating turbine blade. Shaft speeds of 0 to 9000 rpm, <span class="hlt">air</span> mass <span class="hlt">flow</span> rates of 0.0035 to 0.039 kg/sec (0.0077 to 0.085 lbm/sec), and blade <span class="hlt">air</span> temperatures of 300 to 385 K (80 to 233 F) were measured. Comparisons of individual rotating blade <span class="hlt">flows</span> and corresponding stationary supply orifice <span class="hlt">flows</span> agreed to within 10 percent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6118197','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6118197"><span id="translatedtitle">Adiabatic <span class="hlt">air</span> dehumidification in laminar <span class="hlt">flow</span> desiccant matrices</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pesaran, A A</p> <p>1987-07-01</p> <p>Adiabatic step transient heat- and mass-transfer and pressure drop experimental data were obtained for a dehumidifier test matrix that contained microbead-silica-gel desiccant in a <span class="hlt">parallel</span>-plate geometry. The data were analyzed and compared with the results of two other test dehumidifiers: a <span class="hlt">parallel</span>-plate matrix using crushed silica gel, and a staggered, <span class="hlt">parallel</span>-strip matrix using microbead silica gel. The analysis showed that the overall heat- and mass-transfer Nusselt numbers of the staggered, <span class="hlt">parallel</span>-strip matrix were about 70% to 80% larger than those of the <span class="hlt">parallel</span>-plate matrices. It also showed that the solid-side resistance to moisture diffusion in the smaller microbead silica gel was about 45% less than that of crushed silica gel because the particle size was 60% smaller. The ratio of heat- or mass-transfer coefficient to pressure drop of the microbead-silica-gel staggered, <span class="hlt">parallel</span>-strip matrix was higher than the other two test dehumidifiers. Based on these findings, a dehumidifier using microbead silica-gel in a staggered, <span class="hlt">parallel</span>-strip geometry can be made more compact than the other combinations. 15 refs., 9 figs., 5 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/453744','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/453744"><span id="translatedtitle"><span class="hlt">Parallelization</span> of a multiregion <span class="hlt">flow</span> and transport code using software emulated global shared memory and high performance FORTRAN</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>D`Azevedo, E.F.; Gwo, Jin-Ping</p> <p>1997-02-01</p> <p>The objectives of this research are (1) to <span class="hlt">parallelize</span> a suite of multiregion groundwater <span class="hlt">flow</span> and solute transport codes that use Galerkin and Lagrangian- Eulerian finite element methods, (2) to test the compatibility of a global shared memory emulation software with a High Performance FORTRAN (HPF) compiler, and (3) to obtain performance characteristics and scalability of the <span class="hlt">parallel</span> codes. The suite of multiregion <span class="hlt">flow</span> and transport codes, 3DMURF and 3DMURT, were <span class="hlt">parallelized</span> using the DOLIB shared memory emulation, in conjunction with the PGI HPF compiler, to run on the Intel Paragons at the Oak Ridge National Laboratory (ORNL) and a network of workstations. The novelty of this effort is first in the use of HPF and global shared memory emulation concurrently to facilitate the conversion of a serial code to a <span class="hlt">parallel</span> code, and secondly the shared memory library enables efficient implementation of Lagrangian particle tracking along <span class="hlt">flow</span> characteristics. The latter allows long-time-step-size simulation with particle tracking and dynamic particle redistribution for load balancing, thereby reducing the number of time steps needed for most transient problems. The <span class="hlt">parallel</span> codes were applied to a pumping well problem to test the efficiency of the domain decomposition and particle tracking algorithms. The full problem domain consists of over 200,000 degrees of freedom with highly nonlinear soil property functions. Relatively good scalability was obtained for a preliminary test run on the Intel Paragons at the Center for Computational Sciences (CCS), ORNL. However, due to the difficulties we encountered in the PGI HPF compiler, as of the writing of this manuscript we are able to report results from 3DMURF only.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/21517593','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/21517593"><span id="translatedtitle">Parametric study on instabilities in a two-layer electromagnetohydrodynamic channel <span class="hlt">flow</span> confined between two <span class="hlt">parallel</span> electrodes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Reddy, P Dinesh Sankar; Bandyopadhyay, Dipankar; Joo, Sang Woo; Sharma, Ashutosh; Qian, Shizhi</p> <p>2011-03-01</p> <p>Instabilities in a two-phase electromagnetohydrodynamic (EMHD) <span class="hlt">flow</span> between a pair of <span class="hlt">parallel</span> electrodes are explored. A linear stability analysis has been performed based on a coupled Orr-Sommerfeld system generated from the conservation laws. The study shows the presence of a finite-wave-number EMHD mode of instability in addition to the two commonly observed instability modes in the pressure-driven two-layer <span class="hlt">flows</span>, namely, the long-wave interfacial mode arising from the viscosity or density stratification and the finite-wave-number shear <span class="hlt">flow</span> mode engendered by the Reynolds stresses. This extra EMHD mode originates from the additional stresses generated by the Lorenz force acting at the liquid layers and is found to exist under all conditions beyond a critical strength of the externally applied magnetic field. The EMHD mode either can exist as a singular dominant mode or can coexist as a dominant or subdominant mode with the conventional interfacial mode or shear <span class="hlt">flow</span> instabilities in the two-layer <span class="hlt">flows</span>. The EMHD <span class="hlt">flow</span> studied here has numerous potential applications in fluid transport, enhanced heat and mass transfer, mixing, and emulsification because of the low energy requirement, <span class="hlt">flow</span> reversibility, absence of moving parts, and facile control over <span class="hlt">flow</span> rate. The parametric study presented here on the instabilities in the two-layer EMHD <span class="hlt">flow</span> will thus be of great practical use. PMID:21517593</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H43L..05K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H43L..05K"><span id="translatedtitle">Simulations of <span class="hlt">flow</span> mode distributions on rough fracture surfaces using a <span class="hlt">parallelized</span> Smoothed Particle Hydrodynamics (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>Kordilla, J.; Shigorina, E.; Tartakovsky, A. M.; Pan, W.; Geyer, T.</p> <p>2015-12-01</p> <p>Under idealized conditions (smooth surfaces, linear relationship between Bond number and Capillary number of droplets) steady-state <span class="hlt">flow</span> modes on fracture surfaces have been shown to develop from sliding droplets to rivulets and finally (wavy) film <span class="hlt">flow</span>, depending on the specified flux. In a recent study we demonstrated the effect of surface roughness on droplet <span class="hlt">flow</span> in unsaturated wide aperture fractures, however, its effect on other prevailing <span class="hlt">flow</span> modes is still an open question. The objective of this work is to investigate the formation of complex <span class="hlt">flow</span> modes on fracture surfaces employing an efficient three-dimensional <span class="hlt">parallelized</span> SPH model. The model is able to simulate highly intermittent, gravity-driven free-surface <span class="hlt">flows</span> under dynamic wetting conditions. The effect of surface tension is included via efficient pairwise interaction forces. We validate the model using various analytical and semi-analytical relationships for droplet and complex <span class="hlt">flow</span> dynamics. To investigate the effect of surface roughness on <span class="hlt">flow</span> dynamics we construct surfaces with a self-affine fractal geometry and roughness characterized by the Hurst exponent. We demonstrate the effect of surface roughness (on macroscopic scales this can be understood as a tortuosity) on the steady-state distribution of <span class="hlt">flow</span> modes. Furthermore we show the influence of a wide range of natural wetting conditions (defined by static contact angles) on the final distribution of surface coverage, which is of high importance for matrix-fracture interaction processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/6676027','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/6676027"><span id="translatedtitle">Managing <span class="hlt">parallelism</span> and resources in scientific data-<span class="hlt">flow</span> programs. Technical report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Culler, D.E.</p> <p>1990-03-01</p> <p>Exploiting <span class="hlt">parallelism</span> to achieve high performance invariably increases the resource requirements of a program. This is particularly serious under dynamic dataflow execution, because all the potential <span class="hlt">parallelism</span> in a program is exposed. The resource requirements can be excessive, often leading to deadlock. This phenomenon is documented using <span class="hlt">parallelism</span> and resource profiles derived under an ideal dataflow execution model. This report examines how resource requirements can be managed effectively by controlling the ways in which <span class="hlt">parallelism</span> is exposed. A mechanism for controlling <span class="hlt">parallelism</span> in scientific programs, called k-bounded loops, is presented. This involves compiling loops into dataflow graphs in a manner that allows the maximum number of concurrent iterations to be set dynamically, when the loop is invoked. A policy for employing this mechanism is developed and tested on a variety of programs. Through static analysis of the program, parametric resource expressions are formulated and the potential <span class="hlt">parallelism</span> is characterized. Based on this analysis, the program is augmented with resource management code that computes the k-bounds by simple formulae, involving program variables and an overall resource parameter that reflects the capacity of the machine. This approach is shown to be effective for containing the resource requirements of scientific dataflow programs, while exposing adequate <span class="hlt">parallelism</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JPhCS.364a2073P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JPhCS.364a2073P"><span id="translatedtitle">Experimental verification of the four-sensor probe model for <span class="hlt">flow</span> diagnosis in <span class="hlt">air</span> water <span class="hlt">flow</span> in vertical pipe</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pradhan, S.; Mishra, R.</p> <p>2012-05-01</p> <p>Measuring the volumetric <span class="hlt">flow</span> rate of each of the <span class="hlt">flowing</span> components is required to be monitored in production logging applications. Hence it is necessary to measure the <span class="hlt">flow</span> rates of gas, oil and water in vertical and inclined oil wells. An increasing level of interest has been shown by the researchers in developing system for the <span class="hlt">flow</span> rate measurement in multiphase <span class="hlt">flows</span>. This paper describes the experimental methodology using a miniature, local four-sensor probe for the measurement of dispersed <span class="hlt">flow</span> parameters in bubbly two-phase <span class="hlt">flow</span> for spherical bubbles. To establish interdependent among different parameters corresponding to dispersed <span class="hlt">flow</span>, the available model has been used to experimentally obtain different parameters such as volume fraction, velocity and bubble shape of the dispersed phase in the bubbly <span class="hlt">air</span>-water <span class="hlt">flow</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1036044','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1036044"><span id="translatedtitle">Managing the Drivers of <span class="hlt">Air</span> <span class="hlt">Flow</span> and Water Vapor Transport in Existing Single Family Homes (Revised)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cummings, J.; Withers, C.; Martin, E.; Moyer, N.</p> <p>2012-10-01</p> <p>This document focuses on managing the driving forces which move <span class="hlt">air</span> and moisture across the building envelope. While other previously published Measure Guidelines focus on elimination of <span class="hlt">air</span> pathways, the ultimate goal of this Measure Guideline is to manage drivers which cause <span class="hlt">air</span> <span class="hlt">flow</span> and water vapor transport across the building envelope (and also within the home), control <span class="hlt">air</span> infiltration, keep relative humidity (RH) within acceptable limits, avoid combustion safety problems, improve occupant comfort, and reduce house energy use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981Wear...71..211R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981Wear...71..211R"><span id="translatedtitle">Viscoelastic <span class="hlt">flow</span> between two infinite <span class="hlt">parallel</span> porous plates, one plate oscillating and the other plate in uniform motion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roy, J. S.; Nayak, P.</p> <p>1981-09-01</p> <p>An iteration procedure is used to solve fluid dynamics equations describing viscoelastic incompressible <span class="hlt">flow</span> between two infinite <span class="hlt">parallel</span> porous plates, one oscillating and the other in uniform motion. The solutions obtained are valid for small values of the elastic parameter S. The effects of the Reynolds number and the elastic parameter S on the velocity distribution and the shearing stress at the plates are analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22271101','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22271101"><span id="translatedtitle">Two-phase <span class="hlt">air</span>-water stratified <span class="hlt">flow</span> measurement using ultrasonic techniques</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fan, Shiwei; Yan, Tinghu; Yeung, Hoi</p> <p>2014-04-11</p> <p>In this paper, a time resolved ultrasound system was developed for investigating two-phase <span class="hlt">air</span>-water stratified <span class="hlt">flow</span>. The hardware of the system includes a pulsed wave transducer, a pulser/receiver, and a digital oscilloscope. The time domain cross correlation method is used to calculate the velocity profile along ultrasonic beam. The system is able to provide velocities with spatial resolution of around 1mm and the temporal resolution of 200μs. Experiments were carried out on single phase water <span class="hlt">flow</span> and two-phase <span class="hlt">air</span>-water stratified <span class="hlt">flow</span>. For single phase water <span class="hlt">flow</span>, the <span class="hlt">flow</span> rates from ultrasound system were compared with those from electromagnetic <span class="hlt">flow</span> (EM) meter, which showed good agreement. Then, the experiments were conducted on two-phase <span class="hlt">air</span>-water stratified <span class="hlt">flow</span> and the results were given. Compared with liquid height measurement from conductance probe, it indicated that the measured velocities were explainable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JPS...242..195T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JPS...242..195T"><span id="translatedtitle">Experimental investigation on a polymer electrolyte membrane fuel cell (PEMFC) <span class="hlt">parallel</span> <span class="hlt">flow</span> field design with external two-valve regulation on cathode channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tong, Shijie; Bachman, John C.; Santamaria, Anthony; Park, Jae Wan</p> <p>2013-11-01</p> <p><span class="hlt">Parallel</span>/interdigitated/serpentine <span class="hlt">flow</span> field PEM fuel cells have similar performance under low overvoltage operation. At higher overvoltage, interdigitated/serpentine <span class="hlt">flow</span> field performance may exceed <span class="hlt">parallel</span> <span class="hlt">flow</span> field designs due to better water removal and more uniform reactant distribution by convective reactant <span class="hlt">flow</span> in the GDL under land area, i.e. cross <span class="hlt">flow</span>. However, serpentine <span class="hlt">flow</span> field design suffers from high pumping losses and the risk of local flooding at channel U-bends. Additionally, interdigitated <span class="hlt">flow</span> field designs may have higher local flooding risk in the inlet channels and relatively large pumping requirement at low current densities. In this study, a novel <span class="hlt">parallel</span> <span class="hlt">flow</span> field design with external two-valve regulation on the cathode was presented. Two valves introduced continuous pressure differences to two separate manifolds in the cathode that induce cross <span class="hlt">flow</span> across the land areas. Moreover, both valves remained partially open to maintain a good water removal from <span class="hlt">flow</span> channels. Comparative test results showed the proposed design surpasses performance of both <span class="hlt">parallel</span> and interdigitated <span class="hlt">flow</span> field design at operation current density of 0.7 A cm-2 or higher. The performance enhancement is 10.9% at peak power density point (0.387 W cm-2 @ 0.99 A cm-2) compared to <span class="hlt">parallel</span> <span class="hlt">flow</span> field taking into account pumping losses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19740045297&hterms=flow+tube&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dflow%2Btube','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19740045297&hterms=flow+tube&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3Dflow%2Btube"><span id="translatedtitle"><span class="hlt">Flow</span> properties in expansion tube with helium, argon, <span class="hlt">air</span>, and CO2</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.</p> <p>1974-01-01</p> <p>Test <span class="hlt">flow</span> velocities from 5 to 7 km/sec were generated in a 6-in. expansion tube using helium, argon, <span class="hlt">air</span>, and CO2 test gases. Pitot pressure profiles across the <span class="hlt">flow</span> at the test section are presented for the four test gases, and measured <span class="hlt">flow</span> quantities are compared to computer predicted values. Comparison of predicted and measured <span class="hlt">flow</span> quantities suggests the expansion to be near thermochemical equilibrium for all test gases and implies the existence of a totally reflected shock at the secondary diaphragm. Argon, <span class="hlt">air</span>, and CO2 <span class="hlt">flows</span> were observed to attenuate while traversing the acceleration section, whereas no attenuation was observed for helium.</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://www.osti.gov/scitech/biblio/22047134','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22047134"><span id="translatedtitle"><span class="hlt">Parallel</span> and perpendicular velocity sheared <span class="hlt">flows</span> driven tripolar vortices in an inhomogeneous electron-ion quantum magnetoplasma</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mirza, Arshad M.; Masood, W.</p> <p>2011-12-15</p> <p>Nonlinear equations governing the dynamics of finite amplitude drift-ion acoustic-waves are derived by taking into account sheared ion <span class="hlt">flows</span> <span class="hlt">parallel</span> and perpendicular to the ambient magnetic field in a quantum magnetoplasma comprised of electrons and ions. It is shown that stationary solution of the nonlinear equations can be represented in the form of a tripolar vortex for specific profiles of the equilibrium sheared <span class="hlt">flows</span>. The tripolar vortices are, however, observed to form on very short scales in dense quantum plasmas. The relevance of the present investigation with regard to dense astrophysical environments is also pointed out.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1220524','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1220524"><span id="translatedtitle">Laboratory Evaluation of <span class="hlt">Air</span> <span class="hlt">Flow</span> Measurement Methods for Residential HVAC Returns for New Instrument Standards</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Walker, Iain; Stratton, Chris</p> <p>2015-08-01</p> <p>This project improved the accuracy of <span class="hlt">air</span> <span class="hlt">flow</span> measurements used in commissioning California heating and <span class="hlt">air</span> conditioning systems in Title 24 (Building and Appliance Efficiency Standards), thereby improving system performance and efficiency of California residences. The research team at Lawrence Berkeley National Laboratory addressed the issue that typical tools used by contractors in the field to test <span class="hlt">air</span> <span class="hlt">flows</span> may not be accurate enough to measure return <span class="hlt">flows</span> used in Title 24 applications. The team developed guidance on performance of current diagnostics as well as a draft test method for use in future evaluations. The study team prepared a draft test method through ASTM International to determine the uncertainty of <span class="hlt">air</span> <span class="hlt">flow</span> measurements at residential heating ventilation and <span class="hlt">air</span> conditioning returns and other terminals. This test method, when finalized, can be used by the Energy Commission and other entities to specify required accuracy of measurement devices used to show compliance with standards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001APS..DFD.EQ006L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001APS..DFD.EQ006L"><span id="translatedtitle">Numerical Simulation of Two-phase <span class="hlt">Flow</span> in a Microchannel with <span class="hlt">Air</span> Gap</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Xiaojun; Meinhart, Carl D.</p> <p>2001-11-01</p> <p>Fluid transport in nano- and micro-scale devices becomes more and more important. The potential advantages of micro-channel with <span class="hlt">air</span> gap are studied. A simple one-dimensional model of <span class="hlt">air</span>-water two-phase <span class="hlt">flow</span> is investigated theoretically. The <span class="hlt">flow</span> of water is driven by pressure drop. The <span class="hlt">air</span> in the gap is driven by surface tension and friction forces that exist at the interface between the water and <span class="hlt">air</span>. With the limitation that <span class="hlt">air</span> <span class="hlt">flow</span> rate is zero, the theoretical results are obtained based on continuity and Navier-Stokes equations. Because the viscosity of <span class="hlt">air</span> is much less than that of water, under same pressure drop, the <span class="hlt">flow</span> rate of water can be increased to as 4.76 times as that of normal channel without <span class="hlt">air</span> gap. The theoretical results are tested by numerical simulation with three different software package (CFD2000, FEMLab and CFDRC) using a two-dimensional model. The interface shape, interface velocity, water <span class="hlt">flow</span> rate and optimum height ratio are studied. Thenumerical results for different package match each other very well. The numerical results show that increasing water <span class="hlt">flow</span> rate by adding <span class="hlt">air</span> gap in the micro channel is practicable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26918522','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26918522"><span id="translatedtitle">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. PMID:26918522</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003QJRMS.129..117Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003QJRMS.129..117Z"><span id="translatedtitle">The impact of upstream blocking, drainage <span class="hlt">flow</span> and the geostrophic pressure gradient on the persistence of cold-<span class="hlt">air</span> pools</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zängl, G.</p> <p>2003-01-01</p> <p>Idealized numerical simulations are performed to investigate dynamical mechanisms affecting the persistence of cold-<span class="hlt">air</span> pools in basins and valleys. The first orography type considered is a shallow elongated basin located upstream of a mountain ridge. For sensitivity tests, the mountain ridge is removed. The second type is a basin embedded in a plateau-like mountain ridge. In part of the simulations, this basin has an outflow towards the lee-side plain so as to assess the impact of the drainage <span class="hlt">flow</span>.The large-scale <span class="hlt">flow</span> is taken to be in geostrophic balance. In the standard setting, it is perpendicular to the basin and the ridge. The main effect of a large-scale pressure gradient is to induce a circulation within a cold-<span class="hlt">air</span> pool until the upper boundary of the cold pool is inclined such as to compensate for the ambient pressure gradient. The cold <span class="hlt">air</span> accumulates where the ambient pressure is lowest. For a shallow basin, this means that part of the cold <span class="hlt">air</span> may be lost due to advection out of the basin. The upstream influence of a mountain ridge in the lee of a shallow basin is found to be twofold. It tends to deflect the low-level <span class="hlt">flow</span> towards the lower pressure, leading to an additional ridge-<span class="hlt">parallel</span> force on the cold-<span class="hlt">air</span> pool. On the other hand, the absolute wind speed is reduced, diminishing the turbulent mixing near the top of the cold pool. The simulations show that the first effect prevails for ridge-normal <span class="hlt">flow</span> while second effect may dominate for other <span class="hlt">flow</span> directions. Drainage <span class="hlt">flow</span> out of a valley is found to be very important as it promotes the penetration of warm <span class="hlt">air</span> into valleys very effectively. It may cause a cold pool in a deep valley to disappear more quickly than a cold pool in a shallow basin. Sensitivity tests show that the persistence of a cold pool depends on its depth, on its vertically integrated heat deficit, and on the maximum heat deficit at the bottom of the cold pool.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770023145','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770023145"><span id="translatedtitle">Cold <span class="hlt">air</span> performance of a 12.766-centimeter-tip-diameter axial-<span class="hlt">flow</span> cooled turbine. 2: Effect of <span class="hlt">air</span> ejection on turbine performance</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haas, J. E.; Kofskey, M. G.</p> <p>1977-01-01</p> <p>An <span class="hlt">air</span> cooled version of a single-stage, axial-<span class="hlt">flow</span> turbine was investigated to determine aerodynamic performance with and without <span class="hlt">air</span> ejection from the stator and rotor blades surfaces to simulate the effect of cooling <span class="hlt">air</span> discharge. <span class="hlt">Air</span> ejection rate was varied from 0 to 10 percent of turbine mass <span class="hlt">flow</span> for both the stator and the rotor. A primary-to-<span class="hlt">air</span> ejection temperature ratio of about 1 was maintained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770022228','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770022228"><span id="translatedtitle">Experimental and analytical dynamic <span class="hlt">flow</span> characteristics of an axial-<span class="hlt">flow</span> fan from an <span class="hlt">air</span> cushion landing system model</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Thompson, W. C.; Boghani, A. B.; Leland, T. J. W.</p> <p>1977-01-01</p> <p>An investigation was conducted to compare the steady-state and dynamic <span class="hlt">flow</span> characteristics of an axial-<span class="hlt">flow</span> fan which had been used previously as the <span class="hlt">air</span> supply fan for some model <span class="hlt">air</span> cushion landing system studies. Steady-state <span class="hlt">flow</span> characteristics were determined in the standard manner by using differential orifice pressures for the <span class="hlt">flow</span> regime from free <span class="hlt">flow</span> to zero <span class="hlt">flow</span>. In this same regime, a correlative technique was established so that fan inlet and outlet pressures could be used to measure dynamic <span class="hlt">flow</span> as created by a rotating damper. Dynamic tests at damper frequencies up to 5 Hz showed very different <span class="hlt">flow</span> characteristics when compared with steady-state <span class="hlt">flow</span>, particularly with respect to peak pressures and the pressure-<span class="hlt">flow</span> relationship at fan stall and unstall. A generalized, rational mathematical fan model was developed based on physical fan parameters and a steady-state <span class="hlt">flow</span> characteristic. The model showed good correlation with experimental tests at damper frequencies up to 5 Hz.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JPS...259...15Z&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014JPS...259...15Z&link_type=ABSTRACT"><span id="translatedtitle">Computational modeling of <span class="hlt">air</span>-breathing microfluidic fuel cells with <span class="hlt">flow</span>-over and <span class="hlt">flow</span>-through anodes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Biao; Ye, Ding-ding; Sui, Pang-Chieh; Djilali, Ned; Zhu, Xun</p> <p>2014-08-01</p> <p>A three-dimensional computational model for <span class="hlt">air</span>-breathing microfluidic fuel cells (AMFCs) with <span class="hlt">flow</span>-over and <span class="hlt">flow</span>-through anodes is developed. The coupled multiphysics phenomena of fluid <span class="hlt">flow</span>, species transport and electrochemical reactions are resolved numerically. The model has been validated against experimental data using an in-house AMFC prototype with a <span class="hlt">flow</span>-through anode. Characteristics of fuel transfer and fuel crossover for both types of anodes are investigated. The model results reveal that the fuel transport to the <span class="hlt">flow</span>-over anode is intrinsically limited by the fuel concentration boundary layer. Conversely, fuel transport for the <span class="hlt">flow</span>-through anode is convectively enhanced by the permeate <span class="hlt">flow</span>, and no concentration boundary layer is observed. An unexpected additional advantage of the <span class="hlt">flow</span>-through anode configuration is lower parasitic (crossover) current density than the <span class="hlt">flow</span>-over case at practical low <span class="hlt">flow</span> rates. Cell performance of the <span class="hlt">flow</span>-through case is found to be limited by reaction kinetics. The present model provides insights into the fuel transport and fuel crossover in <span class="hlt">air</span>-breathing microfluidic fuel cells and provides guidance for further design and operation optimization.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010CTM....15...47T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010CTM....15...47T"><span id="translatedtitle">Auto-ignition of methane-<span class="hlt">air</span> mixtures <span class="hlt">flowing</span> along an array of thin catalytic plates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Treviño, C.</p> <p>2010-12-01</p> <p>In this paper, the heterogeneous ignition of a methane-<span class="hlt">air</span> mixture <span class="hlt">flowing</span> along an infinite array of catalytic <span class="hlt">parallel</span> plates has been studied by inclusion of gas expansion effects and the finite heat conduction on the plates. The system of equations considers the full compressible Navier-Stokes equations coupled with the energy equations of the plates. The gas expansion effects which arise from temperature changes have been considered. The heterogeneous kinetics considers the adsorption and desorption reactions for both reactants. The limits of large and small longitudinal thermal conductance of the plate material are analyzed and the critical conditions for ignition are obtained in closed form. The governing equations are solved numerically using finite differences. The results show that ignition is more easily produced as the longitudinal wall thermal conductance increases, and the effects of the gas expansion on the catalytic ignition process are rather small due to the large value of the activation energy of the desorption reaction of adsorbed oxygen atoms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1637..600L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1637..600L"><span id="translatedtitle">Optimization of <span class="hlt">air</span>-ejected rocket/missile geometries under validated supersonic <span class="hlt">flow</span> field simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>López, D.; Domínguez, D.; Gonzalo, J.