Does seismic activity control carbon exchanges between transform-faults in old ocean crust and the deep sea? A hypothesis examined by the EU COST network FLOWS

NASA Astrophysics Data System (ADS)

Lever, M. A.

2014-12-01

The European Cooperation in Science and Technology (COST)-Action FLOWS (http://www.cost.eu/domains_actions/essem/Actions/ES1301) was initiated on the 25th of October 2013. It is a consortium formed by members of currently 14 COST countries and external partners striving to better understand the interplay between earthquakes and fluid flow at transform-faults in old oceanic crust. The recent occurrence of large earthquakes and discovery of deep fluid seepage calls for a revision of the postulated hydrogeological inactivity and low seismic activity of old oceanic transform-type plate boundaries, and indicates that earthquakes and fluid flow are intrinsically associated. This Action merges the expertise of a large number of research groups and supports the development of multidisciplinary knowledge on how seep fluid (bio)chemistry relates to seismicity. It aims to identify (bio)geochemical proxies for the detection of precursory seismic signals and to develop innovative physico-chemical sensors for deep-ocean seismogenic faults. National efforts are coordinated through Working Groups (WGs) focused on 1) geophysical and (bio)geochemical data acquisition; 2) modelling of structure and seismicity of faults; 3) engineering of deep-ocean physico-chemical seismic sensors; and 4) integration and dissemination. This poster will illustrate the overarching goals of the FLOWS Group, with special focus to research goals concerning the role of seismic activity in controlling the release of carbon from the old ocean crust into the deep ocean.

Numerical analysis of the turbulent fluid flow through valves. Geometrical aspects influence at different positions

NASA Astrophysics Data System (ADS)

Rigola, J.; Aljure, D.; Lehmkuhl, O.; Pérez-Segarra, C. D.; Oliva, A.

2015-08-01

The aim of this paper is to carry out a group of numerical experiments over the fluid flow through a valve reed, using the CFD&HT code TermoFluids, an unstructured and parallel object-oriented CFD code for accurate and reliable solving of industrial flows. Turbulent flow and its solution is a very complex problem due to there is a non-lineal interaction between viscous and inertial effects further complicated by their rotational nature, together with the three-dimensionality inherent in these types of flow and the non-steady state solutions. In this work, different meshes, geometrical conditions and LES turbulence models (WALE, VMS, QR and SIGMA) are tested and results compared. On the other hand, the fluid flow boundary conditions are obtained by means of the numerical simulation model of hermetic reciprocating compressors tool, NEST-compressor code. The numerical results presented are based on a specific geometry, where the valve gap opening percentage is 11% of hole diameter and Reynolds numbers given by the one-dimensional model is 4.22 × 105, with density meshes of approximately 8 million CVs. Geometrical aspects related with the orifice's shape and its influence on fluid flow behaviour and pressure drop are analysed in detail, furthermore, flow results for different valve openings are also studied.

Axisymmetric flows from fluid injection into a confined porous medium

NASA Astrophysics Data System (ADS)

Guo, Bo; Zheng, Zhong; Celia, Michael A.; Stone, Howard A.

2016-02-01

We study the axisymmetric flows generated from fluid injection into a horizontal confined porous medium that is originally saturated with another fluid of different density and viscosity. Neglecting the effects of surface tension and fluid mixing, we use the lubrication approximation to obtain a nonlinear advection-diffusion equation that describes the time evolution of the sharp fluid-fluid interface. The flow behaviors are controlled by two dimensionless groups: M, the viscosity ratio of displaced fluid relative to injected fluid, and Γ, which measures the relative importance of buoyancy and fluid injection. For this axisymmetric geometry, the similarity solution involving R2/T (where R is the dimensionless radial coordinate and T is the dimensionless time) is an exact solution to the nonlinear governing equation for all times. Four analytical expressions are identified as asymptotic approximations (two of which are new solutions): (i) injection-driven flow with the injected fluid being more viscous than the displaced fluid (Γ ≪ 1 and M < 1) where we identify a self-similar solution that indicates a parabolic interface shape; (ii) injection-driven flow with injected and displaced fluids of equal viscosity (Γ ≪ 1 and M = 1), where we find a self-similar solution that predicts a distinct parabolic interface shape; (iii) injection-driven flow with a less viscous injected fluid (Γ ≪ 1 and M > 1) for which there is a rarefaction wave solution, assuming that the Saffman-Taylor instability does not occur at the reservoir scale; and (iv) buoyancy-driven flow (Γ ≫ 1) for which there is a well-known self-similar solution corresponding to gravity currents in an unconfined porous medium [S. Lyle et al. "Axisymmetric gravity currents in a porous medium," J. Fluid Mech. 543, 293-302 (2005)]. The various axisymmetric flows are summarized in a Γ-M regime diagram with five distinct dynamic behaviors including the four asymptotic regimes and an intermediate regime. The implications of the regime diagram are discussed using practical engineering projects of geological CO2 sequestration, enhanced oil recovery, and underground waste disposal.

HYPERHYDRATION AND PAROTID FLOW IN MAN.

DTIC Science & Technology

Parotid fluid was collected without exogenous stimulation from five groups of 25 subjects each. Each group received a different amount of water...under conditions of forced ingestion. The increase in parotid flow rate brought about by water ingestion was highly significant. Doses of 1,000 ml. or

Particle-fluid interactions for flow measurements

NASA Technical Reports Server (NTRS)

Berman, N. S.

1973-01-01

Study has been made of the motion of single particle and of group of particles, emphasizing solid particles in gaseous fluid. Velocities of fluid and particle are compared for several conditions of physical interest. Mean velocity and velocity fluctuations are calculated for single particle, and some consideration is given to multiparticle systems.

Theoretical Calculations on Sediment Transport on Titan, and the Possible Production of Streamlined Forms

NASA Technical Reports Server (NTRS)

Burr, D. M.; Emery, J. P.; Lorenz, R. D.

2005-01-01

The Cassini Imaging Science System (ISS) has been returning images of Titan, along with other Saturnian satellites. Images taken through the 938 nm methane window see down to Titan's surface. One of the purposes of the Cassini mission is to investigate possible fluid cycling on Titan. Lemniscate features shown recently and radar evidence of surface flow prompted us to consider theoretically the creation by methane fluid flow of streamlined forms on Titan. This follows work by other groups in theoretical consideration of fluid motion on Titan's surface.

Hydrodynamic focusing investigation in a micro-flow cytometer.

PubMed

Yang, An-Shik; Hsieh, Wen-Hsin

2007-04-01

Hydrodynamic focusing behavior is characterized by two fluids coflowing at different velocities inside a micro-flow cytometer. In this study, a two-fluid model has been established to describe the flow transport behavior and interaction of sample and sheath fluids. The analysis treats the sample and sheath fluids as two-dimensional, laminar, incompressible, and isothermal. The theoretical model comprises two groups of transient conservation equations of mass and momentum with consideration of the interfacial momentum exchange. The governing equations are solved numerically through an iterative SIMPLEC algorithm to determine the flow properties. Since the ratio of the sheath velocity to the sample velocity varies from 5 to 70, the predicted focusing width and length are in good agreement with the experimental data in the literature. In addition, the present study explored the hydrodynamic focusing flowfield as well as the pressure drop across a micro-flow cytometer and the time needed for the completion of one focusing event in detail. To enhance the understanding of hydrodynamic focusing in the design of cytometers, ten numerical experiments were conducted to examine the effects of the inner nozzle length, inner nozzle exit width, inner nozzle shape, and fluid properties on the width of the focused sample stream.

Dual Solutions for Nonlinear Flow Using Lie Group Analysis

PubMed Central

Awais, Muhammad; Hayat, Tasawar; Irum, Sania; Saleem, Salman

2015-01-01

`The aim of this analysis is to investigate the existence of the dual solutions for magnetohydrodynamic (MHD) flow of an upper-convected Maxwell (UCM) fluid over a porous shrinking wall. We have employed the Lie group analysis for the simplification of the nonlinear differential system and computed the absolute invariants explicitly. An efficient numerical technique namely the shooting method has been employed for the constructions of solutions. Dual solutions are computed for velocity profile of an upper-convected Maxwell (UCM) fluid flow. Plots reflecting the impact of dual solutions for the variations of Deborah number, Hartman number, wall mass transfer are presented and analyzed. Streamlines are also plotted for the wall mass transfer effects when suction and blowing situations are considered. PMID:26575996

Insertable fluid flow passage bridgepiece and method

DOEpatents

Jones, Daniel O.

2000-01-01

A fluid flow passage bridgepiece for insertion into an open-face fluid flow channel of a fluid flow plate is provided. The bridgepiece provides a sealed passage from a columnar fluid flow manifold to the flow channel, thereby preventing undesirable leakage into and out of the columnar fluid flow manifold. When deployed in the various fluid flow plates that are used in a Proton Exchange Membrane (PEM) fuel cell, bridgepieces of this invention prevent mixing of reactant gases, leakage of coolant or humidification water, and occlusion of the fluid flow channel by gasket material. The invention also provides a fluid flow plate assembly including an insertable bridgepiece, a fluid flow plate adapted for use with an insertable bridgepiece, and a method of manufacturing a fluid flow plate with an insertable fluid flow passage bridgepiece.

Fluid Flow Prediction with Development System Interwell Connectivity Influence

NASA Astrophysics Data System (ADS)

Bolshakov, M.; Deeva, T.; Pustovskikh, A.

2016-03-01

In this paper interwell connectivity has been studied. First of all, literature review of existing methods was made which is divided into three groups: Statistically-Based Methods, Material (fluid) Propagation-Based Methods and Potential (pressure) Change Propagation-Based Method. The disadvantages of the first and second groups are as follows: methods do not involve fluid flow through porous media, ignore any changes of well conditions (BHP, skin factor, etc.). The last group considers changes of well conditions and fluid flow through porous media. In this work Capacitance method (CM) has been chosen for research. This method is based on material balance and uses weight coefficients lambdas to assess well influence. In the next step synthetic model was created for examining CM. This model consists of an injection well and a production well. CM gave good results, it means that flow rates which were calculated by analytical method (CM) show matching with flow rate in model. Further new synthetic model was created which includes six production and one injection wells. This model represents seven-spot pattern. To obtain lambdas weight coefficients, the delta function was entered using by minimization algorithm. Also synthetic model which has three injectors and thirteen producer wells was created. This model simulates seven-spot pattern production system. Finally Capacitance method (CM) has been adjusted on real data of oil Field Ω. In this case CM does not give enough satisfying results in terms of field data liquid rate. In conclusion, recommendations to simplify CM calculations were given. Field Ω is assumed to have one injection and one production wells. In this case, satisfying results for production rates and cumulative production were obtained.

Zero Boil-Off Tank (ZBOT) Experiment

NASA Technical Reports Server (NTRS)

Mcquillen, John

2016-01-01

The Zero-Boil-Off Tank (ZBOT) experiment has been developed as a small scale ISS experiment aimed at delineating important fluid flow, heat and mass transport, and phase change phenomena that affect cryogenic storage tank pressurization and pressure control in microgravity. The experiments use a simulant transparent low boiling point fluid (PnP) in a sealed transparent Dewar to study and quantify: (a) fluid flow and thermal stratification during pressurization; (b) mixing, thermal destratification, depressurization, and jet-ullage penetration during pressure control by jet mixing. The experiment will provide valuable microgravity empirical two-phase data associated with the above-mentioned physical phenomena through highly accurate local wall and fluid temperature and pressure measurements, full-field phase-distribution and flow visualization. Moreover, the experiments are performed under tightly controlled and definable heat transfer boundary conditions to provide reliable high-fidelity data and precise input as required for validation verification of state-of-the-art two-phase CFD models developed as part of this research and by other groups in the international scientific and cryogenic fluid management communities.

Acoustic concentration of particles in fluid flow

DOEpatents

Ward, Michael D.; Kaduchak, Gregory

2010-11-23

An apparatus for acoustic concentration of particles in a fluid flow includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluid flow path to the at least one pressure minima.

Flow of quasi-two dimensional water in graphene channels

NASA Astrophysics Data System (ADS)

Fang, Chao; Wu, Xihui; Yang, Fengchang; Qiao, Rui

2018-02-01

When liquids confined in slit channels approach a monolayer, they become two-dimensional (2D) fluids. Using molecular dynamics simulations, we study the flow of quasi-2D water confined in slit channels featuring pristine graphene walls and graphene walls with hydroxyl groups. We focus on to what extent the flow of quasi-2D water can be described using classical hydrodynamics and what are the effective transport properties of the water and the channel. First, the in-plane shearing of quasi-2D water confined between pristine graphene can be described using the classical hydrodynamic equation, and the viscosity of the water is ˜50% higher than that of the bulk water in the channel studied here. Second, the flow of quasi-2D water around a single hydroxyl group is perturbed at a position of tens of cluster radius from its center, as expected for low Reynolds number flows. Even though water is not pinned at the edge of the hydroxyl group, the hydroxyl group screens the flow greatly, with a single, isolated hydroxyl group rendering drag similar to ˜90 nm2 pristine graphene walls. Finally, the flow of quasi-2D water through graphene channels featuring randomly distributed hydroxyl groups resembles the fluid flow through porous media. The effective friction factor of the channel increases linearly with the hydroxyl groups' area density up to 0.5 nm-2 but increases nonlinearly at higher densities. The effective friction factor of the channel can be fitted to a modified Carman equation at least up to a hydroxyl area density of 2.0 nm-2. These findings help understand the liquid transport in 2D material-based nanochannels for applications including desalination.

Acoustic concentration of particles in fluid flow

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

Ward, Michael W.; Kaduchak, Gregory

Disclosed herein is a acoustic concentration of particles in a fluid flow that includes a substantially acoustically transparent membrane and a vibration generator that define a fluid flow path therebetween. The fluid flow path is in fluid communication with a fluid source and a fluid outlet and the vibration generator is disposed adjacent the fluid flow path and is capable of producing an acoustic field in the fluid flow path. The acoustic field produces at least one pressure minima in the fluid flow path at a predetermined location within the fluid flow path and forces predetermined particles in the fluidmore » flow path to the at least one pressure minima.« less

Proton exchange membrane based on chitosan and solvent-free carbon nanotube fluids for fuel cells applications.

PubMed

Wang, Jie; Gong, Chunli; Wen, Sheng; Liu, Hai; Qin, Caiqin; Xiong, Chuanxi; Dong, Lijie

2018-04-15

Poor dispersion and inert ionic conduction are two major obstacles towards using carbon nanotubes (CNTs) to modify polymer electrolyte membranes (PEMs) in energy conversion devices. In this work, solvent-free carbon nanotube fluids (CNT fluids) with liquid-like behavior are prepared through an ion exchange method and incorporated into a chitosan (CS) matrix to fabricate composite membranes. The electrostatic interactions between SO 3 - groups in the CNT fluids and NH 2 groups in the CS matrix, in addition to the unique flow properties of the CNT fluids, promote the uniform dispersion of CNT fluids in the CS matrix. Markedly, the CS/CNT fluid-3 composite membrane is simultaneously reinforced and toughened by 180% and 300% compared to pure CS membrane, respectively. Moreover, the SO 3 - groups in the CNT fluids facilitate the proton transfer such that the proton conductivity of CS/CNT fluid-3 composite membrane reaches a maximum value of 0.044 S cm -1 at 80 °C. Copyright © 2018 Elsevier Ltd. All rights reserved.

Flagella, flexibility and flow: Physical processes in microbial ecology

NASA Astrophysics Data System (ADS)

Brumley, D. R.; Rusconi, R.; Son, K.; Stocker, R.

2015-12-01

How microorganisms interact with their environment and with their conspecifics depends strongly on their mechanical properties, on the hydrodynamic signatures they generate while swimming and on fluid flows in their environment. The rich fluid-structure interaction between flagella - the appendages microorganisms use for propulsion - and the surrounding flow, has broad reaching effects for both eukaryotic and prokaryotic microorganisms. Here, we discuss selected recent advances in our understanding of the physical ecology of microorganisms, which have hinged on the ability to directly interrogate the movement of individual cells and their swimming appendages, in precisely controlled fluid environments, and to image them at appropriately fast timescales. We review how a flagellar buckling instability can unexpectedly serve a fundamental function in the motility of bacteria, we elucidate the role of hydrodynamics and flexibility in the emergent properties of groups of eukaryotic flagella, and we show how fluid flows characteristic of microbial habitats can strongly bias the migration and spatial distribution of bacteria. The topics covered here are illustrative of the potential inherent in the adoption of experimental methods and conceptual frameworks from physics in understanding the lives of microorganisms.

Flow Cage Assemblies

NASA Technical Reports Server (NTRS)

Bar-Cohen, Yoseph (Inventor); Sherrit, Stewart (Inventor); Badescu, Mircea (Inventor); Bao, Xiaoqi (Inventor)

2017-01-01

Apparatus, systems and methods for implementing flow cages and flow cage assemblies in association with high pressure fluid flows and fluid valves are provided. Flow cages and flow assemblies are provided to dissipate the energy of a fluid flow, such as by reducing fluid flow pressure and/or fluid flow velocity. In some embodiments the dissipation of the fluid flow energy is adapted to reduce erosion, such as from high-pressure jet flows, to reduce cavitation, such as by controllably increasing the flow area, and/or to reduce valve noise associated with pressure surge.

Computational Fluid Dynamics Assessment Associated with Transcatheter Heart Valve Prostheses: A Position Paper of the ISO Working Group.

PubMed

Wei, Zhenglun Alan; Sonntag, Simon Johannes; Toma, Milan; Singh-Gryzbon, Shelly; Sun, Wei

2018-04-19

The governing international standard for the development of prosthetic heart valves is International Organization for Standardization (ISO) 5840. This standard requires the assessment of the thrombus potential of transcatheter heart valve substitutes using an integrated thrombus evaluation. Besides experimental flow field assessment and ex vivo flow testing, computational fluid dynamics is a critical component of this integrated approach. This position paper is intended to provide and discuss best practices for the setup of a computational model, numerical solving, post-processing, data evaluation and reporting, as it relates to transcatheter heart valve substitutes. This paper is not intended to be a review of current computational technology; instead, it represents the position of the ISO working group consisting of experts from academia and industry with regards to considerations for computational fluid dynamic assessment of transcatheter heart valve substitutes.

Microbial community stratification controlled by the subseafloor fluid flow and geothermal gradient at the Iheya North hydrothermal field in the Mid-Okinawa Trough (Integrated Ocean Drilling Program Expedition 331).

PubMed

Yanagawa, Katsunori; Breuker, Anja; Schippers, Axel; Nishizawa, Manabu; Ijiri, Akira; Hirai, Miho; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

2014-10-01

The impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of the Chloroflexi and deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group I Thaumarchaeota dominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Microbial Community Stratification Controlled by the Subseafloor Fluid Flow and Geothermal Gradient at the Iheya North Hydrothermal Field in the Mid-Okinawa Trough (Integrated Ocean Drilling Program Expedition 331)

PubMed Central

Breuker, Anja; Schippers, Axel; Nishizawa, Manabu; Ijiri, Akira; Hirai, Miho; Takaki, Yoshihiro; Sunamura, Michinari; Urabe, Tetsuro; Nunoura, Takuro; Takai, Ken

2014-01-01

The impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of the Chloroflexi and deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group I Thaumarchaeota dominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments. PMID:25063666

A novel microbial habitat in the mid-ocean ridge subseafloor

PubMed Central

Summit, Melanie; Baross, John A.

2001-01-01

The subseafloor at the mid-ocean ridge is predicted to be an excellent microbial habitat, because there is abundant space, fluid flow, and geochemical energy in the porous, hydrothermally influenced oceanic crust. These characteristics also make it a good analog for potential subsurface extraterrestrial habitats. Subseafloor environments created by the mixing of hot hydrothermal fluids and seawater are predicted to be particularly energy-rich, and hyperthermophilic microorganisms that broadly reflect such predictions are ejected from these systems in low-temperature (≈15°C), basalt-hosted diffuse effluents. Seven hyperthermophilic heterotrophs isolated from low-temperature diffuse fluids exiting the basaltic crust in and near two hydrothermal vent fields on the Endeavour Segment, Juan de Fuca Ridge, were compared phylogenetically and physiologically to six similarly enriched hyperthermophiles from samples associated with seafloor metal sulfide structures. The 13 organisms fell into four distinct groups: one group of two organisms corresponding to the genus Pyrococcus and three groups corresponding to the genus Thermococcus. Of these three groups, one was composed solely of sulfide-derived organisms, and the other two related groups were composed of subseafloor organisms. There was no evidence of restricted exchange of organisms between sulfide and subseafloor habitats, and therefore this phylogenetic distinction indicates a selective force operating between the two habitats. Hypotheses regarding the habitat differences were generated through comparison of the physiology of the two groups of hyperthermophiles; some potential differences between these habitats include fluid flow stability, metal ion concentrations, and sources of complex organic matter. PMID:11226209

Theoretical fluid dynamics

NASA Astrophysics Data System (ADS)

Shivamoggi, B. K.

This book is concerned with a discussion of the dynamical behavior of a fluid, and is addressed primarily to graduate students and researchers in theoretical physics and applied mathematics. A review of basic concepts and equations of fluid dynamics is presented, taking into account a fluid model of systems, the objective of fluid dynamics, the fluid state, description of the flow field, volume forces and surface forces, relative motion near a point, stress-strain relation, equations of fluid flows, surface tension, and a program for analysis of the governing equations. The dynamics of incompressible fluid flows is considered along with the dynamics of compressible fluid flows, the dynamics of viscous fluid flows, hydrodynamic stability, and dynamics of turbulence. Attention is given to the complex-variable method, three-dimensional irrotational flows, vortex flows, rotating flows, water waves, applications to aerodynamics, shock waves, potential flows, the hodograph method, flows at low and high Reynolds numbers, the Jeffrey-Hamel flow, and the capillary instability of a liquid jet.

Flow Diode and Method for Controlling Fluid Flow Origin of the Invention

NASA Technical Reports Server (NTRS)

Dyson, Rodger W (Inventor)

2015-01-01

A flow diode configured to permit fluid flow in a first direction while preventing fluid flow in a second direction opposite the first direction is disclosed. The flow diode prevents fluid flow without use of mechanical closures or moving parts. The flow diode utilizes a bypass flowline whereby all fluid flow in the second direction moves into the bypass flowline having a plurality of tortuous portions providing high fluidic resistance. The portions decrease in diameter such that debris in the fluid is trapped. As fluid only travels in one direction through the portions, the debris remains trapped in the portions.

Enhanced Microfluidic Electromagnetic Measurements

NASA Technical Reports Server (NTRS)

Ricco, Antonio J. (Inventor); Kovacs, Gregory (Inventor); Giovangrandi, Laurent (Inventor)

2015-01-01

Techniques for enhanced microfluidic impedance spectroscopy include causing a core fluid to flow into a channel between two sheath flows of one or more sheath fluids different from the core fluid. Flow in the channel is laminar. A dielectric constant of a fluid constituting either sheath flow is much less than a dielectric constant of the core fluid. Electrical impedance is measured in the channel between at least a first pair of electrodes. In some embodiments, enhanced optical measurements include causing a core fluid to flow into a channel between two sheath flows of one or more sheath fluids different from the core fluid. An optical index of refraction of a fluid constituting either sheath flow is much less than an optical index of refraction of the core fluid. An optical property is measured in the channel.

Direct Optical Measurement of Vorticity in Fluid Flow

DTIC Science & Technology

2015-12-11

was later employed to measure the angular velocity of a microparticle trapped and spinning in an optical trap [7]. II. Objectives We believe it...known theoretically. Two sets of experiments are presented. In the first, the signal from a group of 6 μm microparticles is integrated to obtain the...vorticity is known precisely. In one experiment measurements with a group of 6 μm microparticles is used to obtain the average fluid rotation rate about the

Fluid management in space construction

NASA Technical Reports Server (NTRS)

Snyder, Howard

1989-01-01

The low-g fluids management group with the Center for Space Construction is engaged in active research on the following topics: gauging; venting; controlling contamination; sloshing; transfer; acquisition; and two-phase flow. Our basic understanding of each of these topics at present is inadequate to design space structures optimally. A brief report is presented on each topic showing the present status, recent accomplishings by our group and our plans for future research. Reports are presented in graphic and outline form.

Influence of the hole geometry on the flow distribution in ventricular catheters for hydrocephalus.

PubMed

Giménez, Ángel; Galarza, Marcelo; Pellicer, Olga; Valero, José; Amigó, José M

2016-07-15

Hydrocephalus is a medical condition consisting of an abnormal accumulation of cerebrospinal fluid within the brain. A catheter is inserted in one of the brain ventricles and then connected to an external valve to drain the excess of cerebrospinal fluid. The main drawback of this technique is that, over time, the ventricular catheter ends up getting blocked by the cells and macromolecules present in the cerebrospinal fluid. A crucial factor influencing this obstruction is a non-uniform flow pattern through the catheter, since it facilitates adhesion of suspended particles to the walls. In this paper we focus on the effects that tilted holes as well as conical holes have on the flow distribution and shear stress. We have carried out 3D computational simulations to study the effect of the hole geometry on the cerebrospinal fluid flow through ventricular catheters. All the simulations were done with the OpenFOAM® toolbox. In particular, three different groups of models were investigated by varying (i) the tilt angles of the holes, (ii) the inner and outer diameters of the holes, and (iii) the distances between the so-called hole segments. The replacement of cylindrical holes by conical holes was found to have a strong influence on the flow distribution and to lower slightly the shear stress. Tilted holes did not involve flow distribution changes when the hole segments are sufficiently separated, but the mean shear stress was certainly reduced. The authors present new results about the behavior of the fluid flow through ventricular catheters. These results complete earlier work on this topic by adding the influence of the hole geometry. The overall objective pursued by this research is to provide guidelines to improve existing commercially available ventricular catheters.

Monodisperse microdroplet generation and stopping without coalescence

DOEpatents

Beer, Neil Reginald

2015-04-21

A system for monodispersed microdroplet generation and trapping including providing a flow channel in a microchip; producing microdroplets in the flow channel, the microdroplets movable in the flow channel; providing carrier fluid in the flow channel using a pump or pressure source; controlling movement of the microdroplets in the flow channel and trapping the microdroplets in a desired location in the flow channel. The system includes a microchip; a flow channel in the microchip; a droplet maker that generates microdroplets, the droplet maker connected to the flow channel; a carrier fluid in the flow channel, the carrier fluid introduced to the flow channel by a source of carrier fluid, the source of carrier fluid including a pump or pressure source; a valve connected to the carrier fluid that controls flow of the carrier fluid and enables trapping of the microdroplets.

Monodisperse microdroplet generation and stopping without coalescence

DOEpatents

Beer, Neil Reginald

2016-02-23

A system for monodispersed microdroplet generation and trapping including providing a flow channel in a microchip; producing microdroplets in the flow channel, the microdroplets movable in the flow channel; providing carrier fluid in the flow channel using a pump or pressure source; controlling movement of the microdroplets in the flow channel and trapping the microdroplets in a desired location in the flow channel. The system includes a microchip; a flow channel in the microchip; a droplet maker that generates microdroplets, the droplet maker connected to the flow channel; a carrier fluid in the flow channel, the carrier fluid introduced to the flow channel by a source of carrier fluid, the source of carrier fluid including a pump or pressure source; a valve connected to the carrier fluid that controls flow of the carrier fluid and enables trapping of the microdroplets.

Blood transfusion improves renal oxygenation and renal function in sepsis-induced acute kidney injury in rats.

PubMed

Zafrani, Lara; Ergin, Bulent; Kapucu, Aysegul; Ince, Can

2016-12-20

The effects of blood transfusion on renal microcirculation during sepsis are unknown. This study aimed to investigate the effect of blood transfusion on renal microvascular oxygenation and renal function during sepsis-induced acute kidney injury. Twenty-seven Wistar albino rats were randomized into four groups: a sham group (n = 6), a lipopolysaccharide (LPS) group (n = 7), a LPS group that received fluid resuscitation (n = 7), and a LPS group that received blood transfusion (n = 7). The mean arterial blood pressure, renal blood flow, and renal microvascular oxygenation within the kidney cortex were recorded. Acute kidney injury was assessed using the serum creatinine levels, metabolic cost, and histopathological lesions. Nitrosative stress (expression of endothelial (eNOS) and inducible nitric oxide synthase (iNOS)) within the kidney was assessed by immunohistochemistry. Hemoglobin levels, pH, serum lactate levels, and liver enzymes were measured. Fluid resuscitation and blood transfusion both significantly improved the mean arterial pressure and renal blood flow after LPS infusion. Renal microvascular oxygenation, serum creatinine levels, and tubular damage significantly improved in the LPS group that received blood transfusion compared to the group that received fluids. Moreover, the renal expression of eNOS was markedly suppressed under endotoxin challenge. Blood transfusion, but not fluid resuscitation, was able to restore the renal expression of eNOS. However, there were no significant differences in lactic acidosis or liver function between the two groups. Blood transfusion significantly improved renal function in endotoxemic rats. The specific beneficial effect of blood transfusion on the kidney could have been mediated in part by the improvements in renal microvascular oxygenation and sepsis-induced endothelial dysfunction via the restoration of eNOS expression within the kidney.

Evaluation of dentin tubule occlusion after laser irradiation and desensitizing agent application.

PubMed

Kim, Min-Ho; Kim, Ryan Jin-Young; Lee, Woo-Cheol; Lee, In-Bog

2015-10-01

To evaluate the effects of lasers (Nd:YAG and Er:YAG) and of topical desensitizing agents on dentin tubule occlusion by measuring real-time dentin fluid flow (DFF). 32 molars were prepared with V-shape cavity at the cervical area, acid-etched, water rinsed, blotted dry, and treated with (1) Nd:YAG laser; (2) Er:YAG laser; (3) SuperSeal, a desensitizing agent; (4) ClinproXT, a resin-modified glass-ionomer (RMGI) varnish (n = 8 each). A real-time fluid flow measuring instrument (nano-Flow) was used to measure the DFF throughout the procedures. The DFF rates before and after the treatment were compared. Moreover, the surface topography of dentin tubules after each desensitizing method was examined using SEM. DFF varied among the groups. The DFF rate was significantly reduced after laser irradiation/application of the desensitizing agents (P < 0.05). ClinproXT showed the greatest reduction of DFF rate (71.9%), followed by the SuperSeal (34.8%) and laser groups (P< 0.05). However, there was no significant difference between the Nd:YAG (24.1%) and Er:YAG (20.6%) groups (P > 0.05). In SEM images, narrowed dentin tubules were observed in both lased groups and SuperSeal group. In the ClinproXT group, the occluded dentin tubules by the RMGI covering were observed.

Physical aspects of computing the flow of a viscous fluid

NASA Technical Reports Server (NTRS)

Mehta, U. B.