</p> <p>2014-12-01</p> <p>This paper defines a methodology to carry out optimizations of rocket/missile geometries by means of krigingbased algorithms applied to simulations made with computational fluid dynamic (CFD) codes. The first part of the paper is focused on the validation of the open source CFD code against a well-studied 3-dimmensional test case in supersonic conditions. The impact of several turbulence models, different numerical schemes to discretize the equations and different mesh resolution levels have been analyzed demonstrating the performance of using wall functions for supersonic <span class="hlt">flow</span>. Good agreements between numerical, theoretical and experimental results are obtained and some general guidelines are extracted. The best accuracy is obtained with SST k-omega turbulence model with meshes suitable for the use of wall functions in the boundary cells. Then, with this configuration for the simulations, an <span class="hlt">air</span>-ejected rocket fairing is selected to apply a geometrical optimization. The selected method is kriging-based, where a statistical model is generated by means of several numerical experiments dependent on a certain number of design parameters; the final objective is to find the minimum drag coefficient for the model, keeping enough room inside the fairing to install the requested payload. This kriging-based method allows obtaining the samples in a <span class="hlt">parallel</span> manner, looking for the optimum design at the generated metamodel and hence improving its accuracy adding new samples if needed.</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 id="translatedtitle">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://www.osti.gov/scitech/biblio/22311236','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22311236"><span id="translatedtitle">Limitation of <span class="hlt">parallel</span> <span class="hlt">flow</span> in double diffusive convection: Two- and three-dimensional transitions in a horizontal porous domain</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mimouni, N.; Chikh, S.; Rahli, O.; Bennacer, R.</p> <p>2014-07-15</p> <p>Two-dimensional (2D) and three-dimensional (3D) numerical simulations of double diffusion natural convection in an elongated enclosure filled with a binary fluid saturating a porous medium are carried out in the present work. The Boussinesq approximation is made in the formulation of the problem, and Neumann boundary conditions for temperature and concentration are adopted, respectively, on vertical and horizontal walls of the cavity. The used numerical method is based on the control volume approach, with the third order quadratic upstream interpolation scheme in approximating the advection terms. A semi implicit method algorithm is used to handle the velocity-pressure coupling. To avoid the excessively high computer time inherent to the solution of 3D natural convection problems, full approximation storage with full multigrid method is used to solve the problem. A wide range of the controlling parameters (Rayleigh-Darcy number Ra, lateral aspect ratio Ay, Lewis number Le, and the buoyancy ration N) is investigated. We clearly show that increasing the depth of the cavity (i.e., the lateral aspect ratio) has an important effect on the <span class="hlt">flow</span> patterns. The 2D perfect <span class="hlt">parallel</span> <span class="hlt">flows</span> obtained for small lateral aspect ratio are drastically destabilized by increasing the cavity lateral dimension. This yields a 3D fluid motion with a much more complex <span class="hlt">flow</span> pattern and the usually considered 2D <span class="hlt">parallel</span> <span class="hlt">flow</span> model cannot be applied.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010E%26ES...12a2030C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010E%26ES...12a2030C"><span id="translatedtitle">Performance improvement of a cross-<span class="hlt">flow</span> hydro turbine by <span class="hlt">air</span> layer effect</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Choi, Y. D.; Yoon, H. Y.; Inagaki, M.; Ooike, S.; Kim, Y. J.; Lee, Y. H.</p> <p>2010-08-01</p> <p>The purpose of this study is not only to investigate the effects of <span class="hlt">air</span> layer in the turbine chamber on the performance and internal <span class="hlt">flow</span> of the cross-<span class="hlt">flow</span> turbine, but also to suggest a newly developed <span class="hlt">air</span> supply method. Field test is performed in order to measure the output power of the turbine by a new <span class="hlt">air</span> supply method. CFD analysis on the performance and internal <span class="hlt">flow</span> of the turbine is conducted by an unsteady state calculation using a two-phase <span class="hlt">flow</span> model in order to embody the <span class="hlt">air</span> layer effect on the turbine performance effectively.The result shows that <span class="hlt">air</span> layer effect on the performance of the turbine is considerable. The <span class="hlt">air</span> layer located in the turbine runner passage plays the role of preventing a shock loss at the runner axis and suppressing a recirculation <span class="hlt">flow</span> in the runner. The location of <span class="hlt">air</span> suction hole on the chamber wall is very important factor for the performance improvement. Moreover, the ratio between <span class="hlt">air</span> from suction pipe and water from turbine inlet is also significant factor of the turbine performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1242416','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1242416"><span id="translatedtitle">LABORATORY EVALUATION OF <span class="hlt">AIR</span> <span class="hlt">FLOW</span> MEASUREMENT METHODS FOR RESIDENTIAL HVAC RETURNS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Walker, Iain; Stratton, Chris</p> <p>2015-02-01</p> <p>This project improved the accuracy of <span class="hlt">air</span> <span class="hlt">flow</span> measurements used in commissioning California heating and <span class="hlt">air</span> conditioning systems in Title 24 (Building and Appliance Efficiency Standards), thereby improving system performance and efficiency of California residences. The research team at Lawrence Berkeley National Laboratory addressed the issue that typical tools used by contractors in the field to test <span class="hlt">air</span> <span class="hlt">flows</span> may not be accurate enough to measure return <span class="hlt">flows</span> used in Title 24 applications. The team developed guidance on performance of current diagnostics as well as a draft test method for use in future evaluations. The series of tests performed measured <span class="hlt">air</span> <span class="hlt">flow</span> using a range of techniques and devices. The measured <span class="hlt">air</span> <span class="hlt">flows</span> were compared to reference <span class="hlt">air</span> <span class="hlt">flow</span> measurements using inline <span class="hlt">air</span> <span class="hlt">flow</span> meters built into the test apparatus. The experimental results showed that some devices had reasonable results (typical errors of 5 percent or less) but others had much bigger errors (up to 25 percent). Because manufacturers’ accuracy estimates for their equipment do not include many of the sources of error found in actual field measurements (and replicated in the laboratory testing in this study) it is essential for a test method that could be used to determine the actual uncertainty in this specific application. The study team prepared a draft test method through ASTM International to determine the uncertainty of <span class="hlt">air</span> <span class="hlt">flow</span> measurements at residential heating ventilation and <span class="hlt">air</span> conditioning returns and other terminals. This test method, when finalized, can be used by the Energy Commission and other entities to specify required accuracy of measurement devices used to show compliance with standards.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AIPC.1547..659M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AIPC.1547..659M"><span id="translatedtitle">Simulation of <span class="hlt">air</span>-droplet mixed phase <span class="hlt">flow</span> in icing wind-tunnel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mengyao, Leng; Shinan, Chang; Menglong, Wu; Yunhang, Li</p> <p>2013-07-01</p> <p>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 <span class="hlt">air</span> are different, for example, to keep the nozzles from freezing, the droplets are heated while the temperature of <span class="hlt">air</span> is low. It means that complex mass and heat transfer as well as dynamic interactive force would happen between droplets and <span class="hlt">air</span>, and the parameters of droplet will acutely change along the passageway. Therefore, the prediction of droplet-<span class="hlt">air</span> mixed phase <span class="hlt">flow</span> is necessary in the evaluation of icing researching wind-tunnel. In this paper, a simplified droplet-<span class="hlt">air</span> mixed phase <span class="hlt">flow</span> model based on Lagrangian method was built. The variation of temperature, diameter and velocity of droplet, as well as the <span class="hlt">air</span> <span class="hlt">flow</span> field, during the <span class="hlt">flow</span> process were obtained under different condition. With calculating three-dimensional <span class="hlt">air</span> <span class="hlt">flow</span> 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 <span class="hlt">flow</span> and heat and mass transfer characteristics in the mixing process is valuable for the optimization of experimental parameters design and equipment adjustment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title42-vol1/pdf/CFR-2010-title42-vol1-sec84-155.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title42-vol1/pdf/CFR-2010-title42-vol1-sec84-155.pdf"><span id="translatedtitle">42 CFR 84.155 - Airflow resistance test; Type C supplied-<span class="hlt">air</span> respirator, continuous <span class="hlt">flow</span> class and Type CE...</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>2010-10-01</p> <p>... respirator, continuous <span class="hlt">flow</span> class and Type CE supplied-<span class="hlt">air</span> respirator; minimum requirements. 84.155 Section... Respirators § 84.155 Airflow resistance test; Type C supplied-<span class="hlt">air</span> respirator, continuous <span class="hlt">flow</span> class and Type... shall not exceed 25 mm. (1 inch) of water-column height when the <span class="hlt">air</span> <span class="hlt">flow</span> into the...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5216076','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5216076"><span id="translatedtitle">Experiments with data <span class="hlt">flow</span> on a general-purpose <span class="hlt">parallel</span> computer. Memorandum report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Spertus, E.; Dally, W.J.</p> <p>1991-01-01</p> <p>The MIT J-Machine, a massively-<span class="hlt">parallel</span> computer, is an experiment in providing general-purpose mechanisms for communication, synchronization, and naming that will support a wide variety of <span class="hlt">parallel</span> models of computation. Having universal mechanisms allows the separation of issues of language design and machine organization. The authors have developed two experimental dataflow programming systems for the J-Machine. For the first system, they adapted Papadopoulos' explicit token store to implement static and then dynamic dataflow. Each node in a dataflow graph is expanded into a sequence of code, each of which is scheduled individually at runtime. For a later system, they made use of Iannucci's hybrid execution model to combine several dataflow graph nodes into a single sequence, decreasing scheduling overhead. By combining the strengths of the two systems, it is possible to produce a system with competitive performance. They have demonstrated the feasibility of efficiently executing dataflow programs on a general purpose <span class="hlt">parallel</span> computer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009MPLB...23..325T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009MPLB...23..325T"><span id="translatedtitle">Numerical Simulation of Unsteady <span class="hlt">Flow</span> Field around Helicopter in Forward Flight Using a <span class="hlt">Parallel</span> Dynamic Overset Unstructured Grids Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tian, Shuling; Wu, Yizhao; Xia, Jian</p> <p></p> <p>A <span class="hlt">parallel</span> Navier-Stokes solver based on dynamic overset unstructured grids method is presented to simulate the unsteady turbulent <span class="hlt">flow</span> field around helicopter in forward flight. The grid method has the advantages of unstructured grid and Chimera grid and is suitable to deal with multiple bodies in relatively moving. Unsteady Navier-Stokes equations are solved on overset unstructured grids by an explicit dual time-stepping, finite volume method. Preconditioning method applied to inner iteration of the dual-time stepping is used to speed up the convergence of numerical simulation. The Spalart-Allmaras one-equation turbulence model is used to evaluate the turbulent viscosity. <span class="hlt">Parallel</span> computation is based on the dynamic domain decomposition method in overset unstructured grids system at each physical time step. A generic helicopter Robin with a four-blade rotor in forward flight is considered to validate the method presented in this paper. Numerical simulation results show that the <span class="hlt">parallel</span> dynamic overset unstructured grids method is very efficient for the simulation of helicopter <span class="hlt">flow</span> field and the results are reliable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020048420','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020048420"><span id="translatedtitle">Progress in the Simulation of Steady and Time-Dependent <span class="hlt">Flows</span> with 3D <span class="hlt">Parallel</span> Unstructured Cartesian Methods</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Aftosmis, M. J.; Berger, M. J.; Murman, S. M.; Kwak, Dochan (Technical Monitor)</p> <p>2002-01-01</p> <p>The proposed paper will present recent extensions in the development of an efficient Euler solver for adaptively-refined Cartesian meshes with embedded boundaries. The paper will focus on extensions of the basic method to include solution adaptation, time-dependent <span class="hlt">flow</span> simulation, and arbitrary rigid domain motion. The <span class="hlt">parallel</span> multilevel method makes use of on-the-fly <span class="hlt">parallel</span> domain decomposition to achieve extremely good scalability on large numbers of processors, and is coupled with an automatic coarse mesh generation algorithm for efficient processing by a multigrid smoother. Numerical results are presented demonstrating <span class="hlt">parallel</span> speed-ups of up to 435 on 512 processors. Solution-based adaptation may be keyed off truncation error estimates using tau-extrapolation or a variety of feature detection based refinement parameters. The multigrid method is extended to for time-dependent <span class="hlt">flows</span> through the use of a dual-time approach. The extension to rigid domain motion uses an Arbitrary Lagrangian-Eulerlarian (ALE) formulation, and results will be presented for a variety of two- and three-dimensional example problems with both simple and complex geometry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/924836','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/924836"><span id="translatedtitle">Laser sheet light <span class="hlt">flow</span> visualization for evaluating room <span class="hlt">air</span> flowsfrom Registers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Walker, Iain S.; Claret, Valerie; Smith, Brian</p> <p>2006-04-01</p> <p>Forced <span class="hlt">air</span> heating and cooling systems and whole house ventilation systems deliver <span class="hlt">air</span> to individual rooms in a house via supply registers located on walls ceilings or floors; and occasionally less straightforward locations like toe-kicks below cabinets. Ideally, the <span class="hlt">air</span> velocity out of the registers combined with the turbulence of the <span class="hlt">flow</span>, vectoring of <span class="hlt">air</span> by register vanes and geometry of register placement combine to mix the supply <span class="hlt">air</span> within the room. A particular issue that has been raised recently is the performance of multiple capacity and <span class="hlt">air</span> <span class="hlt">flow</span> HVAC systems. These systems vary the <span class="hlt">air</span> <span class="hlt">flow</span> rate through the distribution system depending on the system load, or if operating in a ventilation rather than a space conditioning mode. These systems have been developed to maximize equipment efficiency, however, the high efficiency ratings do not include any room mixing effects. At lower <span class="hlt">air</span> <span class="hlt">flow</span> rates, there is the possibility that room <span class="hlt">air</span> will be poorly mixed, leading to thermal stratification and reduced comfort for occupants. This can lead to increased energy use as the occupants adjust the thermostat settings to compensate and parts of the conditioned space have higher envelope temperature differences than for the well mixed case. In addition, lack of comfort can be a barrier to market acceptance of these higher efficiency systems To investigate the effect on room mixing of reduced <span class="hlt">air</span> <span class="hlt">flow</span> rates requires the measurement of mixing of supply <span class="hlt">air</span> with room <span class="hlt">air</span> throughout the space to be conditioned. This is a particularly difficult exercise if we want to determine the transient performance of the space conditioning system. Full scale experiments can be done in special test chambers, but the spatial resolution required to fully examine the mixing problem is usually limited by the sheer number of thermal sensors required. Current full-scale laboratory testing is therefore severely limited in its resolution. As an alternative, we used a water-filled scale model</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://hdl.handle.net/2060/19930091863','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930091863"><span id="translatedtitle">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('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFDR27009A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015APS..DFDR27009A&link_type=ABSTRACT"><span id="translatedtitle">Experimental study on bi-phase <span class="hlt">flow</span> <span class="hlt">Air</span>-Oil in Water Emulsion</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arnone, Davide; Poesio, Pietro</p> <p>2015-11-01</p> <p>Bi-phase slug <span class="hlt">flow</span> oil-in-water emulsion [5%-20%] and <span class="hlt">air</span> through a horizontal pipe (inner diameter 22mm) is experimentally studied. A test with water and <span class="hlt">air</span> has been performed as comparison. First we create and analyze the <span class="hlt">flow</span> pattern map to identify slug <span class="hlt">flow</span> liquid and <span class="hlt">air</span> inlet conditions. <span class="hlt">Flow</span> maps are similar for all the used liquid. A video analysis procedure using an high speed camera has been created to obtain all the characteristics of unit slugs: slug velocity, slug length, bubble velocity, bubbles length and slug frequency. We compare translational velocity and frequency with models finding a good agreement. We calculate the pdfs of the lengths to find the correlations between mean values and STD on different <span class="hlt">air</span> and liquid superficial velocities. We also perform pressure measurements along the pipe. We conclude that the percentage of oil-in- water has no influence on results in terms of velocity, lengths, frequency and pressure drop.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22253102','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22253102"><span id="translatedtitle">Study of <span class="hlt">flow</span> fields induced by surface dielectric barrier discharge actuator in low-pressure <span class="hlt">air</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Che, Xueke E-mail: st@mail.iee.ac.cn; Nie, Wansheng; Tian, Xihui; Hou, Zhiyong; He, Haobo; Zhou, Penghui; Zhou, Siyin; Yang, Chao; Shao, Tao E-mail: st@mail.iee.ac.cn</p> <p>2014-04-15</p> <p>Surface dielectric barrier discharge (SDBD) is a promising method for a <span class="hlt">flow</span> control. <span class="hlt">Flow</span> fields induced by a SDBD actuator driven by the ac voltage in static <span class="hlt">air</span> at low pressures varying from 1.0 to 27.7 kPa are measured by the particle image velocimetry method. The influence of the applied ac voltage frequency and magnitude on the induced <span class="hlt">flow</span> fields is studied. The results show that three different classes of <span class="hlt">flow</span> fields (wall jet <span class="hlt">flow</span> field, complex <span class="hlt">flow</span> field, and vortex-shape <span class="hlt">flow</span> field) can be induced by the SDBD actuator in the low-pressure <span class="hlt">air</span>. Among them, the wall jet <span class="hlt">flow</span> field is the same as the tangential jet at atmospheric pressure, which is, together with the vertical jet, the complex <span class="hlt">flow</span> field. The vortex-shape <span class="hlt">flow</span> field is composed of one vertical jet which points towards the wall and two opposite tangential jets. The complex and the vortex-shape <span class="hlt">flow</span> fields can be transformed to the wall jet <span class="hlt">flow</span> field when the applied ac voltage frequency and magnitude are changed. It is found that the discharge power consumption increases initially, decreases, and then increases again at the same applied ac voltage magnitude when the <span class="hlt">air</span> pressure decreases. The tangential velocity of the wall jet <span class="hlt">flow</span> field increases when the <span class="hlt">air</span> pressure decreases. It is however opposite for the complex <span class="hlt">flow</span> field. The variation of the applied ac voltage frequency influences differently three different <span class="hlt">flow</span> fields. When the applied ac voltage magnitude increases at the same applied ac voltage frequency, the maximal jet velocity increases, while the power efficiency increases only initially and then decreases again. The discharge power shows either linear or exponential dependences on the applied ac voltage magnitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5327174','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5327174"><span id="translatedtitle">High efficiency, down <span class="hlt">flow</span> <span class="hlt">air</span> filter sealing and support system</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mattison, A.H.</p> <p>1986-07-15</p> <p>An assembly of high efficiency <span class="hlt">air</span> filter units through which essentially all <span class="hlt">air</span> entering a clean space below the units must pass to remove particulate matter down to sub-micron size from the <span class="hlt">air</span>, the assembly comprising: (a) a plurality of <span class="hlt">air</span> filter units each having a filter core of pleated media sealed in <span class="hlt">air</span>-tight engagement on four sides to a surrounding, box-like, rigid frame, having side and end members; (b) means for supporting the filter units adjacent the upper surfaces thereof from structure above the space with adjacent units having the side and end members thereof providing adjoining vertical surfaces in closely spaced relation with the lower surfaces of the units in essentially the same horizontal plane to form at least a portion of the top of the space; and (c) a caulking material filling all spaces between the adjoining vertical surfaces of adjacent filter units, effectively sealing the spaces and providing the sole means preventing passage of <span class="hlt">air</span> around the units.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/6155','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/6155"><span id="translatedtitle">Development of a Low Pressure, <span class="hlt">Air</span> Atomized Oil Burner with High Atomizer <span class="hlt">Air</span> <span class="hlt">Flow</span>: Progress Report FY 1997</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Butcher, T.A.</p> <p>1998-01-01</p> <p>This report describes technical advances made to the concept of a low pressure, <span class="hlt">air</span> atomized oil burner for home heating applications. Currently all oil burners on the market are of the pressure atomized, retention head type. These burners have a lower firing rate limit of about 0.5 gallons per hour of oil, due to reliability problems related to small <span class="hlt">flow</span> passage sizes. High pressure <span class="hlt">air</span> atomized burners have been shown to be one route to avoid this problem but <span class="hlt">air</span> compressor cost and reliability have practically eliminated this approach. With the low pressure <span class="hlt">air</span> atomized burner the <span class="hlt">air</span> required for atomization can be provided by a fan at 5-8 inches of water pressure. A burner using this concept, termed the Fan-Atomized Burner or ''FAB'' has been developed and is currently being commercialized. In the head of the FAB, the combustion <span class="hlt">air</span> is divided into three parts, much like a conventional retention head burner. This report describes development work on a new concept in which 100% of the <span class="hlt">air</span> from the fan goes through the atomizer. The primary advantage of this approach is a great simplification of the head design. A nozzle specifically sized for this concept was built and is described in the report. Basic <span class="hlt">flow</span> pressure tests, cold <span class="hlt">air</span> velocity profiles, and atomization performance have been measured. A burner head/flame tube has been developed which promotes a toroidal recirculation zone near the nozzle for flame stability. The burner head has been tested in several furnace and boiler applications over the firing rate range 0.2 to 0.28 gallons per hour. In all cases the burner can operate with very low excess <span class="hlt">air</span> levels (under 10%) without producing smoke. Flue gas NO{sub x} concentration varied from 42 to 62 ppm at 3% O{sub 2}. The concept is seen as having significant potential and planned development efforts are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AIPC.1738.0002R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016AIPC.1738.0002R&link_type=ABSTRACT"><span id="translatedtitle">Instability due to interfacial tension in <span class="hlt">parallel</span> liquid-liquid <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>Rodriguez, Oscar M. H.</p> <p>2016-06-01</p> <p>The frequent occurrence of multiphase <span class="hlt">flows</span> in pipes has motivated a great research interest over the last decades. The particular case of liquid-liquid <span class="hlt">flow</span> is commonly encountered in the petroleum industry, where a number of applications involve oil-water <span class="hlt">flow</span> such as crude oil production in directional wells. However, it has not received the same attention when compared to gas-liquid <span class="hlt">flow</span>. In addition, most of the available information has to do with <span class="hlt">flow</span> in pipes. When it comes to <span class="hlt">flows</span> in annular ducts the data are scanty. A general transition criterion has been recently proposed in order to obtain the stratified and core-annular <span class="hlt">flow</span>-pattern transition boundaries in viscous oil-water <span class="hlt">flow</span>. The proposed criterion was based on an one-dimensional two-fluid model of liquid-liquid two-phase <span class="hlt">flow</span>. A stability analysis was carried out and interfacial tension is considered. A new destabilizing term arises, which is a function of the cross-section curvature of the interface. It is well accepted that interfacial tension favors the stable condition. However, the analysis of the new interfacial-tension term shows that it can actually destabilize the basic <span class="hlt">flow</span> pattern, playing an important role in regions of extreme volumetric fractions. Such an interesting effect seems to be more pronounced in <span class="hlt">flows</span> of viscous fluids and in annular-duct <span class="hlt">flow</span>. The effect of interfacial tension is explored and the advantages of using a more complete model are discussed and illustrated through comparisons with experimental data from the literature. The evaluation of the effects of fluid viscosity and interfacial tension allows the correction and enhancement of transition models based essentially on data of pipe <span class="hlt">flow</span> of low viscosity fluids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790034302&hterms=pyrolysis+equipment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpyrolysis%2Bequipment','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790034302&hterms=pyrolysis+equipment&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpyrolysis%2Bequipment"><span id="translatedtitle">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/cgi-bin/nph-data_query?bibcode=2014PhDT........72A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014PhDT........72A&link_type=ABSTRACT"><span id="translatedtitle">A <span class="hlt">parallel</span> offline CFD and closed-form approximation strategy for computationally efficient analysis of complex fluid <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>Allphin, Devin</p> <p></p> <p>Computational fluid dynamics (CFD) solution approximations for complex fluid <span class="hlt">flow</span> problems have become a common and powerful engineering analysis technique. These tools, though qualitatively useful, remain limited in practice by their underlying inverse relationship between simulation accuracy and overall computational expense. While a great volume of research has focused on remedying these issues inherent to CFD, one traditionally overlooked area of resource reduction for engineering analysis concerns the basic definition and determination of functional relationships for the studied fluid <span class="hlt">flow</span> variables. This artificial relationship-building technique, called meta-modeling or surrogate/offline approximation, uses design of experiments (DOE) theory to efficiently approximate non-physical coupling between the variables of interest in a fluid <span class="hlt">flow</span> analysis problem. By mathematically approximating these variables, DOE methods can effectively reduce the required quantity of CFD simulations, freeing computational resources for other analytical focuses. An idealized interpretation of a fluid <span class="hlt">flow</span> problem can also be employed to create suitably accurate approximations of fluid <span class="hlt">flow</span> variables for the purposes of engineering analysis. When used in <span class="hlt">parallel</span> with a meta-modeling approximation, a closed-form approximation can provide useful feedback concerning proper construction, suitability, or even necessity of an offline approximation tool. It also provides a short-circuit pathway for further reducing the overall computational demands of a fluid <span class="hlt">flow</span> analysis, again freeing resources for otherwise unsuitable resource expenditures. To validate these inferences, a design optimization problem was presented requiring the inexpensive estimation of aerodynamic forces applied to a valve operating on a simulated piston-cylinder heat engine. The determination of these forces was to be found using <span class="hlt">parallel</span> surrogate and exact approximation methods, thus evidencing the comparative</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/941385','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/941385"><span id="translatedtitle"><span class="hlt">Parallel</span> Computation of Three-Dimensional <span class="hlt">Flows</span> using Overlapping Grids with Adaptive Mesh Refinement</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Henshaw, W; Schwendeman, D</p> <p>2007-11-15</p> <p>This paper describes an approach for the numerical solution of time-dependent partial differential equations in complex three-dimensional domains. The domains are represented by overlapping structured grids, and block-structured adaptive mesh refinement (AMR) is employed to locally increase the grid resolution. In addition, the numerical method is implemented on <span class="hlt">parallel</span> distributed-memory computers using a domain-decomposition approach. The implementation is flexible so that each base grid within the overlapping grid structure and its associated refinement grids can be independently partitioned over a chosen set of processors. A modified bin-packing algorithm is used to specify the partition for each grid so that the computational work is evenly distributed amongst the processors. All components of the AMR algorithm such as error estimation, regridding, and interpolation are performed in <span class="hlt">parallel</span>. The <span class="hlt">parallel</span> time-stepping algorithm is illustrated for initial-boundary-value problems involving a linear advection-diffusion equation and the (nonlinear) reactive Euler equations. Numerical results are presented for both equations to demonstrate the accuracy and correctness of the <span class="hlt">parallel</span> approach. Exact solutions of the advection-diffusion equation are constructed, and these are used to check the corresponding numerical solutions for a variety of tests involving different overlapping grids, different numbers of refinement levels and refinement ratios, and different numbers of processors. The problem of planar shock diffraction by a sphere is considered as an illustration of the numerical approach for the Euler equations, and a problem involving the initiation of a detonation from a hot spot in a T-shaped pipe is considered to demonstrate the numerical approach for the reactive case. For both problems, the solutions are shown to be well resolved on the finest grid. The <span class="hlt">parallel</span> performance of the approach is examined in detail for the shock diffraction problem.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/27046603','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/27046603"><span id="translatedtitle">GPU-Based <span class="hlt">Parallelized</span> Solver for Large Scale Vascular Blood <span class="hlt">Flow</span> Modeling and Simulations.