1984-01-01

One of the main themes in fluid dynamics at present and in the future is going to be computational fluid dynamics with the primary focus on the determination of drag, flow separation, vortex flows, and unsteady flows. A computation of the flow of a viscous fluid requires an understanding and consideration of the physical aspects of the flow. This is done by identifying the flow regimes and the scales of fluid motion, and the sources of vorticity. Discussions of flow regimes deal with conditions of incompressibility, transitional and turbulent flows, Navier-Stokes and non-Navier-Stokes regimes, shock waves, and strain fields. Discussions of the scales of fluid motion consider transitional and turbulent flows, thin- and slender-shear layers, triple- and four-deck regions, viscous-inviscid interactions, shock waves, strain rates, and temporal scales. In addition, the significance and generation of vorticity are discussed. These physical aspects mainly guide computations of the flow of a viscous fluid.

A comparative study of manhole hydraulics using stereoscopic PIV and different RANS models.

PubMed

Beg, Md Nazmul Azim; Carvalho, Rita F; Tait, Simon; Brevis, Wernher; Rubinato, Matteo; Schellart, Alma; Leandro, Jorge

2017-04-01

Flows in manholes are complex and may include swirling and recirculation flow with significant turbulence and vorticity. However, how these complex 3D flow patterns could generate different energy losses and so affect flow quantity in the wider sewer network is unknown. In this work, 2D3C stereo Particle Image Velocimetry measurements are made in a surcharged scaled circular manhole. A computational fluid dynamics (CFD) model in OpenFOAM ® with four different Reynolds Averaged Navier Stokes (RANS) turbulence model is constructed using a volume of fluid model, to represent flows in this manhole. Velocity profiles and pressure distributions from the models are compared with the experimental data in view of finding the best modelling approach. It was found among four different RANS models that the re-normalization group (RNG) k-ɛ and k-ω shear stress transport (SST) gave a better approximation for velocity and pressure.

Similarity solutions for unsteady free-convection flow from a continuous moving vertical surface

NASA Astrophysics Data System (ADS)

Abd-El-Malek, Mina B.; Kassem, Magda M.; Mekky, Mohammad L.

2004-03-01

The transformation group theoretic approach is applied to present an analysis of the problem of unsteady free convection flow over a continuous moving vertical sheet in an ambient fluid. The thermal boundary layer induced within a vertical semi-infinite layer of Boussinseq fluid by a constant heated bounding plate. The application of two-parameter groups reduces the number of independent variables by two, and consequently the system of governing partial differential equations with the boundary conditions reduces to a system of ordinary differential equations with appropriate boundary conditions. The obtained ordinary differential equations are solved analytically for the temperature and numerically for the velocity using the shooting method. Effect of Prandtl number on the thermal boundary-layer and velocity boundary-layer are studied and plotted in curves.

Device and method for measuring multi-phase fluid flow in a conduit using an elbow flow meter

DOEpatents

Ortiz, Marcos G.; Boucher, Timothy J.

1997-01-01

A system for measuring fluid flow in a conduit. The system utilizes pressure transducers disposed generally in line upstream and downstream of the flow of fluid in a bend in the conduit. Data from the pressure transducers is transmitted to a microprocessor or computer. The pressure differential measured by the pressure transducers is then used to calculate the fluid flow rate in the conduit. Control signals may then be generated by the microprocessor or computer to control flow, total fluid dispersed, (in, for example, an irrigation system), area of dispersal or other desired effect based on the fluid flow in the conduit.

Effects of coarse grain size distribution and fine particle content on pore fluid pressure and shear behavior in experimental debris flows

NASA Astrophysics Data System (ADS)

Kaitna, Roland; Palucis, Marisa C.; Yohannes, Bereket; Hill, Kimberly M.; Dietrich, William E.

2016-02-01

Debris flows are typically a saturated mixture of poorly sorted particles and interstitial fluid, whose density and flow properties depend strongly on the presence of suspended fine sediment. Recent research suggests that grain size distribution (GSD) influences excess pore pressures (i.e., pressure in excess of predicted hydrostatic pressure), which in turn plays a governing role in debris flow behaviors. We report a series of controlled laboratory experiments in a 4 m diameter vertically rotating drum where the coarse particle size distribution and the content of fine particles were varied independently. We measured basal pore fluid pressures, pore fluid pressure profiles (using novel sensor probes), velocity profiles, and longitudinal profiles of the flow height. Excess pore fluid pressure was significant for mixtures with high fines fraction. Such flows exhibited lower values for their bulk flow resistance (as measured by surface slope of the flow), had damped fluctuations of normalized fluid pressure and normal stress, and had velocity profiles where the shear was concentrated at the base of the flow. These effects were most pronounced in flows with a wide coarse GSD distribution. Sustained excess fluid pressure occurred during flow and after cessation of motion. Various mechanisms may cause dilation and contraction of the flows, and we propose that the sustained excess fluid pressures during flow and once the flow has stopped may arise from hindered particle settling and yield strength of the fluid, resulting in transfer of particle weight to the fluid. Thus, debris flow behavior may be strongly influenced by sustained excess fluid pressures controlled by particle settling rates.

The flow patterning capability of localized natural convection.

PubMed

Huang, Ling-Ting; Chao, Ling

2016-09-14

Controlling flow patterns to align materials can have various applications in optics, electronics, and biosciences. In this study, we developed a natural-convection-based method to create desirable spatial flow patterns by controlling the locations of heat sources. Fluid motion in natural convection is induced by the spatial fluid density gradient that is caused by the established spatial temperature gradient. To analyze the patterning resolution capability of this method, we used a mathematical model combined with nondimensionalization to correlate the flow patterning resolution with experimental operating conditions. The nondimensionalized model suggests that the flow pattern and resolution is only influenced by two dimensionless parameters, and , where Gr is the Grashof number, representing the ratio of buoyancy to the viscous force acting on a fluid, and Pr is the Prandtl number, representing the ratio of momentum diffusivity to thermal diffusivity. We used the model to examine all of the flow behaviors in a wide range of the two dimensionless parameter group and proposed a flow pattern state diagram which suggests a suitable range of operating conditions for flow patterning. In addition, we developed a heating wire with an angular configuration, which enabled us to efficiently examine the pattern resolution capability numerically and experimentally. Consistent resolutions were obtained between the experimental results and model predictions, suggesting that the state diagram and the identified operating range can be used for further application.

Early pleural fluid dynamics following video-assisted thoracoscopic lobectomy has limited clinical value

PubMed Central

Holbek, Bo Laksáfoss; Petersen, René Horsleben; Kehlet, Henrik

2017-01-01

The objective of this study was to evaluate the potential of predicting the pleural fluid output in patients after video-assisted thoracoscopic lobectomy of the lung. Detailed measurements of continuous fluid output were obtained prospectively using an electronic thoracic drainage device (Thopaz+™, Medela AG, Switzerland). Patients were divided into high (≥500 mL) and low (<500 mL) 24-hour fluid output, and detailed flow curves were plotted graphically to identify arithmetic patterns predicting fluid output in the early (≤24 hours) and later (24–48 hours) post-operative phase. Furthermore, multiple logistic regression analysis was used to predict high 24-hour fluid output using baseline data. Data were obtained from 50 patients, where 52% had a fluid output of <500 mL/24 hours. From visual assessment of flow curves, patients were grouped according to fluid output 6 hours postoperatively. An output ≥200 mL/6 hours was predictive of ‘high 24-hour fluid output’ (P<0.0001). However, 33% of patients with <200 mL/6 hours ended with a ‘high 24-hour fluid output’. Baseline data showed no predictive value of fluid production, and 24-hour fluid output had no predictive value of fluid output between 24 and 48 hours. Assessment of initial fluid production may predict high 24-hour fluid output (≥500 mL) but seems to lack clinical value in drain removal criteria. PMID:28840021

Thermal Analysis of Magnetically-Coupled Pump for Cryogenic Applications

NASA Technical Reports Server (NTRS)

Senocak, Inanc; Udaykumar, H. S.; Ndri, Narcisse; Francois, Marianne; Shyy, Wei

1999-01-01

Magnetically-coupled pump is under evaluation at Kennedy Space Center for possible cryogenic applications. A major concern is the impact of low temperature fluid flows on the pump performance. As a first step toward addressing this and related issues, a computational fluid dynamics and heat transfer tool has been adopted in a pump geometry. The computational tool includes (i) a commercial grid generator to handle multiple grid blocks and complicated geometric definitions, and (ii) an in-house computational fluid dynamics and heat transfer software developed in the Principal Investigator's group at the University of Florida. Both pure-conduction and combined convection-conduction computations have been conducted. A pure-conduction analysis gives insufficient information about the overall thermal distribution. Combined convection-conduction analysis indicates the significant influence of the coolant over the entire flow path. Since 2-D simulation is of limited help, future work on full 3-D modeling of the pump using multi-materials is needed. A comprehensive and accurate model can be developed to take into account the effect of multi-phase flow in the cooling flow loop, and the magnetic interactions.

Device and method for measuring multi-phase fluid flow in a conduit using an elbow flow meter

DOEpatents

Ortiz, M.G.; Boucher, T.J.

1997-06-24

A system is described for measuring fluid flow in a conduit. The system utilizes pressure transducers disposed generally in line upstream and downstream of the flow of fluid in a bend in the conduit. Data from the pressure transducers is transmitted to a microprocessor or computer. The pressure differential measured by the pressure transducers is then used to calculate the fluid flow rate in the conduit. Control signals may then be generated by the microprocessor or computer to control flow, total fluid dispersed, (in, for example, an irrigation system), area of dispersal or other desired effect based on the fluid flow in the conduit. 2 figs.

Cerebrospinal fluid flow abnormalities in patients with neoplastic meningitis. An evaluation using /sup 111/In-DTPA ventriculography

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

Grossman, S.A.; Trump, D.L.; Chen, D.C.

1982-11-01

Cerebrospinal fluid flow dynamics were evaluated by /sup 111/In-diethylenetriamine pentaacetic acid (/sup 111/In-DTPA) ventriculography in 27 patients with neoplastic meningitis. Nineteen patients (70 percent) had evidence of cerebrospinal fluid flow disturbances. These occurred as ventricular outlet obstructions, abnormalities of flow in the spinal canal, or flow distrubances over the cortical convexities. Tumor histology, physical examination, cerebrospinal fluid analysis, myelograms, and computerized axial tomographic scans were not sufficient to predict cerebrospinal fluid flow patterns. These data indicate that cerebrospinal fluid flow abnormalities are common in patients with neoplastic meningitis and that /sup 111/In-DTPA cerebrospinal fluid flow imaging is useful in characterizingmore » these abnormalities. This technique provides insight into the distribution of intraventricularly administered chemotherapy and may provide explanations for treatment failure and drug-induced neurotoxicity in patients with neoplastic meningitis.« less

Gas turbine engine exhaust diffuser including circumferential vane

DOEpatents

Orosa, John A.; Matys, Pawel

2015-05-19

A flow passage defined between an inner and an outer boundary for guiding a fluid flow in an axial direction. A flow control vane is supported at a radial location between the inner and outer boundaries. A fluid discharge opening is provided for discharging a flow of the compressed fluid from a trailing edge of the vane, and a fluid control surface is provided adjacent to the fluid discharge opening and extends in the axial direction at the trailing edge of the vane. The fluid control surface has a curved trailing edge forming a Coanda surface. The fluid discharge opening is selectively provided with a compressed fluid to produce a Coanda effect along the control surface. The Coanda effect has a component in the radial direction effecting a turning of the fluid flow in the flow path radially inward or outward toward one of the inner and outer boundaries.

Electric fluid pump

DOEpatents

Van Dam, Jeremy Daniel; Turnquist, Norman Arnold; Raminosoa, Tsarafidy; Shah, Manoj Ramprasad; Shen, Xiaochun

2015-09-29

An electric machine is presented. The electric machine includes a hollow rotor; and a stator disposed within the hollow rotor, the stator defining a flow channel. The hollow rotor includes a first end portion defining a fluid inlet, a second end portion defining a fluid outlet; the fluid inlet, the fluid outlet, and the flow channel of the stator being configured to allow passage of a fluid from the fluid inlet to the fluid outlet via the flow channel; and wherein the hollow rotor is characterized by a largest cross-sectional area of hollow rotor, and wherein the flow channel is characterized by a smallest cross-sectional area of the flow channel, wherein the smallest cross-sectional area of the flow channel is at least about 25% of the largest cross-sectional area of the hollow rotor. An electric fluid pump and a power generation system are also presented.

Visualization of various working fluids flow regimes in gravity heat pipe

NASA Astrophysics Data System (ADS)

Nemec, Patrik

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

Determining the Coefficient of Discharge for a Draining Container

ERIC Educational Resources Information Center

Hicks, Ashley; Slaton, William

2014-01-01

The flow of fluids through open containers is a topic studied frequently in introductory physics classes. A fluid mechanics class delves deeper into the topic of fluid flow through open containers with holes or barriers. The flow of a fluid jet out of a sharp-edged orifice rarely has the same area as the orifice due to a fluid flow phenomenon…

Flow of two immiscible fluids in a periodically constricted tube: Transitions to stratified, segmented, churn, spray, or segregated flow

NASA Astrophysics Data System (ADS)

Fraggedakis, D.; Kouris, Ch.; Dimakopoulos, Y.; Tsamopoulos, J.

2015-08-01

We study the flow of two immiscible, Newtonian fluids in a periodically constricted tube driven by a constant pressure gradient. Our volume-of-fluid algorithm is used to solve the governing equations. First, the code is validated by comparing its predictions to previously reported results for stratified and pulsing flow. Then, it is used to capture accurately all the significant topological changes that take place. Initially, the fluids have a core-annular arrangement, which is found to either remain the same or change to a different arrangement depending on the fluid properties, the pressure driving the flow, or the flow geometry. The flow-patterns that appear are the core-annular, segmented, churn, spray, and segregated flow. The predicted scalings near pinching of the core fluid concur with similarity predictions and earlier numerical results [I. Cohen et al., "Two fluid drop snap-off problem: Experiments and theory," Phys. Rev. Lett. 83, 1147-1150 (1999)]. Flow-pattern maps are constructed in terms of the Reynolds and Weber numbers. Our result provides deeper insights into the mechanism of the pattern transitions and is in agreement with previous studies on core-annular flow [Ch. Kouris and J. Tsamopoulos, "Core-annular flow in a periodically constricted circular tube, I. Steady state, linear stability and energy analysis," J. Fluid Mech. 432, 31-68 (2001) and Ch. Kouris et al., "Comparison of spectral and finite element methods applied to the study of interfacial instabilities of the core-annular flow in an undulating tube," Int. J. Numer. Methods Fluids 39(1), 41-73 (2002)], segmented flow [E. Lac and J. D. Sherwood, "Motion of a drop along the centreline of a capillary in a pressure-driven flow," J. Fluid Mech. 640, 27-54 (2009)], and churn flow [R. Y. Bai et al., "Lubricated pipelining—Stability of core annular-flow. 5. Experiments and comparison with theory," J. Fluid Mech. 240, 97-132 (1992)].

High-Performance Algorithms and Complex Fluids | Computational Science |

Science.gov Websites

only possible by combining experimental data with simulation. Capabilities Capabilities include: Block -laden, non-Newtonian, as well as traditional internal and external flows. Contact Ray Grout Group

Electrokinetic flow in a capillary with a charge-regulating surface polymer layer.

PubMed

Keh, Huan J; Ding, Jau M

2003-07-15

An analytical study of the steady electrokinetic flow in a long uniform capillary tube or slit is presented. The inside wall of the capillary is covered by a layer of adsorbed or covalently bound charge-regulating polymer in equilibrium with the ambient electrolyte solution. In this solvent-permeable and ion-penetrable surface polyelectrolyte layer, ionogenic functional groups and frictional segments are assumed to distribute at uniform densities. The electrical potential and space charge density distributions in the cross section of the capillary are obtained by solving the linearized Poisson-Boltzmann equation. The fluid velocity profile due to the application of an electric field and a pressure gradient through the capillary is obtained from the analytical solution of a modified Navier-Stokes/Brinkman equation. Explicit formulas for the electroosmotic velocity, the average fluid velocity and electric current density on the cross section, and the streaming potential in the capillary are also derived. The results demonstrate that the direction of the electroosmotic flow and the magnitudes of the fluid velocity and electric current density are dominated by the fixed charge density inside the surface polymer layer, which is determined by the regulation characteristics such as the dissociation equilibrium constants of the ionogenic functional groups in the surface layer and the concentration of the potential-determining ions in the bulk solution.

Oscillatory vortex formation behind a movable plat

NASA Astrophysics Data System (ADS)

Vukicevic, Marija; Pedrizzetti, Gianni

2010-11-01

INTRODUCTION: A wide spectra of application, from industrial to environmental and biological, involve fluid-structure interaction (FSI) at a fundamental level. We investigate a 2D FSI problem for a rigid structure hinged on a wall, freely rotating by the action of an oscillatory fluid flow. METHODS: The Navier-Stokes equations are solved simultaneously with the body dynamics. An accurate numerical solution is developed on the conformal map of the time-varying physical domain. RESULTS: The FSI is primarily influenced by the vortex formation process and by the interaction between vortices generated during the sequential flow oscillations. The emerging bodies can be arranged into a three main groups. The first, made of heavy bodies, terminates the motion during the first few oscillations with the impact of the body on the wall. On the other extreme, the third group made of relatively light bodies presents a flow-driven motion that oscillates periodically in time. In a wide intermediate range, the body oscillates in time presenting non periodic features. CONCLUSIONS: The process of oscillatory vortex formation in presence of fluid-structure interaction shows the emergence of various phenomena that were analyzed in details. In this specific application the results demonstrate that the FSI range from linear to chaotic interaction and finite-time collapse.

Covariance of fluid-turbulence theory.

PubMed

Ariki, Taketo

2015-05-01

Covariance of physical quantities in fluid-turbulence theory and their governing equations under generalized coordinate transformation is discussed. It is shown that the velocity fluctuation and its governing law have a covariance under far wider group of coordinate transformation than that of conventional Euclidean invariance, and, as a natural consequence, various correlations and their governing laws are shown to be formulated in covariant manners under this wider transformation group. In addition, it is also shown that the covariance of the Reynolds stress is tightly connected to the objectivity of the mean flow.

Hydrocarbon fluid, ejector refrigeration system

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

Kowalski, G.J.; Foster, A.R.

1993-08-31

A refrigeration system is described comprising: a vapor ejector cycle including a working fluid having a property such that entropy of the working fluid when in a saturated vapor state decreases as pressure decreases, the vapor ejector cycle comprising: a condenser located on a common fluid flow path; a diverter located downstream from the condenser for diverting the working fluid into a primary fluid flow path and a secondary fluid flow path parallel to the primary fluid flow path; an evaporator located on the secondary fluid flow path; an expansion device located on the secondary fluid flow path upstream ofmore » the evaporator; a boiler located on the primary fluid flow path parallel to the evaporator for boiling the working fluid, the boiler comprising an axially extending core region having a substantially constant cross sectional area and a porous capillary region surrounding the core region, the core region extending a length sufficient to produce a near sonic velocity saturated vapor; and an ejector having an outlet in fluid communication with the inlet of the condenser and an inlet in fluid communication with the outlet of the evaporator and the outlet of the boiler and in which the flows of the working fluid from the evaporator and the boiler are mixed and the pressure of the working fluid is increased to at least the pressure of the condenser, the ejector inlet, located downstream from the axially extending core region, including a primary nozzle located sufficiently close to the outlet of the boiler to minimize a pressure drop between the boiler and the primary nozzle, the primary nozzle of the ejector including a converging section having an included angle and length preselected to receive the working fluid from the boiler as a near sonic velocity saturated vapor.« less

Complex magnetohydrodynamic low-Reynolds-number flows.

PubMed

Xiang, Yu; Bau, Haim H

2003-07-01

The interaction between electric currents and a magnetic field is used to produce body (Lorentz) forces in electrolyte solutions. By appropriate patterning of the electrodes, one can conveniently control the direction and magnitude of the electric currents and induce spatially and temporally complicated flow patterns. This capability is useful, not only for fundamental flow studies, but also for inducing fluid flow and stirring in minute devices in which the incorporation of moving components may be difficult. This paper focuses on a theoretical and experimental study of magnetohydrodynamic flows in a conduit with a rectangular cross section. The conduit is equipped with individually controlled electrodes uniformly spaced at a pitch L. The electrodes are aligned transversely to the conduit's axis. The entire device is subjected to a uniform magnetic field. The electrodes are divided into two groups A and C in such a way that there is an electrode of group C between any two electrodes of group A. We denote the various A and C electrodes with subscripts, i.e., A(i) and C(i), where i=0,+/-1,+/-2, .... When positive and negative potentials are, respectively, applied to the even and odd numbered A electrodes, opposing electric currents are induced on the right and left hand sides of each A electrode. These currents generate transverse forces that drive cellular convection in the conduit. We refer to the resulting flow pattern as A. When electrodes of group C are activated, a similar flow pattern results, albeit shifted in space. We refer to this flow pattern as C. By alternating periodically between patterns A and C, one induces Lagrangian chaos. Such chaotic advection may be beneficial for stirring fluids, particularly in microfluidic devices. Since the flow patterns A and C are shifted in space, they also provide a mechanism for Lagrangian drift that allows net migration of passive tracers along the conduit's length.

Shaded computer graphic techniques for visualizing and interpreting analytic fluid flow models

NASA Technical Reports Server (NTRS)

Parke, F. I.

1981-01-01

Mathematical models which predict the behavior of fluid flow in different experiments are simulated using digital computers. The simulations predict values of parameters of the fluid flow (pressure, temperature and velocity vector) at many points in the fluid. Visualization of the spatial variation in the value of these parameters is important to comprehend and check the data generated, to identify the regions of interest in the flow, and for effectively communicating information about the flow to others. The state of the art imaging techniques developed in the field of three dimensional shaded computer graphics is applied to visualization of fluid flow. Use of an imaging technique known as 'SCAN' for visualizing fluid flow, is studied and the results are presented.

Generating Inviscid and Viscous Fluid-Flow Simulations over an Aircraft Surface Using a Fluid-Flow Mesh

NASA Technical Reports Server (NTRS)

Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

2013-01-01

Fluid-flow simulation over a computer-generated aircraft surface is generated using inviscid and viscous simulations. A fluid-flow mesh of fluid cells is obtained. At least one inviscid fluid property for the fluid cells is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. A set of intersecting fluid cells that intersects the aircraft surface are identified. One surface mesh polygon of the surface mesh is identified for each intersecting fluid cell. A boundary-layer prediction point for each identified surface mesh polygon is determined. At least one boundary-layer fluid property for each boundary-layer prediction point is determined using the at least one inviscid fluid property of the corresponding intersecting fluid cell and a boundary-layer simulation that simulates fluid viscous effects. At least one updated fluid property for at least one fluid cell is determined using the at least one boundary-layer fluid property and the inviscid fluid simulation.

Interfacial Area Development in Two-Phase Fluid Flow: Transient vs. Quasi-Static Flow Conditions

NASA Astrophysics Data System (ADS)

Meisenheimer, D. E.; Wildenschild, D.

2017-12-01

Fluid-fluid interfaces are important in multiphase flow systems in the environment (e.g. groundwater remediation, geologic CO2 sequestration) and industry (e.g. air stripping, fuel cells). Interfacial area controls mass transfer, and therefore reaction efficiency, between the different phases in these systems but they also influence fluid flow processes. There is a need to better understand this relationship between interfacial area and fluid flow processes so that more robust theories and models can be built for engineers and policy makers to improve the efficacy of many multiphase flow systems important to society. Two-phase flow experiments were performed in glass bead packs under transient and quasi-static flow conditions. Specific interfacial area was calculated from 3D images of the porous media obtained using the fast x-ray microtomography capability at the Advanced Photon Source. We present data suggesting a direct relationship between the transient nature of the fluid-flow experiment (fewer equilibrium points) and increased specific interfacial area. The effect of flow condition on Euler characteristic (a representative measure of fluid topology) will also be presented.

That is Cool: the Nature Of Aesthetics in Fluid Physics

NASA Astrophysics Data System (ADS)

Hertzberg, Jean

2013-11-01

Aesthetics has historically been defined as the study of beauty and thus as a metric of art. More recently, psychologists are using the term to describe a spectrum of responses from ``I hate it'' to ``I love it.'' In the context of fluid physics, what is beautiful? What elicits a ``Wow! Awesome! Cool!'' response versus a snore? Can we use aesthetics to deepen or change students' or the public's perceptions of physics and/or the world around them? For example, students seem to appreciate the aesthetics of destruction: environmental fluid dynamics such as storms, tornadoes, floods and wildfires are often responsible for massive destruction, yet humans draw pleasure from watching such physics and the attendant destruction from a safe distance. Can this voyeurism be turned to our advantage in communicating science? Observations of student and Facebook Flow Visualization group choices for fluid physics that draw a positive aesthetic response are sorted into empirical categories; the aesthetics of beauty, power, destruction, and oddness. Each aesthetic will be illustrated with examples drawn from flow visualizations from both the Flow Visualization course (MCEN 4151) taught at the University of Colorado, Boulder, and sources on the web. This work is supported by NSF: EEC 1240294.

Pressure balanced drag turbine mass flow meter

DOEpatents

Dacus, M.W.; Cole, J.H.

1980-04-23

The density of the fluid flowing through a tubular member may be measured by a device comprising a rotor assembly suspended within the tubular member, a fluid bearing medium for the rotor assembly shaft, independent fluid flow lines to each bearing chamber, and a scheme for detection of any difference between the upstream and downstream bearing fluid pressures. The rotor assembly reacts to fluid flow both by rotation and axial displacement; therefore concurrent measurements may be made of the velocity of blade rotation and also bearing pressure changes, where the pressure changes may be equated to the fluid momentum flux imparted to the rotor blades. From these parameters the flow velocity and density of the fluid may be deduced.

Pressure balanced drag turbine mass flow meter

DOEpatents

Dacus, Michael W.; Cole, Jack H.

1982-01-01

The density of the fluid flowing through a tubular member may be measured by a device comprising a rotor assembly suspended within the tubular member, a fluid bearing medium for the rotor assembly shaft, independent fluid flow lines to each bearing chamber, and a scheme for detection of any difference between the upstream and downstream bearing fluid pressures. The rotor assembly reacts to fluid flow both by rotation and axial displacement; therefore concurrent measurements may be made of the velocity of blade rotation and also bearing pressure changes, where the pressure changes may be equated to the fluid momentum flux imparted to the rotor blades. From these parameters the flow velocity and density of the fluid may be deduced.

Performance of three systems for warming intravenous fluids at different flow rates.

PubMed

Satoh, J; Yamakage, M; Wasaki, S I; Namiki, A

2006-02-01

This study compared the intravenous fluid warming capabilities of three systems at different flow rates. The devices studied were a water-bath warmer, a dry-heat plate warmer, and an intravenous fluid tube warmer Ambient temperature was controlled at 22 degrees to 24 degrees C. Normal saline (0.9% NaCl) at either room temperature (21 degrees to 23 degrees C) or at ice-cold temperature (3 degrees to 5 degrees C) was administered through each device at a range of flow rates (2 to 100 ml/min). To mimic clinical conditions, the temperature of the fluid was measured with thermocouples at the end of a one metre tube connected to the outflow of the warmer for the first two devices and at the end of the 1.2 m warming tubing for the intravenous fluid tube warmer The temperature of fluid delivered by the water bath warmer increased as the flow rate was increased up to 15 to 20 ml/min but decreased with greater flow rates. The temperature of the fluid delivered by the dry-heat plate warmer significantly increased as the flow rate was increased within the range tested (due to decreased cooling after leaving the device at higher flow rates). The temperature of fluid delivered by the intravenous fluid tube warmer did not depend on the flow rate up to 20 ml/min but significantly and fluid temperature-dependently decreased at higher flow rates (>30 ml/min). Under the conditions of our testing, the dry heat plate warmer delivered the highest temperature fluid at high flow rates.

Destabilization of confined granular packings due to fluid flow

NASA Astrophysics Data System (ADS)

Monloubou, Martin; Sandnes, Bjørnar

2016-04-01

Fluid flow through granular materials can cause fluidization when fluid drag exceeds the frictional stress within the packing. Fluid driven failure of granular packings is observed in both natural and engineered settings, e.g. soil liquefaction and flowback of proppants during hydraulic fracturing operations. We study experimentally the destabilization and flow of an unconsolidated granular packing subjected to a point source fluid withdrawal using a model system consisting of a vertical Hele-Shaw cell containing a water-grain mixture. The fluid is withdrawn from the cell at a constant rate, and the emerging flow patterns are imaged in time-lapse mode. Using Particle Image Velocimetry (PIV), we show that the granular flow gets localized in a narrow channel down the center of the cell, and adopts a Gaussian velocity profile similar to those observed in dry grain flows in silos. We investigate the effects of the experimental parameters (flow rate, grain size, grain shape, fluid viscosity) on the packing destabilization, and identify the physical mechanisms responsible for the observed complex flow behaviour.

Effect of Er,Cr:YSGG laser on human dentin fluid flow.

PubMed

Al-Omari, Wael M; Palamara, Joseph E

2013-11-01

The aim of the current investigation was to assess the rate and magnitude of dentin fluid flow of dentinal surfaces irradiated with Er,Cr:YSGG laser. Twenty extracted third molars were sectioned, mounted, and irradiated with Er,Cr:YSGG laser at 3.5 and 4.5 W power settings. Specimens were connected to an automated fluid flow measurement apparatus (Flodec). The rate, magnitude, and direction of dentin fluid flow were recorded at baseline and after irradiation. Nonparametric Wilcoxon signed ranks repeated measure t test revealed a statistically significant reduction in fluid flow for all the power settings. The 4.5-W power output reduced the flow significantly more than the 3.5 W. The samples showed a baseline outward flow followed by inward flow due to irradiation then followed by decreased outward flow. It was concluded that Er,Cr:YSGG laser irradiation at 3.5 and 4.5 W significantly reduced dentinal fluid flow rate. The reduction was directly proportional to power output.

Alkaline phosphatase in osteoblasts is down-regulated by pulsatile fluid flow

NASA Technical Reports Server (NTRS)

Hillsley, M. V.; Frangos, J. A.

1997-01-01

It is our hypothesis that interstitial fluid flow plays a role in the bone remodeling response to mechanical loading. The fluid flow-induced expression of three proteins (collagen, osteopontin, and alkaline phosphatase) involved in bone remodeling was investigated. Rat calvarial osteoblasts subjected to pulsatile fluid flow at an average shear stress of 5 dyne/cm2 showed decreased alkaline phosphatase (AP) mRNA expression after only 1 hour of flow. After 3 hours of flow, AP mRNA levels had decreased to 30% of stationary control levels and remained at this level for an additional 5 hours of flow. Steady flow (4 dyne/cm2 fluid shear stress), in contrast, resulted in a delayed and less dramatic decrease in AP mRNA expression to 63% of control levels after 8 hours of flow. The reduced AP mRNA expression under pulsatile flow conditions was followed by reduced AP enzyme activity after 24 hours. No changes in collagen or osteopontin mRNA expression were detected over 8 hours of pulsatile flow. This is the first time fluid flow has been shown to affect gene expression in osteoblasts.

Magnetically suspended miniature fluid pump and method of designing the same

NASA Technical Reports Server (NTRS)

Antaki, James F. (Inventor); Paden, Bradley (Inventor); Burgreen, Gregory (Inventor); Groom, Nelson (Inventor)

2000-01-01

A rotary pump for pumping fluids through a patient having a housing with an internal region, a stator member and an impeller positioned within the housing and having impeller blades, wherein the impeller is magnetically suspended and rotated, and wherein the geometric configuration of the rotary pump is sized and proportioned to minimize stagnant and traumatic fluid flow within the rotary pump. The plurality of magnetic impeller blades are preferably rare earth, high-energy-density magnets selected from the group consisting of samarium cobalt and neodymium-iron-boron alloy.

Analytical solution of two-fluid electro-osmotic flows of viscoelastic fluids.

PubMed

Afonso, A M; Alves, M A; Pinho, F T

2013-04-01

This paper presents an analytical model that describes a two-fluid electro-osmotic flow of stratified fluids with Newtonian or viscoelastic rheological behavior. This is the principle of operation of an electro-osmotic two-fluid pump as proposed by Brask et al. [Tech. Proc. Nanotech., 1, 190-193, 2003], in which an electrically non-conducting fluid is transported by the interfacial dragging viscous force of a conducting fluid that is driven by electro-osmosis. The electric potential in the conducting fluid and the analytical steady flow solution of the two-fluid electro-osmotic stratified flow in a planar microchannel are presented by assuming a planar interface between the two immiscible fluids with Newtonian or viscoelastic rheological behavior. The effects of fluid rheology, shear viscosity ratio, holdup and interfacial zeta potential are analyzed to show the viability of this technique, where an enhancement of the flow rate is observed as the shear-thinning effects are increased. Copyright © 2012 Elsevier Inc. All rights reserved.

Flow accelerated organic coating degradation

NASA Astrophysics Data System (ADS)

Zhou, Qixin

Applying organic coatings is a common and the most cost effective way to protect metallic objects and structures from corrosion. Water entry into coating-metal interface is usually the main cause for the deterioration of organic coatings, which leads to coating delamination and underfilm corrosion. Recently, flowing fluids over sample surface have received attention due to their capability to accelerate material degradation. A plethora of works has focused on the flow induced metal corrosion, while few studies have investigated the flow accelerated organic coating degradation. Flowing fluids above coating surface affect corrosion by enhancing the water transport and abrading the surface due to fluid shear. Hence, it is of great importance to understand the influence of flowing fluids on the degradation of corrosion protective organic coatings. In this study, a pigmented marine coating and several clear coatings were exposed to the laminar flow and stationary immersion. The laminar flow was pressure driven and confined in a flow channel. A 3.5 wt% sodium chloride solution and pure water was employed as the working fluid with a variety of flow rates. The corrosion protective properties of organic coatings were monitored inline by Electrochemical Impedance Spectroscopy (EIS) measurement. Equivalent circuit models were employed to interpret the EIS spectra. The time evolution of coating resistance and capacitance obtained from the model was studied to demonstrate the coating degradation. Thickness, gloss, and other topography characterizations were conducted to facilitate the assessment of the corrosion. The working fluids were characterized by Fourier Transform Infrared Spectrometer (FTIR) and conductivity measurement. The influence of flow rate, fluid shear, fluid composition, and other effects in the coating degradation were investigated. We conclude that flowing fluid on the coating surface accelerates the transport of water, oxygen, and ions into the coating, as well as promotes the migration of coating materials from the coating into the working fluid, where coatings experience more severe deterioration in their barrier property under flowing conditions. Pure water has shown to be a much more aggressive working fluid than electrolyte solutions. The flowing fluid over the coating surface could be used as an effective acceleration method.

Fluid inclusion and vitrinite-reflectance geothermometry compared to heat-flow models of maximum paleotemperature next to dikes, western onshore Gippsland Basin, Australia

USGS Publications Warehouse

Barker, C.E.; Bone, Y.; Lewan, M.D.

1999-01-01

Nine basalt dikes, ranging from 6 cm to 40 m thick, intruding the Upper Jurassic-Lower Cretaceous Strzelecki Group, western onshore Gippsland Basin, were used to study maximum temperatures (Tmax) reached next to dikes. Tmax was estimated from fluid inclusion and vitrinitereflectance geothermometry and compared to temperatures calculated using heat-flow models of contact metamorphism. Thermal history reconstruction suggests that at the time of dike intrusion the host rock was at a temperature of 100-135??C. Fracture-bound fluid inclusions in the host rocks next to thin dikes ( 1.5, using a normalized distance ratio used for comparing measurements between dikes regardless of their thickness. In contrast, the pattern seen next to the thin dikes is a relatively narrow zone of elevated Rv-r. Heat-flow modeling, along with whole rock elemental and isotopic data, suggests that the extended zone of elevated Rv-r is caused by a convection cell with local recharge of the hydrothermal fluids. The narrow zone of elevated Rv-r found next to thin dikes is attributed to the rise of the less dense, heated fluids at the dike contact causing a flow of cooler groundwater towards the dike and thereby limiting its heating effects. The lack of extended heating effects suggests that next to thin dikes an incipient convection system may form in which the heated fluid starts to travel upward along the dike but cooling occurs before a complete convection cell can form. Close to the dike contact at X/D 1.5. ?? 1998 Elsevier Science B.V. All rights reserved.

Magnetically stimulated fluid flow patterns

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

Martin, Jim; Solis, Kyle

2014-03-06

Sandia National Laboratories' Jim Martin and Kyle Solis explain research on the effects of magnetic fields on fluid flows and how they stimulate vigorous flows. Fluid flow is a necessary phenomenon in everything from reactors to cooling engines in cars.

Magnetically stimulated fluid flow patterns

ScienceCinema

Martin, Jim; Solis, Kyle

2018-05-23

Sandia National Laboratories' Jim Martin and Kyle Solis explain research on the effects of magnetic fields on fluid flows and how they stimulate vigorous flows. Fluid flow is a necessary phenomenon in everything from reactors to cooling engines in cars.

Localized arc filament plasma actuators for noise mitigation and mixing enhancement

NASA Technical Reports Server (NTRS)

Samimy, Mohammad (Inventor); Adamovich, Igor (Inventor)

2008-01-01

A device for controlling fluid flow. The device includes an arc generator coupled to electrodes. The electrodes are placed adjacent a fluid flowpath such that upon being energized by the arc generator, an arc filament plasma adjacent the electrodes is formed. In turn, this plasma forms a localized high temperature, high pressure perturbation in the adjacent fluid flowpath. The perturbations can be arranged to produce vortices, such as streamwise vortices, in the flowing fluid to control mixing and noise in such flows. The electrodes can further be arranged within a conduit configured to contain the flowing fluid such that when energized in a particular frequency and sequence, can excite flow instabilities in the flowing fluid. The placement of the electrodes is such that they are unobtrusive relative to the fluid flowpath being controlled.

Localized arc filament plasma actuators for noise mitigation and mixing enhancement

NASA Technical Reports Server (NTRS)

Samimy, Mohammad (Inventor); Adamovich, Igor (Inventor)

2010-01-01

A device for controlling fluid flow. The device includes an arc generator coupled to electrodes. The electrodes are placed adjacent a fluid flowpath such that upon being energized by the arc generator, an arc filament plasma adjacent the electrodes is formed. In turn, this plasma forms a localized high temperature, high pressure perturbation in the adjacent fluid flowpath. The perturbations can be arranged to produce vortices, such as streamwise vortices, in the flowing fluid to control mixing and noise in such flows. The electrodes can further be arranged within a conduit configured to contain the flowing fluid such that when energized in a particular frequency and sequence, can excite flow instabilities in the flowing fluid. The placement of the electrodes is such that they are unobtrusive relative to the fluid flowpath being controlled.

Imaging lateral groundwater flow in the shallow subsurface using stochastic temperature fields

NASA Astrophysics Data System (ADS)

Fairley, Jerry P.; Nicholson, Kirsten N.

2006-04-01

Although temperature has often been used as an indication of vertical groundwater movement, its usefulness for identifying horizontal fluid flow has been limited by the difficulty of obtaining sufficient data to draw defensible conclusions. Here we use stochastic simulation to develop a high-resolution image of fluid temperatures in the shallow subsurface at Borax Lake, Oregon. The temperature field inferred from the geostatistical simulations clearly shows geothermal fluids discharging from a group of fault-controlled hydrothermal springs, moving laterally through the subsurface, and mixing with shallow subsurface flow originating from nearby Borax Lake. This interpretation of the data is supported by independent geochemical and isotopic evidence, which show a simple mixing trend between Borax Lake water and discharge from the thermal springs. It is generally agreed that stochastic simulation can be a useful tool for extracting information from complex and/or noisy data and, although not appropriate in all situations, geostatistical analysis may provide good definition of flow paths in the shallow subsurface. Although stochastic imaging techniques are well known in problems involving transport of species, e.g. delineation of contaminant plumes from soil gas survey data, we are unaware of previous applications to the transport of thermal energy for the purpose of inferring shallow groundwater flow.

Quantitative assessment of cerebrospinal fluid hydrodynamics using a phase-contrast cine MR image in hydrocephalus.

PubMed

Kim, D S; Choi, J U; Huh, R; Yun, P H; Kim, D I

1999-09-01

This investigation was undertaken to characterize CSF flow at the level of the aqueduct of Sylvius with a phase-contrast cine MR pulse sequence in 28 healthy volunteers. Sixteen patients with obstructive hydrocephalus and 11 patients with normal pressure hydrocephalus (NPH) were investigated with the same sequence before and after CSF diversion. The peak CSF flow velocity and stroke volume in the aqueduct increased significantly in the NPH group and decreased significantly in the obstructive hydrocephalus group. After lumboperitoneal shunting in the NPH group, the retrograde flow of CSF was anterogradely converted and the peak flow velocities decreased somewhat. The clinical diagnosis of NPH was well correlated with the results of cine MRI. After endoscopic III ventriculostomy in the obstructive hydrocephalus group we noted increased CSF flow velocity with markedly increased stroke volume at the prepontine cistern. Phase-contrast cine MR is useful in evaluating CSF dynamics in patients with hyperdynamic aqueductal CSF or aqueductal obstruction.

Effect of viscoelasticity on the flow pattern and the volumetric flow rate in electroosmotic flows through a microchannel.

PubMed

Park, H M; Lee, W M

2008-07-01

Many lab-on-a-chip based microsystems process biofluids such as blood and DNA solutions. These fluids are viscoelastic and show extraordinary flow behaviors, not existing in Newtonian fluids. Adopting appropriate constitutive equations these exotic flow behaviors can be modeled and predicted reasonably using various numerical methods. In the present paper, we investigate viscoelastic electroosmotic flows through a rectangular straight microchannel with and without pressure gradient. It is shown that the volumetric flow rates of viscoelastic fluids are significantly different from those of Newtonian fluids under the same external electric field and pressure gradient. Moreover, when pressure gradient is imposed on the microchannel there appear appreciable secondary flows in the viscoelastic fluids, which is never possible for Newtonian laminar flows through straight microchannels. The retarded or enhanced volumetric flow rates and secondary flows affect dispersion of solutes in the microchannel nontrivially.

Renewable fluid dynamic energy derived from aquatic animal locomotion.

PubMed

Dabiri, John O

2007-09-01

Aquatic animals swimming in isolation and in groups are known to extract energy from the vortices in environmental flows, significantly reducing muscle activity required for locomotion. A model for the vortex dynamics associated with this phenomenon is developed, showing that the energy extraction mechanism can be described by simple criteria governing the kinematics of the vortices relative to the body in the flow. In this way, we need not make direct appeal to the fluid dynamics, which can be more difficult to evaluate than the kinematics. Examples of these principles as exhibited in swimming fish and existing energy conversion devices are described. A benefit of the developed framework is that the potentially infinite-dimensional parameter space of the fluid-structure interaction is reduced to a maximum of eight combinations of three parameters. The model may potentially aid in the design and evaluation of unsteady aero- and hydrodynamic energy conversion systems that surpass the Betz efficiency limit of steady fluid dynamic energy conversion systems.

An exact solution for the Hawking effect in a dispersive fluid

NASA Astrophysics Data System (ADS)

Philbin, T. G.

2016-09-01

We consider the wave equation for sound in a moving fluid with a fourth-order anomalous dispersion relation. The velocity of the fluid is a linear function of position, giving two points in the flow where the fluid velocity matches the group velocity of low-frequency waves. We find the exact solution for wave propagation in the flow. The scattering shows amplification of classical waves, leading to spontaneous emission when the waves are quantized. In the dispersionless limit the system corresponds to a 1 +1 -dimensional black-hole or white-hole binary and there is a thermal spectrum of Hawking radiation from each horizon. Dispersion changes the scattering coefficients so that the quantum emission is no longer thermal. The scattering coefficients were previously obtained by Busch and Parentani in a study of dispersive fields in de Sitter space [Phys. Rev. D 86, 104033 (2012)]. Our results give further details of the wave propagation in this exactly solvable case, where our focus is on laboratory systems.

The effects of vasoactive agents on flow through saphenous vein grafts during lower-extremity peripheral vascular surgery.

PubMed

Maslow, Andrew D; Bert, Arthur; Slaiby, Jeffrey; Carney, William; Marcaccio, Edward

2007-06-01

The purpose of this study was to assess the effects of hemodynamic alterations on vein graft flow during peripheral vascular surgery. It was hypothesized that vasopressors can be administered without compromising flow through the vein grafts. Tertiary care center, university medical center. Randomized placebo-controlled double-blinded study. The effects of phenylephrine, epinephrine, milrinone, intravenous fluid, and placebo on newly constructed peripheral vein grafts were assessed in 60 patients (12 patients in each of 5 groups). Systemic and central hemodynamics were measured by using intra-arterial and pulmonary artery catheters. Vein graft flow was measured by using a transultrasonic flow probe (Transultrasonic Inc, Ithaca, NY). Phenylephrine increased systemic mean blood pressure (mBP) (68.2-94.0 mmHg, p < 0.01), systemic vascular resistance (SVR) (1,091-1,696 dynes x sec x cm(-5), p < 0.001), and vein graft flow (39.5-58.9 mL/min, p < 0.01), whereas cardiac output remained unchanged. Epinephrine resulted in increased cardiac output (4.4-6.9 L/min, p < 0.01) and mBP (72.7-89.1 mmHg, p < 0.01), whereas vein graft flow was reduced in 6 of 12 patients. Intravenous fluid administration resulted in a relatively smaller increase in graft flow (37.6-46.0 mL/min, p < 0.05), an increase in cardiac output, and an insignificant decrease in SVR. Other treatments had either little or no effect on vein graft flow. The study hypothesis was partly supported. Although both phenylephrine and epinephrine increased blood pressure, only the former increased vein graft flow in all patients. In conjunction with increases in graft flow after fluid administration, these data suggest that factors affecting vein graft flow are not just simply related to systemic hemodynamics.

International Congress of Fluid Mechanics, 3rd, Cairo, Egypt, Jan. 2-4, 1990, Proceedings. Volumes 1, 2, 3, & 4

NASA Astrophysics Data System (ADS)

Nayfeh, A. H.; Mobarak, A.; Rayan, M. Abou

This conference presents papers in the fields of flow separation, unsteady aerodynamics, fluid machinery, boundary-layer control and stability, grid generation, vorticity dominated flows, and turbomachinery. Also considered are propulsion, waves and sound, rotor aerodynamics, computational fluid dynamics, Euler and Navier-Stokes equations, cavitation, mixing and shear layers, mixing layers and turbulent flows, and fluid machinery and two-phase flows. Also addressed are supersonic and reacting flows, turbulent flows, and thermofluids.

Isotachophoresis system having larger-diameter channels flowing into channels with reduced diameter and with selectable counter-flow

DOEpatents

Mariella, Jr., Raymond P.

2018-03-06

An isotachophoresis system for separating a sample containing particles into discrete packets including a flow channel, the flow channel having a large diameter section and a small diameter section; a negative electrode operably connected to the flow channel; a positive electrode operably connected to the flow channel; a leading carrier fluid in the flow channel; a trailing carrier fluid in the flow channel; and a control for separating the particles in the sample into discrete packets using the leading carrier fluid, the trailing carrier fluid, the large diameter section, and the small diameter section.

Non-Newtonian fluid flow in 2D fracture networks

NASA Astrophysics Data System (ADS)

Zou, L.; Håkansson, U.; Cvetkovic, V.

2017-12-01

Modeling of non-Newtonian fluid (e.g., drilling fluids and cement grouts) flow in fractured rocks is of interest in many geophysical and industrial practices, such as drilling operations, enhanced oil recovery and rock grouting. In fractured rock masses, the flow paths are dominated by fractures, which are often represented as discrete fracture networks (DFN). In the literature, many studies have been devoted to Newtonian fluid (e.g., groundwater) flow in fractured rock using the DFN concept, but few works are dedicated to non-Newtonian fluids.In this study, a generalized flow equation for common non-Newtonian fluids (such as Bingham, power-law and Herschel-Bulkley) in a single fracture is obtained from the analytical solutions for non-Newtonian fluid discharge between smooth parallel plates. Using Monte Carlo sampling based on site characterization data for the distribution of geometrical features (e.g., density, length, aperture and orientations) in crystalline fractured rock, a two dimensional (2D) DFN model is constructed for generic flow simulations. Due to complex properties of non-Newtonian fluids, the relationship between fluid discharge and the pressure gradient is nonlinear. A Galerkin finite element method solver is developed to iteratively solve the obtained nonlinear governing equations for the 2D DFN model. Using DFN realizations, simulation results for different geometrical distributions of the fracture network and different non-Newtonian fluid properties are presented to illustrate the spatial discharge distributions. The impact of geometrical structures and the fluid properties on the non-Newtonian fluid flow in 2D DFN is examined statistically. The results generally show that modeling non-Newtonian fluid flow in fractured rock as a DFN is feasible, and that the discharge distribution may be significantly affected by the geometrical structures as well as by the fluid constitutive properties.

The impact of fluid advection on gas hydrate stability: Investigations at sites of methane seepage offshore Costa Rica

NASA Astrophysics Data System (ADS)

Crutchley, G. J.; Klaeschen, D.; Planert, L.; Bialas, J.; Berndt, C.; Papenberg, C.; Hensen, C.; Hornbach, M. J.; Krastel, S.; Brueckmann, W.

2014-09-01

Fluid flow through marine sediments drives a wide range of processes, from gas hydrate formation and dissociation, to seafloor methane seepage including the development of chemosynthetic ecosystems, and ocean acidification. Here, we present new seismic data that reveal the 3D nature of focused fluid flow beneath two mound structures on the seafloor offshore Costa Rica. These mounds have formed as a result of ongoing seepage of methane-rich fluids. We show the spatial impact of advective heat flow on gas hydrate stability due to the channelled ascent of warm fluids towards the seafloor. The base of gas hydrate stability (BGHS) imaged in the seismic data constrains peak heat flow values to ∼60 mW m and ∼70 mW m beneath two separate seep sites known as Mound 11 and Mound 12, respectively. The initiation of pronounced fluid flow towards these structures was likely controlled by fault networks that acted as efficient pathways for warm fluids ascending from depth. Through the gas hydrate stability zone, fluid flow has been focused through vertical conduits that we suggest developed as migrating fluids generated their own secondary permeability by fracturing strata as they forced their way upwards towards the seafloor. We show that Mound 11 and Mound 12 (about 1 km apart on the seafloor) are sustained by independent fluid flow systems through the hydrate system, and that fluid flow rates across the BGHS are probably similar beneath both mounds. 2D seismic data suggest that these two flow systems might merge at approximately 1 km depth, i.e. much deeper than the BGHS. This study provides a new level of detail and understanding of how channelled, anomalously-high fluid flow towards the seafloor influences gas hydrate stability. Thus, gas hydrate systems have good potential for quantifying the upward flow of subduction system fluids to seafloor seep sites, since the fluids have to interact with and leave their mark on the hydrate system before reaching the seafloor.

The direction of fluid flow during contact metamorphism of siliceous carbonate rocks: new data for the Monzoni and Predazzo aureoles, northern Italy, and a global review

NASA Astrophysics Data System (ADS)

Ferry, John M.; Wing, Boswell A.; Penniston-Dorland, Sarah C.; Rumble, Douglas

2002-03-01

Periclase formed in siliceous dolomitic marbles during contact metamorphism in the Monzoni and Predazzo aureoles, the Dolomites, northern Italy, by infiltration of the carbonate rocks by chemically reactive, H2O-rich fluids at 500 bar and 565-710 °C. The spatial distribution of periclase and oxygen isotope compositions is consistent with reactive fluid flow that was primarily vertical and upward in both aureoles with time-integrated flux ~5,000 and ~300 mol fluid/cm2 rock in the Monzoni and Predazzo aureoles, respectively. The new results for Monzoni and Predazzo are considered along with published studies of 13 other aureoles to draw general conclusions about the direction, amount, and controls on the geometry of reactive fluid flow during contact metamorphism of siliceous carbonate rocks. Flow in 12 aureoles was primarily vertically upward with and without a horizontal component directed away from the pluton. Fluid flow in two of the other three was primarily horizontal, directed from the pluton into the aureole. The direction of flow in the remaining aureole is uncertain. Earlier suggestions that fluid flow is often horizontal, directed toward the pluton, are likely explained by an erroneous assumption that widespread coexisting mineral reactants and products represent arrested prograde decarbonation reactions. With the exception of three samples from one aureole, time-integrated fluid flux was in the range 102-104 mol/cm2. Both the amount and direction of fluid flow are consistent with hydrodynamic models of contact metamorphism. The orientation of bedding and lithologic contacts appears to be the principal control over whether fluid flow was either primarily vertical or horizontal. Other pre-metamorphic structures, including dikes, faults, fold hinges, and fracture zones, served to channel fluid flow as well.

The direction of fluid flow during contact metamorphism of siliceous carbonate rocks: new data for the Monzoni and Predazzo aureoles, northern Italy, and a global review

NASA Astrophysics Data System (ADS)

Ferry, John; Wing, Boswell; Penniston-Dorland, Sarah; Rumble, Douglas

2001-11-01

Periclase formed in siliceous dolomitic marbles during contact metamorphism in the Monzoni and Predazzo aureoles, the Dolomites, northern Italy, by infiltration of the carbonate rocks by chemically reactive, H2O-rich fluids at 500 bar and 565-710 °C. The spatial distribution of periclase and oxygen isotope compositions is consistent with reactive fluid flow that was primarily vertical and upward in both aureoles with time-integrated flux 5,000 and 300 mol fluid/cm2 rock in the Monzoni and Predazzo aureoles, respectively. The new results for Monzoni and Predazzo are considered along with published studies of 13 other aureoles to draw general conclusions about the direction, amount, and controls on the geometry of reactive fluid flow during contact metamorphism of siliceous carbonate rocks. Flow in 12 aureoles was primarily vertically upward with and without a horizontal component directed away from the pluton. Fluid flow in two of the other three was primarily horizontal, directed from the pluton into the aureole. The direction of flow in the remaining aureole is uncertain. Earlier suggestions that fluid flow is often horizontal, directed toward the pluton, are likely explained by an erroneous assumption that widespread coexisting mineral reactants and products represent arrested prograde decarbonation reactions. With the exception of three samples from one aureole, time-integrated fluid flux was in the range 102-104 mol/cm2. Both the amount and direction of fluid flow are consistent with hydrodynamic models of contact metamorphism. The orientation of bedding and lithologic contacts appears to be the principal control over whether fluid flow was either primarily vertical or horizontal. Other pre-metamorphic structures, including dikes, faults, fold hinges, and fracture zones, served to channel fluid flow as well.

Group solution for unsteady free-convection flow from a vertical moving plate subjected to constant heat flux

NASA Astrophysics Data System (ADS)

Kassem, M.

2006-03-01

The problem of heat and mass transfer in an unsteady free-convection flow over a continuous moving vertical sheet in an ambient fluid is investigated for constant heat flux using the group theoretical method. The nonlinear coupled partial differential equation governing the flow and the boundary conditions are transformed to a system of ordinary differential equations with appropriate boundary conditions. The obtained ordinary differential equations are solved numerically using the shooting method. The effect of Prandlt number on the velocity and temperature of the boundary-layer is plotted in curves. A comparison with previous work is presented.

Reducing or stopping the uncontrolled flow of fluid such as oil from a well

DOEpatents

Hermes, Robert E

2014-02-18

The uncontrolled flow of fluid from an oil or gas well may be reduced or stopped by injecting a composition including 2-cyanoacrylate ester monomer into the fluid stream. Injection of the monomer results in a rapid, perhaps instantaneous, polymerization of the monomer within the flow stream of the fluid. This polymerization results in formation of a solid plug that reduces or stops the flow of additional fluid from the well.

Doppler optical coherence tomography imaging of local fluid flow and shear stress within microporous scaffolds

NASA Astrophysics Data System (ADS)

Jia, Yali; Bagnaninchi, Pierre O.; Yang, Ying; Haj, Alicia El; Hinds, Monica T.; Kirkpatrick, Sean J.; Wang, Ruikang K.

2009-05-01

Establishing a relationship between perfusion rate and fluid shear stress in a 3D cell culture environment is an ongoing and challenging task faced by tissue engineers. We explore Doppler optical coherence tomography (DOCT) as a potential imaging tool for in situ monitoring of local fluid flow profiles inside porous chitosan scaffolds. From the measured fluid flow profiles, the fluid shear stresses are evaluated. We examine the localized fluid flow and shear stress within low- and high-porosity chitosan scaffolds, which are subjected to a constant input flow rate of 0.5 ml.min-1. The DOCT results show that the behavior of the fluid flow and shear stress in micropores is strongly dependent on the micropore interconnectivity, porosity, and size of pores within the scaffold. For low-porosity and high-porosity chitosan scaffolds examined, the measured local fluid flow and shear stress varied from micropore to micropore, with a mean shear stress of 0.49+/-0.3 dyn.cm-2 and 0.38+/-0.2 dyn.cm-2, respectively. In addition, we show that the scaffold's porosity and interconnectivity can be quantified by combining analyses of the 3D structural and flow images obtained from DOCT.

Fluid Flow Phenomena during Welding

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

Zhang, Wei

2011-01-01

MOLTEN WELD POOLS are dynamic. Liquid in the weld pool in acted on by several strong forces, which can result in high-velocity fluid motion. Fluid flow velocities exceeding 1 m/s (3.3 ft/s) have been observed in gas tungsten arc (GTA) welds under ordinary welding conditions, and higher velocities have been measured in submerged arc welds. Fluid flow is important because it affects weld shape and is related to the formation of a variety of weld defects. Moving liquid transports heat and often dominates heat transport in the weld pool. Because heat transport by mass flow depends on the direction andmore » speed of fluid motion, weld pool shape can differ dramatically from that predicted by conductive heat flow. Temperature gradients are also altered by fluid flow, which can affect weld microstructure. A number of defects in GTA welds have been attributed to fluid flow or changes in fluid flow, including lack of penetration, top bead roughness, humped beads, finger penetration, and undercutting. Instabilities in the liquid film around the keyhole in electron beam and laser welds are responsible for the uneven penetration (spiking) characteristic of these types of welds.« less

Novel multi-functional fluid flow device for studying cellular mechanotransduction

PubMed Central

Lyons, James S.; Iyer, Shama R.; Lovering, Richard M.; Ward, Christopher W.; Stains, Joseph P.

2016-01-01

Cells respond to their mechanical environment by initiating multiple mechanotransduction signaling pathways. Defects in mechanotransduction have been implicated in a number of pathologies; thus, there is need for convenient and efficient methods for studying the mechanisms underlying these processes. A widely used and accepted technique for mechanically stimulating cells in culture is the introduction of fluid flow on cell monolayers. Here, we describe a novel, multifunctional fluid flow device for exposing cells to fluid flow in culture. This device integrates with common lab equipment including routine cell culture plates and peristaltic pumps. Further, it allows the fluid flow treated cells to be examined with outcomes at the cell and molecular level. We validated the device using the biologic response of cultured UMR-106 osteoblast-like cells in comparison to a commercially available system of laminar sheer stress to track live cell calcium influx in response to fluid flow. In addition, we demonstrate the fluid flow-dependent activation of phospho-ERK in these cells, consistent with the findings in other fluid flow devices. This device provides a low cost, multi-functional alternative to currently available systems, while still providing the ability to generate physiologically relevant conditions for studying processes involved in mechanotransduction in vitro. PMID:27887728

Fluid flow plate for decreased density of fuel cell assembly

DOEpatents

Vitale, Nicholas G.

1999-01-01

A fluid flow plate includes first and second outward faces. Each of the outward faces has a flow channel thereon for carrying respective fluid. At least one of the fluids serves as reactant fluid for a fuel cell of a fuel cell assembly. One or more pockets are formed between the first and second outward faces for decreasing density of the fluid flow plate. A given flow channel can include one or more end sections and an intermediate section. An interposed member can be positioned between the outward faces at an interface between an intermediate section, of one of the outward faces, and an end section, of that outward face. The interposed member can serve to isolate the reactant fluid from the opposing outward face. The intermediate section(s) of flow channel(s) on an outward face are preferably formed as a folded expanse.

Numerical Modelling of Three-Fluid Flow Using The Level-set Method

NASA Astrophysics Data System (ADS)

Li, Hongying; Lou, Jing; Shang, Zhi

2014-11-01

This work presents a numerical model for simulation of three-fluid flow involving two different moving interfaces. These interfaces are captured using the level-set method via two different level-set functions. A combined formulation with only one set of conservation equations for the whole physical domain, consisting of the three different immiscible fluids, is employed. Numerical solution is performed on a fixed mesh using the finite volume method. Surface tension effect is incorporated using the Continuum Surface Force model. Validation of the present model is made against available results for stratified flow and rising bubble in a container with a free surface. Applications of the present model are demonstrated by a variety of three-fluid flow systems including (1) three-fluid stratified flow, (2) two-fluid stratified flow carrying the third fluid in the form of drops and (3) simultaneous rising and settling of two drops in a stationary third fluid. The work is supported by a Thematic and Strategic Research from A*STAR, Singapore (Ref. #: 1021640075).

High precision high flow range control valve

DOEpatents

McCray, J.A.

1999-07-13

A fluid control valve is described having a valve housing having first and second valve housing openings for the ingress and egress of fluid through the control valve. Disposed within a void formed by the control valve is a sleeve having at least one sleeve opening to permit the flow of fluid therethrough. A flow restricter travels within the sleeve to progressively block off the sleeve opening and thereby control flow. A fluid passageway is formed between the first valve housing opening and the outer surface of the sleeve. A second fluid passageway is formed between the inside of the sleeve and the second valve housing opening. Neither fluid passageway contains more than one 90 [degree] turn. In the preferred embodiment only one of the two fluid passageways contains a 90[degree] turn. In another embodiment, the control valve housing is bifurcated by a control surface having control surface opening disposed therethrough. A flow restricter is in slidable contact with the control surface to restrict flow of fluid through the control surface openings. 12 figs.