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Santhanam, Anand P; Neylon, John; Eldredge, Jeff; Teran, Joseph; Dutson, Erik; Benharash, Peyman</p> <p>2016-01-01</p> <p>Cardio-vascular blood <span class="hlt">flow</span> simulations are essential in understanding the blood <span class="hlt">flow</span> behavior during normal and disease conditions. To date, such blood <span class="hlt">flow</span> simulations have only been done at a macro scale level due to computational limitations. In this paper, we present a GPU based large scale solver that enables modeling the <span class="hlt">flow</span> even in the smallest arteries. A mechanical equivalent of the circuit based <span class="hlt">flow</span> modeling system is first developed to employ the GPU computing framework. Numerical studies were employed using a set of 10 million connected vascular elements. Run-time <span class="hlt">flow</span> analysis were performed to simulate vascular blockages, as well as arterial cut-off. Our results showed that we can achieve ~100 FPS using a GTX 680m and ~40 FPS using a Tegra K1 computing platform. PMID:27046603</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/501957','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/501957"><span id="translatedtitle"><span class="hlt">Flow</span> distribution in unglazed transpired plate solar <span class="hlt">air</span> heaters of large area</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Gunnewiek, L.H.; Brundrett, E.; Hollands, K.G.T.</p> <p>1996-10-01</p> <p>Unglazed transpired plate solar <span class="hlt">air</span> heaters have proven to be effective in heating outside <span class="hlt">air</span> on a once-through basis for ventilation and drying applications. Outside <span class="hlt">air</span> is sucked through unglazed plates having uniformly distributed perforations. The <span class="hlt">air</span> is drawn into a plenum behind the plate and then supplied to the application by fans. Large collectors have been built that cover the sides of sizable buildings, and the problem of designing the system so that the <span class="hlt">air</span> is sucked uniformly everywhere (or nearly so) has proven to be a challenging one. This article describes an analytical tool that has been developed to predict the <span class="hlt">flow</span> distribution over the collector. It is based on modelling the <span class="hlt">flow</span>-field in the plenum by means of a commercial CFD (computational fluid mechanics) code, incorporating a special set of boundary conditions to model the plate and the ambient <span class="hlt">air</span>. The article presents the 2D version of the code, and applies it to the problem of predicting the <span class="hlt">flow</span> distribution in still <span class="hlt">air</span> (no wind) conditions, a situation well treated by a 2D code. Results are presented for a wide range of conditions, and design implications are discussed. An interesting finding of the study is that the heat transfer at the back of the plate can play an important role, and because of this heat transfer, the efficiency of a collector in nonuniform <span class="hlt">flow</span> can actually be greater than that of the same collector in uniform <span class="hlt">flow</span>. 15 refs., 7 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982AtmEn..16.1243V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982AtmEn..16.1243V"><span id="translatedtitle">the nature of <span class="hlt">air</span> <span class="hlt">flow</span> near the inlets of blunt dust sampling probes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vincent, J. H.; Hutson, D.; Mark, D.</p> <p></p> <p>This paper sets out to describe the nature of <span class="hlt">air</span> <span class="hlt">flow</span> near blunt dust samplers in a way which allows a relatively simple assessment of their performances for collecting dust particles. Of particular importance is the shape of the limiting stream surface which divides the sampled <span class="hlt">air</span> from that which passes outside the sampler, and how this is affected by the free-stream <span class="hlt">air</span> velocity, the sampling <span class="hlt">flow</span> rate, and the shape of the sampler body. This was investigated for two-dimensional and axially-symmetric sampler systems by means of complementary experiments using electrolytic tank potential <span class="hlt">flow</span> analogues and a wind tunnel respectively. For extreme conditions the <span class="hlt">flow</span> of <span class="hlt">air</span> entering the sampling orifice may be wholly divergent or wholly convergent. For a wide range of intermediate conditions, however, the <span class="hlt">flow</span> first diverges then converges, exhibiting a so-called "spring onion effect". Whichever of these applies for a particular situation, the <span class="hlt">flow</span> may be considered to consist of two parts, the outer one dominated by the <span class="hlt">flow</span> about the sampler body and the inner one dominated by the <span class="hlt">flow</span> into the sampling orifice. Particle transport in this two-part <span class="hlt">flow</span> may be assessed using ideas borrowed from thin-walled probe theory.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850010643','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850010643"><span id="translatedtitle">On the <span class="hlt">flow</span> processes in sharply inclined and stalled airfoils in <span class="hlt">parallel</span> movement and rotation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kohler, M.</p> <p>1984-01-01</p> <p>The purpose of this study is to obtain a deeper insight into the complicated <span class="hlt">flow</span> processes on airfoils in the region of the buoyancy maxima. To this end calculated and experimental investigations are carried out on a straight stationary, a twisted stationary and a straight rotating rectangular wing. According to the available results the method gives results which can be applied sufficiently for <span class="hlt">flow</span> applied firmly on all sides for all rotation values. The reliability of the method may be questioned for a <span class="hlt">flow</span> undergoing transition from the attached to the separated state or for totally separated <span class="hlt">flow</span> and higher rotation values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/663549','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/663549"><span id="translatedtitle">COMIS -- an international multizone <span class="hlt">air-flow</span> and contaminant transport model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Feustel, H.E.</p> <p>1998-08-01</p> <p>A number of interzonal models have been developed to calculate <span class="hlt">air</span> <span class="hlt">flows</span> and pollutant transport mechanisms in both single and multizone buildings. A recent development in multizone <span class="hlt">air-flow</span> 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 <span class="hlt">air-flow</span> 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 and Community Systems program created a working group on multizone <span class="hlt">air-flow</span> modeling, which continued work on COMIS. The group`s objectives were to study physical phenomena causing <span class="hlt">air</span> <span class="hlt">flow</span> and pollutant (e.g., moisture) transport in multizone buildings, develop numerical modules to be integrated in the previously designed multizone <span class="hlt">air</span> <span class="hlt">flow</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730019412','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730019412"><span id="translatedtitle">Apparatus and method for generating large mass <span class="hlt">flow</span> of high temperature <span class="hlt">air</span> at hypersonic speeds</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sabol, A. P.; Stewart, R. B. (Inventor)</p> <p>1973-01-01</p> <p>High temperature, high mass <span class="hlt">air</span> <span class="hlt">flow</span> and a high Reynolds number test <span class="hlt">air</span> <span class="hlt">flow</span> in the Mach number 8-10 regime of adequate test <span class="hlt">flow</span> duration is attained by pressurizing a ceramic-lined storage tank with <span class="hlt">air</span> to a pressure of about 100 to 200 atmospheres. The <span class="hlt">air</span> is heated to temperatures of 7,000 to 8,000 R prior to introduction into the tank by passing the <span class="hlt">air</span> over an electric arc heater means. The <span class="hlt">air</span> cools to 5,500 to 6,000 R while in the tank. A decomposable gas such as nitrous oxide or a combustible gas such as propane is injected into the tank after pressurization and the heated pressurized <span class="hlt">air</span> in the tank is rapidly released through a Mach number 8-10 nozzle. The injected gas medium upon contact with the heated pressurized <span class="hlt">air</span> effects an exothermic reaction which maintains the pressure and temperature of the pressurized <span class="hlt">air</span> during the rapid release.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.T31A4556P&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.T31A4556P&link_type=ABSTRACT"><span id="translatedtitle">Microstructural analysis of the Greater Himalayan Sequence, Annapurna-Dhaulagiri Himalaya, central Nepal: Channel <span class="hlt">Flow</span> and Orogen-<span class="hlt">parallel</span> deformation.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parsons, A. J.; Phillips, R. J.; Lloyd, G. E.; Searle, M. P.; Law, R. D.</p> <p>2014-12-01</p> <p>Knowledge of deformation processes that occur in the lithosphere during orogenesis can be gained from microstructural analysis of exhumed terranes and shear zones. Here, we use Crystallographic Preferred Orientation (CPO) and Anisotropy of Magnetic Susceptibility (AMS) data to reveal the kinematic evolution of the metamorphic core of the Himalayan orogen, the Greater Himalayan Sequence (GHS). The Himalayan orogen is commonly explained with models of channel <span class="hlt">flow</span>, which describe the GHS as a partially molten, rheologically weak mid crustal channel. Extrusion of the channel was facilitated by coeval reverse- and normal-sense shear zones, at the lower and upper channel margins respectively. Whilst many thermobarometric studies support the occurrence of channel <span class="hlt">flow</span>, the spatial and temporal distribution of strain within the GHS is one aspect of the model that is yet to be fully resolved. We present a quantified strain proxy profile for the GHS in the Annapurna-Dhaulagiri region of central Nepal and compare our results with the kinematic predictions of the channel <span class="hlt">flow</span> model. Samples were collected along a NS transect through the Kali Gandaki valley of central Nepal for CPO and AMS analysis. Variations in CPO strength are used as a proxy for relative strain magnitude, whilst AMS data provide a proxy for strain ellipsoid shape. Combining this information with field and microstructural observations and thermobarometric constraints reveals the kinematic evolution of the GHS in this region. Low volumes of leucogranite and sillimanite bearing rocks and evidence of reverse-sense overprinting normal-sense shearing at the top of the GHS suggest that channel <span class="hlt">flow</span> was not as intense as model predictions. Additionally, observed EW mineral lineations and oblate strain ellipsoid proxies in the Upper GHS, indicative of three dimensional flattening and orogen <span class="hlt">parallel</span> stretching, cannot be explained by current channel <span class="hlt">flow</span> models. Whilst the results do not refute the occurrence of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009ApPhL..94b1501C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009ApPhL..94b1501C"><span id="translatedtitle">Atmospheric plasma jet array in <span class="hlt">parallel</span> electric and gas <span class="hlt">flow</span> fields for three-dimensional surface treatment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cao, Z.; Walsh, J. L.; Kong, M. G.</p> <p>2009-01-01</p> <p>This letter reports on electrical and optical characteristics of a ten-channel atmospheric pressure glow discharge jet array in <span class="hlt">parallel</span> electric and gas <span class="hlt">flow</span> fields. Challenged with complex three-dimensional substrates including surgical tissue forceps and sloped plastic plate of up to 15°, the jet array is shown to achieve excellent jet-to-jet uniformity both in time and in space. Its spatial uniformity is four times better than a comparable single jet when both are used to treat a 15° sloped substrate. These benefits are likely from an effective self-adjustment mechanism among individual jets facilitated by individualized ballast and spatial redistribution of surface charges.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/836589','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/836589"><span id="translatedtitle">Piecewise - Parabolic Methods for <span class="hlt">Parallel</span> Computation with Applications to Unstable Fluid <span class="hlt">Flow</span> in 2 and 3 Dimensions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Woodward, P. R.</p> <p>2003-03-26</p> <p>This report summarizes the results of the project entitled, ''Piecewise-Parabolic Methods for <span class="hlt">Parallel</span> Computation with Applications to Unstable Fluid <span class="hlt">Flow</span> in 2 and 3 Dimensions'' This project covers a span of many years, beginning in early 1987. It has provided over that considerable period the core funding to my research activities in scientific computation at the University of Minnesota. It has supported numerical algorithm development, application of those algorithms to fundamental fluid dynamics problems in order to demonstrate their effectiveness, and the development of scientific visualization software and systems to extract scientific understanding from those applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940025146','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940025146"><span id="translatedtitle">Laminar <span class="hlt">Flow</span> Supersonic Wind Tunnel primary <span class="hlt">air</span> injector</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, Brooke Edward</p> <p>1993-01-01</p> <p>This paper describes the requirements, design, and prototype testing of the flex-section and hinge seals for the Laminar <span class="hlt">Flow</span> Supersonic Wind Tunnel Primary Injector. The supersonic atmospheric primary injector operates between Mach 1.8 and Mach 2.2 with mass-<span class="hlt">flow</span> rates of 62 to 128 lbm/s providing the necessary pressure reduction to operate the tunnel in the desired Reynolds number (Re) range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/223877','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/223877"><span id="translatedtitle">Technique for measuring <span class="hlt">air</span> <span class="hlt">flow</span> and carbon dioxide flux in large, open-top chambers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Ham, J.M.; Owensby, C.E.; Coyne, P.I.</p> <p>1993-10-01</p> <p>Open-Top Chambers (OTCs) are commonly used to evaluate the effect of CO{sub 2},O{sub 3}, and other trace gases on vegetation. This study developed and tested a new technique for measuring forced <span class="hlt">air</span> <span class="hlt">flow</span> and net CO{sub 2} flux from OTCs. Experiments were performed with a 4.5-m diam. OTC with a sealed floor and a specialized <span class="hlt">air</span> delivery system. <span class="hlt">Air</span> <span class="hlt">flow</span> through the chamber was computed with the Bernoulli equation using measurements of the pressure differential between the <span class="hlt">air</span> delivery ducts and the chamber interior. An independent measurement of <span class="hlt">air</span> <span class="hlt">flow</span> was made simultaneously to calibrate and verify the accuracy of the Bernoulli relationship. The CO{sub 2} flux density was calculated as the product of chamber <span class="hlt">air</span> <span class="hlt">flow</span> and the difference in CO{sub 2} concentration between the <span class="hlt">air</span> entering and exhausting from the OTC (C{sub in}-C{sub out}). Accuracy was evaluated by releasing CO{sub 2} within the OTC at known rates. Data were collected with OTCs at ambient and elevated CO{sub 2} ({approx}700 {mu}mol{sup -1}). Results showed the Bernoulli equation, with a <span class="hlt">flow</span> coefficient of 0.7, accurately measured <span class="hlt">air</span> <span class="hlt">flow</span> in the OTC within {+-}5% regardless of <span class="hlt">flow</span> rate and <span class="hlt">air</span> duct geometry. Experiments in ambient OTCs showed CO{sub 2} flux density ({mu}mol m{sup -2} s{sup -1}), computed from 2-min averages of <span class="hlt">air</span> <span class="hlt">flow</span> and C{sub in} - C{sub out,} was typically within {+-} 10% of actual flux, provided that the exit <span class="hlt">air</span> velocity at the top of the OTC was greater than 0.6 m s{sup -1}. Obtaining the same accuracy in CO{sub 2}-enriched OTCs required a critical exit velocity near 1.2 m s{sup -1} to minimize the incursion of ambient <span class="hlt">air</span> and prevent contamination of exit gas sample. When flux data were integrated over time to estimate daily CO{sub 2} flux ({mu}mol m{sup -2} d{sup -1}), actual and measured values agreed to within {+-}2% for both ambient and CO{sub 2}-enriched chambers, suggesting that accurate measurements of daily net C exchange are possible with this technique.</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('http://adsabs.harvard.edu/abs/2015APS..DFDM40003S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDM40003S"><span id="translatedtitle">Numerical simulation of the dynamics of a flexible cantilevered plate subjected to a perpendicular or a <span class="hlt">parallel</span> 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>Sansas, Fabien; Laurrendeau, Eric; Gosselin, Frederick</p> <p>2015-11-01</p> <p>We focus on the dynamic deformation of a cantilevered flexible plate immersed in a fluid <span class="hlt">flow</span>. The following two-dimensional numerical study is based on a large deformation beam model solved by finite difference. The fluid is computed by an in-house Arbitrary Eulerian-Lagrangian (ALE) compressible CFD solver. After a validation and verification procedures confirming second order accuracy, two different cases are examined. The first case serves as a validation exercise for the coupling procedure with the <span class="hlt">flow</span> <span class="hlt">parallel</span> to the plate: its leading edge is clamped and the trailing end is free. This case models a flapping flag for which the stability of the plate as a function of its mass and <span class="hlt">flow</span> velocity are investigated. Different vibration modes are compared to previous numerical and experimental results. The second case is that of a plate clamped at its middle, the <span class="hlt">flow</span> being perpendicular to its initial shape. The plate deforms by bending in the <span class="hlt">flow</span> direction. Streamlining and projected area reduction lead to fluid forces reduction but, at some point, dynamic instability occurs. Preliminary results of this instability phenomena are presented, namely the various dynamic behaviours and the trade-offs between streamlining and instability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhST..142a4011Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhST..142a4011Z"><span id="translatedtitle">A <span class="hlt">parallel</span> finite-volume finite-element method for transient compressible turbulent <span class="hlt">flows</span> with heat transfer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ziaei-Rad, Masoud</p> <p>2010-12-01</p> <p>In this paper, a two-dimensional numerical scheme is presented for the simulation of turbulent, viscous, transient compressible <span class="hlt">flows</span> in the simultaneously developing hydraulic and thermal boundary layer region. The numerical procedure is a finite-volume-based finite-element method applied to unstructured grids. This combination together with a new method applied for the boundary conditions allows for accurate computation of the variables in the entrance region and for a wide range of <span class="hlt">flow</span> fields from subsonic to transonic. The Roe-Riemann solver is used for the convective terms, whereas the standard Galerkin technique is applied for the viscous terms. A modified κ-ɛ model with a two-layer equation for the near-wall region combined with a compressibility correction is used to predict the turbulent viscosity. <span class="hlt">Parallel</span> processing is also employed to divide the computational domain among the different processors to reduce the computational time. The method is applied to some test cases in order to verify the numerical accuracy. The results show significant differences between incompressible and compressible <span class="hlt">flows</span> in the friction coefficient, Nusselt number, shear stress and the ratio of the compressible turbulent viscosity to the molecular viscosity along the developing region. A transient <span class="hlt">flow</span> generated after an accidental rupture in a pipeline was also studied as a test case. The results show that the present numerical scheme is stable, accurate and efficient enough to solve the problem of transient wall-bounded <span class="hlt">flow</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19690000043','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19690000043"><span id="translatedtitle">Propagation of density disturbances in <span class="hlt">air</span>-water <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>Nassos, G. P.</p> <p>1969-01-01</p> <p>Study investigated the behavior of density waves propagating vertically in an atmospheric pressure <span class="hlt">air</span>-water system using a technique based on the correlation between density change and electric resistivity. This information is of interest to industries working with heat transfer systems and fluid power and control systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/106986','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/106986"><span id="translatedtitle">A criterion for the onset of slugging in horizontal stratified <span class="hlt">air</span>-water countercurrent <span class="hlt">flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chun, Moon-Hyun; Lee, Byung-Ryung; Kim, Yang-Seok</p> <p>1995-09-01</p> <p>This paper presents an experimental and theoretical investigation of wave height and transition criterion from wavy to slug <span class="hlt">flow</span> in horizontal <span class="hlt">air</span>-water countercurrent stratified <span class="hlt">flow</span> conditions. A theoretical formula for the wave height in a stratified wavy <span class="hlt">flow</span> regime has been developed using the concept of total energy balance over a wave crest to consider the shear stress acting on the interface of two fluids. From the limiting condition of the formula for the wave height, a necessary criterion for transition from a stratified wavy <span class="hlt">flow</span> to a slug <span class="hlt">flow</span> has been derived. A series of experiments have been conducted changing the non-dimensional water depth and the <span class="hlt">flow</span> rates of <span class="hlt">air</span> in a horizontal pipe and a duct. Comparisons between the measured data and the predictions of the present theory show that the agreement is within {plus_minus}8%.</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 id="translatedtitle">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://www.ncbi.nlm.nih.gov/pubmed/22293724','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/22293724"><span id="translatedtitle"><span class="hlt">Flow</span> and containment characteristics of an <span class="hlt">air</span>-curtain fume hood operated at high temperatures.</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; Huang, Rong Fung; Hsin, Pei-Yi; Hsu, Ching Min; Chen, Chun-Wann</p> <p>2012-01-01</p> <p>The <span class="hlt">flow</span> and leakage characteristics of the <span class="hlt">air</span>-curtain fume hood under high temperature operation (between 100°C and 250°C) were studied. Laser-assisted <span class="hlt">flow</span> visualization technique was used to reveal the hot plume movements in the cabinet and the critical conditions for the hood-top leakage. The sulfur hexafluoride tracer-gas concentration test method was employed to examine the containment spillages from the sash opening and the hood top. It was found that the primary parameters dominating the behavior of the <span class="hlt">flow</span> field and hood performance are the sash height and the suction velocity as an <span class="hlt">air</span>-curtain hood is operated at high temperatures. At large sash height and low suction velocity, the <span class="hlt">air</span> curtain broke down and accompanied with three-dimensional <span class="hlt">flow</span> in the cabinet. Since the suction velocity was low and the sash opening was large, the makeup <span class="hlt">air</span> drawn down from the hood top became insufficient to counter act the rising hot plume. Under this situation, containment leakage from the sash opening and the hood top was observed. At small sash opening and high suction velocity, the <span class="hlt">air</span> curtain presented robust characteristics and the makeup <span class="hlt">air</span> <span class="hlt">flow</span> from the hood top was sufficiently large. Therefore the containment leakages from the sash opening and the hood top were not observed. According to the results of experiments, quantitative operation sash height and suction velocity corresponding to the operation temperatures were suggested. PMID:22293724</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008TePhL..34...52C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008TePhL..34...52C"><span id="translatedtitle">Vertical <span class="hlt">air</span> circulation in a low-speed lateral <span class="hlt">flow</span> wind turbine with rotary blades</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheboxarov, Vik. V.; Cheboxarov, Val. V.</p> <p>2008-01-01</p> <p>The model of a large-scale lateral <span class="hlt">flow</span> wind turbine with rotary blades is presented and the conditions of numerical aerodynamic investigation of this turbine are described. The results of numerical experiments show that <span class="hlt">air</span> <span class="hlt">flowing</span> past the turbine exhibits a considerable vertical (axial) circulation, which increases the power coefficient of the turbine. In the inner space of the turbine, two stable vortices are formed through which retarded streams partly leave the turbine upon <span class="hlt">flowing</span> past the windward side, to be replaced by faster streams from adjacent layers of <span class="hlt">air</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/925544','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/925544"><span id="translatedtitle">TMVOC-MP: a <span class="hlt">parallel</span> numerical simulator for Three-PhaseNon-isothermal <span class="hlt">Flows</span> of Multicomponent Hydrocarbon Mixtures inporous/fractured media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Zhang, Keni; Yamamoto, Hajime; Pruess, Karsten</p> <p>2008-02-15</p> <p>TMVOC-MP is a massively <span class="hlt">parallel</span> version of the TMVOC code (Pruess and Battistelli, 2002), a numerical simulator for three-phase non-isothermal <span class="hlt">flow</span> of water, gas, and a multicomponent mixture of volatile organic chemicals (VOCs) in multidimensional heterogeneous porous/fractured media. TMVOC-MP was developed by introducing massively <span class="hlt">parallel</span> computing techniques into TMVOC. It retains the physical process model of TMVOC, designed for applications to contamination problems that involve hydrocarbon fuels or organic solvents in saturated and unsaturated zones. TMVOC-MP can model contaminant behavior under 'natural' environmental conditions, as well as for engineered systems, such as soil vapor extraction, groundwater pumping, or steam-assisted source remediation. With its sophisticated <span class="hlt">parallel</span> computing techniques, TMVOC-MP can handle much larger problems than TMVOC, and can be much more computationally efficient. TMVOC-MP models multiphase fluid systems containing variable proportions of water, non-condensible gases (NCGs), and water-soluble volatile organic chemicals (VOCs). The user can specify the number and nature of NCGs and VOCs. There are no intrinsic limitations to the number of NCGs or VOCs, although the arrays for fluid components are currently dimensioned as 20, accommodating water plus 19 components that may be either NCGs or VOCs. Among them, NCG arrays are dimensioned as 10. The user may select NCGs from a data bank provided in the software. The currently available choices include O{sub 2}, N{sub 2}, CO{sub 2}, CH{sub 4}, ethane, ethylene, acetylene, and <span class="hlt">air</span> (a pseudo-component treated with properties averaged from N{sub 2} and O{sub 2}). Thermophysical property data of VOCs can be selected from a chemical data bank, included with TMVOC-MP, that provides parameters for 26 commonly encountered chemicals. Users also can input their own data for other fluids. The fluid components may partition (volatilize and/or dissolve) among gas, aqueous, and NAPL</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24129356','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24129356"><span id="translatedtitle"><span class="hlt">Parallel</span> array of nanochannels grafted with polymer-brushes-stabilized Au nanoparticles for <span class="hlt">flow</span>-through catalysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Jianxi; Ma, Shuanhong; Wei, Qiangbing; Jia, Lei; Yu, Bo; Wang, Daoai; Zhou, Feng</p> <p>2013-12-01</p> <p>Smart systems on the nanometer scale for continuous <span class="hlt">flow</span>-through reaction present fascinating advantages in heterogeneous catalysis, in which a <span class="hlt">parallel</span> array of straight nanochannels offers a platform with high surface area for assembling and stabilizing metallic nanoparticles working as catalysts. Herein we demonstrate a method for finely modifying the nanoporous anodic aluminum oxide (AAO), and further integration of nanoreactors. By using atomic transfer radical polymerization (ATRP), polymer brushes were successfully grafted on the inner wall of the nanochannels of the AAO membrane, followed by exchanging counter ions with a precursor for nanoparticles (NPs), and used as the template for deposition of well-defined Au NPs. The membrane was used as a functional nanochannel for novel <span class="hlt">flow</span>-through catalysis. High catalytic performance and instantaneous separation of products from the reaction system was achieved in reduction of 4-nitrophenol. PMID:24129356</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012CNSNS..17.1576J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012CNSNS..17.1576J"><span id="translatedtitle">Effect of viscous dissipation on natural convection <span class="hlt">flow</span> between vertical <span class="hlt">parallel</span> plates with time-periodic boundary conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jha, Basant K.; Ajibade, Abiodun O.</p> <p>2012-04-01</p> <p>This article investigates the natural convection <span class="hlt">flow</span> of viscous incompressible fluid in a channel formed by two infinite vertical <span class="hlt">parallel</span> plates. Fully developed laminar <span class="hlt">flow</span> is considered in a vertical channel with steady-periodic temperature regime on the boundaries. The effect of internal heating by viscous dissipation is taken into consideration. Separating the velocity and temperature fields into steady and periodic parts, the resulting second order ordinary differential equations are solved to obtain the expressions for velocity, and temperature. The amplitudes and phases of temperature and velocity are also obtained as well as the rate of heat transfer and the skin-friction on the plates. In presence of viscous dissipation, fluids of relatively small Prandtl number has higher temperature than the channel plates and as such, heat is being transferred from the fluid to the plate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011Th%26Ae..18..561J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011Th%26Ae..18..561J"><span id="translatedtitle">Effect of viscous dissipation on natural convection <span class="hlt">flow</span> between vertical <span class="hlt">parallel</span> plates with time-periodic boundary conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jha, B. K.; Ajibade, A. O.</p> <p>2011-12-01</p> <p>This article investigates the natural convection <span class="hlt">flow</span> of viscous incompressible fluid in a channel formed by two infinite vertical <span class="hlt">parallel</span> plates. Fully developed laminar <span class="hlt">flow</span> is considered in a vertical channel with steady-periodic temperature regime on the boundaries. The effect of internal heating by viscous dissipation is taken into consideration. Separating the velocity and temperature fields into steady and periodic parts, the resulting second order ordinary differential equations are solved to obtain the expressions for velocity, and temperature. The amplitudes and phases of temperature and velocity are also obtained as well as the rate of heat transfer and the skin friction on the plates. In presence of viscous dissipation, fluids of relatively small Prandtl number has higher temperature than the channel plates and as such, heat is being transferred from the fluid to the plate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760015112','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760015112"><span id="translatedtitle">Blade row dynamic digital compressor program. Volume 1: J85 clean inlet <span class="hlt">flow</span> and <span class="hlt">parallel</span> compressor models</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tesch, W. A.; Steenken, W. G.</p> <p>1976-01-01</p> <p>The results are presented of a one-dimensional dynamic digital blade row compressor model study of a J85-13 engine operating with uniform and with circumferentially distorted inlet <span class="hlt">flow</span>. Details of the geometry and the derived blade row characteristics used to simulate the clean inlet performance are given. A stability criterion based upon the self developing unsteady internal <span class="hlt">flows</span> near surge provided an accurate determination of the clean inlet surge line. The basic model was modified to include an arbitrary extent multi-sector <span class="hlt">parallel</span> compressor configuration for investigating 180 deg 1/rev total pressure, total temperature, and combined total pressure and total temperature distortions. The combined distortions included opposed, coincident, and 90 deg overlapped patterns. The predicted losses in surge pressure ratio matched the measured data trends at all speeds and gave accurate predictions at high corrected speeds where the slope of the speed lines approached the vertical.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050214769','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050214769"><span id="translatedtitle">Thin-Film <span class="hlt">Air-Mass-Flow</span> Sensor of Improved Design Developed</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fralick, Gustave C.; Wrbanek, John D.; Hwang, Danny P.</p> <p>2003-01-01</p> <p>Researchers at the NASA Glenn Research Center have developed a new <span class="hlt">air-mass-flow</span> sensor to solve the problems of existing mass <span class="hlt">flow</span> sensor designs. NASA's design consists of thin-film resistors in a Wheatstone bridge arrangement. The resistors are fabricated on a thin, constant-thickness airfoil to minimize disturbance to the airflow being measured. The following photograph shows one of NASA s prototype sensors. In comparison to other <span class="hlt">air-mass-flow</span> sensor designs, NASA s thin-film sensor is much more robust than hot wires, causes less airflow disturbance than pitot tubes, is more accurate than vane anemometers, and is much simpler to operate than thermocouple rakes. NASA s thin-film <span class="hlt">air-mass-flow</span> sensor works by converting the temperature difference seen at each leg of the thin-film Wheatstone bridge into a mass-<span class="hlt">flow</span> rate. The following figure shows a schematic of this sensor with <span class="hlt">air</span> <span class="hlt">flowing</span> around it. The sensor operates as follows: current is applied to the bridge, which increases its temperature. If there is no <span class="hlt">flow</span>, all the arms are heated equally, the bridge remains in balance, and there is no signal. If there is <span class="hlt">flow</span>, the <span class="hlt">air</span> passing over the upstream legs of the bridge reduces the temperature of the upstream legs and that leads to reduced electrical resistance for those legs. After the <span class="hlt">air</span> has picked up heat from the upstream legs, it continues and passes over the downstream legs of the bridge. The heated <span class="hlt">air</span> raises the temperature of these legs, increasing their electrical resistance. The resistance difference between the upstream and downstream legs unbalances the bridge, causing a voltage difference that can be amplified and calibrated to the airflow rate. Separate sensors mounted on the airfoil measure the temperature of the airflow, which is used to complete the calculation for the mass of <span class="hlt">air</span> passing by the sensor. A current application for <span class="hlt">air-mass-flow</span> sensors is as part of the intake system for an internal combustion engine. A mass-<span class="hlt">flow</span> sensor is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950017018','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950017018"><span id="translatedtitle">Phase 2: HGM <span class="hlt">air</span> <span class="hlt">flow</span> tests in support of HEX vane investigation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cox, G. B., Jr.; Steele, L. L.; Eisenhart, D. W.</p> <p>1993-01-01</p> <p>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 <span class="hlt">flow</span> 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 <span class="hlt">air</span> <span class="hlt">flow</span> tests of the ATD HPOTP turbine turnaround duct flowpath in the MSFC Phase 2 HGM <span class="hlt">air</span> <span class="hlt">flow</span> model. These tests included HEX vane strain gages and additional fluctuating pressure gages in the turnaround duct and HEX vane flowpath area. Three-dimensional <span class="hlt">flow</span> 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 <span class="hlt">flow</span> profile and velocity components, with the objective of reproducing <span class="hlt">flow</span> conditions calculated for the actual ATD HPOTP hardware. Testing was done at the MSFC SSME Dynamic Fluid <span class="hlt">Air</span> <span class="hlt">Flow</span> (Dual-Leg) Facility, at <span class="hlt">air</span> supply pressures between 50 and 250 psia. Combinations of turbine exit Mach number and pressure level were run to investigate the effect of <span class="hlt">flow</span> regime. Information presented includes: (1) Descriptions of turbine simulator modifications to produce the desired <span class="hlt">flow</span> environment; (2) Types and locations for instrumentation added to the <span class="hlt">flow</span> model for improved diagnostic capability; (3) Evaluation of the effect of changes to the turbine simulator flowpath on the turbine exit <span class="hlt">flow</span> environment; and (4</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993cfda.work.1607C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993cfda.work.1607C"><span id="translatedtitle">Phase 2: HGM <span class="hlt">air</span> <span class="hlt">flow</span> tests in support of HEX vane investigation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cox, G. B., Jr.; Steele, L. L.; Eisenhart, D. W.</p> <p>1993-07-01</p> <p>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 <span class="hlt">flow</span> 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 <span class="hlt">air</span> <span class="hlt">flow</span> tests of the ATD HPOTP turbine turnaround duct flowpath in the MSFC Phase 2 HGM <span class="hlt">air</span> <span class="hlt">flow</span> model. These tests included HEX vane strain gages and additional fluctuating pressure gages in the turnaround duct and HEX vane flowpath area. Three-dimensional <span class="hlt">flow</span> 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 <span class="hlt">flow</span> profile and velocity components, with the objective of reproducing <span class="hlt">flow</span> conditions calculated for the actual ATD HPOTP hardware. Testing was done at the MSFC SSME Dynamic Fluid <span class="hlt">Air</span> <span class="hlt">Flow</span> (Dual-Leg) Facility, at <span class="hlt">air</span> supply pressures between 50 and 250 psia. Combinations of turbine exit Mach number and pressure level were run to investigate the effect of <span class="hlt">flow</span> regime. Information presented includes: (1) Descriptions of turbine simulator modifications to produce the desired <span class="hlt">flow</span> environment; (2) Types and locations for instrumentation added to the <span class="hlt">flow</span> model for improved diagnostic capability; (3) Evaluation of the effect of changes to the turbine simulator flowpath on the turbine exit <span class="hlt">flow</span> environment; and (4</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ThCFD.tmp...12B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ThCFD.tmp...12B"><span id="translatedtitle">Bifurcations of a creeping <span class="hlt">air</span>-water <span class="hlt">flow</span> in a conical container</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Balci, Adnan; Brøns, Morten; Herrada, Miguel A.; Shtern, Vladimir N.</p> <p>2016-04-01</p> <p>This numerical study describes the eddy emergence and transformations in a slow steady axisymmetric <span class="hlt">air</span>-water <span class="hlt">flow</span>, driven by a rotating top disk in a vertical conical container. As water height Hw and cone half-angle β vary, numerous <span class="hlt">flow</span> metamorphoses occur. They are investigated for β =30°, 45°, and 60°. For small Hw , the <span class="hlt">air</span> <span class="hlt">flow</span> is multi-cellular with clockwise meridional circulation near the disk. The <span class="hlt">air</span> <span class="hlt">flow</span> becomes one cellular as Hw exceeds a threshold depending on β . For all β , the water <span class="hlt">flow</span> has an unbounded number of eddies whose size and strength diminish as the cone apex is approached. As the water level becomes close to the disk, the outmost water eddy with clockwise meridional circulation expands, reaches the interface, and induces a thin layer with anticlockwise circulation in the <span class="hlt">air</span>. Then this layer expands and occupies the entire <span class="hlt">air</span> domain. The physical reasons for the <span class="hlt">flow</span> transformations are provided. The results are of fundamental interest and can be relevant for aerial bioreactors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21277303','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21277303"><span id="translatedtitle">Influence of the <span class="hlt">parallel</span> nonlinearity on zonal <span class="hlt">flows</span> and heat transport in global gyrokinetic particle-in-cell simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jolliet, S.; McMillan, B. F.; Vernay, T.; Villard, L.; Hatzky, R.; Bottino, A.; Angelino, P.</p> <p>2009-07-15</p> <p>In this paper, the influence of the <span class="hlt">parallel</span> nonlinearity on zonal <span class="hlt">flows</span> and heat transport in global particle-in-cell ion-temperature-gradient simulations is studied. Although this term is in theory orders of magnitude smaller than the others, several authors [L. Villard, P. Angelino, A. Bottino et al., Plasma Phys. Contr. Fusion 46, B51 (2004); L. Villard, S. J. Allfrey, A. Bottino et al., Nucl. Fusion 44, 172 (2004); J. C. Kniep, J. N. G. Leboeuf, and V. C. Decyck, Comput. Phys. Commun. 164, 98 (2004); J. Candy, R. E. Waltz, S. E. Parker et al., Phys. Plasmas 13, 074501 (2006)] found different results on its role. The study is performed using the global gyrokinetic particle-in-cell codes TORB (theta-pinch) [R. Hatzky, T. M. Tran, A. Koenies et al., Phys. Plasmas 9, 898 (2002)] and ORB5 (tokamak geometry) [S. Jolliet, A. Bottino, P. Angelino et al., Comput. Phys. Commun. 177, 409 (2007)]. In particular, it is demonstrated that the <span class="hlt">parallel</span> nonlinearity, while important for energy conservation, affects the zonal electric field only if the simulation is noise dominated. When a proper convergence is reached, the influence of <span class="hlt">parallel</span> nonlinearity on the zonal electric field, if any, is shown to be small for both the cases of decaying and driven turbulence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3951970','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3951970"><span id="translatedtitle"><span class="hlt">Parallel</span> microfluidic synthesis of size-tunable polymeric nanoparticles using 3D <span class="hlt">flow</span> focusing towards in vivo study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lim, Jong-Min; Bertrand, Nicolas; Valencia, Pedro M.; Rhee, Minsoung; Langer, Robert; Jon, Sangyong; Farokhzad, Omid C.; Karnik, Rohit</p> <p>2014-01-01</p> <p>Microfluidic synthesis of nanoparticles (NPs) can enhance the controllability and reproducibility in physicochemical properties of NPs compared to bulk synthesis methods. However, applications of microfluidic synthesis are typically limited to in vitro studies due to low production rates. Herein, we report the <span class="hlt">parallelization</span> of NP synthesis by 3D hydrodynamic <span class="hlt">flow</span> focusing (HFF) using a multilayer microfluidic system to enhance the production rate without losing the advantages of reproducibility, controllability, and robustness. Using <span class="hlt">parallel</span> 3D HFF, polymeric poly(lactide-co-glycolide)-b-polyethyleneglycol (PLGA-PEG) NPs with sizes tunable in the range of 13–150 nm could be synthesized reproducibly with high production rate. As a proof of concept, we used this system to perform in vivo pharmacokinetic and biodistribution study of small (20 nm diameter) PLGA-PEG NPs that are otherwise difficult to synthesize. Microfluidic <span class="hlt">parallelization</span> thus enables synthesis of NPs with tunable properties with production rates suitable for both in vitro and in vivo studies. PMID:23969105</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3627095','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3627095"><span id="translatedtitle">A fluid–structure interaction model to characterize bone cell stimulation in <span class="hlt">parallel</span>-plate <span class="hlt">flow</span> chamber systems</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vaughan, T. J.; Haugh, M. G.; McNamara, L. M.</p> <p>2013-01-01</p> <p>Bone continuously adapts its internal structure to accommodate the functional demands of its mechanical environment and strain-induced <span class="hlt">flow</span> of interstitial fluid is believed to be the primary mediator of mechanical stimuli to bone cells in vivo. In vitro investigations have shown that bone cells produce important biochemical signals in response to fluid <span class="hlt">flow</span> applied using <span class="hlt">parallel</span>-plate <span class="hlt">flow</span> chamber (PPFC) systems. However, the exact mechanical stimulus experienced by the cells within these systems remains unclear. To fully understand this behaviour represents a most challenging multi-physics problem involving the interaction between deformable cellular structures and adjacent fluid <span class="hlt">flows</span>. In this study, we use a fluid–structure interaction computational approach to investigate the nature of the mechanical stimulus being applied to a single osteoblast cell under fluid <span class="hlt">flow</span> within a PPFC system. The analysis decouples the contribution of pressure and shear stress on cellular deformation and for the first time highlights that cell strain under <span class="hlt">flow</span> is dominated by the pressure in the PPFC system rather than the applied shear stress. Furthermore, it was found that strains imparted on the cell membrane were relatively low whereas significant strain amplification occurred at the cell–substrate interface. These results suggest that strain transfer through focal attachments at the base of the cell are the primary mediators of mechanical signals to the cell under <span class="hlt">flow</span> in a PPFC system. Such information is vital in order to correctly interpret biological responses of bone cells under in vitro stimulation and elucidate the mechanisms associated with mechanotransduction in vivo. PMID:23365189</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930081225','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930081225"><span id="translatedtitle">The Nature of <span class="hlt">Air</span> <span class="hlt">Flow</span> About the Tail of an Airplane in a Spin</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Scudder, N F; Miller, M P</p> <p>1932-01-01</p> <p><span class="hlt">Air</span> <span class="hlt">flow</span> about the fuselage and empennage during a high-angle-of-attack spin was made visible in flight by means of titanium-tetrachloride smoke and was photographed with a motion-picture camera. The angular relation of the direction of the smoke streamer to the airplane axes was computed and compared with the angular direction of the motion in space derived from instrument measurement of the spin of the airplane for a nearly identical mass distribution. The results showed that the fin and upper part of the rudder were almost completely surrounded by dead <span class="hlt">air</span>, which would render them inoperative; that the <span class="hlt">flow</span> around the lower portion of the rudder and the fuselage was nonturbulent; and that <span class="hlt">air</span> <span class="hlt">flowing</span> past the cockpit in a high-angle-of-attack spin could not subsequently <span class="hlt">flow</span> around control surfaces.</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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864528','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3864528"><span id="translatedtitle">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).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPJWC..9202014D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPJWC..9202014D"><span id="translatedtitle">Analysis of parameters of <span class="hlt">air</span> passing through the rain zone in a 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>Dvořák, Lukáš; Čížek, Jan; Nožička, Jiří</p> <p>2015-05-01</p> <p>The research in the field of cooling towers shows that a rigorous determination of each parameter of <span class="hlt">air</span> passing through areas with water drops is increasingly important. The transfer of heat, mass and momentum is represented, on the side of the <span class="hlt">air</span>, as temperature and humidity increase and static pressure decrease due to the interaction between the <span class="hlt">flowing</span> <span class="hlt">air</span> and falling drops. The present article focuses on the description of the experimental setup allowing the measurement of these parameters on both the <span class="hlt">air</span> and the water side, and possible ways to analyze measured values.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3655160','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3655160"><span id="translatedtitle">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('http://www.ncbi.nlm.nih.gov/pubmed/23691194','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23691194"><span id="translatedtitle">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. PMID:23691194</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhFl...22b2103Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010PhFl...22b2103Y&link_type=ABSTRACT"><span id="translatedtitle">Effect of normal and <span class="hlt">parallel</span> magnetic fields on the stability of interfacial <span class="hlt">flows</span> of magnetic fluids in channels</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yecko, Philip</p> <p>2010-02-01</p> <p>The effect of an imposed magnetic field on the linear stability of immiscible two-fluid Poiseuille <span class="hlt">flow</span> in a channel is examined for low Reynolds numbers. Surface tension acts on the interface, the fluids have different densities and viscosities, and one fluid is magnetic (ferrofluid). A Langevin function is used to model the fluid magnetization, resulting in a nonlinear permeability; the stability properties depend on this permeability relation both directly and indirectly, through the base state solution. Uniform magnetic fields applied normal or <span class="hlt">parallel</span> to the interface both lead to an interfacial instability. Normal fields excite longer wavelength modes, generally having higher growth rates, but <span class="hlt">parallel</span> fields can excite faster growing modes in high permeability fluids at large applied field strength. Whether or not the field stabilizes or destabilizes the <span class="hlt">flow</span> depends on the viscosity and layer thickness ratios in a simple way, while the placement of the magnetic fluid layer does not play a major role. Growth rates predicted for realistic microchannel conditions are shown to be large enough to make ferrofluid manipulation a practical method of control.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990063858&hterms=preconditioner&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpreconditioner','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990063858&hterms=preconditioner&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dpreconditioner"><span id="translatedtitle">A <span class="hlt">Parallel</span> Non-Overlapping Domain-Decomposition Algorithm for Compressible Fluid <span class="hlt">Flow</span> Problems on Triangulated Domains</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Barth, Timothy J.; Chan, Tony F.; Tang, Wei-Pai</p> <p>1998-01-01</p> <p>This paper considers an algebraic preconditioning algorithm for hyperbolic-elliptic fluid <span class="hlt">flow</span> problems. The algorithm is based on a <span class="hlt">parallel</span> non-overlapping Schur complement domain-decomposition technique for triangulated domains. In the Schur complement technique, the triangulation is first partitioned into a number of non-overlapping subdomains and interfaces. This suggests a reordering of triangulation vertices which separates subdomain and interface solution unknowns. The reordering induces a natural 2 x 2 block partitioning of the discretization matrix. Exact LU factorization of this block system yields a Schur complement matrix which couples subdomains and the interface together. The remaining sections of this paper present a family of approximate techniques for both constructing and applying the Schur complement as a domain-decomposition preconditioner. The approximate Schur complement serves as an algebraic coarse space operator, thus avoiding the known difficulties associated with the direct formation of a coarse space discretization. In developing Schur complement approximations, particular attention has been given to improving sequential and <span class="hlt">parallel</span> efficiency of implementations without significantly degrading the quality of the preconditioner. A computer code based on these developments has been tested on the IBM SP2 using MPI message passing protocol. A number of 2-D calculations are presented for both scalar advection-diffusion equations as well as the Euler equations governing compressible fluid <span class="hlt">flow</span> to demonstrate performance of the preconditioning algorithm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003RScI...74.4869W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003RScI...74.4869W"><span id="translatedtitle">An instrument to control <span class="hlt">parallel</span> plate separation for nanoscale <span class="hlt">flow</span> control</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>White, J.; Ma, H.; Lang, J.; Slocum, A.</p> <p>2003-11-01</p> <p>The handling of extremely small samples of gases and liquids has long been a subject of research among biologists, chemists, and engineers. A few scientific instruments, notably the surface force apparatus, have been used extensively to investigate very short-range molecular phenomena. This article describes the design, fabrication, and characterization of an easily manufactured, gas and liquid <span class="hlt">flow</span> control device called the Nanogate. The Nanogate controls liquid <span class="hlt">flows</span> under very high planar confinement, wherein the liquid film is, in one dimension, on the scale of nanometers, but is on the scale of hundreds of microns in its other dimensions. The liquid film is confined between a silica (Pyrex) surface with a typical roughness of Ra≈6 nm and a gold-covered silicon surface with a typical roughness of Ra≈2 nm. During the manufacturing process, the Pyrex <span class="hlt">flows</span> and conforms to the gold-covered silicon surface, improving the mating properties of the two surfaces. The fluid film thickness can be controlled within 2 Å, from sub-10 nm up to 1 μm. Control of helium gas <span class="hlt">flow</span> rates in the 10-9 atm cm3/s range, and sub-nl/s <span class="hlt">flow</span> rates of water and methanol have been predicted and experimentally verified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870013010','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870013010"><span id="translatedtitle">Analysis of a <span class="hlt">parallelized</span> nonlinear elliptic boundary value problem solver with application to reacting <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>Keyes, David E.; Smooke, Mitchell D.</p> <p>1987-01-01</p> <p>A <span class="hlt">parallelized</span> finite difference code based on the Newton method for systems of nonlinear elliptic boundary value problems in two dimensions is analyzed in terms of computational complexity and <span class="hlt">parallel</span> efficiency. An approximate cost function depending on 15 dimensionless parameters is derived for algorithms based on stripwise and boxwise decompositions of the domain and a one-to-one assignment of the strip or box subdomains to processors. The sensitivity of the cost functions to the parameters is explored in regions of parameter space corresponding to model small-order systems with inexpensive function evaluations and also a coupled system of nineteen equations with very expensive function evaluations. The algorithm was implemented on the Intel Hypercube, and some experimental results for the model problems with stripwise decompositions are presented and compared with the theory. In the context of computational combustion problems, multiprocessors of either message-passing or shared-memory type may be employed with stripwise decompositions to realize speedup of O(n), where n is mesh resolution in one direction, for reasonable n.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016LatJP..53...20S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016LatJP..53...20S"><span id="translatedtitle">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('http://adsabs.harvard.edu/abs/2015HMT...tmp..251B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015HMT...tmp..251B"><span id="translatedtitle">An experimental study on refrigerant distribution in a two row/four pass <span class="hlt">parallel</span> <span class="hlt">flow</span> minichannel heat exchanger</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Byun, Ho-Won; Kim, Nae-Hyun</p> <p>2015-12-01</p> <p>R-410A distribution was experimentally studied for a <span class="hlt">parallel</span> <span class="hlt">flow</span> evaporator having two row/four pass configuration. The evaporator has inlet, intermediate and row-crossing headers. Tests were conducted for the mass flux from 70 to 130 kg/m2s with the quality at the inlet of 0.2 and exit superheat 5 °C. Significant heat transfer degradation (13-40 %) was realized for the two row/four pass configuration due to <span class="hlt">flow</span> mal-distribution. Of the three insert hole sizes, 4.0 mm hole yielded the least heat transfer degradation followed by 6.0 and 2.0 mm holes. At the inlet header, more liquid <span class="hlt">flowed</span> into upstream channels. At the intermediate headers, more liquid was supplied into downstream channels. Similar <span class="hlt">flow</span> distribution was obtained before and after the row crossing header. Header pressure drops were obtained by subtracting the flat tube pressure drops and other minor pressure drops from measured pressure drops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1252729','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1252729"><span id="translatedtitle">Experimental and numerical analysis of <span class="hlt">parallel</span> reactant <span class="hlt">flow</span> and transverse mixing with mineral precipitation in homogeneous and heterogeneous porous media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Fox, Don T.; Guo, Luanjing; Fujita, Yoshiko; Huang, Hai; Redden, George</p> <p>2015-12-17</p> <p>Formation of mineral precipitates in the mixing interface between two reactant solutions <span class="hlt">flowing</span> in <span class="hlt">parallel</span> in porous media is governed by reactant mixing by diffusion and dispersion and is coupled to changes in porosity/permeability due to precipitation. The spatial and temporal distribution of mixing-dependent precipitation of barium sulfate in porous media was investigated with side-by-side injection of barium chloride and sodium sulfate solutions in thin rectangular <span class="hlt">flow</span> cells packed with quartz sand. The results for homogeneous sand beds were compared to beds with higher or lower permeability inclusions positioned in the path of the mixing zone. In the homogeneous and high permeability inclusion experiments, BaSO<sub>4</sub> precipitate (barite) formed in a narrow deposit along the length and in the center of the solution–solution mixing zone even though dispersion was enhanced within, and downstream of, the high permeability inclusion. In the low permeability inclusion experiment, the deflected BaSO<sub>4</sub> precipitation zone broadened around one side and downstream of the inclusion and was observed to migrate laterally toward the sulfate solution. A continuum-scale fully coupled reactive transport model that simultaneously solves the nonlinear governing equations for fluid <span class="hlt">flow</span>, transport of reactants and geochemical reactions was used to simulate the experiments and provide insight into mechanisms underlying the experimental observations. Lastly, migration of the precipitation zone in the low permeability inclusion experiment could be explained by the coupling effects among fluid <span class="hlt">flow</span>, reactant transport and localized mineral precipitation reaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008APS..DFD.MJ004Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008APS..DFD.MJ004Z"><span id="translatedtitle"><span class="hlt">Parallel</span> Adaptive Computation of Blood <span class="hlt">Flow</span> in a 3D ``Whole'' Body Model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, M.; Figueroa, C. A.; Taylor, C. A.; Sahni, O.; Jansen, K. E.</p> <p>2008-11-01</p> <p>Accurate numerical simulations of vascular trauma require the consideration of a larger portion of the vasculature than previously considered, due to the systemic nature of the human body's response. A patient-specific 3D model composed of 78 connected arterial branches extending from the neck to the lower legs is constructed to effectively represent the entire body. Recently developed outflow boundary conditions that appropriately represent the downstream vasculature bed which is not included in the 3D computational domain are applied at 78 outlets. In this work, the pulsatile blood <span class="hlt">flow</span> simulations are started on a fairly uniform, unstructured mesh that is subsequently adapted using a solution-based approach to efficiently resolve the <span class="hlt">flow</span> features. The adapted mesh contains non-uniform, anisotropic elements resulting in resolution that conforms with the physical length scales present in the problem. The effects of the mesh resolution on the <span class="hlt">flow</span> field are studied, specifically on relevant quantities of pressure, velocity and wall shear stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title42-vol1/pdf/CFR-2011-title42-vol1-sec84-155.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title42-vol1/pdf/CFR-2011-title42-vol1-sec84-155.pdf"><span id="translatedtitle">42 CFR 84.155 - Airflow resistance test; Type C supplied-<span class="hlt">air</span> respirator, continuous <span class="hlt">flow</span> class and Type CE...</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>2011-10-01</p> <p>... 42 Public Health 1 2011-10-01 2011-10-01 false Airflow resistance test; Type C supplied-<span class="hlt">air</span> respirator, continuous <span class="hlt">flow</span> class and Type CE supplied-<span class="hlt">air</span> respirator; minimum requirements. 84.155 Section... Respirators § 84.155 Airflow resistance test; Type C supplied-<span class="hlt">air</span> respirator, continuous <span class="hlt">flow</span> class and...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JMMM..396..295A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015JMMM..396..295A&link_type=ABSTRACT"><span id="translatedtitle">Hydromagnetic natural convection <span class="hlt">flow</span> between vertical <span class="hlt">parallel</span> plates with time-periodic boundary conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adesanya, S. O.; Oluwadare, E. O.; Falade, J. A.; Makinde, O. D.</p> <p>2015-12-01</p> <p>In this paper, the free convective <span class="hlt">flow</span> of magnetohydrodynamic fluid through a channel with time periodic boundary condition is investigated by taking the effects of Joule dissipation into consideration. Based on simplifying assumptions, the coupled governing equations are reduced to a set of nonlinear boundary valued problem. Approximate solutions are obtained by using semi-analytical Adomian decomposition method. The effect of pertinent parameters on the fluid velocity, temperature distribution, Nusselt number and skin friction are presented graphically and discussed. The result of the computation shows that an increase in the magnetic field intensity has significant influence on the fluid <span class="hlt">flow</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050028474','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050028474"><span id="translatedtitle">An Experimental Investigation of the <span class="hlt">Flow</span> of <span class="hlt">Air</span> in a Flat Broadening Channel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vedernikoff, A. N.