High precision high flow range control valve

DOEpatents

McCray, John A.

1999-01-01

A fluid control valve is described having a valve housing having first and second valve housing openings for the ingress and egress of fluid through the control valve. Disposed within a void formed by the control valve is a sleeve having at least one sleeve opening to permit the flow of fluid therethrough. A flow restricter travels within the sleeve to progressively block off the sleeve opening and thereby control flow. A fluid passageway is formed between the first valve housing opening and the outer surface of the sleeve. A second fluid passageway is formed between the inside of the sleeve and the second valve housing opening. Neither fluid passageway contains more than one 90.degree. turn. In the preferred embodiment only one of the two fluid passageways contains a 90.degree. turn. In another embodiment, the control valve housing is bifurcated by a control surface having control surface opening disposed therethrough. A flow restricter is in slidable contact with the control surface to restrict flow of fluid through the control surface openings.

Experimental investigation of the flow dynamics and rheology of complex fluids in pipe flow by hybrid multi-scale velocimetry

NASA Astrophysics Data System (ADS)

Haavisto, Sanna; Cardona, Maria J.; Salmela, Juha; Powell, Robert L.; McCarthy, Michael J.; Kataja, Markku; Koponen, Antti I.

2017-11-01

A hybrid multi-scale velocimetry method utilizing Doppler optical coherence tomography in combination with either magnetic resonance imaging or ultrasound velocity profiling is used to investigate pipe flow of four rheologically different working fluids under varying flow regimes. These fluids include water, an aqueous xanthan gum solution, a softwood fiber suspension, and a microfibrillated cellulose suspension. The measurement setup enables not only the analysis of the rheological (bulk) behavior of a studied fluid but gives simultaneously information on their wall layer dynamics, both of which are needed for analyzing and solving practical fluid flow-related problems. Preliminary novel results on rheological and boundary layer flow properties of the working fluids are reported and the potential of the hybrid measurement setup is demonstrated.

Stiffening of fluid membranes due to thermal undulations: density-matrix renormalization-group study.

PubMed

Nishiyama, Yoshihiro

2002-12-01

It has been considered that the effective bending rigidity of fluid membranes should be reduced by thermal undulations. However, recent thorough investigation by Pinnow and Helfrich revealed the significance of measure factors for the partition sum. Accepting the local curvature as a statistical measure, they found that fluid membranes are stiffened macroscopically. In order to examine this remarkable idea, we performed extensive ab initio simulations for a fluid membrane. We set up a transfer matrix that is diagonalized by means of the density-matrix renormalization group. Our method has an advantage, in that it allows us to survey various statistical measures. As a consequence, we found that the effective bending rigidity flows toward strong coupling under the choice of local curvature as a statistical measure. On the contrary, for other measures such as normal displacement and tilt angle, we found a clear tendency toward softening.

A New Modular Approach for Tightly Coupled Fluid/Structure Analysis

NASA Technical Reports Server (NTRS)

Guruswamy, Guru

2003-01-01

Static aeroelastic computations are made using a C++ executive suitable for closely coupled fluid/structure interaction studies. The fluid flow is modeled using the Euler/Navier Stokes equations and the structure is modeled using finite elements. FORTRAN based fluids and structures codes are integrated under C++ environment. The flow and structural solvers are treated as separate object files. The data flow between fluids and structures is accomplished using I/O. Results are demonstrated for transonic flow over partially flexible surface that is important for aerospace vehicles. Use of this development to accurately predict flow induced structural failure will be demonstrated.

Mean-Lagrangian formalism and covariance of fluid turbulence.

PubMed

Ariki, Taketo

2017-05-01

Mean-field-based Lagrangian framework is developed for the fluid turbulence theory, which enables physically objective discussions, especially, of the history effect. Mean flow serves as a purely geometrical object of Lie group theory, providing useful operations to measure the objective rate and history integration of the general tensor field. The proposed framework is applied, on the one hand, to one-point closure model, yielding an objective expression of the turbulence viscoelastic effect. Application to two-point closure, on the other hand, is also discussed, where natural extension of known Lagrangian correlation is discovered on the basis of an extended covariance group.

Fluid Structure Interaction in a Cold Flow Test and Transient CFD Analysis of Out-of-Round Nozzles

NASA Technical Reports Server (NTRS)

Ruf, Joseph; Brown, Andrew; McDaniels, David; Wang, Ten-See

2010-01-01

This viewgraph presentation describes two nozzle fluid flow interactions. They include: 1) Cold flow nozzle tests with fluid-structure interaction at nozzle separated flow; and 2) CFD analysis for nozzle flow and side loads of nozzle extensions with various out-of-round cases.

Thermohydrodynamic Analysis of Cryogenic Liquid Turbulent Flow Fluid Film Bearings

NASA Technical Reports Server (NTRS)

SanAndres, Luis

1996-01-01

Computational programs developed for the thermal analysis of tilting and flexure-pad hybrid bearings, and the unsteady flow and transient response of a point mass rotor supported on fluid film bearings are described. The motion of a cryogenic liquid on the thin film annular region of a fluid film bearing is described by a set of mass and momentum conservation, and energy transport equations for the turbulent bulk-flow velocities and pressure, and accompanied by thermophysical state equations for evaluation of the fluid material properties. Zeroth-order equations describe the fluid flow field for a journal static equilibrium position, while first-order (linear) equations govern the fluid flow for small amplitude-journal center translational motions. Solution to the zeroth-order flow field equations provides the bearing flow rate, load capacity, drag torque and temperature rise. Solution to the first-order equations determines the rotordynamic force coefficients due to journal radial motions.

Yield-stress fluids foams: flow patterns and controlled production in T-junction and flow-focusing devices.

PubMed

Laborie, Benoit; Rouyer, Florence; Angelescu, Dan E; Lorenceau, Elise

2016-11-23

We study the formation of yield-stress fluid foams in millifluidic flow-focusing and T-junction devices. First, we provide a phase diagram for the unsteady operating regimes of bubble production when the gas pressure and the yield-stress fluid flow rate are imposed. Three regimes are identified: a co-flow of gas and yield-stress fluid, a transient production of bubble and a flow of yield-stress fluid only. Taking wall slip into account, we provide a model for the pressure at the onset of bubble formation. Then, we detail and compare two simple methods to ensure steady bubble production: regulation of the gas pressure or flow-rate. These techniques, which are easy to implement, thus open pathways for controlled production of dry yield-stress fluid foams as shown at the end of this article.

A systems approach to theoretical fluid mechanics: Fundamentals

NASA Technical Reports Server (NTRS)

Anyiwo, J. C.

1978-01-01

A preliminary application of the underlying principles of the investigator's general system theory to the description and analyses of the fluid flow system is presented. An attempt is made to establish practical models, or elements of the general fluid flow system from the point of view of the general system theory fundamental principles. Results obtained are applied to a simple experimental fluid flow system, as test case, with particular emphasis on the understanding of fluid flow instability, transition and turbulence.

Intracellular Fluid Mechanics: Coupling Cytoplasmic Flow with Active Cytoskeletal Gel

NASA Astrophysics Data System (ADS)

Mogilner, Alex; Manhart, Angelika

2018-01-01

The cell is a mechanical machine, and continuum mechanics of the fluid cytoplasm and the viscoelastic deforming cytoskeleton play key roles in cell physiology. We review mathematical models of intracellular fluid mechanics, from cytoplasmic fluid flows, to the flow of a viscous active cytoskeletal gel, to models of two-phase poroviscous flows, to poroelastic models. We discuss application of these models to cell biological phenomena, such as organelle positioning, blebbing, and cell motility. We also discuss challenges of understanding fluid mechanics on the cellular scale.

Unconventional Liquid Flow in Low-Permeability Media: Theory and Revisiting Darcy's Law

NASA Astrophysics Data System (ADS)

Liu, H. H.; Chen, J.

2017-12-01

About 80% of fracturing fluid remains in shale formations after hydraulic fracturing and the flow back process. It is critical to understand and accurately model the flow process of fracturing fluids in a shale formation, because the flow has many practical applications for shale gas recovery. Owing to the strong solid-liquid interaction in low-permeability media, Darcy's law is not always adequate for describing liquid flow process in a shale formation. This non-Darcy flow behavior (characterized by nonlinearity of the relationship between liquid flux and hydraulic gradient), however, has not been given enough attention in the shale gas community. The current study develops a systematic methodology to address this important issue. We developed a phenomenological model for liquid flow in shale (in which liquid flux is a power function of pressure gradient), an extension of the conventional Darcy's law, and also a methodology to estimate parameters for the phenomenological model from spontaneous imbibition tests. The validity of our new developments is verified by satisfactory comparisons of theoretical results and observations from our and other research groups. The relative importance of this non-Darcy liquid flow for hydrocarbon production in unconventional reservoirs remains an issue that needs to be further investigated.

Generalized Fluid System Simulation Program (GFSSP) Version 6 - General Purpose Thermo-Fluid Network Analysis Software

NASA Technical Reports Server (NTRS)

Majumdar, Alok; Leclair, Andre; Moore, Ric; Schallhorn, Paul

2011-01-01

GFSSP stands for Generalized Fluid System Simulation Program. It is a general-purpose computer program to compute pressure, temperature and flow distribution in a flow network. GFSSP calculates pressure, temperature, and concentrations at nodes and calculates flow rates through branches. It was primarily developed to analyze Internal Flow Analysis of a Turbopump Transient Flow Analysis of a Propulsion System. GFSSP development started in 1994 with an objective to provide a generalized and easy to use flow analysis tool for thermo-fluid systems.

Chaotic Fluid Mixing in Crystalline Sphere Arrays

NASA Astrophysics Data System (ADS)

Turuban, R.; Lester, D. R.; Le Borgne, T.; Méheust, Y.

2017-12-01

We study the Lagrangian dynamics of steady 3D Stokes flow over simple cubic (SC) and body-centered cubic (BCC) lattices of close-packed spheres, and uncover the mechanisms governing chaotic mixing. Due to the cusp-shaped sphere contacts, the topology of the skin friction field is fundamentally different to that of continuous (non-granular) media (e.g. open pore networks), with significant implications for fluid mixing. Weak symmetry breaking of the flow orientation with respect to the lattice symmetries imparts a transition from regular to strong chaotic mixing in the BCC lattice, whereas the SC lattice only exhibits weak mixing. Whilst the SC and BCC lattices share the same symmetry point group, these differences are explained in terms of their space groups, and we find that a glide symmetry of the BCC lattice generates chaotic mixing. These insight are used to develop accurate predictions of the Lyapunov exponent distribution over the parameter space of mean flow orientation, and point to a general theory of mixing and dispersion based upon the inherent symmetries of arbitrary crystalline structures.

Evaporative Cooling Membrane Device

NASA Technical Reports Server (NTRS)

Lomax, Curtis (Inventor); Moskito, John (Inventor)

1999-01-01

An evaporative cooling membrane device is disclosed having a flat or pleated plate housing with an enclosed bottom and an exposed top that is covered with at least one sheet of hydrophobic porous material having a thin thickness so as to serve as a membrane. The hydrophobic porous material has pores with predetermined dimensions so as to resist any fluid in its liquid state from passing therethrough but to allow passage of the fluid in its vapor state, thereby, causing the evaporation of the fluid and the cooling of the remaining fluid. The fluid has a predetermined flow rate. The evaporative cooling membrane device has a channel which is sized in cooperation with the predetermined flow rate of the fluid so as to produce laminar flow therein. The evaporative cooling membrane device provides for the convenient control of the evaporation rates of the circulating fluid by adjusting the flow rates of the laminar flowing fluid.

New views of granular mass flows

USGS Publications Warehouse

Iverson, R.M.; Vallance, J.W.

2001-01-01

Concentrated grain-fluid mixtures in rock avalanches, debris flows, and pyroclastic flows do not behave as simple materials with fixed rheologies. Instead, rheology evolves as mixture agitation, grain concentration, and fluid-pressure change during flow initiation, transit, and deposition. Throughout a flow, however, normal forces on planes parallel to the free upper surface approximately balance the weight of the superincumbent mixture, and the Coulomb friction rule describes bulk intergranular shear stresses on such planes. Pore-fluid pressure can temporarily or locally enhance mixture mobility by reducing Coulomb friction and transferring shear stress to the fluid phase. Initial conditions, boundary conditions, and grain comminution and sorting can influence pore-fluid pressures and cause variations in flow dynamics and deposits.

Respiratory fluid mechanics

NASA Astrophysics Data System (ADS)

Grotberg, James B.

2011-02-01

This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from "capillary-elastic instabilities," as well as nonlinear stabilization from oscillatory core flow which we call the "oscillating butter knife;" liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg-Borgas-Gaver shock.

Concept of planetary gear system to control fluid mixture ratio

NASA Technical Reports Server (NTRS)

Mcgroarty, J. D.

1966-01-01

Mechanical device senses and corrects for fluid flow departures from the selected flow ratio of two fluids. This system has been considered for control of rocket engine propellant mixture control but could find use wherever control of the flow ratio of any two fluids is desired.

ACE-1 experiment

NASA Image and Video Library

2013-06-24

In the International Space Stations Destiny laboratory,NASA astronaut Karen Nyberg,Expedition 36 flight engineer,speaks into a microphone while conducting a session with the Advanced Colloids Experiment (ACE)-1 sample preparation at the Light Microscopy Module (LMM) in the Fluids Integrated Rack / Fluids Combustion Facility (FIR/FCF). ACE-1 is a series of microscopic imaging investigations that uses the microgravity environment to examine flow characteristics and the evolution and ordering effects within a group of colloidal materials.

Viscoelastic fluid-structure interactions between a flexible cylinder and wormlike micelle solution

NASA Astrophysics Data System (ADS)

Dey, Anita A.; Modarres-Sadeghi, Yahya; Rothstein, Jonathan P.

2018-06-01

It is well known that when a flexible or flexibly mounted structure is placed perpendicular to the flow of a Newtonian fluid, it can oscillate due to the shedding of separated vortices at high Reynolds numbers. Unlike Newtonian fluids, the flow of viscoelastic fluids can become unstable even at infinitesimal Reynolds numbers due to a purely elastic flow instability that can occur at large Weissenberg numbers. Recent work has shown that these elastic flow instabilities can drive the motion of flexible sheets. The fluctuating fluid forces exerted on the structure from the elastic flow instabilities can lead to a coupling between an oscillatory structural motion and the state of stress in the fluid flow. In this paper, we present the results of an investigation into the flow of a viscoelastic wormlike micelle solution past a flexible circular cylinder. The time variation of the flow field and the state of stress in the fluid are shown using a combination of particle image tracking and flow-induced birefringence images. The static and dynamic responses of the flexible cylinder are presented for a range of flow velocities. The nonlinear dynamics of the structural motion is studied to better understand an observed transition from a symmetric to an asymmetric structural deformation and oscillation behavior.

Thermoelectric Generation Using Counter-Flows of Ideal Fluids

NASA Astrophysics Data System (ADS)

Meng, Xiangning; Lu, Baiyi; Zhu, Miaoyong; Suzuki, Ryosuke O.

2017-08-01

Thermoelectric (TE) performance of a three-dimensional (3-D) TE module is examined by exposing it between a pair of counter-flows of ideal fluids. The ideal fluids are thermal sources of TE module flow in the opposite direction at the same flow rate and generate temperature differences on the hot and cold surfaces due to their different temperatures at the channel inlet. TE performance caused by different inlet temperatures of thermal fluids are numerically analyzed by using the finite-volume method on 3-D meshed physical models and then compared with those using a constant boundary temperature. The results show that voltage and current of the TE module increase gradually from a beginning moment to a steady flow and reach a stable value. The stable values increase with inlet temperature of the hot fluid when the inlet temperature of cold fluid is fixed. However, the time to get to the stable values is almost consistent for all the temperature differences. Moreover, the trend of TE performance using a fluid flow boundary is similar to that of using a constant boundary temperature. Furthermore, 3-D contours of fluid pressure, temperature, enthalpy, electromotive force, current density and heat flux are exhibited in order to clarify the influence of counter-flows of ideal fluids on TE generation. The current density and heat flux homogeneously distribute on an entire TE module, thus indicating that the counter-flows of thermal fluids have high potential to bring about fine performance for TE modules.

An Immersed Boundary-Lattice Boltzmann Method for Simulating Particulate Flows

NASA Astrophysics Data System (ADS)

Zhang, Baili; Cheng, Ming; Lou, Jing

2013-11-01

A two-dimensional momentum exchange-based immersed boundary-lattice Boltzmann method developed by X.D. Niu et al. (2006) has been extended in three-dimensions for solving fluid-particles interaction problems. This method combines the most desirable features of the lattice Boltzmann method and the immersed boundary method by using a regular Eulerian mesh for the flow domain and a Lagrangian mesh for the moving particles in the flow field. The non-slip boundary conditions for the fluid and the particles are enforced by adding a force density term into the lattice Boltzmann equation, and the forcing term is simply calculated by the momentum exchange of the boundary particle density distribution functions, which are interpolated by the Lagrangian polynomials from the underlying Eulerian mesh. This method preserves the advantages of lattice Boltzmann method in tracking a group of particles and, at the same time, provides an alternative approach to treat solid-fluid boundary conditions. Numerical validations show that the present method is very accurate and efficient. The present method will be further developed to simulate more complex problems with particle deformation, particle-bubble and particle-droplet interactions.

Fluid flows and forces in development: functions, features and biophysical principles

PubMed Central

Freund, Jonathan B.; Goetz, Jacky G.; Hill, Kent L.; Vermot, Julien

2012-01-01

Throughout morphogenesis, cells experience intracellular tensile and contractile forces on microscopic scales. Cells also experience extracellular forces, such as static forces mediated by the extracellular matrix and forces resulting from microscopic fluid flow. Although the biological ramifications of static forces have received much attention, little is known about the roles of fluid flows and forces during embryogenesis. Here, we focus on the microfluidic forces generated by cilia-driven fluid flow and heart-driven hemodynamics, as well as on the signaling pathways involved in flow sensing. We discuss recent studies that describe the functions and the biomechanical features of these fluid flows. These insights suggest that biological flow determines many aspects of cell behavior and identity through a specific set of physical stimuli and signaling pathways. PMID:22395739

Implementation of Finite Volume based Navier Stokes Algorithm Within General Purpose Flow Network Code

NASA Technical Reports Server (NTRS)

Schallhorn, Paul; Majumdar, Alok

2012-01-01

This paper describes a finite volume based numerical algorithm that allows multi-dimensional computation of fluid flow within a system level network flow analysis. There are several thermo-fluid engineering problems where higher fidelity solutions are needed that are not within the capacity of system level codes. The proposed algorithm will allow NASA's Generalized Fluid System Simulation Program (GFSSP) to perform multi-dimensional flow calculation within the framework of GFSSP s typical system level flow network consisting of fluid nodes and branches. The paper presents several classical two-dimensional fluid dynamics problems that have been solved by GFSSP's multi-dimensional flow solver. The numerical solutions are compared with the analytical and benchmark solution of Poiseulle, Couette and flow in a driven cavity.

Chaos analysis of viscoelastic chaotic flows of polymeric fluids in a micro-channel

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

Lim, C. P.; Lam, Y. C., E-mail: myclam@ntu.edu.sg; BioSystems and Micromechanics

2015-07-15

Many fluids, including biological fluids such as mucus and blood, are viscoelastic. Through the introduction of chaotic flows in a micro-channel and the construction of maps of characteristic chaos parameters, differences in viscoelastic properties of these fluids can be measured. This is demonstrated by creating viscoelastic chaotic flows induced in an H-shaped micro-channel through the steady infusion of a polymeric fluid of polyethylene oxide (PEO) and another immiscible fluid (silicone oil). A protocol for chaos analysis was established and demonstrated for the analysis of the chaotic flows generated by two polymeric fluids of different molecular weight but with similar relaxationmore » times. The flows were shown to be chaotic through the computation of their correlation dimension (D{sub 2}) and the largest Lyapunov exponent (λ{sub 1}), with D{sub 2} being fractional and λ{sub 1} being positive. Contour maps of D{sub 2} and λ{sub 1} of the respective fluids in the operating space, which is defined by the combination of polymeric fluids and silicone oil flow rates, were constructed to represent the characteristic of the chaotic flows generated. It was observed that, albeit being similar, the fluids have generally distinct characteristic maps with some similar trends. The differences in the D{sub 2} and λ{sub 1} maps are indicative of the difference in the molecular weight of the polymers in the fluids because the driving force of the viscoelastic chaotic flows is of molecular origin. This approach in constructing the characteristic maps of chaos parameters can be employed as a diagnostic tool for biological fluids and, more generally, chaotic signals.« less

Influence of mantle viscosity structure and mineral grain size on fluid migration pathways in the mantle wedge.

NASA Astrophysics Data System (ADS)

Cerpa, N. G.; Wada, I.; Wilson, C. R.; Spiegelman, M. W.

2016-12-01

We develop a 2D numerical porous flow model that incorporates both grain size distribution and matrix compaction to explore the fluid migration (FM) pathways in the mantle wedge. Melt generation for arc volcanism is thought to be triggered by slab-derived fluids that migrate into the hot overlying mantle and reduce its melting temperature. While the narrow location of the arcs relative to the top of the slab ( 100±30 km) is a robust observation, the release of fluids is predicted to occur over a wide range of depth. Reconciling such observations and predictions remains a challenge for the geodynamic community. Fluid transport by porous flow depends on the permeability of the medium which in turn depends on fluid fraction and mineral grain size. The grain size distribution in the mantle wedge predicted by laboratory derived laws was found to be a possible mechanism to focusing of fluids beneath the arcs [Wada and Behn, 2015]. The viscous resistance of the matrix to the volumetric strain generates compaction pressure that affects fluid flow and can also focus fluids towards the arc [Wilson et al, 2014]. We thus have developed a 2D one-way coupled Darcy's-Stokes flow model (solid flow independent of fluid flow) for the mantle wedge that combines both effects. For the solid flow calculation, we use a kinematic-dynamic approach where the system is driven by the prescribed slab velocity. The solid rheology accounts for both dislocation and diffusion creep and we calculate the grain size distribution following Wada and Behn [2015]. In our fluid flow model, the permeability of the medium is grain size dependent and the matrix bulk viscosity depends on solid shear viscosity and fluid fraction. The fluid influx from the slab is imposed as a boundary condition at the base of the mantle wedge. We solve the discretized governing equations using the software package TerraFERMA. Applying a range of model parameter values, including slab age, slab dip, subduction rate, and fluid influx, we quantify the combined effects of grain size and compaction on fluid flow paths.

Renal excretion of water in men under hypokinesia and physical exercise with fluid and salt supplementation

NASA Astrophysics Data System (ADS)

Zorbas, Yan G.; Federenko, Youri F.; Togawa, Mitsui N.

It has been suggested that under hypokinesia (reduced number of steps/day) and intensive physical exercise, the intensification of fluid excretion in men is apparently caused as a result of the inability of the body to retain optimum amounts of water. Thus, to evaluate this hypothesis, studies were performed with the use of fluid and sodium chloride (NaCl) supplements on 12 highly trained physically healthy male volunteers aged 19-24 years under 364 days of hypokinesis (HK) and a set of intensive physical exercises (PE). They were divided into two groups with 6 volunteers per group. The first group of subjects were submitted to HK and took daily fluid and salt supplements in very small doses and the second group of volunteers were subjected to intensive PE and fluid-salt supplements. For the simulation of the hypokinetic effect, both groups of subjects were kept under an average of 4000 steps/day. During the prehypokinetic period of 60 days and under the hypokinetic period of 364 days water consumed and eliminated in urine by the men, water content in blood, plasma volume, rate of glomerular filtration, renal blood flow, osmotic concentration of urine and blood were measured. Under HK, the rate of renal excretion of water increased considerably in both groups. The additional fluid and salt intake failed to normalize water balance adequately under HK and PE. It was concluded that negative water balance evidently resulted not from shortage of water in the diet but from the inability of the body to retain optimum amounts of fluid under HK and a set of intensive PEs.

Effects of magnetic-fluid flow on structural instability of a carbon nanotube conveying nanoflow under a longitudinal magnetic field

NASA Astrophysics Data System (ADS)

Sadeghi-Goughari, Moslem; Jeon, Soo; Kwon, Hyock-Ju

2017-09-01

In drug delivery systems, carbon nanotubes (CNTs) can be used to deliver anticancer drugs into target site to kill metastatic cancer cells under the magnetic field guidance. Deep understanding of dynamic behavior of CNTs in drug delivery systems may enable more efficient use of the drugs while reducing systemic side effects. In this paper, we study the effect of magnetic-fluid flow on the structural instability of a CNT conveying nanoflow under a longitudinal magnetic field. The Navier-Stokes equation of magnetic-fluid flow is coupled with Euler-Bernoulli beam theory for modeling fluid structure interaction (FSI). Size effects of the magnetic fluid and the CNT are addressed through small-scale parameters including the Knudsen number (Kn) and the nonlocal parameter. Results show the positive role of magnetic properties of fluid flow on the structural stability of CNT. Specifically, magnetic force applied to the fluid flow has an effect of decreasing the structural stiffness of system while increasing the critical flow velocity. Furthermore, we discover that the nanoscale effects of CNT and fluid flow tend to amplify the influence of magnetic field on the vibrational behavior of the system.

Device and method for measuring multi-phase fluid flow and density of fluid in a conduit having a gradual bend

DOEpatents

Ortiz, Marcos German; Boucher, Timothy J.

1998-01-01

A system for measuring fluid flow in a conduit having a gradual bend or arc, and a straight section. The system includes pressure transducers, one or more disposed in the conduit on the outside of the arc, and one disposed in the conduit in a straight section thereof. The pressure transducers measure the pressure of fluid in the conduit at the locations of the pressure transducers and this information is used by a computational device to calculate fluid flow rate in the conduit. For multi-phase fluid, the density of the fluid is measured by another pair of pressure transducers, one of which is located in the conduit elevationally above the other. The computation device then uses the density measurement along with the fluid pressure measurements, to calculate fluid flow.

VISCOPLASTIC FLUID MODEL FOR DEBRIS FLOW ROUTING.

USGS Publications Warehouse

Chen, Cheng-lung

1986-01-01

This paper describes how a generalized viscoplastic fluid model, which was developed based on non-Newtonian fluid mechanics, can be successfully applied to routing a debris flow down a channel. The one-dimensional dynamic equations developed for unsteady clear-water flow can be used for debris flow routing if the flow parameters, such as the momentum (or energy) correction factor and the resistance coefficient, can be accurately evaluated. The writer's generalized viscoplastic fluid model can be used to express such flow parameters in terms of the rheological parameters for debris flow in wide channels. A preliminary analysis of the theoretical solutions reveals the importance of the flow behavior index and the so-called modified Froude number for uniformly progressive flow in snout profile modeling.

Sampling device for withdrawing a representative sample from single and multi-phase flows

DOEpatents

Apley, Walter J.; Cliff, William C.; Creer, James M.

1984-01-01

A fluid stream sampling device has been developed for the purpose of obtaining a representative sample from a single or multi-phase fluid flow. This objective is carried out by means of a probe which may be inserted into the fluid stream. Individual samples are withdrawn from the fluid flow by sampling ports with particular spacings, and the sampling parts are coupled to various analytical systems for characterization of the physical, thermal, and chemical properties of the fluid flow as a whole and also individually.

Method and apparatus for measuring the mass flow rate of a fluid

DOEpatents

Evans, Robert P.; Wilkins, S. Curtis; Goodrich, Lorenzo D.; Blotter, Jonathan D.

2002-01-01

A non invasive method and apparatus is provided to measure the mass flow rate of a multi-phase fluid. An accelerometer is attached to a pipe carrying a multi-phase fluid. Flow related measurements in pipes are sensitive to random velocity fluctuations whose magnitude is proportional to the mean mass flow rate. An analysis of the signal produced by the accelerometer shows a relationship between the mass flow of a fluid and the noise component of the signal of an accelerometer. The noise signal, as defined by the standard deviation of the accelerometer signal allows the method and apparatus of the present invention to non-intrusively measure the mass flow rate of a multi-phase fluid.

Safety drain system for fluid reservoir

NASA Technical Reports Server (NTRS)

England, John Dwight (Inventor); Kelley, Anthony R. (Inventor); Cronise, Raymond J. (Inventor)

2012-01-01

A safety drain system includes a plurality of drain sections, each of which defines distinct fluid flow paths. At least a portion of the fluid flow paths commence at a side of the drain section that is in fluid communication with a reservoir's fluid. Each fluid flow path at the side communicating with the reservoir's fluid defines an opening having a smallest dimension not to exceed approximately one centimeter. The drain sections are distributed over at least one surface of the reservoir. A manifold is coupled to the drain sections.

The effect of dentinal fluid flow during loading in various directions--simulation of fluid-structure interaction.

PubMed

Su, Kuo-Chih; Chang, Chih-Han; Chuang, Shu-Fen; Ng, Eddie Yin-Kwee

2013-06-01

This study uses a fluid-structure interaction (FSI) simulation to evaluate the fluid flow in a dental intrapulpal chamber induced by the deformation of the tooth structure during loading in various directions. The FSI is used for the biomechanics simulation of dental intrapulpal responses with the force loading gradually increasing from 0 to 100N at 0°, 30°, 45°, 60°, and 90° on the tooth surface in 1s, respectively. The effect of stress or deformation on tooth and fluid flow changes in the pulp chamber are evaluated. A horizontal loading force on a tooth may induce tooth structure deformation, which increases fluid flow velocity in the coronal pulp. Thus, horizontal loading on a tooth may easily induce tooth pain. This study suggests that experiments to investigate the relationship between loading in various directions and dental pain should avoid measuring the bulk pulpal fluid flow from radicular pulp, but rather should measure the dentinal fluid flow in the dentinal tubules or coronal pulp. The FSI analysis used here could provide a powerful tool for investigating problems with coupled solid and fluid structures in dental biomechanics. Copyright © 2012 Elsevier Ltd. All rights reserved.