</p> <p>1944-01-01</p> <p>The wide use of diffusers, in various fields of technology, has resulted in several experimental projects to study the action and design of diffusers. Most of the projects dealt with steam (steam turbine nozzles). But diffusers have other applications - that is, ventilators, smoke ducts, <span class="hlt">air</span> coolers, refrigeration, drying, and so forth. At present there is another application for diffusers in wind-tunnel design. Because of higher requirements and increased power of such installations more attention must be paid to the correctness of work and the decrease in losses due to every section of the tunnel. A diffuser, being one of the component parts of a tunnel , can in the event of faulty construction introduce considerable losses. Therefore, in the design of the new CAHI wind tunnel, it was suggested that an experimental study of diffusers be made, with a view to applying the results to wind tunnels. The experiments conducted by K. K. Baulin in the laboratories of CAHI upon models of diffusers of different cross sections, lengths, and angles of divergence, were a valuable source of experimental data. They were of no help, however, in reaching any conclusion regarding the optimum shape because of the complexity and diversity of the factors which all appeared simultaneously, thereby precluding the.study of the effects of any one factor separately. On the suggestion of the director of the CAHI,Prof. B. N. Ureff, it was decided to experiment on a two-dimensional diffuser model and determine the effect, of the angle of divergence. The author is acquainted with two experimental projects of like nature: the first was conducted with water, the other with <span class="hlt">air</span>. The first of these works, although containing a wealth of experimental data, does not indicate the nature of <span class="hlt">flow</span> or its relation to the angle of divergence. The second work is limited to four angles - that is, 12 deg, 24 deg, 45 deg, 90 deg. The study of this diffuser did not supply any information about the effect of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPJWC..9202080S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPJWC..9202080S"><span id="translatedtitle">Scalability of the <span class="hlt">parallel</span> CFD simulations of <span class="hlt">flow</span> past a fluttering airfoil in OpenFOAM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Šidlof, Petr; Řidký, Václav</p> <p>2015-05-01</p> <p>The paper is devoted to investigation of unsteady subsonic airflow past an elastically supported airfoil during onset of the flutter instability. Based on the geometry, boundary conditions and airfoil motion data identified from wind-tunnel measurements, a 3D CFD model has been set up in OpenFOAM. The model is based on incompressible Navier-Stokes equations. The turbulence is modelled by the Menter's k-omega shear stress transport turbulence model. The computational mesh was generated in GridPro, a mesh generator capable of producing highly orthogonal structured C-type meshes. The mesh totals 3.1 million elements. <span class="hlt">Parallel</span> scalability was measured on a small shared-memory SGI Altix UV 100 supercomputer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9049E..15B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9049E..15B"><span id="translatedtitle">Demonstration of EDA <span class="hlt">flow</span> for massively <span class="hlt">parallel</span> e-beam lithography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brandt, P.; Belledent, J.; Tranquillin, C.; Figueiro, T.; Meunier, S.; Bayle, S.; Fay, A.; Milléquant, M.; Icard, B.; Wieland, M.</p> <p>2014-03-01</p> <p>Today's soaring complexity in pushing the limits of 193nm immersion lithography drives the development of other technologies. One of these alternatives is mask-less massively <span class="hlt">parallel</span> electron beam lithography, (MP-EBL), a promising candidate in which future resolution needs can be fulfilled at competitive cost. MAPPER Lithography's MATRIX MP-EBL platform has currently entered an advanced stage of development. The first tool in this platform, the FLX 1200, will operate using more than 1,300 beams, each one writing a stripe 2.2μm wide. 0.2μm overlap from stripe to stripe is allocated for stitching. Each beam is composed of 49 individual sub-beams that can be blanked independently in order to write in a raster scan pixels onto the wafer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/10108404','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/10108404"><span id="translatedtitle">Implementation of a <span class="hlt">parallel</span> algorithm for thermo-chemical nonequilibrium <span class="hlt">flow</span> simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wong, C.C.; Blottner, F.G.; Payne, J.L.; Soetrisno, M.</p> <p>1995-01-01</p> <p>Massively <span class="hlt">parallel</span> (MP) computing is considered to be the future direction of high performance computing. When engineers apply this new MP computing technology to solve large-scale problems, one major interest is what is the maximum problem size that a MP computer can handle. To determine the maximum size, it is important to address the code scalability issue. Scalability implies whether the code can provide an increase in performance proportional to an increase in problem size. If the size of the problem increases, by utilizing more computer nodes, the ideal elapsed time to simulate a problem should not increase much. Hence one important task in the development of the MP computing technology is to ensure scalability. A scalable code is an efficient code. In order to obtain good scaled performance, it is necessary to first have the code optimized for a single node performance before proceeding to a large-scale simulation with a large number of computer nodes. This paper will discuss the implementation of a massively <span class="hlt">parallel</span> computing strategy and the process of optimization to improve the scaled performance. Specifically, we will look at domain decomposition, resource management in the code, communication overhead, and problem mapping. By incorporating these improvements and adopting an efficient MP computing strategy, an efficiency of about 85% and 96%, respectively, has been achieved using 64 nodes on MP computers for both perfect gas and chemically reactive gas problems. A comparison of the performance between MP computers and a vectorized computer, such as Cray-YMP, will also be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MS%26E...72d2047Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MS%26E...72d2047Y"><span id="translatedtitle">Numerical simulation and analysis of the internal <span class="hlt">flow</span> in a Francis turbine with <span class="hlt">air</span> admission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, A.; Luo, X. W.; Ji, B.</p> <p>2015-01-01</p> <p>In case of hydro turbines operated at part-load condition, vortex ropes usually occur in the draft tube, and consequently generate violent pressure fluctuation. This unsteady <span class="hlt">flow</span> phenomenon is believed harmful to hydropower stations. This paper mainly treats the internal <span class="hlt">flow</span> simulation in the draft tube of a Francis turbine. In order to alleviate the pressure fluctuation induced by the vortex rope, <span class="hlt">air</span> admission from the main shaft center is applied, and the water-<span class="hlt">air</span> two phase <span class="hlt">flow</span> in the entire <span class="hlt">flow</span> passage of a model turbine is simulated based on a homogeneous <span class="hlt">flow</span> assumption and SST k-ω turbulence model. It is noted that the numerical simulation reasonably predicts the pressure fluctuations in the draft tube, which agrees fairly well with experimental data. The analysis based on the vorticity transport equation shows that the vortex dilation plays a major role in the vortex evolution with <span class="hlt">air</span> admission in the turbine draft tube, and there is large value of vortex dilation along the vortex rope. The results show that the aeration with suitable <span class="hlt">air</span> volume fraction can depress the vortical <span class="hlt">flow</span>, and alleviate the pressure fluctuation in the draft tube.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/19398506','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19398506"><span id="translatedtitle"><span class="hlt">Flow</span> and performance of an <span class="hlt">air</span>-curtain biological safety cabinet.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Rong Fung; Chou, Chun I</p> <p>2009-06-01</p> <p>Using laser-assisted smoke <span class="hlt">flow</span> visualization and tracer gas concentration detection techniques, this study examines aerodynamic <span class="hlt">flow</span> properties and the characteristics of escape from containment, inward dispersion, and cross-cabinet contamination of a biological safety cabinet installed with an <span class="hlt">air</span> 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 <span class="hlt">air</span> 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 <span class="hlt">flow</span> going through a suction slot installed at the front edge of the work surface. Varying the combination of jet velocity, suction <span class="hlt">flow</span> velocity, and descending <span class="hlt">flow</span> velocity reveals three types of characteristic <span class="hlt">flow</span> modes: 'straight curtain', 'slightly concave curtain', and 'severely concave curtain'. Operating the cabinet in the straight curtain mode causes the <span class="hlt">air</span> 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 <span class="hlt">air</span> entered into the cabinet and a three-dimensional vortical <span class="hlt">flow</span> structure formed in the cabinet. The slightly concave curtain mode presents a smooth and two-dimensional <span class="hlt">flow</span> pattern with an <span class="hlt">air</span> 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. PMID:19398506</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('http://adsabs.harvard.edu/abs/2016PlST...18..485Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PlST...18..485Z"><span id="translatedtitle">Investigation on Plasma Jet <span class="hlt">Flow</span> Phenomena During DC <span class="hlt">Air</span> Arc Motion in Bridge-Type Contacts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhai, Guofu; Bo, Kai; Chen, Mo; Zhou, Xue; Qiao, Xinlei</p> <p>2016-05-01</p> <p>Arc plasma jet <span class="hlt">flow</span> in the <span class="hlt">air</span> was investigated under a bridge-type contacts in a DC 270 V resistive circuit. We characterized the arc plasma jet <span class="hlt">flow</span> appearance at different currents by using high-speed photography, and two polished contacts were used to search for the relationship between roughness and plasma jet <span class="hlt">flow</span>. Then, to make the nature of arc plasma jet <span class="hlt">flow</span> phenomena clear, a simplified model based on magnetohydrodynamic (MHD) theory was established and calculated. The simulated DC arc plasma was presented with the temperature distribution and the current density distribution. Furthermore, the calculated arc <span class="hlt">flow</span> velocity field showed that the circular vortex was an embodiment of the arc plasma jet <span class="hlt">flow</span> progress. The combined action of volume force and contact surface was the main reason of the arc jet <span class="hlt">flow</span>. supported by National Natural Science Foundation of China (Nos. 51307030, 51277038)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JFST....4..546H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JFST....4..546H"><span id="translatedtitle">Effect of Moist <span class="hlt">Air</span> on Transonic Internal <span class="hlt">Flow</span> around a Plate</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hasan, A. B. M. Toufique; Matsuo, Shigeru; Setoguchi, Toshiaki; Kim, Heuy Dong</p> <p></p> <p>The unsteady phenomena in the transonic <span class="hlt">flow</span> around airfoils are observed in the <span class="hlt">flow</span> field of fan, compressor blades and butterfly valves, and this causes often serious problems such as the aeroacoustic noise and the vibration. In the transonic or supersonic <span class="hlt">flow</span> where vapor is contained in the main <span class="hlt">flow</span>, the rapid expansion of the <span class="hlt">flow</span> may give rise to a non-equilibrium condensation. In the present study, the effect of non-equilibrium condensation of moist <span class="hlt">air</span> on the shock induced <span class="hlt">flow</span> field oscillation around a plate was investigated numerically. The results showed that in the case with non-equilibrium condensation, the <span class="hlt">flow</span> field aerodynamic unsteadiness is reduced significantly compared with those without the non-equilibrium condensation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.H23E1246K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.H23E1246K"><span id="translatedtitle">Massively <span class="hlt">parallel</span> multiple interacting continua formulation for modeling <span class="hlt">flow</span> in fractured porous media using the subsurface reactive <span class="hlt">flow</span> and transport code PFLOTRAN</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kumar, J.; Mills, R. T.; Lichtner, P. C.; Hammond, G. E.</p> <p>2010-12-01</p> <p>Fracture dominated <span class="hlt">flows</span> occur in numerous subsurface geochemical processes and at many different scales in rock pore structures, micro-fractures, fracture networks and faults. Fractured porous media can be modeled as multiple interacting continua which are connected to each other through transfer terms that capture the <span class="hlt">flow</span> of mass and energy in response to pressure, temperature and concentration gradients. However, the analysis of large-scale transient problems using the multiple interacting continuum approach presents an algorithmic and computational challenge for problems with very large numbers of degrees of freedom. A generalized dual porosity model based on the Dual Continuum Disconnected Matrix approach has been implemented within a massively <span class="hlt">parallel</span> multiphysics-multicomponent-multiphase subsurface reactive <span class="hlt">flow</span> and transport code PFLOTRAN. Developed as part of the Department of Energy's SciDAC-2 program, PFLOTRAN provides subsurface simulation capabilities that can scale from laptops to ultrascale supercomputers, and utilizes the PETSc framework to solve the large, sparse algebraic systems that arises in complex subsurface reactive <span class="hlt">flow</span> and transport problems. It has been successfully applied to the solution of problems composed of more than two billions degrees of freedom, utilizing up to 131,072 processor cores on Jaguar, the Cray XT5 system at Oak Ridge National Laboratory that is the world’s fastest supercomputer. Building upon the capabilities and computational efficiency of PFLOTRAN, we will present an implementation of the multiple interacting continua formulation for fractured porous media along with an application case study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4551065','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4551065"><span id="translatedtitle"><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('http://www.osti.gov/scitech/servlets/purl/933177','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/933177"><span id="translatedtitle">Implications of <span class="hlt">Air</span> Ingress Induced by Density-Difference Driven Stratified <span class="hlt">Flow</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Chang Oh; Eung Soo Kim; Richard Schultz; David Petti; C. P. Liou</p> <p>2008-06-01</p> <p>One of the design basis accidents for the Next Generation Nuclear Plant (NGNP), a high temperature gas-cooled reactor, is <span class="hlt">air</span> ingress subsequent to a pipe break. Following a postulated double-ended guillotine break in the hot duct, and the subsequent depressurization to nearly reactor cavity pressure levels, <span class="hlt">air</span> present in the reactor cavity will enter the reactor vessel via density-gradient-driven-stratified <span class="hlt">flow</span>. Because of the significantly higher molecular weight and lower initial temperature of the reactor cavity <span class="hlt">air</span>-helium mixture, in contrast to the helium in the reactor vessel, the <span class="hlt">air</span>-helium mixture in the cavity always has a larger density than the helium discharging from the reactor vessel through the break into the reactor cavity. In the later stages of the helium blowdown, the momentum of the helium <span class="hlt">flow</span> decreases sufficiently for the heavier cavity <span class="hlt">air</span>-helium mixture to intrude into the reactor vessel lower plenum through the lower portion of the break. Once it has entered, the heavier gas will pool at the bottom of the lower plenum. From there it will move upwards into the core via diffusion and density-gradient effects that stem from heating the <span class="hlt">air</span>-helium mixture and from the pressure differences between the reactor cavity and the reactor vessel. This scenario (considering density-gradient-driven stratified <span class="hlt">flow</span>) is considerably different from the heretofore commonly used scenario that attributes movement of <span class="hlt">air</span> into the reactor vessel and from thence to the core region via diffusion. When density-gradient-driven stratified <span class="hlt">flow</span> is considered as a contributing phenomena for <span class="hlt">air</span> ingress into the reactor vessel, the following factors contribute to a much earlier natural circulation-phase in the reactor vessel: (a) density-gradient-driven stratified <span class="hlt">flow</span> is a much more rapid mechanism (at least one order of magnitude) for moving <span class="hlt">air</span> into the reactor vessel lower plenum than diffusion, and consequently, (b) the diffusion dominated phase begins with a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJWC.11402148J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJWC.11402148J"><span id="translatedtitle"><span class="hlt">Air</span> <span class="hlt">flow</span> phenomena in the model of the blind drift</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jaszczur, Marek; Karch, Michał; Zych, Marcin; Hanus, Robert; Petryka, Leszek; Świsulski, Dariusz</p> <p>2016-03-01</p> <p>In the presented paper, Particle Image Velocimetry (PIV) has been used to investigate <span class="hlt">flow</span> pattern and turbulent structure in the model of blind drift. The presented model exist in mining, and has been analyzed to resolve ventilation issues. Blind region is particularly susceptible to unsafe methane accumulation. The measurement system allows us to evaluate all components of the velocity vector in channel cross-section simultaneously. First order and second order statistic of the velocity fields from different channel cross-section are computed and analyzed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003APS..DFD.FE004B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003APS..DFD.FE004B"><span id="translatedtitle">Modeling <span class="hlt">Air</span> <span class="hlt">Flow</span> in the Lungs during In-exsufflation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bukiet, Bruce; Chaudhry, Hans; Kirshblum, Steven; Bach, John</p> <p>2003-11-01</p> <p>Patients with weak respiratory systems experience build-up of fluid in the lungs. This can lead to infection and hospitalization. Although endotracheal suctioning can help relieve this problem, it is invasive and uncomfortable. Patients prefer the non-invasive mechanical in-exsufflation technique. In this talk, we describe these techniques for easing the problem of mucus build-up and present ideas for mathematical and computational modeling of the <span class="hlt">flow</span> in the branches of the lungs during mechanical in-exsufflation. The implications of the results of the computations on the safety of the technique and on patient treatment are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17215498','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17215498"><span id="translatedtitle">Responses of the rat olfactory epithelium to retronasal <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>Scott, John W; Acevedo, Humberto P; Sherrill, Lisa; Phan, Maggie</p> <p>2007-03-01</p> <p>Responses of the rat olfactory epithelium were assessed with the electroolfactogram while odorants were presented to the external nares with an artificial sniff or to the internal nares by positive pressure. A series of seven odorants that varied from very polar, hydrophilic odorants to very nonpolar, hydrophobic odorants were used. Although the polar odorants activated the dorsal olfactory epithelium when presented by the external nares (orthonasal presentation), they were not effective when forced through the nasal cavity from the internal nares (retronasal presentation). However, the nonpolar odorants were effective in both stimulus modes. These results were independent of stimulus concentration or of humidity of the carrier <span class="hlt">air</span>. Similar results were obtained with multiunit recordings from olfactory bulb. These results help to explain why human investigations often report differences in the sensation or ability to discriminate odorants presented orthonasally versus retronasally. The results also strongly support the importance of odorant sorption in normal olfactory processes. PMID:17215498</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2225990','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2225990"><span id="translatedtitle">Responses of the Rat Olfactory Epithelium to Retronasal <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>Scott, John W.; Acevedo, Humberto P.; Sherrill, Lisa; Phan, Maggie</p> <p>2008-01-01</p> <p>Responses of the rat olfactory epithelium were assessed with the electroolfactogram while odorants were presented to the external nares with an artificial sniff or to the internal nares by positive pressure. A series of seven odorants that varied from very polar, hydrophilic odorants to very non-polar, hydrophobic odorants were used. While the polar odorants activated the dorsal olfactory epithelium when presented by the external nares (orthonasal presentation), they were not effective when forced through the nasal cavity from the internal nares (retronasal presentation). However, the non-polar odorants were effective in both stimulus modes. These results were independent of stimulus concentration or of humidity of the carrier <span class="hlt">air</span>. Similar results were obtained with multiunit recording from olfactory bulb. These results help to explain why human investigations often report differences in the sensation or ability to discriminate odorants presented orthonasally vs. retronasally. The results also strongly support the importance of odorant sorption in normal olfactory processes. PMID:17215498</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDE32005C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDE32005C"><span id="translatedtitle">Drainage of the <span class="hlt">air</span> film during drop impact on <span class="hlt">flowing</span> liquid films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Che, Zhizhao; Matar, Omar</p> <p>2015-11-01</p> <p>Immediately upon the impact of a droplet on a liquid or a solid, a thin <span class="hlt">air</span> cushion is formed by trapping <span class="hlt">air</span> beneath the droplet. The drainage of the <span class="hlt">air</span> film is critical in determining the eventual outcome of the impact. Here we propose a model to study the drainage of the gas film between a droplet and a <span class="hlt">flowing</span> liquid film. The effects of a wide range of parameters influencing the drainage process are studied, such as the fluid viscosities, the surface tension, the velocity of the droplet, the velocity of the liquid film. The results show that the tangential movement of the liquid film can delay the drainage of the <span class="hlt">air</span> film and promote the bouncing of droplets. This confirms our previous experimental results, which show that during the impact of droplets on <span class="hlt">flow</span> liquid films, the probability of bouncing increases with the Reynolds number of the liquid film. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AGUFM.H23D0981O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AGUFM.H23D0981O"><span id="translatedtitle">Adaptive particle-based pore-level modeling of incompressible fluid <span class="hlt">flow</span> in porous media: a direct and <span class="hlt">parallel</span> approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ovaysi, S.; Piri, M.</p> <p>2009-12-01</p> <p>We present a three-dimensional fully dynamic <span class="hlt">parallel</span> particle-based model for direct pore-level simulation of incompressible viscous fluid <span class="hlt">flow</span> in disordered porous media. The model was developed from scratch and is capable of simulating <span class="hlt">flow</span> directly in three-dimensional high-resolution microtomography images of naturally occurring or man-made porous systems. It reads the images as input where the position of the solid walls are given. The entire medium, i.e., solid and fluid, is then discretized using particles. The model is based on Moving Particle Semi-implicit (MPS) technique. We modify this technique in order to improve its stability. The model handles highly irregular fluid-solid boundaries effectively. It takes into account viscous pressure drop in addition to the gravity forces. It conserves mass and can automatically detect any false connectivity with fluid particles in the neighboring pores and throats. It includes a sophisticated algorithm to automatically split and merge particles to maintain hydraulic connectivity of extremely narrow conduits. Furthermore, it uses novel methods to handle particle inconsistencies and open boundaries. To handle the computational load, we present a fully <span class="hlt">parallel</span> version of the model that runs on distributed memory computer clusters and exhibits excellent scalability. The model is used to simulate unsteady-state <span class="hlt">flow</span> problems under different conditions starting from straight noncircular capillary tubes with different cross-sectional shapes, i.e., circular/elliptical, square/rectangular and triangular cross-sections. We compare the predicted dimensionless hydraulic conductances with the data available in the literature and observe an excellent agreement. We then test the scalability of our <span class="hlt">parallel</span> model with two samples of an artificial sandstone, samples A and B, with different volumes and different distributions (non-uniform and uniform) of solid particles among the processors. An excellent linear scalability is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930090895','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930090895"><span id="translatedtitle">Improving the performance of a compression ignition engine by directing <span class="hlt">flow</span> of inlet <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>Kemper, Carlton</p> <p>1946-01-01</p> <p>The object of this report is to present the results of tests performed by the National Advisory Committee for Aeronautics to determine the effect on engine performance of directing the <span class="hlt">flow</span> of the inlet <span class="hlt">air</span> to a 5-inch by 7-inch cylinder, solid injection, compression ignition engine, After a few preliminary tests, comparative runs were made at a speed of 1500 r.p.m. with and without directed <span class="hlt">air</span> <span class="hlt">flow</span>. It was found that directing the <span class="hlt">flow</span> of the inlet <span class="hlt">air</span> toward the fuel injection valve gave steadier engine operation, and an appreciable increase in power, and decreased fuel consumption. The results indicate the possibility of improving the performance of a given type of combustion chamber without changing its shape and with no change in valve timing. They would also seem to prove that directional turbulence, set up before the inlet valve of a four-stroke cycle engine, continues in the engine cylinder throughout the compression stroke.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ChPhB..25b0204J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ChPhB..25b0204J"><span id="translatedtitle">Simulation of the 3D viscoelastic free surface <span class="hlt">flow</span> by a <span class="hlt">parallel</span> corrected particle scheme</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jin-Lian, Ren; Tao, Jiang</p> <p>2016-02-01</p> <p>In this work, the behavior of the three-dimensional (3D) jet coiling based on the viscoelastic Oldroyd-B model is investigated by a corrected particle scheme, which is named the smoothed particle hydrodynamics with corrected symmetric kernel gradient and shifting particle technique (SPH_CS_SP) method. The accuracy and stability of SPH_CS_SP method is first tested by solving Poiseuille <span class="hlt">flow</span> and Taylor-Green <span class="hlt">flow</span>. Then the capacity for the SPH_CS_SP method to solve the viscoelastic fluid is verified by the polymer <span class="hlt">flow</span> through a periodic array of cylinders. Moreover, the convergence of the SPH_CS_SP method is also investigated. Finally, the proposed method is further applied to the 3D viscoelastic jet coiling problem, and the influences of macroscopic parameters on the jet coiling are discussed. The numerical results show that the SPH_CS_SP method has higher accuracy and better stability than the traditional SPH method and other corrected SPH method, and can improve the tensile instability. Project supported by the Natural Science Foundation of Jiangsu Province, China (Grant Nos. BK20130436 and BK20150436) and the Natural Science Foundation of the Higher Education Institutions of Jiangsu Province, China (Grant No. 15KJB110025).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011APS..DFDE18010C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011APS..DFDE18010C"><span id="translatedtitle">Electrokinetic <span class="hlt">flows</span> through a <span class="hlt">parallel</span>-plate channel with slipping stripes on walls</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chu, Henry C. W.; Ng, Chiu-On</p> <p>2011-11-01</p> <p>Electrohydrodynamic <span class="hlt">flows</span> through a periodically-micropatterned plane channel are considered. One unit of wall pattern consists of a slipping and non-slipping stripe, each with a distinct zeta potential. The problems are solved semi-analytically by eigenfunction expansion and point collocation. In the regime of linear response, the Onsager relation for the fluid and current fluxes are deduced as linear functions of the hydrodynamic and electric forcings. The phenomenological coefficients are explicitly expressed as functions of the channel height, the Debye parameter, the slipping area fraction of the wall, the intrinsic slip length, and the zeta potentials. We generalize the theoretical limits made in previous studies on electrokinetic <span class="hlt">flow</span> over an inhomogeneously slipping surface. One should be cautious when applying these limits. First, when a surface is not 100% uniformly slipping but has a small fraction of area being covered by no-slip slots, the electroosmotic enhancement can be appreciably reduced. Second, when the electric double layer is only moderately thin, slipping-uncharged regions on a surface will have finite inhibition effect on the electroosmotic <span class="hlt">flow</span>. Financial support by the RGC of the HKSAR, China: Project Nos. HKU715609E, HKU715510E; and the HKU under the Seed Funding Programme for Basic Research: Project Code 200911159024.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.girlshealth.gov/environmental/air/index.html','NIH-MEDLINEPLUS'); return false;" href="http://www.girlshealth.gov/environmental/air/index.html"><span id="translatedtitle"><span class="hlt">Air</span></span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... do to protect yourself from dirty <span class="hlt">air</span> . Indoor <span class="hlt">air</span> pollution and outdoor <span class="hlt">air</span> pollution <span class="hlt">Air</span> can be polluted indoors and it can ... this chart to see what things cause indoor <span class="hlt">air</span> pollution and what things cause outdoor <span class="hlt">air</span> pollution! Indoor ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JChPh.118.3368S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JChPh.118.3368S"><span id="translatedtitle"><span class="hlt">Air</span> shear driven <span class="hlt">flow</span> of thin perfluoropolyether polymer films</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Scarpulla, Michael A.; Mate, C. Mathew; Carter, Malika D.</p> <p>2003-02-01</p> <p>We have studied the wind driven movement of thin perfluoropolyether (PFPE) polymer films on silicon wafers and CNx overcoats using the blow-off technique. The ease with which a liquid polymer film moves across a surface when sheared is described by a shear mobility χS, which can be interpreted both in terms of continuum <span class="hlt">flow</span> and in terms of wind driven diffusion. Generally, we find that the movement of PFPE films can be described as a <span class="hlt">flow</span> process with an effective viscosity, even when the film thickness is smaller than the polymer's diameter of gyration. Only in the special case of sparse coverage of a polymer with neutral end groups is the motion better described by a wind driven diffusion process. The addition of alcohol end groups to the PFPE polymer chain results in strong interactions with the substrate, creating a restricted layer having an effective viscosity an order of magnitude larger than the mobile layer that sits on top of the restricted layer.</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 id="translatedtitle">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('http://www.osti.gov/scitech/biblio/20013511','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/20013511"><span id="translatedtitle">Accurate burner <span class="hlt">air</span> <span class="hlt">flow</span> measurement for low NO{sub x} burners</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Earley, D.; Penterson, C.