Flow of two immiscible fluids in a periodically constricted tube: Transitions to stratified, segmented, churn, spray or segregated flow

NASA Astrophysics Data System (ADS)

Tsamopoulos, John; Fraggedakis, Dimitris; Dimakopoulos, Yiannis

2015-11-01

We study the flow of two immiscible, Newtonian fluids in a periodically constricted tube driven by a constant pressure gradient. Our Volume-of-Fluid algorithm is used to solve the governing equations. First the code is validated by comparing its predictions to previously reported results for stratified and pulsing flow. Then it is used to capture accurately all the significant topological changes that take place. Initially, the fluids have a core-annular arrangement, which is found to either remain the same or change to a different arrangement depending on the fluid properties, the pressure driving the flow or the flow geometry. The flow-patterns that appear are the core-annular, segmented, churn, spray and segregated flow. The predicted scalings near pinching of the core fluid concur with similarity predictions and earlier numerical results (Cohen et al. (1999)). Flow-pattern maps are constructed in terms of the Reynolds and Weber numbers. Our results provide deeper insights in the mechanism of the pattern transitions and are in agreement with previous studies on core-annular flow (Kouris & Tsamopoulos (2001 & 2002)), segmented flow (Lac & Sherwood (2009)) and churn flow (Bai et al. (1992)). GSRT of Greece through the program ``Excellence'' (Grant No. 1918, entitled ``FilCoMicrA'').

Monodisperse granular flows in viscous dispersions in a centrifugal acceleration field

NASA Astrophysics Data System (ADS)

Cabrera, Miguel Angel; Wu, Wei

2016-04-01

Granular flows are encountered in geophysical flows and innumerable industrial applications with particulate materials. When mixed with a fluid, a complex network of interactions between the particle- and fluid-phase develops, resulting in a compound material with a yet unclear physical behaviour. In the study of granular suspensions mixed with a viscous dispersion, the scaling of the stress-strain characteristics of the fluid phase needs to account for the level of inertia developed in experiments. However, the required model dimensions and amount of material becomes a main limitation for their study. In recent years, centrifuge modelling has been presented as an alternative for the study of particle-fluid flows in a reduced scaled model in an augmented acceleration field. By formulating simple scaling principles proportional to the equivalent acceleration Ng in the model, the resultant flows share many similarities with field events. In this work we study the scaling principles of the fluid phase and its effects on the flow of granular suspensions. We focus on the dense flow of a monodisperse granular suspension mixed with a viscous fluid phase, flowing down an inclined plane and being driven by a centrifugal acceleration field. The scaled model allows the continuous monitoring of the flow heights, velocity fields, basal pressure and mass flow rates at different Ng levels. The experiments successfully identify the effects of scaling the plastic viscosity of the fluid phase, its relation with the deposition of particles over the inclined plane, and allows formulating a discussion on the suitability of simulating particle-fluid flows in a centrifugal acceleration field.

Simultaneous Multiple-Location Separation Control

NASA Technical Reports Server (NTRS)

Greenblatt, David (Inventor)

2009-01-01

A method of controlling a shear layer for a fluid dynamic body introduces first periodic disturbances into the fluid medium at a first flow separation location. Simultaneously, second periodic disturbances are introduced into the fluid medium at a second flow separation location. A phase difference between the first and second periodic disturbances is adjusted to control flow separation of the shear layer as the fluid medium moves over the fluid dynamic body.

Bernoulli's Principle Applied to Brain Fluids: Intracranial Pressure Does Not Drive Cerebral Perfusion or CSF Flow.

PubMed

Schmidt, Eric; Ros, Maxime; Moyse, Emmanuel; Lorthois, Sylvie; Swider, Pascal

2016-01-01

In line with the first law of thermodynamics, Bernoulli's principle states that the total energy in a fluid is the same at all points. We applied Bernoulli's principle to understand the relationship between intracranial pressure (ICP) and intracranial fluids. We analyzed simple fluid physics along a tube to describe the interplay between pressure and velocity. Bernoulli's equation demonstrates that a fluid does not flow along a gradient of pressure or velocity; a fluid flows along a gradient of energy from a high-energy region to a low-energy region. A fluid can even flow against a pressure gradient or a velocity gradient. Pressure and velocity represent part of the total energy. Cerebral blood perfusion is not driven by pressure but by energy: the blood flows from high-energy to lower-energy regions. Hydrocephalus is related to increased cerebrospinal fluid (CSF) resistance (i.e., energy transfer) at various points. Identification of the energy transfer within the CSF circuit is important in understanding and treating CSF-related disorders. Bernoulli's principle is not an abstract concept far from clinical practice. We should be aware that pressure is easy to measure, but it does not induce resumption of fluid flow. Even at the bedside, energy is the key to understanding ICP and fluid dynamics.

Multiphase flow in geometrically simple fracture intersections

USGS Publications Warehouse

Basagaoglu, H.; Meakin, P.; Green, C.T.; Mathew, M.; ,

2006-01-01

A two-dimensional lattice Boltzmann (LB) model with fluid-fluid and solid-fluid interaction potentials was used to study gravity-driven flow in geometrically simple fracture intersections. Simulated scenarios included fluid dripping from a fracture aperture, two-phase flow through intersecting fractures and thin-film flow on smooth and undulating solid surfaces. Qualitative comparisons with recently published experimental findings indicate that for these scenarios the LB model captured the underlying physics reasonably well.

Solids mass flow determination

DOEpatents

Macko, Joseph E.

1981-01-01

Method and apparatus for determining the mass flow rate of solids mixed with a transport fluid to form a flowing mixture. A temperature differential is established between the solids and fluid. The temperature of the transport fluid prior to mixing, the temperature of the solids prior to mixing, and the equilibrium temperature of the mixture are monitored and correlated in a heat balance with the heat capacities of the solids and fluid to determine the solids mass flow rate.

Method and apparatus for a self-cleaning filter

DOEpatents

Diebold, James P.; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael

2013-09-10

A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.

Method and apparatus for a self-cleaning filter

DOEpatents

Diebold, James P.; Lilley, Arthur; Browne, III, Kingsbury; Walt, Robb Ray; Duncan, Dustin; Walker, Michael; Steele, John; Fields, Michael

2010-11-16

A method and apparatus for removing fine particulate matter from a fluid stream without interrupting the overall process or flow. The flowing fluid inflates and expands the flexible filter, and particulate is deposited on the filter media while clean fluid is permitted to pass through the filter. This filter is cleaned when the fluid flow is stopped, the filter collapses, and a force is applied to distort the flexible filter media to dislodge the built-up filter cake. The dislodged filter cake falls to a location that allows undisrupted flow of the fluid after flow is restored. The shed particulate is removed to a bin for periodic collection. A plurality of filter cells can operate independently or in concert, in parallel, or in series to permit cleaning the filters without shutting off the overall fluid flow. The self-cleaning filter is low cost, has low power consumption, and exhibits low differential pressures.

Generating Inviscid and Viscous Fluid Flow Simulations over a Surface Using a Quasi-simultaneous Technique

NASA Technical Reports Server (NTRS)

Sturdza, Peter (Inventor); Martins-Rivas, Herve (Inventor); Suzuki, Yoshifumi (Inventor)

2014-01-01

A fluid-flow simulation over a computer-generated surface is generated using a quasi-simultaneous technique. The simulation includes a fluid-flow mesh of inviscid and boundary-layer fluid cells. An initial fluid property for an inviscid fluid cell is determined using an inviscid fluid simulation that does not simulate fluid viscous effects. An initial boundary-layer fluid property a boundary-layer fluid cell is determined using the initial fluid property and a viscous fluid simulation that simulates fluid viscous effects. An updated boundary-layer fluid property is determined for the boundary-layer fluid cell using the initial fluid property, initial boundary-layer fluid property, and an interaction law. The interaction law approximates the inviscid fluid simulation using a matrix of aerodynamic influence coefficients computed using a two-dimensional surface panel technique and a fluid-property vector. An updated fluid property is determined for the inviscid fluid cell using the updated boundary-layer fluid property.

The 'upstream wake' of swimming and flying animals and its correlation with propulsive efficiency.

PubMed

Peng, Jifeng; Dabiri, John O

2008-08-01

The interaction between swimming and flying animals and their fluid environments generates downstream wake structures such as vortices. In most studies, the upstream flow in front of the animal is neglected. In this study, we demonstrate the existence of upstream fluid structures even though the upstream flow is quiescent or possesses a uniform incoming velocity. Using a computational model, the flow generated by a swimmer (an oscillating flexible plate) is simulated and a new fluid mechanical analysis is applied to the flow to identify the upstream fluid structures. These upstream structures show the exact portion of fluid that is going to interact with the swimmer. A mass flow rate is then defined based on the upstream structures, and a metric for propulsive efficiency is established using the mass flow rate and the kinematics of the swimmer. We propose that the unsteady mass flow rate defined by the upstream fluid structures can be used as a metric to measure and objectively compare the efficiency of locomotion in water and air.

Persistent Homology to describe Solid and Fluid Structures during Multiphase Flow

NASA Astrophysics Data System (ADS)

Herring, A. L.; Robins, V.; Liu, Z.; Armstrong, R. T.; Sheppard, A.

2017-12-01

The question of how to accurately and effectively characterize essential fluid and solid distributions and structures is a long-standing topic within the field of porous media and fluid transport. For multiphase flow applications, considerable research effort has been made to describe fluid distributions under a range of conditions; including quantification of saturation levels, fluid-fluid pressure differences and interfacial areas, and fluid connectivity. Recent research has effectively used topological metrics to describe pore space and fluid connectivity, with researchers demonstrating links between pore-scale nonwetting phase topology to fluid mobilization and displacement mechanisms, relative permeability, fluid flow regimes, and thermodynamic models of multiphase flow. While topology is clearly a powerful tool to describe fluid distribution, topological metrics by definition provide information only on the connectivity of a phase, not its geometry (shape or size). Physical flow characteristics, e.g. the permeability of a fluid phase within a porous medium, are dependent on the connectivity of the pore space or fluid phase as well as the size of connections. Persistent homology is a technique which provides a direct link between topology and geometry via measurement of topological features and their persistence from the signed Euclidean distance transform of a segmented digital image (Figure 1). We apply persistent homology analysis to measure the occurrence and size of pore-scale topological features in a variety of sandstones, for both the dry state and the nonwetting phase fluid during two-phase fluid flow (drainage and imbibition) experiments, visualized with 3D X-ray microtomography. The results provide key insights into the dominant topological features and length scales of a media which control relevant field-scale engineering properties such as fluid trapping, absolute permeability, and relative permeability.

Fluid-cooled heat sink with improved fin areas and efficiencies for use in cooling various devices

DOEpatents

Bharathan, Desikan; Bennion, Kevin; Kelly, Kenneth; Narumanchi, Sreekant

2015-04-21

The disclosure provides a fluid-cooled heat sink having a heat transfer base and a plurality of heat transfer fins in thermal communication with the heat transfer base, where the heat transfer base and the heat transfer fins form a central fluid channel through which a forced or free cooling fluid may flow. The heat transfer pins are arranged around the central fluid channel with a flow space provided between adjacent pins, allowing for some portion of the central fluid channel flow to divert through the flow space. The arrangement reduces the pressure drop of the flow through the fins, optimizes average heat transfer coefficients, reduces contact and fin-pin resistances, and reduces the physical footprint of the heat sink in an operating environment.

Thin-channel electrospray emitter

DOEpatents

Van Berkel, Gary J.

2004-08-31

An electrospray device includes a high voltage electrode chamber. The high voltage electrode chamber includes an inlet for receiving a fluid to be ionized and for directing the fluid into the chamber and at least one electrode having an exposed surface within the chamber. A flow channel directs fluid over a surface of the electrode and out of the chamber. The length of the flow channel over the electrode is greater than the height of the flow channel over the electrode, thereby producing enhanced mass transport to the working electrode resulting in improved electrolysis efficiency. An outlet is provided for transmitting the fluid out from the electrode chamber. A method of creating charged droplets includes flowing a fluid over an electrode where the length over the electrode is greater than the height of the fluid flowing over the electrode.

Estimating the hemodynamic impact of interventional treatments of aneurysms: numerical simulation with experimental validation: technical case report.

PubMed

Acevedo-Bolton, Gabriel; Jou, Liang-Der; Dispensa, Bradley P; Lawton, Michael T; Higashida, Randall T; Martin, Alastair J; Young, William L; Saloner, David

2006-08-01

The goal of this study was to use phase-contrast magnetic resonance imaging and computational fluid dynamics to estimate the hemodynamic outcome that might result from different interventional options for treating a patient with a giant fusiform aneurysm. We followed a group of patients with giant intracranial aneurysms who have no clear surgical options. One patient demonstrated dramatic aneurysm growth and was selected for further analysis. The aneurysm geometry and input and output flow conditions were measured with contrast-enhanced magnetic resonance angiography and phase-contrast magnetic resonance imaging. The data was imported into a computational fluid dynamics program and the velocity fields and wall shear stress distributions were calculated for the presenting physiological condition and for cases in which the opposing vertebral arteries were either occluded or opened. These models were validated with in vitro flow experiments using a geometrically exact silicone flow phantom. Simulation indicated that altering the flow ratio in the two vertebrals would deflect the main blood jet into the aneurysm belly, and that this would likely reduce the extent of the region of low wall shear stress in the growth zone. Computational fluid dynamics flow simulations in a complex patient-specific aneurysm geometry were validated by in vivo and in vitro phase-contrast magnetic resonance imaging, and were shown to be useful in modeling the likely hemodynamic impact of interventional treatment of the aneurysm.

Non-Darcian flow of shear-thinning fluids through packed beads: Experiments and predictions using Forchheimer's law and Ergun's equation

NASA Astrophysics Data System (ADS)

Rodríguez de Castro, Antonio; Radilla, Giovanni

2017-02-01

The flow of shear-thinning fluids through unconsolidated porous media is present in a number of important industrial applications such as soil depollution, Enhanced Oil Recovery or filtration of polymeric liquids. Therefore, predicting the pressure drop-flow rate relationship in model porous media has been the scope of major research efforts during the last decades. Although the flow of Newtonian fluids through packs of spherical particles is well understood in most cases, much less is known regarding the flow of shear-thinning fluids as high molecular weight polymer aqueous solutions. In particular, the experimental data for the non-Darcian flow of shear-thinning fluids are scarce and so are the current approaches for their prediction. Given the relevance of non-Darcian shear-thinning flow, the scope of this work is to perform an experimental study to systematically evaluate the effects of fluid shear rheology on the flow rate-pressure drop relationships for the non-Darcian flow through different packs of glass spheres. To do so, xanthan gum aqueous solutions with different polymer concentrations are injected through four packs of glass spheres with uniform size under Darcian and inertial flow regimes. A total of 1560 experimental data are then compared with predictions coming from different methods based on the extension of widely used Ergun's equation and Forchheimer's law to the case of shear thinning fluids, determining the accuracy of these predictions. The use of a proper definition for Reynolds number and a realistic model to represent the rheology of the injected fluids results in the porous media are shown to be key aspects to successfully predict pressure drop-flow rate relationships for the inertial shear-thinning flow in packed beads.

Cryogenic and Simulated Fuel Jet Breakup in Argon, Helium and Nitrogen Gas Flows

NASA Technical Reports Server (NTRS)

Ingebo, Robert D.

1995-01-01

Two-phase flow atomization of liquid nitrogen jets was experimentally investigated. They were co-axially injected into high-velocity gas flows of helium, nitrogen and argon, respectively, and atomized internally inside a two-fluid fuel nozzle. Cryogenic sprays with relatively high specific surface areas were produced, i.e., ratios of surface area to volume were fairly high. This was indicated by values of reciprocal Sauter mean diameters, RSMD's, as measured with a scattered- light scanning instrument developed at NASA Lewis Research Center. Correlating expressions were derived for the three atomizing gases over a gas temperature range of 111 to 422 K. Also, the correlation was extended to include waterjet breakup data that had been previously obtained in simulating fuel jet breakup in sonic velocity gas flow. The final correlating expression included a new dimensionless molecular-scale acceleration group. It was needed to correlate RSMD data, for LN2 and H2O sprays, with the fluid properties of the liquid jets and atomizing gases used in this investigation.

Device and method for measuring multi-phase fluid flow and density of fluid in a conduit having a gradual bend

DOEpatents

Ortiz, M.G.; Boucher, T.J.

1998-10-27

A system is described for measuring fluid flow in a conduit having a gradual bend or arc, and a straight section. The system includes pressure transducers, one or more disposed in the conduit on the outside of the arc, and one disposed in the conduit in a straight section thereof. The pressure transducers measure the pressure of fluid in the conduit at the locations of the pressure transducers and this information is used by a computational device to calculate fluid flow rate in the conduit. For multi-phase fluid, the density of the fluid is measured by another pair of pressure transducers, one of which is located in the conduit elevationally above the other. The computation device then uses the density measurement along with the fluid pressure measurements, to calculate fluid flow. 1 fig.

Geothermal state and fluid flow within ODP Hole 843B: results from wireline logging

NASA Astrophysics Data System (ADS)

Wiggins, Sean M.; Hildebrand, John A.; Gieskes, Joris M.

2002-02-01

Borehole fluid temperatures were measured with a wireline re-entry system in Ocean Drilling Program Hole 843B, the site of the Ocean Seismic Network Pilot Experiment. These temperature data, recorded more than 7 years after drilling, are compared to temperature data logged during Leg 136, approximately 1 day after drilling had ceased. Qualitative interpretations of the temperature data suggest that fluid flowed slowly downward in the borehole immediately following drilling, and flowed slowly upward 7 years after drilling. Quantitative analysis suggests that the upward fluid flow rate in the borehole is approximately 1 m/h. Slow fluid flow interpreted from temperature data only, however, requires estimates of other unmeasured physical properties. If fluid flows upward in Hole 843B, it may have led to undesirable noise for the borehole seismometer emplaced in this hole as part of the Ocean Seismic Network Pilot Experiment. Estimates of conductive heat flow from ODP Hole 843B are 51 mW/m 2 for the sediment and the basalt. These values are lower than the most recent Hawaiian Arch seafloor heat flow studies.

Hydrodynamic schooling of flapping swimmers

NASA Astrophysics Data System (ADS)

Becker, Alexander D.; Masoud, Hassan; Newbolt, Joel W.; Shelley, Michael; Ristroph, Leif

2015-10-01

Fish schools and bird flocks are fascinating examples of collective behaviours in which many individuals generate and interact with complex flows. Motivated by animal groups on the move, here we explore how the locomotion of many bodies emerges from their flow-mediated interactions. Through experiments and simulations of arrays of flapping wings that propel within a collective wake, we discover distinct modes characterized by the group swimming speed and the spatial phase shift between trajectories of neighbouring wings. For identical flapping motions, slow and fast modes coexist and correspond to constructive and destructive wing-wake interactions. Simulations show that swimming in a group can enhance speed and save power, and we capture the key phenomena in a mathematical model based on memory or the storage and recollection of information in the flow field. These results also show that fluid dynamic interactions alone are sufficient to generate coherent collective locomotion, and thus might suggest new ways to characterize the role of flows in animal groups.

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

Becker, Alexander D.; Masoud, Hassan; Newbolt, Joel W.

Fish schools and bird flocks are fascinating examples of collective behaviours in which many individuals generate and interact with complex flows. Motivated by animal groups on the move, here we explore how the locomotion of many bodies emerges from their flow-mediated interactions. Through experiments and simulations of arrays of flapping wings that propel within a collective wake, we discover distinct modes characterized by the group swimming speed and the spatial phase shift between trajectories of neighbouring wings. For identical flapping motions, slow and fast modes coexist and correspond to constructive and destructive wing–wake interactions. Simulations show that swimming in amore » group can enhance speed and save power, and we capture the key phenomena in a mathematical model based on memory or the storage and recollection of information in the flow field. Lastly, these results also show that fluid dynamic interactions alone are sufficient to generate coherent collective locomotion, and thus might suggest new ways to characterize the role of flows in animal groups.« less

Hydrodynamic schooling of flapping swimmers

DOE PAGES

Becker, Alexander D.; Masoud, Hassan; Newbolt, Joel W.; ...

2015-10-06

Fish schools and bird flocks are fascinating examples of collective behaviours in which many individuals generate and interact with complex flows. Motivated by animal groups on the move, here we explore how the locomotion of many bodies emerges from their flow-mediated interactions. Through experiments and simulations of arrays of flapping wings that propel within a collective wake, we discover distinct modes characterized by the group swimming speed and the spatial phase shift between trajectories of neighbouring wings. For identical flapping motions, slow and fast modes coexist and correspond to constructive and destructive wing–wake interactions. Simulations show that swimming in amore » group can enhance speed and save power, and we capture the key phenomena in a mathematical model based on memory or the storage and recollection of information in the flow field. Lastly, these results also show that fluid dynamic interactions alone are sufficient to generate coherent collective locomotion, and thus might suggest new ways to characterize the role of flows in animal groups.« less

Ascent Aerodynamic Pressure Distributions on WB001

NASA Technical Reports Server (NTRS)

Vu, B.; Ruf, J.; Canabal, F.; Brunty, J.

1996-01-01

To support the reusable launch vehicle concept study, the aerodynamic data and surface pressure for WB001 were predicted using three computational fluid dynamic (CFD) codes at several flow conditions between code to code and code to aerodynamic database as well as available experimental data. A set of particular solutions have been selected and recommended for use in preliminary conceptual designs. These computational fluid dynamic (CFD) results have also been provided to the structure group for wing loading analysis.

ACE-1 experiment

NASA Image and Video Library

2013-06-24

ISS036-E-019760 (24 June 2013) --- In the International Space Station’s Destiny laboratory, NASA astronaut Karen Nyberg, Expedition 36 flight engineer, conducts a session with the Advanced Colloids Experiment (ACE)-1 sample preparation at the Light Microscopy Module (LMM) in the Fluids Integrated Rack / Fluids Combustion Facility (FIR/FCF). ACE-1 is a series of microscopic imaging investigations that uses the microgravity environment to examine flow characteristics and the evolution and ordering effects within a group of colloidal materials.

Fluidic Oscillator Array for Synchronized Oscillating Jet Generation

NASA Technical Reports Server (NTRS)

Koklu, Mehti (Inventor)

2017-01-01

A fluidic oscillator array includes a plurality of fluidic-oscillator main flow channels. Each main flow channel has an inlet and an outlet. Each main flow channel has first and second control ports disposed at opposing sides thereof, and has a first and a second feedback ports disposed at opposing sides thereof. The feedback ports are located downstream of the control ports with respect to a direction of a fluid flow through the main flow channel. The system also includes a first fluid accumulator in fluid communication with each first control port and each first feedback port, and a second fluid accumulator in fluid communication with each second control port and each second feedback port.

Fluidic Oscillator Array for Synchronized Oscillating Jet Generation

NASA Technical Reports Server (NTRS)

Koklu, Mehti (Inventor)

2016-01-01

A fluidic oscillator array includes a plurality of fluidic-oscillator main flow channels. Each main flow channel has an inlet and an outlet. Each main flow channel has first and second control ports disposed at opposing sides thereof, and has a first and a second feedback ports disposed at opposing sides thereof. The feedback ports are located downstream of the control ports with respect to a direction of a fluid flow through the main flow channel. The system also includes a first fluid accumulator in fluid communication with each first control port and each first feedback port, and a second fluid accumulator in fluid communication with each second control port and each second feedback port.

Magnetic heat pump flow director

NASA Technical Reports Server (NTRS)

Howard, Frank S. (Inventor)

1995-01-01

A fluid flow director is disclosed. The director comprises a handle body and combed-teeth extending from one side of the body. The body can be formed of a clear plastic such as acrylic. The director can be used with heat exchangers such as a magnetic heat pump and can minimize the undesired mixing of fluid flows. The types of heat exchangers can encompass both heat pumps and refrigerators. The director can adjust the fluid flow of liquid or gas along desired flow directions. A method of applying the flow director within a magnetic heat pump application is also disclosed where the comb-teeth portions of the director are inserted into the fluid flow paths of the heat pump.

Exhaust bypass flow control for exhaust heat recovery

DOEpatents

Reynolds, Michael G.

2015-09-22

An exhaust system for an engine comprises an exhaust heat recovery apparatus configured to receive exhaust gas from the engine and comprises a first flow passage in fluid communication with the exhaust gas and a second flow passage in fluid communication with the exhaust gas. A heat exchanger/energy recovery unit is disposed in the second flow passage and has a working fluid circulating therethrough for exchange of heat from the exhaust gas to the working fluid. A control valve is disposed downstream of the first and the second flow passages in a low temperature region of the exhaust heat recovery apparatus to direct exhaust gas through the first flow passage or the second flow passage.

Heat Flow Budget of the Gulf of California Rift: Preliminary Results of a High Resolution Survey Across the Wagner Basin

NASA Astrophysics Data System (ADS)

Negrete-Aranda, R.; Neumann, F.; Harris, R. N.; Contreras, J.; Gonzalez-Fernandez, A.; Sclater, J. G.

2016-12-01

The thermal regime exerts a primary control on rift dynamics and mode of extension for continental lithosphere. We present three heat-flow profiles across the southern terminus of the Cerro Prieto fault, in the northern Gulf of California. The longest profile is 42 km and has a measurement spacing of 1 km that spans the hanging-wall block (Wagner basin) and the footwall block of that fault. Measurements were taken with a 6.5 m long Fielax, violin-bow probe. Most measurements are of good quality, i.e., the probe fully penetrated sediments and measurements were stable enough to perform reliable inversion for heat flow and thermal properties. However, it was necessary to perform numerous corrections due to environmental phenomena related the copious sedimentation in the area, and seasonal changes in water temperature. Our measurements indicate the total throughput across the central rift and its east shoulder is 15 KW/m per meter of rift length. More important, heat flow values cluster in three distinct spatial groups: (i) heat flow in the well sedimented depocenter of the Wagner basin is approximately 200 mW/m2; (ii) the footwall block heat-flow is approximately 400 mW/m2; and (iii) heat flow across the fault zone is very high, up to 5,000 mW/m2. Our interpretation is that the former value represents the background conductive heat flow in the rift whereas heat flow across the fault represents advective heat transport by hydrothermal fluids. The high heat flow in the footwall block of the Cerro Prieto fault might be result of both conductive and advective heat transfer by fluid seepage from the basin. These data provide evidence that fluids from deep magma bodies transported along faults assist rifting in the northern Gulf of California. We are exploring how fluids may play a role in weakening the lithosphere and help localizing/delocalizing strain along major transforms and numerous normal faults observed in the area.

RANS Simulations using OpenFOAM Software

DTIC Science & Technology

2016-01-01

Averaged Navier- Stokes (RANS) simulations is described and illustrated by applying the simpleFoam solver to two case studies; two dimensional flow...to run in parallel over large processor arrays. The purpose of this report is to illustrate and test the use of the steady-state Reynolds Averaged ...Group in the Maritime Platforms Division he has been simulating fluid flow around ships and submarines using finite element codes, Lagrangian vortex

Rindler fluid with weak momentum relaxation

NASA Astrophysics Data System (ADS)

Khimphun, Sunly; Lee, Bum-Hoon; Park, Chanyong; Zhang, Yun-Long

2018-01-01

We realize the weak momentum relaxation in Rindler fluid, which lives on the time-like cutoff surface in an accelerating frame of flat spacetime. The translational invariance is broken by massless scalar fields with weak strength. Both of the Ward identity and the momentum relaxation rate of Rindler fluid are obtained, with higher order correction in terms of the strength of momentum relaxation. The Rindler fluid with momentum relaxation could also be approached through the near horizon limit of cutoff AdS fluid with momentum relaxation, which lives on a finite time-like cutoff surface in Anti-de Sitter(AdS) spacetime, and further could be connected with the holographic conformal fluid living on AdS boundary at infinity. Thus, in the holographic Wilson renormalization group flow of the fluid/gravity correspondence with momentum relaxation, the Rindler fluid can be considered as the Infrared Radiation(IR) fixed point, and the holographic conformal fluid plays the role of the ultraviolet(UV) fixed point.

Interwoven channels for internal cooling of airfoil

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

Weaver, Adam M.

An apparatus and method for passing fluid flow through at least a portion of a blade of turbomachinery, such as a gas turbine or the like. The fluid flow is directed through a plurality of flow channels which are interwoven with each other. Each flow channel is non-intersecting with any other flow channel and thus does not contact fluid flowing within any other flow channel. The method and apparatus can be used to reduce heat transfer and thus reduce thermal stresses, particularly in the blade.

Device and method for measuring fluid flow in a conduit having a gradual bend

DOEpatents

Ortiz, M.G.; Boucher, T.J.

1998-11-10

A system is described for measuring fluid flow in a conduit having a gradual bend or arc, and a straight section. The system includes pressure transducers, one or more disposed in the conduit on the outside of the arc, and one disposed in the conduit in a straight section thereof. The pressure transducers measure the pressure of fluid in the conduit at the locations of the pressure transducers and this information is used by a computational device to calculate fluid flow rate in the conduit. For multi-phase fluid, the density of the fluid is measured by another pair of pressure transducers, one of which is located in the conduit elevationally above the other. The computation device then uses the density measurement along with the fluid pressure measurements, to calculate fluid flow. 1 fig.

Device and method for measuring multi-phase fluid flow in a conduit having an abrupt gradual bend

DOEpatents

Ortiz, M.G.

1998-02-10

A system is described for measuring fluid flow in a conduit having an abrupt bend. The system includes pressure transducers, one disposed in the conduit at the inside of the bend and one or more disposed in the conduit at the outside of the bend but spaced a distance therefrom. The pressure transducers measure the pressure of fluid in the conduit at the locations of the pressure transducers and this information is used by a computational device to calculate fluid flow rate in the conduit. For multi-phase fluid, the density of the fluid is measured by another pair of pressure transducers, one of which is located in the conduit elevationally above the other. The computation device then uses the density measurement along with the fluid pressure measurements, to calculate fluid flow. 1 fig.

Device and method for measuring fluid flow in a conduit having a gradual bend

DOEpatents

Ortiz, Marcos German; Boucher, Timothy J

1998-01-01

A system for measuring fluid flow in a conduit having a gradual bend or arc, and a straight section. The system includes pressure transducers, one or more disposed in the conduit on the outside of the arc, and one disposed in the conduit in a straight section thereof. The pressure transducers measure the pressure of fluid in the conduit at the locations of the pressure transducers and this information is used by a computational device to calculate fluid flow rate in the conduit. For multi-phase fluid, the density of the fluid is measured by another pair of pressure transducers, one of which is located in the conduit elevationally above the other. The computation device then uses the density measurement along with the fluid pressure measurements, to calculate fluid flow.

Device and method for measuring multi-phase fluid flow in a conduit having an abrupt gradual bend

DOEpatents

Ortiz, Marcos German

1998-01-01

A system for measuring fluid flow in a conduit having an abrupt bend. The system includes pressure transducers, one disposed in the conduit at the inside of the bend and one or more disposed in the conduit at the outside of the bend but spaced a distance therefrom. The pressure transducers measure the pressure of fluid in the conduit at the locations of the pressure transducers and this information is used by a computational device to calculate fluid flow rate in the conduit. For multi-phase fluid, the density of the fluid is measured by another pair of pressure transducers, one of which is located in the conduit elevationally above the other. The computation device then uses the density measurement along with the fluid pressure measurements, to calculate fluid flow.

Rankine cycle load limiting through use of a recuperator bypass

DOEpatents

Ernst, Timothy C.

2011-08-16

A system for converting heat from an engine into work includes a boiler coupled to a heat source for transferring heat to a working fluid, a turbine that transforms the heat into work, a condenser that transforms the working fluid into liquid, a recuperator with one flow path that routes working fluid from the turbine to the condenser, and another flow path that routes liquid working fluid from the condenser to the boiler, the recuperator being configured to transfer heat to the liquid working fluid, and a bypass valve in parallel with the second flow path. The bypass valve is movable between a closed position, permitting flow through the second flow path and an opened position, under high engine load conditions, bypassing the second flow path.

Personal cooling air filtering device

DOEpatents

Klett, James [Knoxville, TN; Conway, Bret [Denver, NC

2002-08-13

A temperature modification system for modifying the temperature of fluids includes at least one thermally conductive carbon foam element, the carbon foam element having at least one flow channel for the passage of fluids. At least one temperature modification device is provided, the temperature modification device thermally connected to the carbon foam element and adapted to modify the temperature of the carbon foam to modify the temperature of fluids flowing through the flow channels. Thermoelectric and/or thermoionic elements can preferably be used as the temperature modification device. A method for the reversible temperature modification of fluids includes the steps of providing a temperature modification system including at least one thermally conductive carbon foam element having flow channels and at least one temperature modification device, and flowing a fluid through the flow channels.

Cine phase-contrast MRI evaluation of normal aqueductal cerebrospinal fluid flow according to sex and age.

PubMed

Unal, Ozkan; Kartum, Alp; Avcu, Serhat; Etlik, Omer; Arslan, Halil; Bora, Aydin

2009-12-01

The aim of this study was cerebrospinal flow quantification in the cerebral aqueduct using cine phase-contrast magnetic resonance imaging (MRI) technique in both sexes and five different age groups to provide normative data. Sixty subjects with no cerebral pathology were included in this study. Subjects were divided into five age groups: < or =14 years, 15-24 years, 25-34 years, 35-44 years, and > or =45 years. Phase, rephase, and magnitude images were acquired by 1.5 T MR unit at the level of cerebral aqueduct with spoiled gradient echo through-plane, which is a cine phase-contrast sequence. At this level, peak flow velocity (cm/s), average flow rate (cm/ s), average flow (L/min), volumes in cranial and caudal directions (mL), and net volumes (mL) were studied. There was a statistically significant difference in peak flow between the age group of < or =14 years and the older age groups. There were no statistically significant differences in average velocity, cranial and caudal volume, net volume, and average flow parameters among different age groups. Statistically significant differences were not detected in flow parameters between sexes. When using cine-phase contrast MRI in the cerebral aqueduct, only the peak velocity showed a statistically significant difference between age groups; it was higher in subjects aged < or =14 years than those in older age groups. When performing age-dependent clinical studies including adolescents, this should be taken into consideration.

Fluid mechanics in fluids at rest.

PubMed

Brenner, Howard

2012-07-01

Using readily available experimental thermophoretic particle-velocity data it is shown, contrary to current teachings, that for the case of compressible flows independent dye- and particle-tracer velocity measurements of the local fluid velocity at a point in a flowing fluid do not generally result in the same fluid velocity measure. Rather, tracer-velocity equality holds only for incompressible flows. For compressible fluids, each type of tracer is shown to monitor a fundamentally different fluid velocity, with (i) a dye (or any other such molecular-tagging scheme) measuring the fluid's mass velocity v appearing in the continuity equation and (ii) a small, physicochemically and thermally inert, macroscopic (i.e., non-Brownian), solid particle measuring the fluid's volume velocity v(v). The term "compressibility" as used here includes not only pressure effects on density, but also temperature effects thereon. (For example, owing to a liquid's generally nonzero isobaric coefficient of thermal expansion, nonisothermal liquid flows are to be regarded as compressible despite the general perception of liquids as being incompressible.) Recognition of the fact that two independent fluid velocities, mass- and volume-based, are formally required to model continuum fluid behavior impacts on the foundations of contemporary (monovelocity) fluid mechanics. Included therein are the Navier-Stokes-Fourier equations, which are now seen to apply only to incompressible fluids (a fact well-known, empirically, to experimental gas kineticists). The findings of a difference in tracer velocities heralds the introduction into fluid mechanics of a general bipartite theory of fluid mechanics, bivelocity hydrodynamics [Brenner, Int. J. Eng. Sci. 54, 67 (2012)], differing from conventional hydrodynamics in situations entailing compressible flows and reducing to conventional hydrodynamics when the flow is incompressible, while being applicable to both liquids and gases.

Concentric catalytic combustor

DOEpatents

Bruck, Gerald J [Oviedo, FL; Laster, Walter R [Oviedo, FL

2009-03-24

A catalytic combustor (28) includes a tubular pressure boundary element (90) having a longitudinal flow axis (e.g., 56) separating a first portion (94) of a first fluid flow (e.g., 24) from a second portion (95) of the first fluid flow. The pressure boundary element includes a wall (96) having a plurality of separate longitudinally oriented flow paths (98) annularly disposed within the wall and conducting respective portions (100, 101) of a second fluid flow (e.g., 26) therethrough. A catalytic material (32) is disposed on a surface (e.g., 102, 103) of the pressure boundary element exposed to at least one of the first and second portions of the first fluid flow.

Microelectromechanical flow control apparatus

DOEpatents

Okandan, Murat [NE Albuquerque, NM

2009-06-02

A microelectromechanical (MEM) flow control apparatus is disclosed which includes a fluid channel formed on a substrate from a first layer of a nonconducting material (e.g. silicon nitride). A first electrode is provided on the first layer of the nonconducting material outside the flow channel; and a second electrode is located on a second layer of the nonconducting material above the first layer. A voltage applied between the first and second electrodes deforms the fluid channel to increase its cross-sectional size and thereby increase a flow of a fluid through the channel. In certain embodiments of the present invention, the fluid flow can be decreased or stopped by applying a voltage between the first electrode and the substrate. A peristaltic pumping of the fluid through the channel is also possible when the voltage is applied in turn between a plurality of first electrodes and the substrate. A MEM flow control assembly can also be formed by providing one or more MEM flow control devices on a common substrate together with a submicron filter. The MEM flow control assembly can optionally include a plurality of pressure sensors for monitoring fluid pressure and determining flow rates through the assembly.

Respiratory fluid mechanics

PubMed Central

Grotberg, James B.

2011-01-01

This article covers several aspects of respiratory fluid mechanics that have been actively investigated by our group over the years. For the most part, the topics involve two-phase flows in the respiratory system with applications to normal and diseased lungs, as well as therapeutic interventions. Specifically, the topics include liquid plug flow in airways and at airway bifurcations as it relates to surfactant, drug, gene, or stem cell delivery into the lung; liquid plug rupture and its damaging effects on underlying airway epithelial cells as well as a source of crackling sounds in the lung; airway closure from “capillary-elastic instabilities,” as well as nonlinear stabilization from oscillatory core flow which we call the “oscillating butter knife;” liquid film, and surfactant dynamics in an oscillating alveolus and the steady streaming, and surfactant spreading on thin viscous films including our discovery of the Grotberg–Borgas–Gaver shock. PMID:21403768

Teaching Technical Competencies for Fluid Mechanics Research

NASA Astrophysics Data System (ADS)

Tagg, Randall

2014-11-01

We are developing an ``on demand'' framework for students to learn techniques used in fluid mechanics research. The site for this work is a university-grade laboratory situated next to Gateway High School in Aurora, Colorado. Undergraduate university students work with K-12 students on research and technical innovation projects. Both groups need customized training as their projects proceed. A modular approach allows particular competencies such as pump selection, construction of flow piping and channels, flow visualization, and specific flow measurement methods to be acquired through focused lessons. These lessons can be learned in either a stand-alone fashion or assembled into units for formal courses. A research example was a student project on diffusion of infectious material in micro-gravity in the event of an intestinal puncture wound. A curriculum example is a 9-week quarter of high-school instruction on instrumentation that uses small-scale water treatment systems as a case study.

Molded underfill (MUF) encapsulation for flip-chip package: A numerical investigation

NASA Astrophysics Data System (ADS)

Azmi, M. A.; Abdullah, M. K.; Abdullah, M. Z.; Ariff, Z. M.; Saad, Abdullah Aziz; Hamid, M. F.; Ismail, M. A.

2017-07-01

This paper presents the numerical simulation of epoxy molding compound (EMC) filling in multi flip-chip packages during encapsulation process. The empty and a group flip chip packages were considered in the mold cavity in order to study the flow profile of the EMC. SOLIDWORKS software was used for three-dimensional modeling and it was incorporated into fluid analysis software namely as ANSYS FLUENT. The volume of fluid (VOF) technique was used for capturing the flow front profiles and Power Law model was applied for its rheology model. The numerical result are compared and discussed with previous experimental and it was shown a good conformity for model validation. The prediction of flow front was observed and analyzed at different filling time. The possibility and visual of void formation in the package is captured and the number of flip-chip is one factor that contributed to the void formation.

Flow void of cerebrospinal fluid in idiopathic normal pressure hydrocephalus of the elderly: can it predict outcome after shunting?

PubMed

Krauss, J K; Regel, J P; Vach, W; Jüngling, F D; Droste, D W; Wakhloo, A K

1997-01-01

We investigate the predictive value of cerebrospinal fluid (CSF) flow void on outcome after shunting in a prospective series of patients with idiopathic normal pressure hydrocephalus (NPH). The degree and extension of CSF flow void were examined on T2-weighted magnetic resonance imaging scans of 37 elderly patients with idiopathic NPH who underwent subsequent shunting. The degree of flow void was assessed in comparison with the signal of large cerebral arteries. The extension was evaluated via the calculation of sum scores for the occurrence of flow void in different locations of the ventricular system. Those parameters were not considered in the decision to perform shunting. CSF flow void in the aqueduct and the adjacent third and fourth ventricles of the 37 patients with idiopathic NPH was compared with that of 37 age-matched control patients. CSF flow void scores in patients with idiopathic NPH were investigated for correlations between postoperative outcome scores and ventricular width indices. No difference was found between the occurrence of aqueductal CSF flow void in patients with idiopathic NPH and the control group. A significant difference, however, was noted for the extension of the CSF flow void, which was greater in the NPH group. Postoperative improvement was found in 33 of 37 patients with idiopathic NPH at a mean follow-up of 15.6 months. Only small, statistically not significant correlations were found between CSF flow void and postoperative outcome. Flow void sum scores, however, correlated significantly with ventricular width indices. The degree and extension of CSF flow void on T2-weighted magnetic resonance imaging scans have little predictive value for outcome after shunting in patients with idiopathic NPH. The greater extension of the CSF flow void in patients with NPH is most likely related to increased ventricular width. It is not useful to consider CSF flow void findings on conventional magnetic resonance imaging scans in making the decision to offer shunting in patients with idiopathic NPH.

Comparing fluid mechanics models with experimental data.

PubMed Central

Spedding, G R

2003-01-01

The art of modelling the physical world lies in the appropriate simplification and abstraction of the complete problem. In fluid mechanics, the Navier-Stokes equations provide a model that is valid under most circumstances germane to animal locomotion, but the complexity of solutions provides strong incentive for the development of further, more simplified practical models. When the flow organizes itself so that all shearing motions are collected into localized patches, then various mathematical vortex models have been very successful in predicting and furthering the physical understanding of many flows, particularly in aerodynamics. Experimental models have the significant added convenience that the fluid mechanics can be generated by a real fluid, not a model, provided the appropriate dimensionless groups have similar values. Then, analogous problems can be encountered in making intelligible but independent descriptions of the experimental results. Finally, model predictions and experimental results may be compared if, and only if, numerical estimates of the likely variations in the tested quantities are provided. Examples from recent experimental measurements of wakes behind a fixed wing and behind a bird in free flight are used to illustrate these principles. PMID:14561348

Numerical modeling of fluid migration in subduction zones

NASA Astrophysics Data System (ADS)

Walter, M. J.; Quinteros, J.; Sobolev, S. V.

2015-12-01

It is well known that fluids play a crucial role in subduction evolution. For example, mechanical weakening along tectonic interfaces, due to high fluid pressure, may enable oceanic subduction. Hence, the fluid content seems to be a critical parameter for subduction initiation. Studies have also shown a correlation between the location of slab dehydration and intermediate seismic activity. Furthermore, expelled fluids from the subduction slab affect the melting temperature, consequently, contributing to partial melting in the wedge above the down-going plate and extensive volcanism. In summary, fluids have a great impact on tectonic processes and therefore should be incorporated into geodynamic numerical models. Here we use existing approaches to couple and solve fluid flow equations in the SLIM-3D thermo-mechanical code. SLIM-3D is a three-dimensional thermo-mechanical code capable of simulating lithospheric deformation with elasto-visco-plastic rheology. It has been successfully applied to model geodynamic processes at different tectonic settings, including subduction zones. However, although SLIM-3D already includes many features, fluid migration has not been incorporated into the model yet. To this end, we coupled solid and fluid flow assuming that fluids flow through a porous and deformable solid. Thereby, we introduce a two-phase flow into the model, in which the Stokes flow is coupled with the Darcy law for fluid flow. Ultimately, the evolution of porosity is governed by a compaction pressure and the advection of the porous solid. We show the details of our implementation of the fluid flow into the existing thermo-mechanical finite element code and present first results of benchmarks and experiments. We are especially interested in the coupling of subduction processes and the evolution of the magmatic arc. Thereby, we focus on the key factors controlling magma emplacement and its influence on subduction processes.

Numerical Temperature And Fluid-Flow Modelling For The Topographic Effects On Hydrothermal Circulation; A case study in Lucy Strike Vent Field

NASA Astrophysics Data System (ADS)

Erçetin, Engin; Düşünür Doǧan, Doǧa

2017-04-01

The aim of the study is to present a numerical temperature and fluid-flow modelling for the topographic effects on hydrothermal circulation. Bathymetry can create a major disturbance on fluid flow pattern. ANSYS Fluent Computational fluid dynamics software is used for simulations. Coupled fluid flow and temperature quations are solved using a 2-Dimensional control volume finite difference approach. Darcy's law is assumed to hold, the fluid is considered to be anormal Boussinesq incompressible fluid neglecting inertial effects. Several topographic models were simulated and both temperature and fluid flow calculations obtained for this study. The preliminary simulations examine the effect of a ingle bathymetric high on a single plume and the secondary study of simulations investigates the effect of multiple bathymetric highs on multiple plume. The simulations were also performed for the slow spreading Lucky Strike segment along the Mid-Atlantic Ridge (MAR), one of the best studied regions along the MAR, where a 3.4 km deep magma chamber extending 6 km along-axis is found at its center. The Lucky Strike segment displays a transitional morphology between that of the FAMOUS - North FAMOUS segments, which are characterized by well-developed axial valleys typical of slow-spreading segments, and that of the Menez Gwen segment, characterized by an axial high at the segment center. Lucky Strike Segment hosts a central volcano and active vent field located at the segment center and thus constitutes an excellent case study to simulate the effects of bathymetry on fluid flow. Results demonstrate that bathymetric relief has an important influence on hydrothermal flow. Subsurface pressure alterations can be formed by bathymetric highs, for this reason, bathymetric relief ought to be considered while simulating hydrothermal circulation systems. Results of this study suggest the dominant effect of bathymetric highs on fluid flow pattern and Darcy velocities will be presented. Keywords: Hydrothermal Circulation, Lucky Strike, Bathymetry - Topography, Vent Location, Fluid Flow, Numerical Modelling

Composition Pulse Time-Of-Flight Mass Flow Sensor

DOEpatents

Mosier, Bruce P.; Crocker, Robert W.; Harnett, Cindy K. l

2004-01-13

A device for measuring fluid flow rates over a wide range of flow rates (<1 nL/min to >10 .mu.L/min) and at pressures at least as great as 10,000 psi. The invention is particularly adapted for use in microfluidic systems. The device operates by producing compositional variations in the fluid, or pulses, that are subsequently detected downstream from the point of creation to derive a flow rate. Each pulse, comprising a small fluid volume, whose composition is different from the mean composition of the fluid, can be created by electrochemical means, such as by electrolysis of a solvent, electrolysis of a dissolved species, or electrodialysis of a dissolved ionic species. Measurements of the conductivity of the fluid can be used to detect the arrival time of the pulses, from which the fluid flow rate can be determined

Fluid-cooled heat sink for use in cooling various devices

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

Bharathan, Desikan; Bennion, Kevin; Kelly, Kenneth

The disclosure provides a fluid-cooled heat sink having a heat transfer base, a shroud, and a plurality of heat transfer fins in thermal communication with the heat transfer base and the shroud, where the heat transfer base, heat transfer fins, and the shroud form a central fluid channel through which a forced or free cooling fluid may flow. The heat transfer pins are arranged around the central fluid channel with a flow space provided between adjacent pins, allowing for some portion of the central fluid channel flow to divert through the flow space. The arrangement reduces the pressure drop ofmore » the flow through the fins, optimizes average heat transfer coefficients, reduces contact and fin-pin resistances, and reduces the physical footprint of the heat sink in an operating environment.« less

Crystalloids versus colloids for goal-directed fluid therapy in major surgery

PubMed Central

Hiltebrand, Luzius B; Kimberger, Oliver; Arnberger, Michael; Brandt, Sebastian; Kurz, Andrea; Sigurdsson, Gisli H

2009-01-01

Introduction Perioperative hypovolemia arises frequently and contributes to intestinal hypoperfusion and subsequent postoperative complications. Goal-directed fluid therapy might reduce these complications. The aim of this study was to compare the effects of goal-directed administration of crystalloids and colloids on the distribution of systemic, hepatosplanchnic, and microcirculatory (small intestine) blood flow after major abdominal surgery in a clinically relevant pig model. Methods Twenty-seven pigs were anesthetized and mechanically ventilated and underwent open laparotomy. They were randomly assigned to one of three treatment groups: the restricted Ringer lactate (R-RL) group (n = 9) received 3 mL/kg per hour of RL, the goal-directed RL (GD-RL) group (n = 9) received 3 mL/kg per hour of RL and intermittent boluses of 250 mL of RL, and the goal-directed colloid (GD-C) group (n = 9) received 3 mL/kg per hour of RL and boluses of 250 mL of 6% hydroxyethyl starch (130/0.4). The latter two groups received a bolus infusion when mixed venous oxygen saturation was below 60% ('lockout' time of 30 minutes). Regional blood flow was measured in the superior mesenteric artery and the celiac trunk. In the small bowel, microcirculatory blood flow was measured using laser Doppler flowmetry. Intestinal tissue oxygen tension was measured with intramural Clark-type electrodes. Results After 4 hours of treatment, arterial blood pressure, cardiac output, mesenteric artery flow, and mixed oxygen saturation were significantly higher in the GD-C and GD-RL groups than in the R-RL group. Microcirculatory flow in the intestinal mucosa increased by 50% in the GD-C group but remained unchanged in the other two groups. Likewise, tissue oxygen tension in the intestine increased by 30% in the GD-C group but remained unchanged in the GD-RL group and decreased by 18% in the R-RL group. Mesenteric venous glucose concentrations were higher and lactate levels were lower in the GD-C group compared with the two crystalloid groups. Conclusions Goal-directed colloid administration markedly increased microcirculatory blood flow in the small intestine and intestinal tissue oxygen tension after abdominal surgery. In contrast, goal-directed crystalloid and restricted crystalloid administrations had no such effects. Additionally, mesenteric venous glucose and lactate concentrations suggest that intestinal cellular substrate levels were higher in the colloid-treated than in the crystalloid-treated animals. These results support the notion that perioperative goal-directed therapy with colloids might be beneficial during major abdominal surgery. PMID:19302713

Multiscale Modeling of Multiphase Fluid Flow

DTIC Science & Technology

2016-08-01

the disparate time and length scales involved in modeling fluid flow and heat transfer. Molecular dynamics simulations were carried out to provide a...fluid dynamics methods were used to investigate the heat transfer process in open-cell micro-foam with phase change material; enhancement of natural...Computational fluid dynamics, Heat transfer, Phase change material in Micro-foam, Molecular Dynamics, Multiphase flow, Multiscale modeling, Natural

Evaluation and comparison of nasal airway flow patterns among three subjects from Caucasian, Chinese and Indian ethnic groups using computational fluid dynamics simulation.

PubMed

Zhu, Jian Hua; Lee, Heow Pueh; Lim, Kian Meng; Lee, Shu Jin; Wang, De Yun

2011-01-31

Nasal airflow is one of the most important determinants for nasal physiology. During the long evolution of human beings, different races have developed their own attributes of nasal morphologies which result in variations of nasal airflow patterns and nasal functions. This study evaluated and compared the effects of differences of nasal morphology among three healthy male subjects from Caucasian, Chinese and Indian ethnic groups on nasal airflow patterns using computational fluid dynamics simulation. By examining the anterior nasal airway, the nasal indices and the nostril shapes of the three subjects were found to be similar to nasal cavities of respective ethnic groups. Computed tomography images of these three subjects were obtained to reconstruct 3-dimensional models of nasal cavities. To retain the flow characteristics around the nasal vestibules, a 40 mm-radius semi sphere was assembled around the human face for the prescription of zero ambient gauge pressure. The results show that more airflow tends to pass through the middle passage of the nasal airway in the Caucasian model, and through the inferior portion in the Indian model. The Indian model was found with extremely low flow flux flowing through the olfactory region. The sizes of vortexes near the anterior cavity were found to be correlated with the angles between the upper nasal valve wall and the anterior head of the nasal cavity. Copyright © 2010 Elsevier B.V. All rights reserved.

Bone tissue engineering: the role of interstitial fluid flow

NASA Technical Reports Server (NTRS)

Hillsley, M. V.; Frangos, J. A.

1994-01-01

It is well established that vascularization is required for effective bone healing. This implies that blood flow and interstitial fluid (ISF) flow are required for healing and maintenance of bone. The fact that changes in bone blood flow and ISF flow are associated with changes in bone remodeling and formation support this theory. ISF flow in bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of bone during exercise. These conditions also induce changes in bone remodeling. Previously, we hypothesized that interstitial fluid flow in bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF flow results in the bone loss observed in disuse and microgravity. The purpose of this article is to review ISF flow in bone and its role in osteogenesis.

Pigtail catheters used for percutaneous fluid drainage: comparison of performance characteristics.

PubMed

Macha, Douglas B; Thomas, John; Nelson, Rendon C

2006-03-01

To compare the performance characteristics of various single-lumen all-purpose pigtail drainage catheters. The following parameters were compared: flow rates between catheters of the same size, whether changing the fluid viscosity has any effect on catheter comparisons, the effect on flow of leaving an open three-way stopcock in the drainage pathway, the tendency of the catheters to kink, and catheter patency after kinking, as measured according to flow. All-purpose 8.0-, 8.3-, and 8.5-F (collectively referred to as 8-F); 10.0-, 10.2-, and 10.3-F (collectively referred to as 10-F); and 12.0-F pigtail drainage catheters from three manufacturers were evaluated. Data were compared by using two-tailed t tests after normal distributions were confirmed. P < .05 was considered to represent a significant difference. At comparison of the 8-F catheters, the C.R. Bard catheters demonstrated better flow rates than the Cook and Boston Scientific devices. Among the 10-F catheters, there were no significant differences in the flow rates of fluid with viscosity equivalent to that of water between the C.R. Bard and Boston Scientific catheters; however, both these catheter types demonstrated significantly (P < .05) better flow rates than the Cook devices. Among the 12-F catheters, the C.R. Bard catheters demonstrated significantly (P < .05) better flow rates than the other two catheter types. Changing the fluid viscosity caused no changes in comparison results. In all catheter groups, the presence of a stopcock significantly (P < .05) impaired flow. None of the evaluated catheters demonstrated a clear advantage in terms of patency or susceptibility to kinking. At comparison of the in vitro performances of catheters from different manufacturers, the C.R. Bard 8.0-F and Cook 10.2-F catheters had comparable flow rates, and flow rates through the C.R. Bard and Boston Scientific 10.0-F catheters were comparable to flow rates through the Cook and Boston Scientific 12.0-F catheters. Varying viscosity had no effect on comparisons of catheter flow rates; however, a stopcock between the vacuum source and the catheter was noted to impair flow rates in all brands and sizes of evaluated catheters. Copyright RSNA, 2006.

Monitoring Subsurface Fluid Flow Using Perfluorocarbon Tracers: Another Tool Potentially Available for Subsurface Fluid Flow Assessments

EPA Pesticide Factsheets

Perfluorocarbon Tracers (PFTs) Complement stable Isotopes and Geochemistry for Verifying, Assessing or Modeling Fluid Flow. Geochemistry, Isotopes and PFT’s complement Geophysics to monitor and verify plume movement, leakage to shallow aquifers or surface

Low pressure drop, multi-slit virtual impactor

DOEpatents

Bergman, Werner

2002-01-01

Fluid flow is directed into a multiplicity of slit nozzles positioned so that the fluid flow is directed into a gap between the nozzles and (a) a number of receiving chambers and (b) a number of exhaust chambers. The nozzles and chambers are select so that the fluid flow will be separated into a first particle flow component with larger and a second particle flow component with the smaller particles.

A Parallel-Plate Flow Chamber for Mechanical Characterization of Endothelial Cells Exposed to Laminar Shear Stress

PubMed Central

Wong, Andrew K.; LLanos, Pierre; Boroda, Nickolas; Rosenberg, Seth R.; Rabbany, Sina Y.

2017-01-01

Shear stresses induced by laminar fluid flow are essential to properly recapitulate the physiological microenvironment experienced by endothelial cells (ECs). ECs respond to these stresses via mechanotransduction by modulating their phenotype and biomechanical characteristics, which can be characterized by Atomic Force Microscopy (AFM). Parallel Plate Flow Chambers (PPFCs) apply unidirectional laminar fluid flow to EC monolayers in vitro. Since ECs in sealed PPFCs are inaccessible to AFM probes, cone-and-plate viscometers (CPs) are commonly used to apply shear stress. This paper presents a comparison of the efficacies of both methods. Computational Fluid Dynamic simulation and validation testing using EC responses as a metric have indicated limitations in the use of CPs to apply laminar shear stress. Monolayers subjected to laminar fluid flow in a PPFC respond by increasing cortical stiffness, elongating, and aligning filamentous actin in the direction of fluid flow to a greater extent than CP devices. Limitations using CP devices to provide laminar flow across an EC monolayer suggest they are better suited when studying EC response for disturbed flow conditions. PPFC platforms allow for exposure of ECs to laminar fluid flow conditions, recapitulating cellular biomechanical behaviors, whereas CP platforms allow for mechanical characterization of ECs under secondary flow. PMID:28989541

Composition pulse time-of-flight mass flow sensor

DOEpatents

Harnett, Cindy K [Livermore, CA; Crocker, Robert W [Fremont, CA; Mosier, Bruce P [San Francisco, CA; Caton, Pamela F [Berkeley, CA; Stamps, James F [Livermore, CA

2007-06-05

A device for measuring fluid flow rates over a wide range of flow rates (<1 nL/min to >10 .mu.L/min) and at pressures at least as great as 2,000 psi. The invention is particularly adapted for use in microfluidic systems. The device operates by producing compositional variations in the fluid, or pulses, that are subsequently detected downstream from the point of creation to derive a flow rate. Each pulse, comprising a small fluid volume, whose composition is different from the mean composition of the fluid, can be created by electrochemical means, such as by electrolysis of a solvent, electrolysis of a dissolved species, or electrodialysis of a dissolved ionic species. Measurements of the conductivity of the fluid can be used to detect the arrival time of the pulses, from which the fluid flow rate can be determined. A pair of spaced apart electrodes can be used to produce the electrochemical pulse. In those instances where it is desired to measure a wide range of fluid flow rates a three electrode configuration in which the electrodes are spaced at unequal distances has been found to be desirable.

Unsteady magnetohydrodynamics micropolar fluid in boundary layer flow past a sphere influenced by magnetic fluid

NASA Astrophysics Data System (ADS)

Pratomo, Rizky Verdyanto; Widodo, Basuki; Adzkiya, Dieky

2017-12-01

Research about fluid flow was very interesting because have a lot of advantages and it can be applied in many aspects of life. The study on fluid flow which is now widely studied is on magnetohydrodynamic (MHD). Magnetohydrodynamic is a conductive and electrical in a magnetic field. This paper considers the effect of unsteady magnetic fields on the flow of magneto-hydrodynamic fluid on the boundary layer that flows past a sphere in micropolar fluid influenced by magnetic field. Our approach is as follows. First, we construct a mathematical model and then the system of equations obtained will be solved numerically using the Keller-Box scheme. Then the system is simulated to assess its effect on the fluid flow velocity profile and the profile of microrotation particles. The result of this research indicates, that when the magnetic parameters increase, then velocity profile increases. If material parameters increase, then velocity profile decreases and magnetic parameters increase for n = 0. For n = 0.5, if magnetic parameters increase, then microrotation profile decreases.

LOx breathing system with gas permeable-liquid impermeable heat exchange and delivery hose

DOEpatents

Hall, M.N.

1996-04-30

Life support apparatus is composed of: a garment for completely enclosing a wearer and constructed for preventing passage of gas from the environment surrounding the garment; a portable receptacle holding a quantity of an oxygen-containing fluid in liquid state, the fluid being in a breathable gaseous state when at standard temperature and pressure; a fluid flow member secured within the garment and coupled to the receptacle for conducting the fluid in liquid state from the receptacle to the interior of the garment; and a fluid flow control device connected for causing fluid to flow from the receptacle to the fluid flow member at a rate determined by the breathable air requirement of the wearer, wherein fluid in liquid state is conducted into the interior of the garment at a rate to be vaporized and heated to a breathable temperature by body heat produced by the wearer. 6 figs.

Unbalanced-flow, fluid-mixing plug with metering capabilities

NASA Technical Reports Server (NTRS)

England, John Dwight (Inventor); Kelley, Anthony R. (Inventor); Van Buskirk, Paul D. (Inventor)

2009-01-01

A fluid mixer plug has holes formed therethrough such that a remaining portion is closed to fluid flow. The plug's inlet face defines a central circuit region and a ring-shaped region with the ring-shaped region including at least some of the plug's remaining portion so-closed to fluid flow. This remaining portion or closed region at each radius R of the ring shaped region satisfies a radius independent, flow-based relationship. Entry openings are defined in the plug's inlet face in correspondence with the holes. The entry openings define an open flow area at each radius of the ring-shaped region. The open flow area at each such radius satisfies the inverse of the flow-based relationship defining the closed regions of the plug.

Modification of equation of motion of fluid-conveying pipe for laminar and turbulent flow profiles

NASA Astrophysics Data System (ADS)

Guo, C. Q.; Zhang, C. H.; Païdoussis, M. P.