</p> <p>1998-07-01</p> <p>In 1990, Congress enacted an amendment to the Clean <span class="hlt">Air</span> Act that required reductions in NO{sub x} emissions through the application of low NO{sub x} burner systems on fossil fueled utility steam generators. For most of the existing steam generator population, the original burning equipment incorporated highly turbulent burners that created significant in-furnace flame interaction. Thus, the measurement and control of <span class="hlt">air</span> <span class="hlt">flow</span> to the individual burners was much less critical than in recent years with low NO{sub x} combustion systems. With low NO{sub x} systems, the reduction of NO{sub x} emissions, as well as minimizing flyash unburned carbon levels, is very much dependent on the ability to control the relative ratios of <span class="hlt">air</span> and fuel on a per-burner basis and their rate of mixing, particularly in the near burner zones. <span class="hlt">Air</span> Monitor Corporation (AMC) and DB Riley, Inc. (DBR), and a large Midwestern electric utility have successfully developed and applied AMC's equipment to low NO{sub x} coal burners in order to enhance NO{sub x} control combustion systems. The results have improved burner optimization and provided real time continuous <span class="hlt">air</span> <span class="hlt">flow</span> balancing capability and the control of individual burner stoichiometries. To date, these enhancements have been applied to wall-fired low NO{sub x} systems for balancing individual burner <span class="hlt">air</span> <span class="hlt">flows</span> in a common windbox and to staged combustion systems. Most recently, calibration testing in a wind tunnel facility of AMC's individual burner <span class="hlt">air</span> measurement (IBAM{trademark}) probes installed in DB Riley's low NO{sub x} CCV{reg{underscore}sign} burners has demonstrated the ability to produce reproducible and consistent <span class="hlt">air</span> <span class="hlt">flow</span> measurement accurate to within 5%. This paper will summarize this product development and quantify the benefits of its application to low NO{sub x} combustion systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/152940','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/152940"><span id="translatedtitle">Effects of saline-water <span class="hlt">flow</span> rate and <span class="hlt">air</span> speed on leakage current in RTV coatings</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kim, S.H.; Hackam, R.</p> <p>1995-10-01</p> <p>Room temperature vulcanizing (RTV) silicone rubber is increasingly being used to coat porcelain and glass insulators in order to improve their electrical performance in the presence of pollution and moisture. A study of the dependence of leakage current, pulse current count and total charge <span class="hlt">flowing</span> across the surface of RTV on the <span class="hlt">flow</span> rate of the saline water and on the compressed <span class="hlt">air</span> pressure used to create the salt-fog is reported. The fog was directed at the insulating rods either from one or two sides. The RTV was fabricated from polydimethylsiloxane polymer, a filler of alumina trihydrate (ATH), a polymerization catalyst and fumed silica reinforcer, all dispersed in 1,1,1-trichloroethane solvent. The saline water <span class="hlt">flow</span> rate was varied in the range 0.4 to 2.0 l/min. The compressed <span class="hlt">air</span> pressure at the input of the fog nozzles was varied from 0.20 to 0.63 MPa. The <span class="hlt">air</span> speed at the surface of the insulating rods was found to depend linearly on the <span class="hlt">air</span> pressure measured at the inlet to the nozzles and varied in the range 3 to 14 km/hr. The leakage current increased with increasing <span class="hlt">flow</span> rate and increasing <span class="hlt">air</span> speed. This is attributed to the increased loss of hydrophobicity with a larger quantity of saline fog and a larger impact velocities of fog droplets interacting with the surface of the RTV coating.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26235126','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26235126"><span id="translatedtitle">Apoptosis progression studied using <span class="hlt">parallel</span> dielectrophoresis electrophysiological analysis and <span class="hlt">flow</span> cytometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mulhall, H J; Cardnell, A; Hoettges, K F; Labeed, F H; Hughes, M P</p> <p>2015-11-01</p> <p>Apoptosis is characterised by many cellular events, but the standard Annexin-V assay identifies two; the transfer of the phospholipid phosphatidylserine (PS) from inner to outer leaflets of the plasma membrane, acting as an "eat me" signal to macrophages, and the permeabilisation of the plasma membrane. In this paper we compare the results from the Annexin-V assay with electrophysiology data obtained in <span class="hlt">parallel</span> using dielectrophoresis, which highlights two changes in cell electrophysiology; a change in cytoplasmic conductivity which correlates with PS expression, and a membrane conductance spike that correlates with permeabilisation. Combining results from both methods shows a strong inverse relationship between conductivity and PS externalisation. One mechanism which may explain this correlation is related to intracellular Ca(2+), which is known to increase early in apoptosis. PS expression occurs when enzymes called scramblases swap external and internal phospholipids, and which are usually activated by Ca(2+), whilst the change in cytoplasmic conductivity may be due to K(+) efflux from intermediate conductance (IK) ion channels that are also activated by Ca(2+). PMID:26235126</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://hdl.handle.net/2060/19930091664','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930091664"><span id="translatedtitle">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.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 id="translatedtitle">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>... 30 Mineral Resources 1 2010-07-01 2010-07-01 false <span class="hlt">Air</span> <span class="hlt">flow</span> (I-C, II-A, and V-A mines). 57.22212... 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,...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1983CRASM.296..229L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1983CRASM.296..229L"><span id="translatedtitle">Noise emission and propagation in an <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>Legendre, R.</p> <p>1983-01-01</p> <p>Sound propagation from a jet engine on an aircraft moving at a constant airspeed is examined in terms of the turbulent field, the near field, and the far field. The near and far fields are irrotational disturbances of a permanently adiabatic <span class="hlt">flow</span> for which the entropy and enthalpy are the critical parameters. The propagation velocity of the noise is formulated, together with the extent of the acoustic field. The acoustic excitation is shown to dominate the extent of the acoustic field, while the pseudo-noise and the sound density are equal to the sound pressure and are not noise sources. The unsteady part of the turbulence noise is controlled by the pressure gradient, particularly that around the axes of the eddies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1012388','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1012388"><span id="translatedtitle"><span class="hlt">Flow</span> of a binary mixture of linearly incompressible viscous fluids between two horizontal <span class="hlt">parallel</span> plates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Massoudi, M.</p> <p>2008-01-01</p> <p>In this paper, we use the classical Mixture Theory and present exact solutions to the equations of motion for the steady <span class="hlt">flow</span> of two linearly viscous fluids between two horizontal plates. We show that for a saturated mixture and under very special conditions, namely when the body forces are assumed negligible, the only interaction force is due to relative velocity (drag force), and if the two velocities are assumed to be related to each other in a linear fashion, then it is possible to integrate the coupled ordinary differential equations and obtain analytical expressions for the velocities and the volume fraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/947220','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/947220"><span id="translatedtitle"><span class="hlt">Flow</span> of a binary mixture of linearly incompressible viscous fluids between two horizontal <span class="hlt">parallel</span> plates</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Massoudi, Mehrdad</p> <p>2008-12-01</p> <p>In this paper, we use the classical Mixture Theory and present exact solutions to the equations of motion for the steady <span class="hlt">flow</span> of two linearly viscous fluids between two horizontal plates. We show that for a saturated mixture and under very special conditions, namely when the body forces are assumed negligible, the only interaction force is due to relative velocity (drag force), and if the two velocities are assumed to be related to each other in a linear fashion, then it is possible to integrate the coupled ordinary differential equations and obtain analytical expressions for the velocities and the volume fraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920001764','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920001764"><span id="translatedtitle">Viscous computations of cold <span class="hlt">air/air</span> <span class="hlt">flow</span> around scramjet nozzle afterbody</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Baysal, Oktay; Engelund, Walter C.</p> <p>1991-01-01</p> <p>The <span class="hlt">flow</span> field in and around the nozzle afterbody section of a hypersonic vehicle was computationally simulated. The compressible, Reynolds averaged, Navier Stokes equations were solved by an implicit, finite volume, characteristic based method. The computational grids were adapted to the <span class="hlt">flow</span> as the solutions were developing in order to improve the accuracy. The exhaust gases were assumed to be cold. The computational results were obtained for the two dimensional longitudinal plane located at the half span of the internal portion of the nozzle for over expanded and under expanded conditions. Another set of results were obtained, where the three dimensional simulations were performed for a half span nozzle. The surface pressures were successfully compared with the data obtained from the wind tunnel tests. The results help in understanding this complex <span class="hlt">flow</span> field and, in turn, should help the design of the nozzle afterbody section.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.A53L3364K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFM.A53L3364K&link_type=ABSTRACT"><span id="translatedtitle">Numerical Study on a Detailed <span class="hlt">Air</span> <span class="hlt">Flows</span> in an Urban Area Using a CFD model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwon, A.</p> <p>2014-12-01</p> <p>In this study, detailed <span class="hlt">air</span> <span class="hlt">flows</span> in an urban area were analyzed using a computational fluid dynamics (CFD) model. For this model buildings used as the surface boundary in the model were constructed using Los Angeles Region Imagery Acquisition Consortium 2 Geographic Information System (LARIAC2 GIS) data. Three target areas centered at the cross roads of Broadway & 7th St., Olive & 12th St., and Wilshire blvd. & Carondelet, Los Angeles, California were considered. The size of each numerical domain is 400 m, 400 m, and 200 m in the x‒, y‒, and z‒directions, respectively. The grid sizes in the x‒, y‒, and z‒directions are 2 m, 2 m, and 2 m, respectively. Based on the inflow wind data provided by California <span class="hlt">Air</span> Resources Board, detailed <span class="hlt">flow</span> characteristics were investigated for each target area. Descending <span class="hlt">air</span> <span class="hlt">flow</span> were developed at the leeward area of tall building and ascending <span class="hlt">air</span> current were occurred on the windward area of tall building. Vertically rotating vortices were formed in spaces between buildings, so-called, street canyons and horizontally rotating vortices appeared near cross roads. When <span class="hlt">flows</span> came into narrow street canyon from wide street canyon, channeling effects appeared and <span class="hlt">flow</span> speed increased for satisfying mass continuity.</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 id="translatedtitle">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('http://ntrs.nasa.gov/search.jsp?R=19890060028&hterms=flow+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dflow%2Belectric','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890060028&hterms=flow+electric&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dflow%2Belectric"><span id="translatedtitle">d.c. electric field stabilization of plasma fluctuations due to a velocity shear in the <span class="hlt">parallel</span> ion <span class="hlt">flow</span>. [in ionosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ganguli, G.; Lee, Y. C.; Palmadesso, P. J.; Ossakow, S. L.</p> <p>1989-01-01</p> <p>Consideration is given to the suggestion by Basu and Coppi (1988, 1989) that the DE-2 observations of broadband turbulence associated with sheared ion <span class="hlt">flows</span> can be explained by electrostatic waves driven by a sheared ion <span class="hlt">flow</span> along the magnetic field. It is pointed out that such a theory ignores the stronger shear in the ion <span class="hlt">flow</span> transverse to the magnetic field, and that, when this shear is taken into account, the modes described by Basu and Coppi are easily destabilized. The theory of Basu and Coppi is shown to break down even when the shear in the <span class="hlt">parallel</span> <span class="hlt">flow</span> exceeds the shear in the transverse <span class="hlt">flow</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007RScI...78j3902W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007RScI...78j3902W"><span id="translatedtitle">A new <span class="hlt">parallel</span> plate shear cell for in situ real-space measurements of complex fluids under shear <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>Wu, Yu Ling; Brand, Joost H. J.; van Gemert, Josephus L. A.; Verkerk, Jaap; Wisman, Hans; van Blaaderen, Alfons; Imhof, Arnout</p> <p>2007-10-01</p> <p>We developed and tested a <span class="hlt">parallel</span> plate shear cell that can be mounted on top of an inverted microscope to perform confocal real-space measurements on complex fluids under shear. To follow structural changes in time, a plane of zero velocity is created by letting the plates move in opposite directions. The location of this plane is varied by changing the relative velocities of the plates. The gap width is variable between 20 and 200μm with <span class="hlt">parallelism</span> better than 1μm. Such a small gap width enables us to examine the total sample thickness using high numerical aperture objective lenses. The achieved shear rates cover the range of 0.02-103s-1. This shear cell can apply an oscillatory shear with adjustable amplitude and frequency. The maximum travel of each plate equals 1cm, so that strains up to 500 can be applied. For most complex fluids, an oscillatory shear with such a large amplitude can be regarded as a continuous shear. We measured the <span class="hlt">flow</span> profile of a suspension of silica colloids in this shear cell. It was linear except for a small deviation caused by sedimentation. To demonstrate the excellent performance and capabilities of this new setup we examined shear induced crystallization and melting of concentrated suspensions of 1μm diameter silica colloids.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17979430','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17979430"><span id="translatedtitle">A new <span class="hlt">parallel</span> plate shear cell for in situ real-space measurements of complex fluids under shear <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>Wu, Yu Ling; Brand, Joost H J; van Gemert, Josephus L A; Verkerk, Jaap; Wisman, Hans; van Blaaderen, Alfons; Imhof, Arnout</p> <p>2007-10-01</p> <p>We developed and tested a <span class="hlt">parallel</span> plate shear cell that can be mounted on top of an inverted microscope to perform confocal real-space measurements on complex fluids under shear. To follow structural changes in time, a plane of zero velocity is created by letting the plates move in opposite directions. The location of this plane is varied by changing the relative velocities of the plates. The gap width is variable between 20 and 200 microm with <span class="hlt">parallelism</span> better than 1 microm. Such a small gap width enables us to examine the total sample thickness using high numerical aperture objective lenses. The achieved shear rates cover the range of 0.02-10(3) s(-1). This shear cell can apply an oscillatory shear with adjustable amplitude and frequency. The maximum travel of each plate equals 1 cm, so that strains up to 500 can be applied. For most complex fluids, an oscillatory shear with such a large amplitude can be regarded as a continuous shear. We measured the <span class="hlt">flow</span> profile of a suspension of silica colloids in this shear cell. It was linear except for a small deviation caused by sedimentation. To demonstrate the excellent performance and capabilities of this new setup we examined shear induced crystallization and melting of concentrated suspensions of 1 microm diameter silica colloids. PMID:17979430</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EnOp...45.1409X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EnOp...45.1409X"><span id="translatedtitle">An effective shuffled frog-leaping algorithm for solving the hybrid <span class="hlt">flow</span>-shop scheduling problem with identical <span class="hlt">parallel</span> machines</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xu, Ye; Wang, Ling; Wang, Shengyao; Liu, Min</p> <p>2013-12-01</p> <p>In this article, an effective shuffled frog-leaping algorithm (SFLA) is proposed to solve the hybrid <span class="hlt">flow</span>-shop scheduling problem with identical <span class="hlt">parallel</span> machines (HFSP-IPM). First, some novel heuristic decoding rules for both job order decision and machine assignment are proposed. Then, three hybrid decoding schemes are designed to decode job order sequences to schedules. A special bi-level crossover and multiple local search operators are incorporated in the searching framework of the SFLA to enrich the memetic searching behaviour and to balance the exploration and exploitation capabilities. Meanwhile, some theoretical analysis for the local search operators is provided for guiding the local search. The parameter setting of the algorithm is also investigated based on the Taguchi method of design of experiments. Finally, numerical testing based on well-known benchmarks and comparisons with some existing algorithms are carried out to demonstrate the effectiveness of the proposed algorithm.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012ChPhL..29k4705A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012ChPhL..29k4705A&link_type=ABSTRACT"><span id="translatedtitle">Analytical and Numerical Approaches to Squeezing <span class="hlt">Flow</span> and Heat Transfer between Two <span class="hlt">Parallel</span> Disks with Velocity Slip and Temperature Jump</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amjad, Hussain; Syed Tauseef, Mohyud-Din; Taqi, Ahmed Cheema</p> <p>2012-11-01</p> <p>Analytic and numerical techniques are presented to analyze the influence of temperature and wall slip conditions on the unsteady <span class="hlt">flow</span> and heat transfer via viscous fluid squeezed between two <span class="hlt">parallel</span> disks in the presence of an applied magnetic field. The governing partial differential equations for momentum and heat transfer are reduced to a system of coupled nonlinear ordinary differential equations using similarity transformations. The homotopy analysis method (HAM) is then utilized to find explicit series solution of the resulting problem. The convergence of the obtained solution is carefully analyzed. To check the reliability of the method the same problem is also solved by using the shooting method and an excellent agreement is observed between the two sets of results. Influence of various parameters of practical importance on the velocity and temperature profiles is studied and portrayed graphically. Values of skin friction coefficient and local Nusselt number are tabulated by assigning different values to various emerging parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014FrME....9..270G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014FrME....9..270G"><span id="translatedtitle">On the MHD squeeze <span class="hlt">flow</span> between two <span class="hlt">parallel</span> disks with suction or injection via HAM and HPM</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ganji, D. D.; Abbasi, M.; Rahimi, J.; Gholami, M.; Rahimipetroudi, I.</p> <p>2014-09-01</p> <p>An analysis has been performed to study the problem of magneto-hydrodynamic (MHD) squeeze <span class="hlt">flow</span> of an electrically conducting fluid between two infinite, <span class="hlt">parallel</span> disks. The analytical methods called Homotopy Analysis Method (HAM) and Homotopy Perturbation Method (HPM) have been used to solve nonlinear differential equations. It has been attempted to show the capabilities and wide-range applications of the proposed methods in comparison with a type of numerical analysis as Boundary Value Problem (BVP) in solving this problem. Also, the velocity fields have been computed and shown graphically for various values of physical parameters. The objective of the present work is to investigate the effect of squeeze Reynolds number, Hartmann number and the suction/injection parameter on the velocity field. Furthermore, the results reveal that HAM and HPM are very effective and convenient.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhDT.........1G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhDT.........1G"><span id="translatedtitle">Numerical solution of multi-dimensional compressible reactive <span class="hlt">flow</span> using a <span class="hlt">parallel</span> wavelet adaptive multi-resolution method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grenga, Temistocle</p> <p></p> <p>The aim of this research is to further develop a dynamically adaptive algorithm based on wavelets that is able to solve efficiently multi-dimensional compressible reactive <span class="hlt">flow</span> problems. This work demonstrates the great potential for the method to perform direct numerical simulation (DNS) of combustion with detailed chemistry and multi-component diffusion. In particular, it addresses the performance obtained using a massive <span class="hlt">parallel</span> implementation and demonstrates important savings in memory storage and computational time over conventional methods. In addition, fully-resolved simulations of challenging three dimensional problems involving mixing and combustion processes are performed. These problems are particularly challenging due to their strong multiscale characteristics. For these solutions, it is necessary to combine the advanced numerical techniques applied to modern computational resources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21333925','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21333925"><span id="translatedtitle">Scalable <span class="hlt">parallel</span> methods for monolithic coupling in fluid-structure interaction with application to blood <span class="hlt">flow</span> modeling</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barker, Andrew T. Cai Xiaochuan</p> <p>2010-02-01</p> <p>We introduce and study numerically a scalable <span class="hlt">parallel</span> finite element solver for the simulation of blood <span class="hlt">flow</span> in compliant arteries. The incompressible Navier-Stokes equations are used to model the fluid and coupled to an incompressible linear elastic model for the blood vessel walls. Our method features an unstructured dynamic mesh capable of modeling complicated geometries, an arbitrary Lagrangian-Eulerian framework that allows for large displacements of the moving fluid domain, monolithic coupling between the fluid and structure equations, and fully implicit time discretization. Simulations based on blood vessel geometries derived from patient-specific clinical data are performed on large supercomputers using scalable Newton-Krylov algorithms preconditioned with an overlapping restricted additive Schwarz method that preconditions the entire fluid-structure system together. The algorithm is shown to be robust and scalable for a variety of physical parameters, scaling to hundreds of processors and millions of unknowns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/15093213','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/15093213"><span id="translatedtitle">Segmented <span class="hlt">flow</span> generation by chip reactors for highly <span class="hlt">parallelized</span> cell cultivation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Grodrian, Andreas; Metze, Josef; Henkel, Thomas; Martin, Karin; Roth, Martin; Köhler, J Michael</p> <p>2004-06-15</p> <p>Micro system technology offers convenient tools for the production of handling devices for small liquid volumes which can be used in cell cultivation. Here, a modular system for the rapid generation of cell suspension aliquots is presented. The system is used to produce and analyze high numbers of well-separated culture volumes. Selected clones may be retrieved from the system. Therefore, the principle of segmented <span class="hlt">flow</span> is applied. Portions of aqueous culture medium containing one cell or very small cell ensembles are separated from each other by a nonmiscible liquid like dodecane, tetradecane or mineral oil. In addition, the alkane separates the culture droplets from the innerside of the walls of chip channels and capillaries. This way, compatibility problems between cell wall surfaces and the chemical character of walls are excluded. The separated culture droplets are guided by micro <span class="hlt">flow</span> transportation in different channel and chamber topologies. The whole system has the character of a serially operating cell processing system. The aliquot generation can be sped up to frequencies of about 30 Hz in each microchannel. That means, that about 10(5) individual cultural volumes can be produced per hour or about 2 million per day. The survival and the growth of microorganisms has been shown for model organisms as well as for organisms from a natural sample (soil). PMID:15093213</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002SPIE.4937..174G&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002SPIE.4937..174G&link_type=ABSTRACT"><span id="translatedtitle">Segmented <span class="hlt">flow</span> generation by chip reactors for highly <span class="hlt">parallelized</span> cell cultivation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grodrian, A.; Metze, J.; Henkel, Thomas; Roth, M.; Kohler, Johann M.</p> <p>2002-11-01</p> <p>Micro system technology offers convenient tools for the production of handling devices for small liquid volumes which can be used in cell cultivation. Here, a modular system for the rapid generation of cell suspension aliquotes is presented. The system is used to produce and analyze high numbers of strongly separated cultural volumes. Selected clones may be retrieved from the system. Therefore, the principle of segmented <span class="hlt">flow</span> is applies. Portions of aqueous culture medium containing one cell or very small cell ensembles are separated from each other by a nonmiscible liquid like dodecane or mineral oil. In addition, the oil separates the cultivation droplets from the innerside of the walls of chip channels and capillaries. This way, compatibility problems between cell wall surfaces and the chemical character of technical walls are excluded. The separated cultivation droplets are guided by micro <span class="hlt">flow</span> transportation in different channel and chamber topologies. The whole system has the character of a serially working cell processing system. The aliquot generation can be speeded up to frequencies of about 30 Hz in each micro channel. That means, that about 105 individual cultural volumes can be produced per hour or about 2 million per day.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910006683','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910006683"><span id="translatedtitle">On the receptivity and non-<span class="hlt">parallel</span> stability of travelling disturbances in rotating disk <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>Balakumar, P.; Hall, P.; Malik, M. R.</p> <p>1990-01-01</p> <p>The generation and evolution of small amplitude wavelength traveling disturbances in rotating disk <span class="hlt">flow</span> is discussed. The steady rotational speed of the disk is perturbed so as to introduce high frequency oscillations in the <span class="hlt">flow</span> field. Secondly, surface imperfections are introduced on the disk such as roughness elements. The interaction of these two disturbances will generate the instability waves whose evolution is governed by parabolic partial differential equations that are solved numerically. For the class of disturbances considered (wavelength on the order of Reynolds number), it is found that eigensolutions exist which decay or grow algebraically in the radial direction. However, these solutions grow only for frequencies larger than 4.58 times the steady rotational speed of the disk. The computed receptivity coefficient shows that there is an optimum size of roughness for which these modes are excited the most. The width of these roughness elements in the radial direction is about .1 r(sub 0) where r(sub 0) is the radial location of the roughness. It is also found that the receptivity coefficient is larger for a negative spanwise wavenumber than for a positive one. Typical wave angles found for these disturbances are about -26 degrees.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000APS..DFD.DH001L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000APS..DFD.DH001L"><span id="translatedtitle">Robust control of linear global instability in models of non-<span class="hlt">parallel</span> shear <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>Lauga, Eric; Bewley, Thomas</p> <p>2000-11-01</p> <p>The present study investigates the control of self-excited oscillations in spatially developing <span class="hlt">flows</span> such as jets and wakes using H_∞ control theory on a linear complex Ginzburg Landau model. The coefficients of this 1D model equation, which is known to exhibit a generic hydrodynamic instability behavior, are those scaled by Roussopoulos & Monkewitz ( Physica D, 1996) to display behavior modeling that of the near-wake of a circular cylinder, in which a large pocket of local absolute instability is embedded within a convectively unstable <span class="hlt">flow</span>. Based on noisy measurements at a point sensor typically located inside the wake, the compensator uses an \\cal H_∞ filter to construct a state estimate. This estimate is then used to compute \\cal H_∞ control feedback at a point actuator location, which is typically located upstream of the sensor. The goal of the control scheme is to stabilize the system by minimizing a weighted average of the ``system response'' and the ``control effort'' (both appropriately defined) while rigorously bounding the response of the controlled system to external disturbances. The application of such modern control rules leads to better performance than the control feedback proposed by previous studies by delaying the Reynolds number at which the onset of global instability appears by a factor of 3 and substantially decreasing the sensitivity of the system to external perturbations.</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://hdl.handle.net/2060/20100003381','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100003381"><span id="translatedtitle">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('http://www.osti.gov/scitech/biblio/316097','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/316097"><span id="translatedtitle"><span class="hlt">Air</span>-side <span class="hlt">flow</span> and heat transfer in compact heat exchangers: A discussion of enhancement mechanisms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Jacobi, A.M.; Shah, R.K.</p> <p>1998-10-01</p> <p>The behavior of <span class="hlt">air</span> <span class="hlt">flows</span> in complex heat exchanger passages is reviewed with a focus on the heat transfer effects of boundary-layer development, turbulence, spanwise and streamwise vortices, and wake management. Each of these <span class="hlt">flow</span> features is discussed for the plain, wavy, and interrupted passages found in contemporary compact heat exchanger designs. Results from the literature are used to help explain the role of these mechanisms in heat transfer enhancement strategies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JTePh..58..144F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JTePh..58..144F"><span id="translatedtitle">Experimental investigation of the magnetohydrodynamic parachute effect in a hypersonic <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>Fomichev, V. P.; Yadrenkin, M. A.