2010-07-01

Considering the non-uniformity of the flow velocity distribution in fluid-conveying pipes caused by the viscosity of real fluids, the centrifugal force term in the equation of motion of the pipe is modified for laminar and turbulent flow profiles. The flow-profile-modification factors are found to be 1.333, 1.015-1.040 and 1.035-1.055 for laminar flow in circular pipes, turbulent flow in smooth-wall circular pipes and turbulent flow in rough-wall circular pipes, respectively. The critical flow velocities for divergence in the above-mentioned three cases are found to be 13.4%, 0.74-1.9% and 1.7-2.6%, respectively, lower than that with plug flow, while those for flutter are even lower, which could reach 36% for the laminar flow profile. By introducing two new concepts of equivalent flow velocity and equivalent mass, fluid-conveying pipe problems with different flow profiles can be solved with the equation of motion for plug flow.

Thermally conductive porous element-based recuperators

NASA Technical Reports Server (NTRS)

Du, Jian Hua (Inventor); Chow, Louis C (Inventor); Lin, Yeong-Ren (Inventor); Wu, Wei (Inventor); Kapat, Jayanta (Inventor); Notardonato, William U. (Inventor)

2012-01-01

A heat exchanger includes at least one hot fluid flow channel comprising a first plurality of open cell porous elements having first gaps there between for flowing a hot fluid in a flow direction and at least one cold fluid flow channel comprising a second plurality of open cell porous elements having second gaps therebetween for flowing a cold fluid in a countercurrent flow direction relative to the flow direction. The thermal conductivity of the porous elements is at least 10 W/mK. A separation member is interposed between the hot and cold flow channels for isolating flow paths associated these flow channels. The first and second plurality of porous elements at least partially overlap one another to form a plurality of heat transfer pairs which transfer heat from respective ones of the first porous elements to respective ones of the second porous elements through the separation member.

Quantifying the flow rate of the Deepwater Horizon Macondo Well oil spill

NASA Astrophysics Data System (ADS)

Camilli, R.; Bowen, A.; Yoerger, D. R.; Whitcomb, L. L.; Techet, A. H.; Reddy, C. M.; Sylva, S.; Seewald, J.; di Iorio, D.; Whoi Flow Rate Measurement Group

2010-12-01

The Deepwater Horizon blowout in the Mississippi Canyon block 252 of the Gulf of Mexico created the largest recorded offshore oil spill. The well outflow’s multiple leak sources, turbulent multiphase flow, tendency for hydrate formation, and extreme source depth of 1500 m below the sea surface complicated the quantitative estimation of oil and gas leakage rates. We present methods and results from a U.S. Coast Guard sponsored flow assessment study of the Deepwater Horizon’s damaged blow out preventer and riser. This study utilized a remotely operated vehicle equipped with in-situ acoustic sensors (a Doppler sonar and an imaging multibeam sonar) and isobaric gas-tight fluid samplers to measure directly outflow from the damaged well. Findings from this study indicate oil release rates and total release volume estimates that corroborate estimates made by the federal government’s Flow Rate Technical Group using non-acoustic techniques. The acoustic survey methods reported here provides a means for estimating fluid flow rates in subsurface environments, and are potentially useful for a diverse range of oceanographic applications. Photograph of the Discoverer Enterprise burning natural gas collected from the Macondo well blowout preventer during flow measurement operations. Copyright Wood Hole Oceanographic Institution.

Miniaturized pressurization system

DOEpatents

Whitehead, John C.; Swink, Don G.

1991-01-01

The invention uses a fluid stored at a low pressure and provides the fluid at a high pressure. The invention allows the low pressure fluid to flow to a fluid bore of a differential pump and from the pump to a fluid pressure regulator. After flowing through the regulator the fluid is converted to a gas which is directed to a gas bore of the differential pump. By controlling the flow of gas entering and being exhausted from the gas bore, the invention provides pressure to the fluid. By setting the regulator, the high pressure fluid can be set at predetermined values. Because the invention only needs a low pressure fluid, the inventive apparatus has a low mass, and therefore would be useful in rocket propulsion systems.

Effect of a new desensitizing material on human dentin permeability.

PubMed

Rusin, Richard P; Agee, Kelli; Suchko, Michael; Pashley, David H

2010-06-01

Resin-modified glass ionomers (RMGI) have demonstrated clinical success providing immediate and long-term relief from root sensitivity. RMGIs have been recently introduced as paste-liquid systems for convenience of clinical usage. The objective of this study was to measure the ability of a new paste-liquid RMGI to reduce fluid flow through human dentin, compared to an established single-bottle nanofilled total etch resin adhesive indicated for root desensitization. Dentin permeability was measured on human crown sections on etched dentin, presenting a model for the exposed tubules typical of root sensitivity, and permitting measurement of the maximum permeability. In the first two groups, the etched dentin was coated with either the RMGI or adhesive, and permeability measured on the coated dentin. In a third group, a smear layer was created on the dentin with sandpaper, then the specimens were coated with the RMGI; permeability was measured on the smeared and coated dentin. Specimens from each group were sectioned and examined via scanning electron microscopy (SEM). Both the resin adhesive and the new paste-liquid RMGI protective material significantly reduced fluid flow through dentin, and exhibited excellent seal on dentin with either open tubules or smear-layer occluded tubules. The RMGI infiltrated the smear layer with resin during placement, penetrated dentin tubules, and formed resin tags. The RMGI was equivalent to the adhesive in its ability to reduce fluid flow and seal dentin. It is therefore concluded that the new RMGI and the adhesive show the potential to offer excellent sensitivity relief on exposed root dentin. Copyright (c) 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Intracellular fluid flow in rapidly moving cells

PubMed Central

Keren, Kinneret; Yam, Patricia T.; Kinkhabwala, Anika; Mogilner, Alex; Theriot, Julie A.

2010-01-01

Cytosolic fluid dynamics have been implicated in cell motility1–5 because of the hydrodynamic forces they induce and because of their influence on transport of components of the actin machinery to the leading edge. To investigate the existence and the direction of fluid flow in rapidly moving cells, we introduced inert quantum dots into the lamellipodia of fish epithelial keratocytes and analysed their distribution and motion. Our results indicate that fluid flow is directed from the cell body towards the leading edge in the cell frame of reference, at about 40% of cell speed. We propose that this forward-directed flow is driven by increased hydrostatic pressure generated at the rear of the cell by myosin contraction, and show that inhibition of myosin II activity by blebbistatin reverses the direction of fluid flow and leads to a decrease in keratocyte speed. We present a physical model for fluid pressure and flow in moving cells that quantitatively accounts for our experimental data. PMID:19767741

Design and Development of Low-Cost Water Tunnel for Educational Purpose

NASA Astrophysics Data System (ADS)

Zahari, M.; Dol, S. S.

2015-04-01

The hydrodynamic behaviour of immersed body is essential in fluid dynamics study. Water tunnel is an example of facility required to provide a controlled condition for fluid flow research. The operational principle of water tunnel is quite similar to the wind tunnel but with different working fluid and higher flow-pumping capacity. Flow visualization in wind tunnel is more difficult to conduct as turbulent flows in wind dissipate quickly whilst water tunnel is more suitable for such purpose due to higher fluid viscosity and wide variety of visualization techniques can be employed. The present work focusses on the design and development of open flow water tunnel for the purpose of studying vortex-induced vibration from turbulent vortex shedding phenomenon. The water tunnel is designed to provide a steady and uniform flow speed within the test section area. Construction details are discussed for development of low-cost water tunnel for quantitative and qualitative fluid flow measurements. The water tunnel can also be used for educational purpose such as fluid dynamics class activity to provide quick access to visualization medium for better understanding of various turbulence motion learnt in class.

Computational modelling of the flow of viscous fluids in carbon nanotubes

NASA Astrophysics Data System (ADS)

Khosravian, N.; Rafii-Tabar, H.

2007-11-01

Carbon nanotubes will have extensive application in all areas of nano-technology, and in particular in the field of nano-fluidics, wherein they can be used for molecular separation, nano-scale filtering and as nano-pipes for conveying fluids. In the field of nano-medicine, nanotubes can be functionalized with various types of receptors to act as bio-sensors for the detection and elimination of cancer cells, or be used as bypasses and even neural connections. Modelling fluid flow inside nanotubes is a very challenging problem, since there is a complex interplay between the motion of the fluid and the stability of the walls. A critical issue in the design of nano-fluidic devices is the induced vibration of the walls, due to the fluid flow, which can promote structural instability. It has been established that the resonant frequencies depend on the flow velocity. We have studied, for the first time, the flow of viscous fluids through multi-walled carbon nanotubes, using the Euler-Bernoulli classical beam theory to model the nanotube as a continuum structure. Our aim has been to compute the effect of the fluid flow on the structural stability of the nanotubes, without having to consider the details of the fluid-walls interaction. The variations of the resonant frequencies with the flow velocity are obtained for both unembedded nanotubes, and when they are embedded in an elastic medium. It is found that a nanotube conveying a viscous fluid is more stable against vibration-induced buckling than a nanotube conveying a non-viscous fluid, and that the aspect ratio plays the same role in both cases.

The two-dimensional pattern of metamorphic fluid flow at Mary Kathleen, Australia: Fluid focusing, transverse dispersion, and implications for modeling fluid flow

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

Cartwright, I.

The pattern of [delta][sup 18]O values in layered Corella calc-silicate rocks adjacent to a scapolitized metadolerite dike at Timberu in the Mary Kathleen fold belt illustrates some of the complexities of two-dimensional metamorphic fluid flow. Fluids flowing from the dike ([delta][sup 18]O = 9-10%) into the calc-silicate rocks lowered calcite [delta][sup 18]O values form 19-20% to as low as 10.3%. Time-integrate advectite fluid fluxes varied from 0.72 to > 8.1 m[sup 3]/m[sup 2] over a 4.5-m lateral distance, and there are two distinct channels of higher fluid flux. If the duration of fluid flow was similar across the outcrop, intrinsicmore » permeabilities varied laterally by at least an order of magnitude. Fluid flow was largely focused across lithological layering, with rare excursions parallel to layering, suggesting that (up to 1 m) to those at the isotopic front ([approximately]1.2 m), indicating that the coefficients of transverse and longitudinal dispersion are of similar orders of magnitude. Localities in other terrains probably show similar complex patterns of isotopic resetting that in two dimensions correspond to the predictions of the advective-dispersive transport models, but which are difficult to interpret using a one-dimensional analysis. Transverse dispersion during channeled fluid flow will potentially reset O-isotope ratios adjacent to the channels and cause decoupling of geochemical parameters during advective and dispersive transport. 43 refs., 5 figs., 2 tabs.« less

Value for controlling flow of cryogenic fluid

DOEpatents

Knapp, Philip A.

1996-01-01

A valve is provided for accurately controlling the flow of cryogenic fluids such as liquid nitrogen. The valve comprises a combination of disc and needle valves affixed to a valve stem in such a manner that the disc and needle are free to rotate about the stem, but are constrained in lateral and vertical movements. This arrangement provides accurate and precise fluid flow control and positive fluid isolation.

Poiseuille equation for steady flow of fractal fluid

NASA Astrophysics Data System (ADS)

Tarasov, Vasily E.

2016-07-01

Fractal fluid is considered in the framework of continuous models with noninteger dimensional spaces (NIDS). A recently proposed vector calculus in NIDS is used to get a description of fractal fluid flow in pipes with circular cross-sections. The Navier-Stokes equations of fractal incompressible viscous fluids are used to derive a generalization of the Poiseuille equation of steady flow of fractal media in pipe.

Microgravity Fluid Separation Physics: Experimental and Analytical Results

NASA Technical Reports Server (NTRS)

Shoemaker, J. Michael; Schrage, Dean S.

1997-01-01

Effective, low power, two-phase separation systems are vital for the cost-effective study and utilization of two-phase flow systems and flow physics of two-phase flows. The study of microgravity flows have the potential to reveal significant insight into the controlling mechanisms for the behavior of flows in both normal and reduced gravity environments. The microgravity environment results in a reduction in gravity induced buoyancy forces acting on the discrete phases. Thus, surface tension, viscous, and inertial forces exert an increased influence on the behavior of the flow as demonstrated by the axisymmetric flow patterns. Several space technology and operations groups have studied the flow behavior in reduced gravity since gas-liquid flows are encountered in several systems such as cabin humidity control, wastewater treatment, thermal management, and Rankine power systems.

Development of a Mechatronic Syringe Pump to Control Fluid Flow in a Microfluidic Device Based on Polyimide Film

NASA Astrophysics Data System (ADS)

Sek Tee, Kian; Sharil Saripan, Muhammad; Yap, Hiung Yin; Fhong Soon, Chin

2017-08-01

With the advancement in microfluidic technology, fluid flow control for syringe pump is always essential. In this paper, a mechatronic syringe pump will be developed and customized to control the fluid flow in a poly-dimethylsiloxane (PDMS) microfluidic device based on a polyimide laminating film. The syringe pump is designed to drive fluid with flow rates of 100 and 1000 μl/min which intended to drive continuous fluid in a polyimide based microfluidic device. The electronic system consists of an Arduino microcontroller board and a uni-polar stepper motor. In the system, the uni-polar stepper motor was coupled to a linear slider attached to the plunger of a syringe pump. As the motor rotates, the plunger pumps the liquid out of the syringe. The accuracy of the fluid flow rate was determined by adjusting the number of micro-step/revolution to drive the stepper motor to infuse fluid into the microfluidic device. With the precise control of the electronic system, the syringe pump could accurately inject fluid volume at 100 and 1000 μl/min into a microfluidic device.

ACE-1 experiment

NASA Image and Video Library

2013-06-24

ISS036-E-019830 (24 June 2013) --- In the International Space Station’s Destiny laboratory, NASA astronaut Karen Nyberg, Expedition 36 flight engineer, speaks into a microphone while conducting a session with the Advanced Colloids Experiment (ACE)-1 sample preparation at the Light Microscopy Module (LMM) in the Fluids Integrated Rack / Fluids Combustion Facility (FIR/FCF). ACE-1 is a series of microscopic imaging investigations that uses the microgravity environment to examine flow characteristics and the evolution and ordering effects within a group of colloidal materials.

Numerical study of soap-film flow by nonuniform alternating electric fields

NASA Astrophysics Data System (ADS)

Nasiri, M.; Shirsavar, R.; Mollaei, S.; Ramos, A.

2017-02-01

Fluid flow of suspended liquid films induced by non-uniform alternating electric fields has been reported. The electric fields were generated by two rod-like electrodes perpendicular to the fluid surface. The observed fluid flow was explained qualitatively by considering a charge induction mechanism, where the electric field actuates on the charge induced on the film surface. In this paper we perform a numerical study of this fluid flow taking into account the charge induction mechanism. The numerical results are compared with experiments and good agreement is found. Finally, we propose the application of the device as a new kind of two dimensional fluid pump.

Numerical study of soap-film flow by nonuniform alternating electric fields.

PubMed

Nasiri, M; Shirsavar, R; Mollaei, S; Ramos, A

2017-02-01

Fluid flow of suspended liquid films induced by non-uniform alternating electric fields has been reported. The electric fields were generated by two rod-like electrodes perpendicular to the fluid surface. The observed fluid flow was explained qualitatively by considering a charge induction mechanism, where the electric field actuates on the charge induced on the film surface. In this paper we perform a numerical study of this fluid flow taking into account the charge induction mechanism. The numerical results are compared with experiments and good agreement is found. Finally, we propose the application of the device as a new kind of two dimensional fluid pump.

Instability patterns in a miscible core annular flow

NASA Astrophysics Data System (ADS)

D'Olce, Marguerite; Martin, Jerome; Rakotomalala, Nicole; Salin, Dominique; Talon, Laurent

2006-11-01

Laboratoire FAST, batiment 502, campus universitaire, 91405 Orsay Cedex (France). Experiments are performed with two miscible fluids of equal density but different viscosities. The fluids are injected co-currently and concentrically into a cylindrical pipe. The so-obtained base state is an axisymmetric parallel flow, for which the ratio of the flow rates of the two fluids monitors the relative amount (and so the radius) of the fluids. Depending on this relative amount and on the total flow rate of the fluids, unstable axisymmetric patterns such as mushrooms and pearls are observed. We delineate the diagram of occurrence of the two patterns and characterize the instabilities.

Ultrasonic flow metering system

DOEpatents

Gomm, Tyler J.; Kraft, Nancy C.; Mauseth, Jason A.; Phelps, Larry D.; Taylor, Steven C.

2002-01-01

A system for determining the density, flow velocity, and mass flow of a fluid comprising at least one sing-around circuit that determines the velocity of a signal in the fluid and that is correlatable to a database for the fluid. A system for determining flow velocity uses two of the inventive circuits with directional transmitters and receivers, one of which is set at an angle to the direction of flow that is different from the others.

Pre-Darcy Flow in Porous Media

NASA Astrophysics Data System (ADS)

Dejam, Morteza; Hassanzadeh, Hassan; Chen, Zhangxin

2017-10-01

Fluid flow in porous media is very important in a wide range of science and engineering applications. The entire establishment of fluid flow application in porous media is based on the use of an experimental law proposed by Darcy (1856). There are evidences in the literature that the flow of a fluid in consolidated and unconsolidated porous media does not follow Darcy law at very low fluxes, which is called pre-Darcy flow. In this paper, the unsteady flow regimes of a slightly compressible fluid under the linear and radial pre-Darcy flow conditions are modeled and the corresponding highly nonlinear diffusivity equations are solved analytically by aid of a generalized Boltzmann transformation technique. The influence of pre-Darcy flow on the pressure diffusion for homogeneous porous media is studied in terms of the nonlinear exponent and the threshold pressure gradient. In addition, the pressure gradient, flux, and cumulative production per unit area are compared with the classical solution of the diffusivity equation based on Darcy flow. The presented results advance our understanding of fluid flow in low-permeability media such as shale and tight formations, where pre-Darcy is the dominant flow regime.

Microwave fluid flow meter

DOEpatents

Billeter, Thomas R.; Philipp, Lee D.; Schemmel, Richard R.

1976-01-01

A microwave fluid flow meter is described utilizing two spaced microwave sensors positioned along a fluid flow path. Each sensor includes a microwave cavity having a frequency of resonance dependent upon the static pressure of the fluid at the sensor locations. The resonant response of each cavity with respect to a variation in pressure of the monitored fluid is represented by a corresponding electrical output which can be calibrated into a direct pressure reading. The pressure drop between sensor locations is then correlated as a measure of fluid velocity. In the preferred embodiment the individual sensor cavities are strategically positioned outside the path of fluid flow and are designed to resonate in two distinct frequency modes yielding a measure of temperature as well as pressure. The temperature response can then be used in correcting for pressure responses of the microwave cavity encountered due to temperature fluctuations.

Modeling steady-state dynamics of macromolecules in exponential-stretching flow using multiscale molecular-dynamics-multiparticle-collision simulations.

PubMed

Ghatage, Dhairyasheel; Chatterji, Apratim

2013-10-01

We introduce a method to obtain steady-state uniaxial exponential-stretching flow of a fluid (akin to extensional flow) in the incompressible limit, which enables us to study the response of suspended macromolecules to the flow by computer simulations. The flow field in this flow is defined by v(x) = εx, where v(x) is the velocity of the fluid and ε is the stretch flow gradient. To eliminate the effect of confining boundaries, we produce the flow in a channel of uniform square cross section with periodic boundary conditions in directions perpendicular to the flow, but simultaneously maintain uniform density of fluid along the length of the tube. In experiments a perfect elongational flow is obtained only along the axis of symmetry in a four-roll geometry or a filament-stretching rheometer. We can reproduce flow conditions very similar to extensional flow near the axis of symmetry by exponential-stretching flow; we do this by adding the right amounts of fluid along the length of the flow in our simulations. The fluid particles added along the length of the tube are the same fluid particles which exit the channel due to the flow; thus mass conservation is maintained in our model by default. We also suggest a scheme for possible realization of exponential-stretching flow in experiments. To establish our method as a useful tool to study various soft matter systems in extensional flow, we embed (i) spherical colloids with excluded volume interactions (modeled by the Weeks-Chandler potential) as well as (ii) a bead-spring model of star polymers in the fluid to study their responses to the exponential-stretched flow and show that the responses of macromolecules in the two flows are very similar. We demonstrate that the variation of number density of the suspended colloids along the direction of flow is in tune with our expectations. We also conclude from our study of the deformation of star polymers with different numbers of arms f that the critical flow gradient ε(c) at which the star undergoes the coil-to-stretch transition is independent of f for f = 2,5,10, and 20.

Heating and cooling system for an on-board gas adsorbent storage vessel

DOEpatents

Tamburello, David A.; Anton, Donald L.; Hardy, Bruce J.; Corgnale, Claudio

2017-06-20

In one aspect, a system for controlling the temperature within a gas adsorbent storage vessel of a vehicle may include an air conditioning system forming a continuous flow loop of heat exchange fluid that is cycled between a heated flow and a cooled flow. The system may also include at least one fluid by-pass line extending at least partially within the gas adsorbent storage vessel. The fluid by-pass line(s) may be configured to receive a by-pass flow including at least a portion of the heated flow or the cooled flow of the heat exchange fluid at one or more input locations and expel the by-pass flow back into the continuous flow loop at one or more output locations, wherein the by-pass flow is directed through the gas adsorbent storage vessel via the by-pass line(s) so as to adjust an internal temperature within the gas adsorbent storage vessel.

Deformation of a 3D granular media caused by fluid invasion

NASA Astrophysics Data System (ADS)

Dalbe, M. J.; Juanes, R.

2016-12-01

Multiphase flow in porous media plays a fundamental role in many natural and engineered subsurface processes. The interplay between fluid flow, medium deformation and fracture is essential in geoscience problems as disparate as fracking for unconventional hydrocarbon production, conduit formation and methane venting from lake and ocean sediments, and desiccation cracks in soil. Several experimental and computational studies have shown that the competition between capillary and friction forces can lead to different regimes of deformation, from frictional fingering to hydro-capillary fracturing (Sandnes et al., Nat. Comm. 2011, Holtzman et al., PRL 2012). Most of these investigations have focused, however, on 2D or quasi-2D systems. Here, we develop an experimental set-up that allows us to observe two-phase flow in a fully 3D granular bed and measure the fluid pressure while controlling the level of confining stress. We use an index matching technique to directly visualize the injection of a liquid in a granular media saturated with another, immiscible liquid. We extract the deformation the whole granular bulk as well as at the particle level. Our results show the existence of different regimes of invasion patterns depending on key dimensionless groups that control the system.

Deformation of a 3D granular media caused by fluid invasion

NASA Astrophysics Data System (ADS)

Dalbe, Marie-Julie; Juanes, Ruben

2016-11-01

Multiphase flow in porous media plays a fundamental role in many natural and engineered subsurface processes. The interplay between fluid flow, medium deformation and fracture is essential in geoscience problems as disparate as fracking for unconventional hydrocarbon production, conduit formation and methane venting from lake and ocean sediments, and desiccation cracks in soil. Several experimental and computational studies have shown that the competition between capillary and friction forces can lead to different regimes of deformation, from frictional fingering to hydro-capillary fracturing. Most of these investigations have focused, however, on 2D or quasi-2D systems. Here, we develop an experimental set-up that allows us to observe two-phase flow in a fully 3D granular bed and measure the fluid pressure while controlling the level of confining stress. We use an index matching technique to directly visualize the injection of a liquid in a granular media saturated with another, immiscible liquid. We extract the deformation the whole granular bulk as well as at the particle level. Our results show the existence of different regimes of invasion patterns depending on key dimensionless groups that control the system.

Online capacitive densitometer

DOEpatents

Porges, K.G.

1988-01-21

This invention is an apparatus for measuring fluid density of mixed phase fluid flow. The apparatus employs capacitive sensing of the mixed phased flow combined with means for uniformizing the electric field between the capacitor plates to account for flow line geometry. From measurement of fluid density, the solids feedrate can be ascertained. 7 figs.

Online capacitive densitometer

DOEpatents

Porges, Karl G.

1990-01-01

This invention is an apparatus for measuring fluid density of mixed phase fluid flow. The apparatus employs capacitive sensing of the mixed phased flow combined with means for uniformizing the electric field between the capacitor plates to account for flow line geometry. From measurement of fluid density, the solids feedrate can be ascertained.

Thermal transient anemometer

DOEpatents

Bailey, James L.; Vresk, Josip

1989-01-01

A thermal transient anemometer having a thermocouple probe which is utilized to measure the change in temperature over a period of time to provide a measure of fluid flow velocity. The thermocouple probe is located in the fluid flow path and pulsed to heat or cool the probe. The cooling of the heated probe or the heating of the cooled probe from the fluid flow over a period of time is measured to determine the fluid flow velocity. The probe is desired to be locally heated near the tip to increase the efficiency of devices incorporating the probe.

Thermohydrodynamic analysis of cryogenic liquid turbulent flow fluid film bearings

NASA Technical Reports Server (NTRS)

Andres, Luis San

1993-01-01

A thermohydrodynamic analysis is presented and a computer code developed for prediction of the static and dynamic force response of hydrostatic journal bearings (HJB's), annular seals or damper bearing seals, and fixed arc pad bearings for cryogenic liquid applications. The study includes the most important flow characteristics found in cryogenic fluid film bearings such as flow turbulence, fluid inertia, liquid compressibility and thermal effects. The analysis and computational model devised allow the determination of the flow field in cryogenic fluid film bearings along with the dynamic force coefficients for rotor-bearing stability analysis.

Finite element analysis in fluids; Proceedings of the Seventh International Conference on Finite Element Methods in Flow Problems, University of Alabama, Huntsville, Apr. 3-7, 1989

NASA Technical Reports Server (NTRS)

Chung, T. J. (Editor); Karr, Gerald R. (Editor)

1989-01-01

Recent advances in computational fluid dynamics are examined in reviews and reports, with an emphasis on finite-element methods. Sections are devoted to adaptive meshes, atmospheric dynamics, combustion, compressible flows, control-volume finite elements, crystal growth, domain decomposition, EM-field problems, FDM/FEM, and fluid-structure interactions. Consideration is given to free-boundary problems with heat transfer, free surface flow, geophysical flow problems, heat and mass transfer, high-speed flow, incompressible flow, inverse design methods, MHD problems, the mathematics of finite elements, and mesh generation. Also discussed are mixed finite elements, multigrid methods, non-Newtonian fluids, numerical dissipation, parallel vector processing, reservoir simulation, seepage, shallow-water problems, spectral methods, supercomputer architectures, three-dimensional problems, and turbulent flows.

Hydraulic modeling of unsteady debris-flow surges with solid-fluid interactions

USGS Publications Warehouse

Iverson, Richard M.

1997-01-01

Interactions of solid and fluid constituents produce the unique style of motion that typifies debris flows. To simulate this motion, a new hydraulic model represents debris flows as deforming masses of granular solids variably liquefied by viscous pore fluid. The momentum equation of the model describes how internal and boundary forces change as coarse-grained surge heads dominated by grain-contact friction grade into muddy debris-flow bodies more strongly influenced by fluid viscosity and pressure. Scaling analysis reveals that pore-pressure variations can cause flow resistance in surge heads to surpass that in debris-flow bodies by orders of magnitude. Numerical solutions of the coupled momentum and continuity equations provide good predictions of unsteady, nonuniform motion of experimental debris flows from initiation through deposition.

Lateral fluid flow in a compacting sand-shale sequence: South Caspian basin.

USGS Publications Warehouse

Bredehoeft, J.D.; Djevanshir, R.D.; Belitz, K.R.

1988-01-01

The South Caspian basin contains both sands and shales that have pore-fluid pressures substantially in excess of hydrostatic fluid pressure. Pore-pressure data from the South Caspian basin demonstrate that large differences in excess hydraulic head exist between sand and shale. The data indicate that sands are acting as drains for overlying and underlying compacting shales and that fluid flows laterally through the sand on a regional scale from the basin interior northward to points of discharge. The major driving force for the fluid movement is shale compaction. We present a first- order mathematical analysis in an effort to test if the permeability of the sands required to support a regional flow system is reasonable. The results of the analysis suggest regional sand permeabilities ranging from 1 to 30 md; a range that seems reasonable. This result supports the thesis that lateral fluid flow is occurring on a regional scale within the South Caspian basin. If vertical conduits for flow exist within the basin, they are sufficiently impermeable and do not provide a major outlet for the regional flow system. The lateral fluid flow within the sands implies that the stratigraphic sequence is divided into horizontal units that are hydraulically isolated from one another, a conclusion that has important implications for oil and gas migration.-Authors

Hydromechanical Modeling of Fluid Flow in the Lower Crust

NASA Astrophysics Data System (ADS)

Connolly, J.

2011-12-01

The lower crust lies within an ambiguous rheological regime between the brittle upper crust and ductile sub-lithospheric mantle. This ambiguity has allowed two schools of thought to develop concerning the nature of fluid flow in the lower crust. The classical school holds that lower crustal rocks are inviscid and that any fluid generated by metamorphic devolatilization is squeezed out of rocks as rapidly as it is produced. According to this school, permeability is a dynamic property and fluid flow is upward. In contrast, the modern school uses concepts from upper crustal hydrology that presume implicitly, if not explicitly, that rocks are rigid or, at most, brittle. For the modern school, the details of crustal permeability determine fluid flow and as these details are poorly known almost anything is possible. Reality, to the extent that it is reflected by inference from field studies, offers some support to both schools. In particular, evidence of significant lateral and channelized fluid flow are consistent with flow in rigid media, while evidence for short (104 - 105 y) grain-scale fluid-rock interaction during much longer metamorphic events, suggests that reaction-generated grain-scale permeability is sealed rapidly by compaction; a phenomenon that is also essential to prevent extensive retrograde metamorphism. These observations provide a compelling argument for recognizing in conceptual models of lower crustal fluid flow that rocks are neither inviscid nor rigid, but compact by viscous mechanisms on a finite time-scale. This presentation will review the principle consequences of, and obstacles to, incorporating compaction in such models. The role of viscous compaction in the lower crust is extraordinarily uncertain, but ignoring this uncertainty in models of lower crustal fluid flow does not make the models any more certain. Models inevitably invoke an initial steady state hydraulic regime. This initial steady state is critical to model outcomes because it determines the compaction time and length scales and, thereby, the response of the system to perturbations. Unfortunately, because metamorphic devolatilization is the most probable source of lower crustal fluids, the assumption of an initial steady state leaves much to be desired. In truth, in the modeling of lower crustal fluid flow, less is known about the initial state than is known about possible perturbations to it, e.g., metamorphic fluid production. Compaction is a bad and good news story. The bad news is that local flow patterns may be influenced by unknowable details; the good news is that compaction-driven fluid flow has a tendency to self-organize. Self-organization eliminates the dependence on details that are present on spatial or temporal scales that are smaller than the compaction length and time scales. Porosity waves are the mechanism for this self-organization, through which dilational deformation is localized in time and space to create pathways for fluid expulsion. The resulting flow patterns are sensitive to material properties and initial state, thus, inversion of natural flow patterns offers the greatest hope for constraining the compaction scales. Knowledge of these scales is also important because they limit the influence of external forcings on flow patterns, e.g., a shear zone may induce lateral or downward fluid flow, but only on the compaction time and length scales.