</p> <p>2013-01-01</p> <p>New data on experimental implementation of the magnetohydrodynamic (MHD) parachute configuration in an <span class="hlt">air</span> <span class="hlt">flow</span> with Mach number M = 6 about a flat plate are considered. It is shown that MHD interaction near a flat plate may transform an attached oblique shock wave into a normal detached one, which considerably extends the area of body-incoming <span class="hlt">flow</span> interaction. This effect can be employed in optimizing return space vehicle deceleration conditions in the upper atmosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1252729-experimental-numerical-analysis-parallel-reactant-flow-transverse-mixing-mineral-precipitation-homogeneous-heterogeneous-porous-media','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1252729-experimental-numerical-analysis-parallel-reactant-flow-transverse-mixing-mineral-precipitation-homogeneous-heterogeneous-porous-media"><span id="translatedtitle">Experimental and numerical analysis of <span class="hlt">parallel</span> reactant <span class="hlt">flow</span> and transverse mixing with mineral precipitation in homogeneous and heterogeneous porous media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGESBeta</a></p> <p>Fox, Don T.; Guo, Luanjing; Fujita, Yoshiko; Huang, Hai; Redden, George</p> <p>2015-12-17</p> <p>Formation of mineral precipitates in the mixing interface between two reactant solutions <span class="hlt">flowing</span> in <span class="hlt">parallel</span> in porous media is governed by reactant mixing by diffusion and dispersion and is coupled to changes in porosity/permeability due to precipitation. The spatial and temporal distribution of mixing-dependent precipitation of barium sulfate in porous media was investigated with side-by-side injection of barium chloride and sodium sulfate solutions in thin rectangular <span class="hlt">flow</span> cells packed with quartz sand. The results for homogeneous sand beds were compared to beds with higher or lower permeability inclusions positioned in the path of the mixing zone. In the homogeneous andmore » high permeability inclusion experiments, BaSO4 precipitate (barite) formed in a narrow deposit along the length and in the center of the solution–solution mixing zone even though dispersion was enhanced within, and downstream of, the high permeability inclusion. In the low permeability inclusion experiment, the deflected BaSO4 precipitation zone broadened around one side and downstream of the inclusion and was observed to migrate laterally toward the sulfate solution. A continuum-scale fully coupled reactive transport model that simultaneously solves the nonlinear governing equations for fluid <span class="hlt">flow</span>, transport of reactants and geochemical reactions was used to simulate the experiments and provide insight into mechanisms underlying the experimental observations. Lastly, migration of the precipitation zone in the low permeability inclusion experiment could be explained by the coupling effects among fluid <span class="hlt">flow</span>, reactant transport and localized mineral precipitation reaction.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/17945610','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/17945610"><span id="translatedtitle">Analysis of breathing <span class="hlt">air</span> <span class="hlt">flow</span> patterns in thermal imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fei, Jin; Pavlidis, Ioannis</p> <p>2006-01-01</p> <p>We introduce a novel methodology to characterize breathing patterns based on thermal infrared imaging. We have retrofitted a Mid-Wave Infra-Red (MWIR) imaging system with a narrow band-pass filter in the CO(2) absorption band (4130 - 4427 nm). We use this system to record the radiation information from within the breathing <span class="hlt">flow</span> region. Based on this information we compute the mean dynamic thermal signal of breath. The breath signal is quasi-periodic due to the interleaving of high and low intensities corresponding to expirations and inspirations respectively. We sample the signal at a constant rate and then filter the high frequency noise due to tracking instability. We detect the breathing cycles through zero cross thresholding, which is insensitive to noise around the zero line. We normalize the breathing cycles and align them at the transition point from inhalation to exhalation. Then, we compute the mean breathing cycle. We use the first eight (8) harmonic components of the mean cycle to characterize the breathing pattern. The harmonic analysis highlights the intra-individual similarity of breathing patterns. Our method opens the way for desktop, unobtrusive monitoring of human respiration and may find widespread applications in clinical studies of chronic ailments. It also brings up the intriguing possibility of using breathing patterns as a novel biometric. PMID:17945610</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002HMT....38..221H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002HMT....38..221H"><span id="translatedtitle">Convective heat transfer characteristics of laminar pulsating pipe <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>Habib, M. A.; Attya, A. M.; Eid, A. I.; Aly, A. Z.</p> <p></p> <p>Heat transfer characteristics to laminar pulsating pipe <span class="hlt">flow</span> under different conditions of Reynolds number and pulsation frequency were experimentally investigated. The tube wall of uniform heat flux condition was considered. Reynolds number was varied from 780 to 1987 while the frequency of pulsation ranged from 1 to 29.5Hz. The results showed that the relative mean Nusselt number is strongly affected by pulsation frequency while it is slightly affected by Reynolds number. The results showed enhancements in the relative mean Nusselt number. In the frequency range of 1-4Hz, an enhancement up to 30% (at Reynolds number of 1366 and pulsation frequency of 1.4Hz) was obtained. In the frequency range of 17-25Hz, an enhancement up to 9% (at Reynolds number of 1366 and pulsation frequency of 17.5Hz) was indicated. The rate of enhancement of the relative mean Nusselt number decreased as pulsation frequency increased or as Reynolds number increased. A reduction in relative mean Nusselt number occurred outside these ranges of pulsation frequencies. A reduction in relative mean Nusselt number up to 40% for pulsation frequency range of 4.1-17Hz and a reduction up to 20% for pulsation frequency range of 25-29.5Hz for Reynolds numbers range of 780-1987 were considered. This reduction is directly proportional to the pulsation frequency. Empirical dimensionless equations have been developed for the relative mean Nusselt number that related to Reynolds number (750<Re<2000) and the dimensionless frequency (3<Ω<18) with about 10%rms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21137949','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21137949"><span id="translatedtitle">An experimental study on the effect of <span class="hlt">air</span> bubble injection on the <span class="hlt">flow</span> induced rotational hub</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Nouri, N.M.; Sarreshtehdari, A.</p> <p>2009-01-15</p> <p>Modification of shear stress due to <span class="hlt">air</span> bubbles injection in a rotary device was investigated experimentally. <span class="hlt">Air</span> bubbles inject to the water <span class="hlt">flow</span> crosses the neighbor of the hub which can rotate just by water <span class="hlt">flow</span> shear stresses, in this device. Increasing <span class="hlt">air</span> void fraction leads to decrease of shear stresses exerted on the hub surface until in high void fractions, the hub motion stopped as observed. Amount of skin friction decrease has been estimated by counting central hub rotations. Wall shear stress was decreased by bubble injection in all range of tested Reynolds number, changing from 50,378 to 71,238, and also by increasing <span class="hlt">air</span> void fraction from zero to 3.06%. Skin friction reduction more than 85% was achieved in this study as maximum measured volume of <span class="hlt">air</span> fraction injected to fluid <span class="hlt">flow</span> while bubbles are distinct and they do not make a gas layer. Significant skin friction reduction obtained in this special case indicate that using small amount of bubble injection causes large amount of skin friction reduction in some rotary parts in the liquid phases like as water. (author)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EUCAS...7..401S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EUCAS...7..401S"><span id="translatedtitle">A blunted cone in a supersonic high-enthalpy nonequilibrium <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>Sakharov, V. I.; Shtapov, V. V.; Vasilevskiy, E. B.; Zhestkov, B. E.</p> <p>2015-06-01</p> <p>A calculation and experimental study was conducted with the <span class="hlt">flow</span>, heat flux, and pressure distributions over the front and side surfaces of a blunt cone in a nonequilibrium high-enthalpy (h0 = 25 MJ/kg) supersonic (M = 4) <span class="hlt">air</span> <span class="hlt">flow</span>. The experiments were performed in a VAT-104 wind tunnel (WT), TsAGI. The nose part of the model with a small-radius nose Rw = 10 mm and half angle θ = 10° was inside the "Mach cone" of the underexpanded jet <span class="hlt">flowing</span> out from the WT nozzle. Numerical and experimental results are in good agreement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910064614&hterms=flow+tube&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dflow%2Btube','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910064614&hterms=flow+tube&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dflow%2Btube"><span id="translatedtitle">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://hdl.handle.net/2060/19660000370','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19660000370"><span id="translatedtitle">Brazing retort manifold design concept may minimize <span class="hlt">air</span> contamination and enhance uniform gas <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>Ruppe, E. P.</p> <p>1966-01-01</p> <p>Brazing retort manifold minimizes <span class="hlt">air</span> contamination, prevents gas entrapment during purging, and provides uniform gas <span class="hlt">flow</span> into the retort bell. The manifold is easily cleaned and turbulence within the bell is minimized because all manifold construction lies outside the main enclosure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol2/pdf/CFR-2011-title7-vol2-sec28-603.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title7-vol2/pdf/CFR-2011-title7-vol2-sec28-603.pdf"><span id="translatedtitle">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=2011&page.go=Go">Code of Federal Regulations, 2011 CFR</a></p> <p></p> <p>2011-01-01</p> <p>... 7 Agriculture 2 2011-01-01 2011-01-01 false Procedures for <span class="hlt">air</span> <span class="hlt">flow</span> tests of micronaire reading... micronaire reading. In determining in terms of micronaire readings, the fiber fineness and maturity, in... cotton in terms of micronaire reading on the curvilinear scale adopted in September 1950 by...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol2/pdf/CFR-2010-title7-vol2-sec28-603.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title7-vol2/pdf/CFR-2010-title7-vol2-sec28-603.pdf"><span id="translatedtitle">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=2010&page.go=Go">Code of Federal Regulations, 2010 CFR</a></p> <p></p> <p>2010-01-01</p> <p>... 7 Agriculture 2 2010-01-01 2010-01-01 false Procedures for <span class="hlt">air</span> <span class="hlt">flow</span> tests of micronaire reading... micronaire reading. In determining in terms of micronaire readings, the fiber fineness and maturity, in... cotton in terms of micronaire reading on the curvilinear scale adopted in September 1950 by...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=226245','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/Publications.htm?seq_no_115=226245"><span id="translatedtitle">Wind Tunnel Evaluation of Vegetative Buffer Effects on <span class="hlt">Air</span> <span class="hlt">Flow</span> near Swine Production Facilities</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Increasing concerns about generation and transport of swine odor constituents have substantiated wind tunnel simulation studies on <span class="hlt">air</span> <span class="hlt">flow</span> dynamics near swine production facilities. A possible odor mitigation strategy is a forest vegetative buffer as a windbreak barrier near swine facilities becaus...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title42-vol1/pdf/CFR-2010-title42-vol1-sec84-148.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title42-vol1/pdf/CFR-2010-title42-vol1-sec84-148.pdf"><span id="translatedtitle">42 CFR 84.148 - Type C supplied-<span class="hlt">air</span> respirator, continuous <span class="hlt">flow</span> class; minimum requirements.</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>2010-10-01</p> <p>... 42 Public Health 1 2010-10-01 2010-10-01 false Type C supplied-<span class="hlt">air</span> respirator, continuous <span class="hlt">flow</span> class; minimum requirements. 84.148 Section 84.148 Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES OCCUPATIONAL SAFETY AND HEALTH RESEARCH AND RELATED ACTIVITIES APPROVAL OF RESPIRATORY PROTECTIVE DEVICES...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title30-vol1/pdf/CFR-2013-title30-vol1-sec57-22211.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title30-vol1/pdf/CFR-2013-title30-vol1-sec57-22211.pdf"><span id="translatedtitle">30 CFR 57.22211 - <span class="hlt">Air</span> <span class="hlt">flow</span> (I-A mines).</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>... 30 Mineral Resources 1 2013-07-01 2013-07-01 false <span class="hlt">Air</span> <span class="hlt">flow</span> (I-A mines). 57.22211 Section 57.22211 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2011-title30-vol1/pdf/CFR-2011-title30-vol1-sec57-22211.pdf','CFR2011'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2011-title30-vol1/pdf/CFR-2011-title30-vol1-sec57-22211.pdf"><span id="translatedtitle">30 CFR 57.22211 - <span class="hlt">Air</span> <span class="hlt">flow</span> (I-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-A mines). 57.22211 Section 57.22211 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title30-vol1/pdf/CFR-2014-title30-vol1-sec57-22211.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title30-vol1/pdf/CFR-2014-title30-vol1-sec57-22211.pdf"><span id="translatedtitle">30 CFR 57.22211 - <span class="hlt">Air</span> <span class="hlt">flow</span> (I-A mines).</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>... 30 Mineral Resources 1 2014-07-01 2014-07-01 false <span class="hlt">Air</span> <span class="hlt">flow</span> (I-A mines). 57.22211 Section 57.22211 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2012-title30-vol1/pdf/CFR-2012-title30-vol1-sec57-22211.pdf','CFR2012'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2012-title30-vol1/pdf/CFR-2012-title30-vol1-sec57-22211.pdf"><span id="translatedtitle">30 CFR 57.22211 - <span class="hlt">Air</span> <span class="hlt">flow</span> (I-A mines).</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>... 30 Mineral Resources 1 2012-07-01 2012-07-01 false <span class="hlt">Air</span> <span class="hlt">flow</span> (I-A mines). 57.22211 Section 57.22211 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol1/pdf/CFR-2010-title30-vol1-sec57-22211.pdf','CFR'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2010-title30-vol1/pdf/CFR-2010-title30-vol1-sec57-22211.pdf"><span id="translatedtitle">30 CFR 57.22211 - <span class="hlt">Air</span> <span class="hlt">flow</span> (I-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>... 30 Mineral Resources 1 2010-07-01 2010-07-01 false <span class="hlt">Air</span> <span class="hlt">flow</span> (I-A mines). 57.22211 Section 57.22211 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR METAL AND NONMETAL MINE SAFETY AND HEALTH SAFETY AND HEALTH STANDARDS-UNDERGROUND METAL AND NONMETAL MINES Safety Standards...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930090930','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930090930"><span id="translatedtitle">Investigation of <span class="hlt">Flow</span> in an Axially Symmetrical Heated Jet of <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>Corrsin, Stanley</p> <p>1943-01-01</p> <p>The work done under this contract falls essentially into two parts: the first part was the design and construction of the equipment and the running of preliminary tests on the 3-inch jet, carried out by Mr. Carl Thiele in 1940; the second part consisting in the measurement in the 1-inch jet <span class="hlt">flow</span> in an axially symmetrical heated jet of <span class="hlt">air</span>. (author)</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://www.ncbi.nlm.nih.gov/pubmed/19840985','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/19840985"><span id="translatedtitle">A <span class="hlt">parallel</span> second-order adaptive mesh algorithm for incompressible <span class="hlt">flow</span> in porous media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Pau, George S H; Almgren, Ann S; Bell, John B; Lijewski, Michael J</p> <p>2009-11-28</p> <p>In this paper, we present a second-order accurate adaptive algorithm for solving multi-phase, incompressible <span class="hlt">flow</span> in porous media. We assume a multi-phase form of Darcy's law with relative permeabilities given as a function of the phase saturation. The remaining equations express conservation of mass for the fluid constituents. In this setting, the total velocity, defined to be the sum of the phase velocities, is divergence free. The basic integration method is based on a total-velocity splitting approach in which we solve a second-order elliptic pressure equation to obtain a total velocity. This total velocity is then used to recast component conservation equations as nonlinear hyperbolic equations. Our approach to adaptive refinement uses a nested hierarchy of logically rectangular grids with simultaneous refinement of the grids in both space and time. The integration algorithm on the grid hierarchy is a recursive procedure in which coarse grids are advanced in time, fine grids are advanced multiple steps to reach the same time as the coarse grids and the data at different levels are then synchronized. The single-grid algorithm is described briefly, but the emphasis here is on the time-stepping procedure for the adaptive hierarchy. Numerical examples are presented to demonstrate the algorithm's accuracy and convergence properties and to illustrate the behaviour of the method. PMID:19840985</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/957033','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/957033"><span id="translatedtitle">A <span class="hlt">Parallel</span> Second-Order Adaptive Mesh Algorithm for Incompressible <span class="hlt">Flow</span> in Porous Media</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Pau, George Shu Heng; Almgren, Ann S.; Bell, John B.; Lijewski, Michael J.</p> <p>2008-04-01</p> <p>In this paper we present a second-order accurate adaptive algorithm for solving multiphase, incompressible <span class="hlt">flows</span> in porous media. We assume a multiphase form of Darcy's law with relative permeabilities given as a function of the phase saturation. The remaining equations express conservation of mass for the fluid constituents. In this setting the total velocity, defined to be the sum of the phase velocities, is divergence-free. The basic integration method is based on a total-velocity splitting approach in which we solve a second-order elliptic pressure equation to obtain a total velocity. This total velocity is then used to recast component conservation equations as nonlinear hyperbolic equations. Our approach to adaptive refinement uses a nested hierarchy of logically rectangular grids with simultaneous refinement of the grids in both space and time. The integration algorithm on the grid hierarchy is a recursive procedure in which coarse grids are advanced in time, fine grids areadvanced multiple steps to reach the same time as the coarse grids and the data atdifferent levels are then synchronized. The single grid algorithm is described briefly,but the emphasis here is on the time-stepping procedure for the adaptive hierarchy. Numerical examples are presented to demonstrate the algorithm's accuracy and convergence properties and to illustrate the behavior of the method.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010OPhy....8..604A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010OPhy....8..604A"><span id="translatedtitle">A <span class="hlt">parallel</span> three-dimensional scour model to predict <span class="hlt">flow</span> and scour below a submarine pipeline</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alam, Muhammad; Cheng, Liang</p> <p>2010-08-01</p> <p>A three-dimensional Lattice Boltzmann <span class="hlt">flow</span> and scour model is developed to simulate time-dependent scour below a submarine pipeline. The proposed model presented in this paper is able to predict streamwise and spanwise propagations of scour with respect to lattice unit of time. It is evident from this study that the existence of a spiral vortex in the proximity of the span shoulder is quite noteworthy. It is revealed that the critical regime of the 2-D scour process is found to be up to one pipe diameter away in both directions from the middle of the unsupported length of pipelines. The equilibrium maximum scour depth and the shape of streamwise equilibrium scour hole compare well with the available experimental data. The speed of propagation of scour along the pipeline length maintains an almost constant rate, which is consistent with the experimental observations found in literature. In addition, it is seen that the scour slope at the shoulder region remains fairly constant throughout the whole scour process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4897457','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4897457"><span id="translatedtitle">MHD Two-Fluid <span class="hlt">Flow</span> and Heat Transfer between Two Inclined <span class="hlt">Parallel</span> Plates in a Rotating System</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sri Ramachandra Murty, P.; Balaji Prakash, G.</p> <p>2014-01-01</p> <p>Two-phase magnetohydrodynamic convective <span class="hlt">flow</span> of electrically conducting fluid through an inclined channel is studied under the action of a constant transverse magnetic field in a rotating system. The fluids in the two phases are steady, incompressible, laminar, immiscible, and electrically conducting, having different densities, viscosities, and thermal and electrical conductivities. The transport properties of both the fluids are assumed constant. The bounding infinite inclined <span class="hlt">parallel</span> plates are maintained at different constant temperatures, making an angle ϕ with the horizontal. Approximate solutions for velocity and temperature distributions are obtained by using a straightforward regular perturbation technique. An in-depth study has been done on the effects of rotation parameter, Hartmann number, inclination angle, the ratio of electrical conductivities, and viscosities of two fluids on the <span class="hlt">flow</span>. It is observed that the effect of increasing rotation is to decrease the primary velocity. Further it is noticed that as the rotation increases, the secondary velocity increases for smaller rotation, while for larger rotation it decreases. It is also found that the temperature distribution decreases as the rotation increases. PMID:27351017</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/372191','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/372191"><span id="translatedtitle">Two-phase <span class="hlt">air</span>/oil <span class="hlt">flow</span> in aero engine bearing chambers: Characterization of oil film <span class="hlt">flows</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Glahn, A.; Wittig, S.</p> <p>1996-07-01</p> <p>For the design of secondary <span class="hlt">air</span> and lubrication oil systems, a sufficient knowledge of two-phase <span class="hlt">flow</span> and heat transfer phenomena under bearing chamber <span class="hlt">flow</span> conditions is required. The characterization of oil film <span class="hlt">flows</span> at the bearing chamber walls is one of the major tasks for a better understanding of these processes and, therefore, a necessity for improvements of the efficiency of aero engines. The present paper gives a contribution to this subject. Utilizing a fiber-optic LDV setup, measurements of oil film velocity profiles have been performed in the high-speed bearing chamber rig simulating real engine conditions. All data have been compared with different theoretical approaches, which have been derived from a force balance at a liquid film element, including geometric conditions and temperature dependent fluid properties, and by approaches for the eddy viscosity available in the literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/1083401','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/1083401"><span id="translatedtitle">Uncertainty Analysis for a Virtual <span class="hlt">Flow</span> Meter Using an <span class="hlt">Air</span>-Handling Unit Chilled Water Valve</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Song, Li; Wang, Gang; Brambley, Michael R.</p> <p>2013-04-28</p> <p>A virtual water <span class="hlt">flow</span> meter is developed that uses the chilled water control valve on an <span class="hlt">air</span>-handling unit as a measurement device. The <span class="hlt">flow</span> rate of water through the valve is calculated using the differential pressure across the valve and its associated coil, the valve command, and an empirically determined valve characteristic curve. Thus, the probability of error in the measurements is significantly greater than for conventionally manufactured <span class="hlt">flow</span> meters. In this paper, mathematical models are developed and used to conduct uncertainty analysis for the virtual <span class="hlt">flow</span> meter, and the results from the virtual meter are compared to measurements made with an ultrasonic <span class="hlt">flow</span> meter. Theoretical uncertainty analysis shows that the total uncertainty in <span class="hlt">flow</span> rates from the virtual <span class="hlt">flow</span> meter is 1.46% with 95% confidence; comparison of virtual <span class="hlt">flow</span> meter results with measurements from an ultrasonic <span class="hlt">flow</span> meter yielded anuncertainty of 1.46% with 99% confidence. The comparable results from the theoretical uncertainty analysis and empirical comparison with the ultrasonic <span class="hlt">flow</span> meter corroborate each other, and tend to validate the approach to computationally estimating uncertainty for virtual sensors introduced in this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4477291','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4477291"><span id="translatedtitle">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="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</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. PMID:26180842</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/26180842','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/26180842"><span id="translatedtitle">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. PMID:26180842</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011SCPMA..54..690Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011SCPMA..54..690Z"><span id="translatedtitle">The measurement error analysis when a pitot probe is used in supersonic <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>Zhang, XiWen; Hao, PengFei; Yao, ZhaoHui</p> <p>2011-04-01</p> <p>Pitot probes enable a simple and convenient way of measuring mean velocity in <span class="hlt">air</span> <span class="hlt">flow</span>. The contrastive numerical simulation between free supersonic airflow and pitot tube at different positions in supersonic <span class="hlt">air</span> <span class="hlt">flow</span> was performed using Navier-Stokes equations, the ENN scheme with time-dependent boundary conditions (TDBC) and the Spalart-Allmaras turbulence model. The physical experimental results including pitot pressure and shadowgraph are also presented. Numerical results coincide with the experimental data. The <span class="hlt">flow</span> characteristics of the pitot probe on the supersonic <span class="hlt">flow</span> structure show that the measurement gives actually the total pressure behind the detached shock wave by using the pitot probe to measure the total pressure. The measurement result of the distribution of the total pressure can still represent the real free jet <span class="hlt">flow</span>. The similar features of the intersection and reflection of shock waves can be identified. The difference between the measurement results and the actual ones is smaller than 10%. When the pitot probe is used to measure the region of L=0-4 D, the measurement is smaller than the real one due to the increase of the shock wave strength. The difference becomes larger where the waves intersect. If the pitot probe is put at L=8 D-10 D, where the <span class="hlt">flow</span> changes from supersonic to subsonic, the addition of the pitot probe turns the original supersonic <span class="hlt">flow</span> region subsonic and causes bigger measurement errors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040105528','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040105528"><span id="translatedtitle">Simulation of 3-D Nonequilibrium Seeded <span class="hlt">Air</span> <span class="hlt">Flow</span> in the NASA-Ames MHD Channel</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gupta, Sumeet; Tannehill, John C.; Mehta, Unmeel B.</p> <p>2004-01-01</p> <p>The 3-D nonequilibrium seeded <span class="hlt">air</span> <span class="hlt">flow</span> 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 <span class="hlt">flow</span>. In recent tests, velocity increases of up to 40% have been achieved in the accelerator section. The <span class="hlt">flow</span> in the channel is numerically computed us ing a 3-D parabolized Navier-Stokes (PNS) algorithm that has been developed to efficiently compute MHD <span class="hlt">flows</span> 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 <span class="hlt">air</span> <span class="hlt">flows</span>. The electrical conductivity of the <span class="hlt">flow</span> 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 <span class="hlt">flow</span>. The computed results are in good agreement with the experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Metro..53.1012K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016Metro..53.1012K&link_type=ABSTRACT"><span id="translatedtitle">Calibration of a system for measuring low <span class="hlt">air</span> <span class="hlt">flow</span> velocity in a wind tunnel</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krach, Andrzej; Kruczkowski, Janusz</p> <p>2016-08-01</p> <p>This article presents the calibration of a system for measuring <span class="hlt">air</span> <span class="hlt">flow</span> velocity in a wind tunnel with a multiple-hole orifice. The comparative method was applied for the calibration. The method consists in equalising the <span class="hlt">air</span> <span class="hlt">flow</span> velocity in a test section of the tunnel with that of the hot-wire anemometer probe which should then read zero value. The hot-wire anemometer probe moves reciprocally in the tunnel test section with a constant velocity, aligned and opposite to the <span class="hlt">air</span> velocity. <span class="hlt">Air</span> velocity in the tunnel test section is adjusted so that the minimum values of a periodic hot-wire anemometer signal displayed on an oscilloscope screen reach the lowest position (the minimum method). A sinusoidal component can be superimposed to the probe constant velocity. Then, the <span class="hlt">air</span> <span class="hlt">flow</span> velocity in the tunnel test section is adjusted so that, when the probe moves in the direction of <span class="hlt">air</span> <span class="hlt">flow</span>, only the second harmonic of the periodically variable velocity superimposed on the constant velocity (second harmonic method) remains at the output of the low-pass filter to which the hot-wire anemometer signal, displayed on the oscilloscope screen, is supplied. The velocity of the uniform motion of the hot-wire anemometer probe is measured with a magnetic linear encoder. The calibration of the system for the measurement of low <span class="hlt">air</span> velocities in the wind tunnel was performed in the following steps: 1. Calibration of the linear encoder for the measurement of the uniform motion velocity of the hot-wire anemometer probe in the test section of the tunnel. 2. Calibration of the system for measurement of low <span class="hlt">air</span> velocities with a multiple-hole orifice for the velocities of 0.1 and 0.25 m s‑1: - (a) measurement of the probe movement velocity setting; - (b) measurement of <span class="hlt">air</span> velocity in the tunnel test section with comparison according to the second harmonic method; - (c) measurement of <span class="hlt">air</span> velocity in the tunnel with comparison according to the minimum method. The calibration</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/23609636','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/23609636"><span id="translatedtitle">Laser filamentation induced <span class="hlt">air-flow</span> motion in a diffusion cloud chamber.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sun, Haiyi; Liu, Jiansheng; Wang, Cheng; Ju, Jingjing; Wang, Zhanxin; Wang, Wentao; Ge, Xiaochun; Li, Chuang; Chin, See Leang; Li, Ruxin; Xu, Zhizhan</p> <p>2013-04-22</p> <p>We numerically simulated the <span class="hlt">air-flow</span> motion in a diffusion cloud chamber induced by femtosecond laser filaments for different chopping rates. A two dimensional model was employed, where the laser filaments were treated as a heat flux source. The simulated patterns of <span class="hlt">flow</span> fields and maximum velocity of updraft compare well with the experimental results for the chopping rates of 1, 5, 15 and 150 Hz. A quantitative inconsistency appears between simulated and experimental maximum velocity of updraft for 1 kHz repetition rate although a similar pattern of <span class="hlt">flow</span> field is obtained, and the possible reasons were analyzed. Based on the present simulated results, the experimental observation of more water condensation/snow at higher chopping rate can be explained. These results indicate that the specific way of laser filament heating plays a significant role in the laser-induced motion of <span class="hlt">air</span> <span class="hlt">flow</span>, and at the same time, our previous conclusion of <span class="hlt">air</span> <span class="hlt">flow</span> having an important effect on water condensation/snow is confirmed. PMID:23609636</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009PhDT........75H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009PhDT........75H"><span id="translatedtitle">Mechanistic modeling of evaporating thin liquid film instability on a BWR fuel rod with <span class="hlt">parallel</span> and cross vapor <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, Chih-Chieh</p> <p></p> <p>This work has been aimed at developing a mechanistic, transient, 3-D numerical model to predict the behavior of an evaporating thin liquid film on a non-uniformly heated cylindrical rod with simultaneous <span class="hlt">parallel</span> and cross <span class="hlt">flow</span> of vapor. Interest in this problem has been motivated by the fact that the liquid film on a full-length boiling water reactor fuel rod may experience significant axial and azimuthal heat flux gradients and cross <span class="hlt">flow</span> due to variations in the thermal-hydraulic conditions in surrounding subchannels caused by proximity to inserted control blade tip and/or the top of part-length fuel rods. Such heat flux gradients coupled with localized cross <span class="hlt">flow</span> may cause the liquid film on the fuel rod surface to rupture, thereby forming a dry hot spot. These localized dryout phenomena can not be accurately predicted by traditional subchannel analysis methods in conjunction with empirical dryout correlations. To this end, a numerical model based on the Level Contour Reconstruction Method was developed. The Standard k-ε turbulence model is included. A cylindrical coordinate system has been used to enhance the resolution of the Level Contour Reconstruction Model. Satisfactory agreement has been achieved between the model predictions and experimental data. A model of this type is necessary to supplement current state-of-the-art BWR core thermal-hydraulic design methods based on subchannel analysis techniques coupled with empirical dry out correlations. In essence, such a model would provide the core designer with a "magnifying glass" by which the behavior of the liquid film at specific locations within the core (specific axial node on specific location within a specific bundle in the subchannel analysis model) can be closely examined. A tool of this type would allow the designer to examine the effectiveness of possible design changes and/or modified control strategies to prevent conditions leading to localized film instability and possible fuel failure.</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 id="translatedtitle">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('http://adsabs.harvard.edu/abs/1989shfl.confQ....R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989shfl.confQ....R"><span id="translatedtitle"><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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reed, Jason C.; Weinstein, Leonard M.</p> <p>1989-03-01</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://hdl.handle.net/2060/19940011006','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940011006"><span id="translatedtitle">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('http://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="http://ntrs.nasa.gov/search.jsp?R=19890043107&hterms=surfactants&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dsurfactants"><span id="translatedtitle"><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/2010APS..DFD.QE006M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010APS..DFD.QE006M"><span id="translatedtitle">Combined experimental and computational investigation of sterile <span class="hlt">air</span> <span class="hlt">flows</span> in surgical environments</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>McNeill, James; Hertzberg, Jean; Zhai, Zhiqiang</p> <p>2010-11-01</p> <p>Surgical environments in hospitals utilize downward, low-turbulence, sterile <span class="hlt">air</span> <span class="hlt">flow</span> across the patient to inhibit transmission of infectious diseases to the surgical site. Full-scale laboratory experiments using particle image velocimetry were conducted to investigate the <span class="hlt">air</span> distribution above the patient area. Computational fluid dynamics models were developed to further investigate the <span class="hlt">air</span> distribution within the operating room in order to determine the impact of ventilation design of airborne infectious disease pathways. Both Reynolds-averaged Navier-Stokes equations and large eddy simulation techniques are currently being used in the computational modeling to study the effect of turbulence modeling on the indoor <span class="hlt">air</span> distribution. CFD models are being calibrated based on the experimental data and will be used to study the probability of infectious particles entering the sterile region of the room.</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 id="translatedtitle">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/2005ASAJ..118Q1918L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005ASAJ..118Q1918L"><span id="translatedtitle"><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> </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/2013MeScT..24c5403O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013MeScT..24c5403O"><span id="translatedtitle">Measurement of <span class="hlt">air</span> distribution and void fraction of an upwards <span class="hlt">air</span>-water <span class="hlt">flow</span> using electrical resistance tomography and a wire-mesh sensor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Olerni, Claudio; Jia, Jiabin; Wang, Mi</p> <p>2013-03-01</p> <p>Measurements on an upwards <span class="hlt">air</span>-water <span class="hlt">flow</span> are reported that were obtained simultaneously with a dual-plane electrical resistance tomograph (ERT) and a wire-mesh sensor (WMS). The ultimate measurement target of both ERT and WMS is the same, the electrical conductivity of the medium. The ERT is a non-intrusive device whereas the WMS requires a net of wires that physically crosses the <span class="hlt">flow</span>. This paper presents comparisons between the results obtained simultaneously from the ERT and the WMS for evaluation and calibration of the ERT. The length of the vertical testing pipeline section is 3 m with an internal diameter of 50 mm. Two distinct sets of <span class="hlt">air</span>-water <span class="hlt">flow</span> rate scenarios, bubble and slug regimes, were produced in the experiments. The fast impedance camera ERT recorded the data at an approximate time resolution of 896 frames per second (fps) per plane in contrast with the 1024 fps of the wire-mesh sensor WMS200. The set-up of the experiment was based on well established knowledge of <span class="hlt">air</span>-water upwards <span class="hlt">flow</span>, particularly the specific <span class="hlt">flow</span> regimes and wall peak effects. The local <span class="hlt">air</span> void fraction profiles and the overall <span class="hlt">air</span> void fraction were produced from two systems to establish consistency for comparison of the data accuracy. Conventional bulk <span class="hlt">flow</span> measurements in <span class="hlt">air</span> mass and electromagnetic <span class="hlt">flow</span> metering, as well as pressure and temperature, were employed, which brought the necessary calibration to the <span class="hlt">flow</span> measurements. The results show that the profiles generated from the two systems have a certain level of inconsistency, particularly in a wall peak and a core peak from the ERT and WMS respectively, whereas the two tomography instruments achieve good agreement on the overall <span class="hlt">air</span> void fraction for bubble <span class="hlt">flow</span>. For slug <span class="hlt">flow</span>, when the void fraction is over 30%, the ERT underestimates the void fraction, but a linear relation between ERT and WMS is still observed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.water.usgs.gov/ofr20041318/','USGSPUBS'); return false;" href="http://pubs.water.usgs.gov/ofr20041318/"><span id="translatedtitle">Base-<span class="hlt">flow</span> data in the Arnold <span class="hlt">Air</span> Force Base area, Tennessee, June and October 2002</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Robinson, John A.; Haugh, Connor J.</p> <p>2004-01-01</p> <p>Arnold <span class="hlt">Air</span> Force Base (AAFB) occupies about 40,000 acres in Coffee and Franklin Counties, Tennessee. The primary mission of AAFB is to support the development of aerospace systems. This mission is accomplished through test facilities at Arnold Engineering Development Center (AEDC), which occupies about 4,000 acres in the center of AAFB. Base-<span class="hlt">flow</span> data including discharge, temperature, and specific conductance were collected for basins in and near AAFB during high base-<span class="hlt">flow</span> and low base-<span class="hlt">flow</span> conditions. Data representing high base-<span class="hlt">flow</span> conditions from 109 sites were collected on June 3 through 5, 2002, when discharge measurements at sites with <span class="hlt">flow</span> ranged from 0.005 to 46.4 ft3/s. Data representing low base-<span class="hlt">flow</span> conditions from 109 sites were collected on October 22 and 23, 2002, when discharge measurements at sites with <span class="hlt">flow</span> ranged from 0.02 to 44.6 ft3/s. Discharge from the basin was greater during high base-<span class="hlt">flow</span> conditions than during low base-<span class="hlt">flow</span> conditions. In general, major tributaries on the north side and southeastern side of the study area (Duck River and Bradley Creek, respectively) had the highest <span class="hlt">flows</span> during the study. Discharge data were used to categorize stream reaches and sub-basins. Stream reaches were categorized as gaining, losing, wet, dry, or unobserved for each base-<span class="hlt">flow</span> measurement period. Gaining stream reaches were more common during the high base-<span class="hlt">flow</span> period than during the low base-<span class="hlt">flow</span> period. Dry stream reaches were more common during the low base-<span class="hlt">flow</span> period than during the high base-<span class="hlt">flow</span> period. Losing reaches were more predominant in Bradley Creek and Crumpton Creek. Values of <span class="hlt">flow</span> per square mile for the study area of 0.55 and 0.37 (ft3/s)/mi2 were calculated using discharge data collected on June 3 through 5, 2002, and October 22 and 23, 2002, respectively. Sub-basin areas with surplus or deficient <span class="hlt">flow</span> were defined within the basin. Drainage areas for each stream measurement site were delineated and measured from topographic maps</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/118726','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/118726"><span id="translatedtitle"><span class="hlt">Parallel</span> pipelining</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Joseph, D.D.; Bai, R.; Liao, T.Y.; Huang, A.; Hu, H.H.</p> <p>1995-09-01</p> <p>In this paper the authors introduce the idea of <span class="hlt">parallel</span> pipelining for water lubricated transportation of oil (or other viscous material). A <span class="hlt">parallel</span> system can have major advantages over a single pipe with respect to the cost of maintenance and continuous operation of the system, to the pressure gradients required to restart a stopped system and to the reduction and even elimination of the fouling of pipe walls in continuous operation. The authors show that the action of capillarity in small pipes is more favorable for restart than in large pipes. In a <span class="hlt">parallel</span> pipeline system, they estimate the number of small pipes needed to deliver the same oil flux as in one larger pipe as N = (R/r){sup {alpha}}, where r and R are the radii of the small and large pipes, respectively, and {alpha} = 4 or 19/7 when the lubricating water <span class="hlt">flow</span> is laminar or turbulent.</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 id="translatedtitle">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://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4099170','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4099170"><span id="translatedtitle">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="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</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. PMID:25057511</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/24245889','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/24245889"><span id="translatedtitle">Mathematical modeling and microbiological verification of ohmic heating of a multicomponent mixture of particles in a continuous <span class="hlt">flow</span> ohmic heater system with electric field <span class="hlt">parallel</span> to <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>Kamonpatana, Pitiya; Mohamed, Hussein M H; Shynkaryk, Mykola; Heskitt, Brian; Yousef, Ahmed E; Sastry, Sudhir K</p> <p>2013-11-01</p> <p>To accomplish continuous <span class="hlt">flow</span> ohmic heating of a low-acid food product, sufficient heat treatment needs to be delivered to the slowest-heating particle at the outlet of the holding section. This research was aimed at developing mathematical models for sterilization of a multicomponent food in a pilot-scale ohmic heater with electric-field-oriented <span class="hlt">parallel</span> to the <span class="hlt">flow</span> and validating microbial inactivation by inoculated particle methods. The model involved 2 sets of simulations, one for determination of fluid temperatures, and a second for evaluating the worst-case scenario. A residence time distribution study was conducted using radio frequency identification methodology to determine the residence time of the fastest-moving particle from a sample of at least 300 particles. Thermal verification of the mathematical model showed good agreement between calculated and experimental fluid temperatures (P > 0.05) at heater and holding tube exits, with a maximum error of 0.6 °C. To achieve a specified target lethal effect at the cold spot of the slowest-heating particle, the length of holding tube required was predicted to be 22 m for a 139.6 °C process temperature with volumetric <span class="hlt">flow</span> rate of 1.0 × 10(-4) m3/s and 0.05 m in diameter. To verify the model, a microbiological validation test was conducted using at least 299 chicken-alginate particles inoculated with Clostridium sporogenes spores per run. The inoculated pack study indicated the absence of viable microorganisms at the target treatment and its presence for a subtarget treatment, thereby verifying model predictions. PMID:24245889</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012PhDT.......194W&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2012PhDT.......194W&link_type=ABSTRACT"><span id="translatedtitle">CFD analyses of <span class="hlt">flow</span> structures in <span class="hlt">air</span>-ingress and rod bundle problems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, Hong-Chan</p> <p></p> <p>Two topics from nuclear engineering field are included in this dissertation. One study is the <span class="hlt">air</span>-ingress phenomenon during a loss of coolant accident (LOCA) scenario, and the other is a 5-by-5 bundle assembly with a PWR design. The objectives were to investigate the Kelvin-Helmholtz instability of the gravity-driven stratified <span class="hlt">flows</span> inside a coaxial pipe and the effects caused by two types of spacers at the downstream of the rod bundle. Richardson extrapolation was used for the grid independent study. The simulation results show good agreements with the experiments. Wavelet analysis and Proper Orthogonal Decomposition (POD) were used to study the <span class="hlt">flow</span> behaviors and <span class="hlt">flow</span> patterns. For the <span class="hlt">air</span>-ingress phenomenon, Brunt-Vaisala frequency, or buoyancy frequency, predicts a frequency of 2.34 Hz; this is confirmed by the dominant frequency of 2.4 Hz obtained from the wavelet analysis between times 1.2 s and 1.85 s. For the rod bundle study, the dominant frequency at the center of the subchannel was determined to be 2.4 Hz with a secondary dominant frequency of 4 Hz and a much minor frequency of 6 Hz. Generally, wavelet analysis has much better performance than POD, in the <span class="hlt">air</span>-ingress phenomenon, for a strongly transient scenario; they are both appropriate for the rod bundle study. Based on this study, when the fluid pair in a real condition is used, the time which <span class="hlt">air</span> intrudes into the reactor is predictable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.H31B0845S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.H31B0845S"><span id="translatedtitle">Effect of the Entrapped <span class="hlt">air</span> on Water <span class="hlt">Flow</span> in Heterogeneous Soil: Experimental Set- up</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Snehota, M.; Sobotkova, M.; Cislerova, M.</p> <p>2008-12-01</p> <p>Temporal variations of steady state water <span class="hlt">flow</span> rates were observed in laboratory infiltration experiments done on a sample of compacted sand and on an undisturbed soil sample (Eutric Cambisol). These variations are found to be in relation with entrapped <span class="hlt">air</span> content. Infiltration-outflow experiments consisted of a series of ponded infiltration runs with seepage face boundary condition at the lower end of columns. The amount of the entrapped was derived from continuous weighing of the sample. The initial water contents were different for each run, which led to different amount of the <span class="hlt">air</span> trapped in the soil during the first stages of infiltrations. The results of the experiments done on undisturbed soil showed that the flux rates and water contents varied during quasi-steady state. This finding contradicts the standard theory. The fluctuations of the water content during the steady state <span class="hlt">flow</span> can be ascribed to the variations in volume of the entrapped <span class="hlt">air</span>. Similarly, shape of the bromide breakthrough curve, which were performed simultaneously during the quasi-steady state varied for undisturbed soil. The same behaviour was not observed in the sample of homogeneous sand. Computer tomography was used to characterize the structure of the undisturbed soil sample with focus on potential preferential <span class="hlt">flow</span> pathways, which are likely to host the entrapped <span class="hlt">air</span>. To formulate more general conclusions, an extended series of infiltration outflow and bromide breakthrough experiments is in progress. This research has been supported by research project GACR 103/08/1552 and MSMT CEZ MSM 6840770002.</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 id="translatedtitle">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('http://hdl.handle.net/2060/20100014068','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100014068"><span id="translatedtitle">Computing Isentropic <span class="hlt">Flow</span> Properties of <span class="hlt">Air</span>/R-134a Mixtures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kvaternik, Ray</p> <p>2006-01-01</p> <p>MACHRK is a computer program that calculates isentropic <span class="hlt">flow</span> properties of mixtures of <span class="hlt">air</span> and refrigerant R-134a (tetrafluoroethane), which are used in transonic aerodynamic testing in a wind tunnel at Langley Research Center. Given the total temperature, total pressure, static pressure, and mole fraction of R-134a in a mixture, MACHRK calculates the Mach number and the following associated <span class="hlt">flow</span> properties: dynamic pressure, velocity, density, static temperature, speed of sound, viscosity, ratio of specific heats, Reynolds number, and Prandtl number. Real-gas effects are taken into account by treating the gases comprising the mixture as both thermally and calorically imperfect. The Redlich-Kwong equation of state for mixtures and the constant-pressure ideal heat-capacity equation for the mixture are used in combination with the departure- function approach of thermodynamics to obtain the equations for computing the <span class="hlt">flow</span> properties. In addition to the aforementioned calculations for <span class="hlt">air</span>/R-134a mixtures, a research version of MACHRK can perform the corresponding calculations for mixtures of <span class="hlt">air</span> and R-12 (dichlorodifluoromethane) and for <span class="hlt">air</span>/SF6 mixtures. [R-12 was replaced by R-134a because of environmental concerns. SF6 has been considered for use in increasing the Reynolds-number range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22390748','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22390748"><span id="translatedtitle">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/scitech">SciTech Connect</a></p> <p>Othman, M. N. K. E-mail: zuradzman@unimap.edu.my E-mail: khairunizam@unimap.edu.my E-mail: s.yaacob@unimap.edu.my E-mail: abadal@unimap.edu.my; Zuradzman, M. Razlan E-mail: zuradzman@unimap.edu.my E-mail: khairunizam@unimap.edu.my E-mail: s.yaacob@unimap.edu.my E-mail: abadal@unimap.edu.my; Hazry, D. E-mail: zuradzman@unimap.edu.my E-mail: khairunizam@unimap.edu.my E-mail: s.yaacob@unimap.edu.my E-mail: abadal@unimap.edu.my; Khairunizam, Wan E-mail: zuradzman@unimap.edu.my E-mail: khairunizam@unimap.edu.my E-mail: s.yaacob@unimap.edu.my E-mail: abadal@unimap.edu.my; Shahriman, A. B. E-mail: zuradzman@unimap.edu.my E-mail: khairunizam@unimap.edu.my E-mail: s.yaacob@unimap.edu.my E-mail: abadal@unimap.edu.my; Yaacob, S. E-mail: zuradzman@unimap.edu.my E-mail: khairunizam@unimap.edu.my E-mail: s.yaacob@unimap.edu.my E-mail: abadal@unimap.edu.my; Ahmed, S. Faiz E-mail: zuradzman@unimap.edu.my E-mail: khairunizam@unimap.edu.my E-mail: s.yaacob@unimap.edu.my E-mail: abadal@unimap.edu.my; and others</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 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('http://adsabs.harvard.edu/abs/2014APJAS..50..365K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APJAS..50..365K"><span id="translatedtitle">Effects of building-roof cooling on <span class="hlt">flow</span> and <span class="hlt">air</span> temperature in urban street canyons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Jae-Jin; Pardyjak, Eric; Kim, Do-Yong; Han, Kyoung-Soo; Kwon, Byung-Hyuk</p> <p>2014-05-01</p> <p>The effects of building-roof cooling on <span class="hlt">flow</span> and <span class="hlt">air</span> temperature in 3D urban street canyons are numerically investigated using a computational fluid dynamics (CFD) model. The aspect ratios of the building and street canyon considered are unity. For investigating the building-roof cooling effects, the building-roof temperatures are systematically changed. The traditional <span class="hlt">flow</span> pattern including a portal vortex appears in the spanwise canyon. Compared with the case of the control run, there are minimal differences in <span class="hlt">flow</span> pattern in the cases in which maximum building-roof cooling is considered. However, as the building roof becomes cooler, the mean kinetic energy increases and the <span class="hlt">air</span> temperature decreases in the spanwise canyon. Building-roof cooling suppresses the upward and inward motions above the building roof, resultantly increasing the horizontal velocity near the roof level. The increase in wind velocity above the roof level intensifies the secondarily driven vortex circulation as well as the inward (outward) motion into (out of) the spanwise canyon. Finally, building-roof cooling reduces the <span class="hlt">air</span> temperature in the spanwise canyon, supplying much relatively cool <span class="hlt">air</span> from the streamwise canyon into the spanwise canyon.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JPhCS.656a2113F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JPhCS.656a2113F"><span id="translatedtitle"><span class="hlt">Air</span> release measurements of V-oil 1404 downstream of a micro orifice at choked <span class="hlt">flow</span> conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Freudigmann, H.-A.; Iben, U.; Pelz, P. F.</p> <p>2015-12-01</p> <p>This study presents measurements on <span class="hlt">air</span> release of V-oil 1404 in the back <span class="hlt">flow</span> of a micro orifice at choked <span class="hlt">flow</span> conditions using a shadowgraph imaging method. The released <span class="hlt">air</span> was determined at three positions downstream of the orifice for different pressure conditions. It was found that more than 23% of the initially dissolved <span class="hlt">air</span> is released and appears downstream of the orifice in the form of bubbles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/5628516','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/5628516"><span id="translatedtitle">A <span class="hlt">parallel</span> numerical simulation for supersonic <span class="hlt">flows</span> using zonal overlapped grids and local time steps for common and distributed memory multiprocessors</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Patel, N.R.; Sturek, W.B.; Hiromoto, R.</p> <p>1989-01-01</p> <p><span class="hlt">Parallel</span> Navier-Stokes codes are developed to solve both two- dimensional and three-dimensional <span class="hlt">flow</span> fields in and around ramjet and nose tip configurations. A multi-zone overlapped grid technique is used to extend an explicit finite-difference method to more complicated geometries. <span class="hlt">Parallel</span> implementations are developed for execution on both distributed and common-memory multiprocessor architectures. For the steady-state solutions, the use of the local time-step method has the inherent advantage of reducing the communications overhead commonly incurred by <span class="hlt">parallel</span> implementations. Computational results of the codes are given for a series of test problems. The <span class="hlt">parallel</span> partitioning of computational zones is also discussed. 5 refs., 18 figs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1159373','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1159373"><span id="translatedtitle">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/scitech">SciTech Connect</a></p> <p>Kozubal, E.; Herrmann, L.; Deru, M.; Clark, J.; Lowenstein, A.</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 first 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950044396&hterms=froude+number&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfroude%2Bnumber','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950044396&hterms=froude+number&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dfroude%2Bnumber"><span id="translatedtitle">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/1993JAtS...50.3790L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JAtS...50.3790L"><span id="translatedtitle">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://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Yuh-Lang; Wang, Ting-An; Weglarz, Ronald P.</p> <p>1993-11-01</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/1997PhDT.......250L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1997PhDT.......250L"><span id="translatedtitle">Simulations of the loading and radiated sound of airfoils and wings in unsteady <span class="hlt">flow</span> using computational aeroacoustics and <span class="hlt">parallel</span> computers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lockard, David Patrick</p> <p></p> <p>This thesis makes contributions towards the use of computational aeroacoustics (CAA) as a tool for noise analysis. CAA uses numerical methods to simulate acoustic phenomena. CAA algorithms have been shown to reproduce wave propagation much better than traditional computational fluid dynamics (CFD) methods. In the current approach, a finite-difference, time-domain algorithm is used to simulate unsteady, compressible <span class="hlt">flows</span>. Dispersion-relation-preserving methodology is used to extend the range of frequencies that can be represented properly by the scheme. Since CAA algorithms are relatively inefficient at obtaining a steady-state solution, multigrid methods are applied to accelerate the convergence. All of the calculations are performed on <span class="hlt">parallel</span> computers. Excellent speedup ratios are obtained for the explicit, time-stepping algorithm used in this research. A common problem in the area of broadband noise is the prediction of the acoustic field generated by a vortical gust impinging on a solid body. The problem is modeled initially in two-dimensions by a flat plate experiencing a uniform mean <span class="hlt">flow</span> with a sinusoidal, vertical velocity perturbation. Good agreement is obtained with results from semi-analytic methods for several gust frequencies. Then, a cascade of plates is used to simulate a turbomachinery blade row. A new approach is used to impose the vortical disturbance inside the computational domain rather than imposing it at the computational boundary. The influence of the mean <span class="hlt">flow</span> on the radiated noise is examined by considering NACA0012 and RAE2822 airfoils. After a steady-state is obtained from the multigrid method, the un-steady simulation is used to model the vortical gust's interaction with the airfoil. The mean loading on the airfoil is shown to have a significant effect on the directivity of the sound with the strongest influence observed for high frequencies. Camber is shown to have a similar effect as the angle of attack. A three-dimensional problem</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3482535','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3482535"><span id="translatedtitle">Changes in nasal <span class="hlt">air</span> <span class="hlt">flow</span> and school grades after rapid maxillary expansion in oral breathing children</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Torre, Hilda</p> <p>2012-01-01</p> <p>Objective: To analyse the changes in nasal <span class="hlt">air</span> <span class="hlt">flow</span> and school grades after rapid maxillary expansion (RME) in oral breathing children with maxillary constriction. Material and Methods: Forty-four oral breathing children (mean age 10.57 y) underwent orthodontic RME with a Hyrax screw. Forty-four age-matched children (mean age 10.64 y) with nasal physiological breathing and adequate transverse maxillary dimensions served as the control group. The maxillary widths, nasal <span class="hlt">air</span> <span class="hlt">flow</span> assessed via peak nasal inspiratory <span class="hlt">flow</span> (PNIF), and school grades were recorded at baseline, and 6 months and one year following RME. Results: After RME, there were significant increases in all the maxillary widths in the study group. PNIF was reduced in the study group (60.91 ± 13.13 l/min) compared to the control group (94.50 ± 9.89 l/min) (P < 0.000) at the beginning of the study. Six months after RME, a significant improvement of PNIF was observed in the study group (36.43 ± 22.61). School grades were lower in the study group (85.52 ± 5.74) than in the control group (89.77 ± 4.44) (P < 0.05) at the baseline, but it increased six months after RME (2.77 ± 3.90) (P < 0.001) and one year later (5.02 ± 15.23) (P < 0.05). Conclusions: Nasal <span class="hlt">air</span> <span class="hlt">flow</span> improved in oral breathing children six months and one year after RME. School grades also improved, but not high enough to be academically significant. Key words:Maxillary constriction, oral breathing, nasal <span class="hlt">air</span> <span class="hlt">flow</span>, rapid maxillary expansion, school grades. PMID:22322516</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1044760','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1044760"><span id="translatedtitle">Thermal characteristics of <span class="hlt">air</span> <span class="hlt">flow</span> cooling in the lithium ion batteries experimental chamber</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Lukhanin A.; Rohatgi U.; Belyaev, A.; Fedorchenko, D.; Khazhmuradov, M.; Lukhanin, O; Rudychev, I.</p> <p>2012-07-08</p> <p>A battery pack prototype has been designed and built to evaluate various <span class="hlt">air</span> cooling concepts for the thermal management of Li-ion batteries. The heat generation from the Li-Ion batteries was simulated with electrical heat generation devices with the same dimensions as the Li-Ion battery (200 mm x 150 mm x 12 mm). Each battery simulator generates up to 15W of heat. There are 20 temperature probes placed uniformly on the surface of the battery simulator, which can measure temperatures in the range from -40 C to +120 C. The prototype for the pack has up to 100 battery simulators and temperature probes are recorder using a PC based DAQ system. We can measure the average surface temperature of the simulator, temperature distribution on each surface and temperature distributions in the pack. The pack which holds the battery simulators is built as a crate, with adjustable gap (varies from 2mm to 5mm) between the simulators for <span class="hlt">air</span> <span class="hlt">flow</span> channel studies. The total system <span class="hlt">flow</span> rate and the inlet <span class="hlt">flow</span> temperature are controlled during the test. The cooling channel with various heat transfer enhancing devices can be installed between the simulators to investigate the cooling performance. The prototype was designed to configure the number of cooling channels from one to hundred Li-ion battery simulators. The pack is thermally isolated which prevents heat transfer from the pack to the surroundings. The <span class="hlt">flow</span> device can provide the <span class="hlt">air</span> <span class="hlt">flow</span> rate in the gap of up to 5m/s velocity and <span class="hlt">air</span> temperature in the range from -30 C to +50 C. Test results are compared with computational modeling of the test configurations. The present test set up will be used for future tests for developing and validating new cooling concepts such as surface conditions or heat pipes.</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 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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