Motion estimation under location uncertainty for turbulent fluid flows

NASA Astrophysics Data System (ADS)

Cai, Shengze; Mémin, Etienne; Dérian, Pierre; Xu, Chao

2018-01-01

In this paper, we propose a novel optical flow formulation for estimating two-dimensional velocity fields from an image sequence depicting the evolution of a passive scalar transported by a fluid flow. This motion estimator relies on a stochastic representation of the flow allowing to incorporate naturally a notion of uncertainty in the flow measurement. In this context, the Eulerian fluid flow velocity field is decomposed into two components: a large-scale motion field and a small-scale uncertainty component. We define the small-scale component as a random field. Subsequently, the data term of the optical flow formulation is based on a stochastic transport equation, derived from the formalism under location uncertainty proposed in Mémin (Geophys Astrophys Fluid Dyn 108(2):119-146, 2014) and Resseguier et al. (Geophys Astrophys Fluid Dyn 111(3):149-176, 2017a). In addition, a specific regularization term built from the assumption of constant kinetic energy involves the very same diffusion tensor as the one appearing in the data transport term. Opposite to the classical motion estimators, this enables us to devise an optical flow method dedicated to fluid flows in which the regularization parameter has now a clear physical interpretation and can be easily estimated. Experimental evaluations are presented on both synthetic and real world image sequences. Results and comparisons indicate very good performance of the proposed formulation for turbulent flow motion estimation.

Segmented heat exchanger

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

Baldwin, Darryl Dean; Willi, Martin Leo; Fiveland, Scott Byron

2010-12-14

A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least amore » portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.« less

Heat exchanger efficiently operable alternatively as evaporator or condenser

DOEpatents

Ecker, Amir L.

1981-01-01

A heat exchanger adapted for efficient operation alternatively as evaporator or condenser and characterized by flexible outer tube having a plurality of inner conduits and check valves sealingly disposed within the outer tube and connected with respective inlet and outlet master flow conduits and configured so as to define a parallel flow path for a first fluid such as a refrigerant when flowed in one direction and to define a serpentine and series flow path for the first fluid when flowed in the opposite direction. The flexible outer tube has a heat exchange fluid, such as water, flowed therethrough by way of suitable inlet and outlet connections. The inner conduits and check valves form a package that is twistable so as to define a spiral annular flow path within the flexible outer tube for the heat exchange fluid. The inner conduits have thin walls of highly efficient heat transfer material for transferring heat between the first and second fluids. Also disclosed are specific materials and configurations.

Growth rate of a penny-shaped crack in hydraulic fracturing of rocks

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

Abe, H.; Keer, L.M.; Mura, T.

1976-01-01

The deformation and growth of a crack, fractured hydraulically, is investigated when fluid is injected from an inlet into the crack at a constant flow rate. The total flow rate at the inlet is divided as follows: flow rate extracted from an outlet hole; fluid loss rate from the crack surface; and total fluid mass change in the crack. Two cases are considered: (1) inlet flow rate is initially greater than the sum of the outlet flow and fluid loss rates; and (2) the reverse holds true. Ranges are shown for which the crack attains stationary states for given inletmore » flow rate and outlet pressure. For these two cases reasonable outlet flow rates are obtained when the outlet pressure is less than or equal to the difference between the tectonic stress and the fluid head at the inlet. Results are expected to be of use in considerations of heat extraction from hot, dry rock.« less

Modeling the migration of fluids in subduction zones

NASA Astrophysics Data System (ADS)

Spiegelman, M.; Wilson, C. R.; van Keken, P. E.; Hacker, B. R.

2010-12-01

Fluids play a major role in the formation of arc volcanism and the generation of continental crust. Progressive dehydration reactions in the downgoing slab release fluids to the hot overlying mantle wedge, causing flux melting and the migration of melts to the volcanic front. While the qualitative concept is well established the quantitative details of fluid release and especially that of fluid migration and generation of hydrous melting in the wedge is still poorly understood. Here we present new models of the fluid migration through the mantle wedge for subduction zones that span the spectrum of arcs worldwide. We focus on the flow of water and use an existing set of high resolution thermal and metamorphic models (van Keken et al., JGR, in review) to predict the regions of water release from the sediments, upper and lower crust, and upper most mantle. We use this water flux as input for the fluid migration calculation based on new finite element models built on advanced computational libraries (FEniCS/PETSc) for efficient and flexible solution of coupled multi-physics problems. The first generation of these models solves for the evolution of porosity and fluid-pressure/flux throughout the slab and wedge given solid flow, viscosity and thermal fields from the existing thermal models. Fluid flow in the new models depends on both permeability and the rheology of the slab-wedge system as interaction with rheological variability can induce additional pressure gradients that affect the fluid flow pathways. We will explore the sensitivity of fluid flow paths for a range of subduction zones and fluid flow parameters with emphasis on variability of the location of the volcanic arc with respect to flow paths and expected degrees of hydrous melting which can be estimated given a variety of wet-melting parameterizations (e.g. Katz et al, 2003, Kelley et al, 2010). The current models just include dehydration reactions but work continues on the next generation of models which will include both dehydration and hydration reactions as well as parameterized flux melting in a consistent reactive-flow framework. We have also begun work on re-implementing the solid-flow thermal calculations in FEniCS/PETSc which are open-source libraries in preparation for developing a fully coupled fluid-solid dynamics models for exploring subduction zone processes

Systems for column-based separations, methods of forming packed columns, and methods of purifying sample components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2000-01-01

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2006-02-21

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Systems For Column-Based Separations, Methods Of Forming Packed Columns, And Methods Of Purifying Sample Components.

DOEpatents

Egorov, Oleg B.; O'Hara, Matthew J.; Grate, Jay W.; Chandler, Darrell P.; Brockman, Fred J.; Bruckner-Lea, Cynthia J.

2004-08-24

The invention encompasses systems for column-based separations, methods of packing and unpacking columns and methods of separating components of samples. In one aspect, the invention includes a method of packing and unpacking a column chamber, comprising: a) packing a matrix material within a column chamber to form a packed column; and b) after the packing, unpacking the matrix material from the column chamber without moving the column chamber. In another aspect, the invention includes a system for column-based separations, comprising: a) a fluid passageway, the fluid passageway comprising a column chamber and a flow path in fluid communication with the column chamber, the flow path being obstructed by a retaining material permeable to a carrier fluid and impermeable to a column matrix material suspended in the carrier fluid, the flow path extending through the column chamber and through the retaining material, the flow path being configured to form a packed column within the column chamber when a suspension of the fluid and the column matrix material is flowed along the flow path; and b) the fluid passageway extending through a valve intermediate the column chamber and the retaining material.

Time Accurate CFD Simulations of the Orion Launch Abort Vehicle in the Transonic Regime

NASA Technical Reports Server (NTRS)

Ruf, Joseph; Rojahn, Josh

2011-01-01

Significant asymmetries in the fluid dynamics were calculated for some cases in the CFD simulations of the Orion Launch Abort Vehicle through its abort trajectories. The CFD simulations were performed steady state with symmetric boundary conditions and geometries. The trajectory points at issue were in the transonic regime, at 0 and 5 angles of attack with the Abort Motors with and without the Attitude Control Motors (ACM) firing. In some of the cases the asymmetric fluid dynamics resulted in aerodynamic side forces that were large enough that would overcome the control authority of the ACMs. MSFC s Fluid Dynamics Group supported the investigation into the cause of the flow asymmetries with time accurate CFD simulations, utilizing a hybrid RANS-LES turbulence model. The results show that the flow over the vehicle and the subsequent interaction with the AB and ACM motor plumes were unsteady. The resulting instantaneous aerodynamic forces were oscillatory with fairly large magnitudes. Time averaged aerodynamic forces were essentially symmetric.

Time Accurate CFD Simulations of the Orion Launch Abort Vehicle in the Transonic Regime

NASA Technical Reports Server (NTRS)

Rojahn, Josh; Ruf, Joe

2011-01-01

Significant asymmetries in the fluid dynamics were calculated for some cases in the CFD simulations of the Orion Launch Abort Vehicle through its abort trajectories. The CFD simulations were performed steady state and in three dimensions with symmetric geometries, no freestream sideslip angle, and motors firing. The trajectory points at issue were in the transonic regime, at 0 and +/- 5 angles of attack with the Abort Motors with and without the Attitude Control Motors (ACM) firing. In some of the cases the asymmetric fluid dynamics resulted in aerodynamic side forces that were large enough that would overcome the control authority of the ACMs. MSFC's Fluid Dynamics Group supported the investigation into the cause of the flow asymmetries with time accurate CFD simulations, utilizing a hybrid RANS-LES turbulence model. The results show that the flow over the vehicle and the subsequent interaction with the AB and ACM motor plumes were unsteady. The resulting instantaneous aerodynamic forces were oscillatory with fairly large magnitudes. Time averaged aerodynamic forces were essentially symmetric.

Deployable Emergency Shutoff Device Blocks High-Velocity Fluid Flows

NASA Technical Reports Server (NTRS)

Nabors, Sammy A.

2015-01-01

NASA's Marshall Space Flight Center has developed a device and method for blocking the flow of fluid from an open pipe. Motivated by the sea-bed oil-drilling catastrophe in the Gulf of Mexico in 2010, NASA innovators designed the device to plug, control, and meter the flow of gases and liquids. Anchored with friction fittings, spikes, or explosively activated fasteners, the device is well-suited for harsh environments and high fluid velocities and pressures. With the addition of instrumentation, it can also be used as a variable area flow metering valve that can be set based upon flow conditions. With robotic additions, this patent-pending innovation can be configured to crawl into a pipe then anchor and activate itself to block or control fluid flow.

Hydraulic jumps in inhomogeneous strongly coupled toroidal dust flows

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

Piel, Alexander, E-mail: piel@physik.uni-kiel.de; Wilms, Jochen

2016-07-15

The inhomogeneous flow of strongly coupled dust particles in a toroidal particle trap with harmonic radial confinement is analyzed in the incompressible fluid limit. It is shown that the flow can spontaneously generate shock-like events, which are similar to the hydraulic jump in open channel flows. A definition of the Froude number for this model is given and the critical speed is recovered as the group velocity of surface waves. This hydraulic model is compared with molecular-dynamics simulations, which show that a sudden bifurcation of the flow lines and a localized temperature peak appear just at the point where themore » critical condition for the hydraulic jump is located.« less

Hydrodynamic cavitation in Stokes flow of anisotropic fluids.

PubMed

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G; Sengupta, Anupam

2017-05-30

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids.

Hydrodynamic cavitation in Stokes flow of anisotropic fluids

PubMed Central

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G.; Sengupta, Anupam

2017-01-01

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids. PMID:28555615

A qualitative view of cryogenic fluid injection into high speed flows

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Schlumberger, J.; Proctor, M.

1991-01-01

The injection of supercritical pressure, subcritical temperature fluids, into a 2-D, ambient, static temperature and static pressure supersonic tunnel and free jet supersonic nitrogen flow field was observed. Observed patterns with fluid air were the same as those observed for fluid nitrogen injected into the tunnel at 90 deg to the supersonic flow. The nominal injection pressure was of 6.9 MPa and tunnel Mach number was 2.7. When injected directly into and opposing the tunnel exhaust flow, the observed patterns with fluid air were similar to those observed for fluid nitrogen but appeared more diffusive. Cryogenic injection creates a high density region within the bow shock wake but the standoff distance remains unchanged from the gaseous value. However, as the temperature reaches a critical value, the shock faded and advanced into the supersonic stream. For both fluids, nitrogen and air, the phenomena was completely reversible.

Hydrodynamic cavitation in Stokes flow of anisotropic fluids

NASA Astrophysics Data System (ADS)

Stieger, Tillmann; Agha, Hakam; Schoen, Martin; Mazza, Marco G.; Sengupta, Anupam

2017-05-01

Cavitation, the nucleation of vapour in liquids, is ubiquitous in fluid dynamics, and is often implicated in a myriad of industrial and biomedical applications. Although extensively studied in isotropic liquids, corresponding investigations in anisotropic liquids are largely lacking. Here, by combining liquid crystal microfluidic experiments, nonequilibrium molecular dynamics simulations and theoretical arguments, we report flow-induced cavitation in an anisotropic fluid. The cavitation domain nucleates due to sudden pressure drop upon flow past a cylindrical obstacle within a microchannel. For an anisotropic fluid, the inception and growth of the cavitation domain ensued in the Stokes regime, while no cavitation was observed in isotropic liquids flowing under similar hydrodynamic parameters. Using simulations we identify a critical value of the Reynolds number for cavitation inception that scales inversely with the order parameter of the fluid. Strikingly, the critical Reynolds number for anisotropic fluids can be 50% lower than that of isotropic fluids.

Microbial community structure across fluid gradients in the Juan de Fuca Ridge hydrothermal system.

PubMed

Anderson, Rika E; Beltrán, Mónica Torres; Hallam, Steven J; Baross, John A

2013-02-01

Physical and chemical gradients are dominant factors in shaping hydrothermal vent microbial ecology, where archaeal and bacterial habitats encompass a range between hot, reduced hydrothermal fluid and cold, oxidized seawater. To determine the impact of these fluid gradients on microbial communities inhabiting these systems, we surveyed bacterial and archaeal community structure among and between hydrothermal plumes, diffuse flow fluids, and background seawater in several hydrothermal vent sites on the Juan de Fuca Ridge using 16S rRNA gene diversity screening (clone libraries and terminal restriction length polymorphisms) and quantitative polymerase chain reaction methods. Community structure was similar between hydrothermal plumes and background seawater, where a number of taxa usually associated with low-oxygen zones were observed, whereas high-temperature diffuse fluids exhibited a distinct phylogenetic profile. SUP05 and Arctic96BD-19 sulfur-oxidizing bacteria were prevalent in all three mixing regimes where they exhibited overlapping but not identical abundance patterns. Taken together, these results indicate conserved patterns of redox-driven niche partitioning between hydrothermal mixing regimes and microbial communities associated with sinking particles and oxygen-deficient waters. Moreover, the prevalence of SUP05 and Arctic96BD-19 in plume and diffuse flow fluids indicates a more cosmopolitan role for these groups in the ecology and biogeochemistry of the dark ocean. © 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

Morphogenetic Implications of Peristalsis-Driven Fluid Flow in the Embryonic Lung

PubMed Central

Bokka, Kishore K.; Jesudason, Edwin C.; Lozoya, Oswaldo A.; Guilak, Farshid; Warburton, David; Lubkin, Sharon R.

2015-01-01

Epithelial organs are almost universally secretory. The lung secretes mucus of extremely variable consistency. In the early prenatal period, the secretions are of largely unknown composition, consistency, and flow rates. In addition to net outflow from secretion, the embryonic lung exhibits transient reversing flows from peristalsis. Airway peristalsis (AP) begins as soon as the smooth muscle forms, and persists until birth. Since the prenatal lung is liquid-filled, smooth muscle action can transport fluid far from the immediately adjacent tissues. The sensation of internal fluid flows has been shown to have potent morphogenetic effects, as has the transport of morphogens. We hypothesize that these effects play an important role in lung morphogenesis. To test these hypotheses in a quantitative framework, we analyzed the fluid-structure interactions between embryonic tissues and lumen fluid resulting from peristaltic waves that partially occlude the airway. We found that if the airway is closed, fluid transport is minimal; by contrast, if the trachea is open, shear rates can be very high, particularly at the stenosis. We performed a parametric analysis of flow characteristics' dependence on tissue stiffnesses, smooth muscle force, geometry, and fluid viscosity, and found that most of these relationships are governed by simple ratios. We measured the viscosity of prenatal lung fluid with passive bead microrheology. This paper reports the first measurements of the viscosity of embryonic lung lumen fluid. In the range tested, lumen fluid can be considered Newtonian, with a viscosity of 0.016 ± 0.008 Pa-s. We analyzed the interaction between the internal flows and diffusion and conclude that AP has a strong effect on flow sensing away from the tip and on transport of morphogens. These effects may be the intermediate mechanisms for the enhancement of branching seen in occluded embryonic lungs. PMID:26147967

The fluid dynamics of the chocolate fountain

NASA Astrophysics Data System (ADS)

Townsend, Adam K.; Wilson, Helen J.

2016-01-01

We consider the fluid dynamics of the chocolate fountain. Molten chocolate is a mildly shear-thinning non-Newtonian fluid. Dividing the flow into three main domains—the pumped flow up the centre, the film flow over each dome, and the freely falling curtain flow between the domes—we generate a wide-ranging study of Newtonian and non-Newtonian fluid mechanics. The central pumped flow is a benchmark to elucidate the effects of shear-thinning. The dome flow can be modelled as a thin-film flow with the leading-order effects being a simple balance of gravity and viscosity. Finally, the curtain flow is analytically intractable but is related to the existing theory of water bells (both inviscid and viscous). In pipe flow, Newtonian fluids exhibit a parabolic velocity profile; shear-thinning makes the profile more blunted. In thin-film flow over the dome, gravitational and viscous effects balance and the dome shape is not important beyond the local slope. We find that the chocolate thins and slows down as it travels down the dome. Finally, in the curtain flow, we predict the shape of the falling sheet for an inviscid fluid, and compare this with the literature to predict the shape for a viscous fluid, having shown that viscous forces are too great to ignore. We also find that the primary effect driving the shape of the curtain (which falls inwards towards the axis of the fountain) is surface tension. We find that the three domains provide excellent introductions to non-Newtonian mechanics, the important mathematical technique of scaling, and how to manipulate existing data to make our own predictions. We also find that the topic generates interest among the public in our engagement work.

Stability of miscible core?annular flows with viscosity stratification

NASA Astrophysics Data System (ADS)

Selvam, B.; Merk, S.; Govindarajan, Rama; Meiburg, E.

The linear stability of variable viscosity, miscible core-annular flows is investigated. Consistent with pipe flow of a single fluid, the flow is stable at any Reynolds number when the magnitude of the viscosity ratio is less than a critical value. This is in contrast to the immiscible case without interfacial tension, which is unstable at any viscosity ratio. Beyond the critical value of the viscosity ratio, the flow can be unstable even when the more viscous fluid is in the core. This is in contrast to plane channel flows with finite interface thickness, which are always stabilized relative to single fluid flow when the less viscous fluid is in contact with the wall. If the more viscous fluid occupies the core, the axisymmetric mode usually dominates over the corkscrew mode. It is demonstrated that, for a less viscous core, the corkscrew mode is inviscidly unstable, whereas the axisymmetric mode is unstable for small Reynolds numbers at high Schmidt numbers. For the parameters under consideration, the switchover occurs at an intermediate Schmidt number of about 500. The occurrence of inviscid instability for the corkscrew mode is shown to be consistent with the Rayleigh criterion for pipe flows. In some parameter ranges, the miscible flow is seen to be more unstable than its immiscible counterpart, and the physical reasons for this behaviour are discussed.A detailed parametric study shows that increasing the interface thickness has a uniformly stabilizing effect. The flow is least stable when the interface between the two fluids is located at approximately 0.6 times the tube radius. Unlike for channel flow, there is no sudden change in the stability with radial location of the interface. The instability originates mainly in the less viscous fluid, close to the interface.

Intrinsic particle-induced lateral transport in microchannels

PubMed Central

Amini, Hamed; Sollier, Elodie; Weaver, Westbrook M.; Di Carlo, Dino

2012-01-01

In microfluidic systems at low Reynolds number, the flow field around a particle is assumed to maintain fore-aft symmetry, with fluid diverted by the presence of a particle, returning to its original streamline downstream. This current model considers particles as passive components of the system. However, we demonstrate that at finite Reynolds number, when inertia is taken into consideration, particles are not passive elements in the flow but significantly disturb and modify it. In response to the flow field, particles translate downstream while rotating. The combined effect of the flow of fluid around particles, particle rotation, channel confinement (i.e., particle dimensions approaching those of the channel), and finite fluid inertia creates a net recirculating flow perpendicular to the primary flow direction within straight channels that resembles the well-known Dean flow in curved channels. Significantly, the particle generating this flow remains laterally fixed as it translates downstream and only the fluid is laterally transferred. Therefore, as the particles remain inertially focused, operations can be performed around the particles in a way that is compatible with downstream assays such as flow cytometry. We apply this particle-induced transfer to perform fluid switching and mixing around rigid microparticles as well as deformable cells. This transport phenomenon, requiring only a simple channel geometry with no external forces to operate, offers a practical approach for fluid transfer at high flow rates with a wide range of applications, including sample preparation, flow reaction, and heat transfer. PMID:22761309

Fast intraslab fluid-flow events linked to pulses of high pore fluid pressure at the subducted plate interface

NASA Astrophysics Data System (ADS)

Taetz, Stephan; John, Timm; Bröcker, Michael; Spandler, Carl; Stracke, Andreas

2018-01-01

A better understanding of the subduction zone fluid cycle and its chemical-mechanical feedback requires in-depth knowledge about how fluids flow within and out of descending slabs. Relicts of fluid-flow systems in exhumed rocks of fossil subduction zones allow for identification of the general relationships between dehydration reactions, fluid pathway formation, the dimensions and timescales of distinct fluid flow events; all of which are required for quantitative models for fluid-induced subduction zone processes. Two types of garnet-quartz-phengite veins can be distinguished in an eclogite-facies mélange block from the Pouébo Eclogite Mélange, New Caledonia. These veins record synmetamorphic internal fluid release by mineral breakdown reactions (type I veins), and infiltration of an external fluid (type II veins) with the associated formation of a reaction selvage. The dehydration and fluid migration documented by the type I veins likely occurred on a timescale of 105-106 years, based on average subduction rates and metamorphic conditions required for mineral dehydration and fluid flow. The timeframe of fluid-rock interaction between the external fluid and the wall-rock of the type II veins is quantified using a continuous bulk-rock Li-diffusion profile perpendicular to a vein and its metasomatic selvage. Differences in Li concentration between the internal and external fluid reservoirs resulted in a distinct diffusion profile (decreasing Li concentration and increasing δ7 Li) as the reaction front propagated into the host rock. Li-chronometric constraints indicate that the timescales of fluid-rock interaction associated with type II vein formation are on the order of 1 to 4 months (0.150-0.08+0.14 years). The short-lived, pulse-like character of this process is consistent with the notion that fluid flow caused by oceanic crust dehydration at the blueschist-to-eclogite transition contributes to or even dominates episodic pore fluid pressure increases at the plate interface, which in turn, may trigger slip events reported from many subduction zones.

On the connection between Maximum Drag Reduction and Newtonian fluid flow

NASA Astrophysics Data System (ADS)

Whalley, Richard; Park, Jae-Sung; Kushwaha, Anubhav; Dennis, David; Graham, Michael; Poole, Robert

2014-11-01

To date, the most successful turbulence control technique is the dissolution of certain rheology-modifying additives in liquid flows, which results in a universal maximum drag reduction (MDR) asymptote. The MDR asymptote is a well-known phenomenon in the turbulent flow of complex fluids; yet recent direct numerical simulations of Newtonian fluid flow have identified time intervals showing key features of MDR. These intervals have been termed ``hibernating turbulence'' and are a weak turbulence state which is characterised by low wall-shear stress and weak vortical flow structures. Here, in this experimental investigation, we monitor the instantaneous wall-shear stress in a fully-developed turbulent channel flow of a Newtonian fluid with a hot-film probe whilst simultaneously measuring the streamwise velocity at various distances above the wall with laser Doppler velocimetry. We show, by conditionally sampling the streamwise velocity during low wall-shear stress events, that the MDR velocity profile is approached in an additive-free, Newtonian fluid flow. This result corroborates recent numerical investigations, which suggest that the MDR asymptote in polymer solutions is closely connected to weak, transient Newtonian flow structures.

Hydrodynamic interaction of two deformable drops in confined shear flow.

PubMed

Chen, Yongping; Wang, Chengyao

2014-09-01

We investigate hydrodynamic interaction between two neutrally buoyant circular drops in a confined shear flow based on a computational fluid dynamics simulation using the volume-of-fluid method. The rheological behaviors of interactive drops and the flow regimes are explored with a focus on elucidation of underlying physical mechanisms. We find that two types of drop behaviors during interaction occur, including passing-over motion and reversing motion, which are governed by the competition between the drag of passing flow and the entrainment of reversing flow in matrix fluid. With the increasing confinement, the drop behavior transits from the passing-over motion to reversing motion, because the entrainment of the reversing-flow matrix fluid turns to play the dominant role. The drag of the ambient passing flow is increased by enlarging the initial lateral separation due to the departure of the drop from the reversing flow in matrix fluid, resulting in the emergence of passing-over motion. In particular, a corresponding phase diagram is plotted to quantitatively illustrate the dependence of drop morphologies during interaction on confinement and initial lateral separation.

Fluid Flow Characteristics and Porosity Behavior in Full Penetration Laser Welding of a Titanium Alloy

NASA Astrophysics Data System (ADS)

Chang, Baohua; Allen, Chris; Blackburn, Jon; Hilton, Paul; Du, Dong

2015-04-01

In this paper, a computational fluid mechanics model is developed for full penetration laser welding of titanium alloy Ti6Al4V. This has been used to analyze possible porosity formation mechanisms, based on predictions of keyhole behavior and fluid flow characteristics in the weld pool. Numerical results show that when laser welding 3 mm thickness titanium alloy sheets with given laser beam focusing optics, keyhole depth oscillates before a full penetration keyhole is formed, but thereafter keyhole collapses are not predicted numerically. For lower power, lower speed welding, the fluid flow behind the keyhole is turbulent and unstable, and vortices are formed. Molten metal is predicted to flow away from the center plane of the weld pool, and leave a gap or void within the weld pool behind the keyhole. For higher power, higher speed welding, fluid flow is less turbulent, and such vortices are not formed. Corresponding experimental results show that porosity was absent in the melt runs made at higher power and higher welding speed. In contrast, large pores were present in melt runs made at lower power and lower welding speed. Based on the combination of experimental results and numerical predictions, it is proposed that porosity formation when keyhole laser welding may result from turbulent fluid flow behind the keyhole, with the larger the value of associated Reynolds number, the higher the possibility of porosity formation. For such fluid flow controlled porosities, measures to decrease Reynolds number of the fluid flow close to the keyhole could prove effective in reducing or avoiding porosity.

Influence of the shaft rotation on the stability of magnetic fluid shaft seal characteristics

NASA Astrophysics Data System (ADS)

Krakov, M. S.; Nikiforov, I. V.

2008-12-01

Distribution of the magnetic particles concentration in a magnetic fluid shaft seal is studied numerically for a rotating shaft. It is revealed that the shaft rotation causes not only an azimuthal flow of the magnetic fluid, but a meridional flow as well. This meridional flow prevents the growth of magnetic particle concentration in the gap of the magnetic fluid shaft seal. As a result, the burst pressure of the magnetic fluid shaft seal for the rotating shaft is stable and does not change with time. Figs 6, Refs 7.

COMPARING SIMULATED AND EXPERIMENTAL HYSTERETIC TWO- PHASE TRANSIENT FLUID FLOW PHENOMENA

EPA Science Inventory

A hysteretic model for two-phase permeability (k)-saturation (S)-pressure (P) relations is outlined that accounts for effects of nonwetting fluid entrapment. The model can be employed in unsaturated fluid flow computer codes to predict temporal and spatial fluid distributions. Co...

Lox breathing system with gas permeable-liquid impermeable heat exchange and delivery hose

DOEpatents

Hall, Mark N.

1996-01-01

Life support apparatus composed of: a garment (2): for completely enclosing a wearer and constructed for preventing passage of gas from the environment surrounding the garment (2); a portable receptacle (6) holding a quantity of an oxygen-containing fluid in liquid state, the fluid being in a breathable gaseous; state when at standard temperature and pressure; a fluid flow member (16) secured within the garment (2) and coupled to the receptacle (6) for conducting the fluid in liquid state from the receptacle (6) to the interior of the garment (2); and a fluid flow control device (14) connected for causing fluid to flow from the receptacle (6) to the fluid flow member (16) at a rate determined by the breathable air requirement of the wearer, wherein fluid in liquid state is conducted into the interior of the garment (2) at a rate to be vaporized and heated to a breathable temperature by body heat produced by the wearer.

Fluid flow stimulates rapid and continuous release of nitric oxide in osteoblasts

NASA Technical Reports Server (NTRS)

Johnson, D. L.; McAllister, T. N.; Frangos, J. A.

1996-01-01

Interstitial fluid flow may mediate skeletal remodeling in response to mechanical loading. Because nitric oxide (NO) has been shown to be an osteoblast mitogen and inhibitor of osteoclastic resorption, we investigated and characterized the role of fluid shear on the release of NO in osteoblasts. Rat calvarial cells in a stationary culture produced undetectable levels of NO. Fluid shear stress (6 dyn/cm2) rapidly increased NO release rate to 9.8 nmol.h-1.mg protein-1 and sustained this production for 12 h of exposure to flow. Cytokine treatment also induced NO synthesis after a 12-h lag phase of zero production, followed by a production rate of 0.6 nmol.h-1.mg protein-1. Flow-induced NO production was blocked by the NO synthase (NOS) inhibitor NG-amino-L-arginine, but not by dexamethasone, which suggests that the flow stimulated a constitutive NOS isoform. This is the first time that a functional constitutively present NOS isoform has been identified in osteoblasts. Moreover, fluid flow represents the most potent stimulus of NO release in osteoblasts reported to date. Fluid flow-induced NO production may therefore play a primary role in bone maintenance and remodeling.

Flow over a membrane-covered, fluid-filled cavity.

PubMed

Thomson, Scott L; Mongeau, Luc; Frankel, Steven H

2007-01-01

The flow-induced response of a membrane covering a fluid-filled cavity located in a section of a rigid-walled channel was explored using finite element analysis. The membrane was initially aligned with the channel wall and separated the channel fluid from the cavity fluid. As fluid flowed over the membrane-covered cavity, a streamwise-dependent transmural pressure gradient caused membrane deformation. This model has application to synthetic models of the vocal fold cover layer used in voice production research. In this paper, the model is introduced and responses of the channel flow, the membrane, and the cavity flow are summarized for a range of flow and membrane parameters. It is shown that for high values of cavity fluid viscosity, the intracavity pressure and the beam deflection both reached steady values. For combinations of low cavity viscosity and sufficiently large upstream pressures, large-amplitude membrane vibrations resulted. Asymmetric conditions were introduced by creating cavities on opposing sides of the channel and assigning different stiffness values to the two membranes. The asymmetry resulted in reduction in or cessation of vibration amplitude, depending on the degree of asymmetry, and in significant skewing of the downstream flow field.

Ultrasonic Fluid Quality Sensor System

DOEpatents

Gomm, Tyler J.; Kraft, Nancy C.; Phelps, Larry D.; Taylor, Steven C.

2003-10-21

A system for determining the composition of a multiple-component fluid and for determining linear flow comprising at least one sing-around circuit that determines the velocity of a signal in the multiple-component fluid and that is correlatable to a database for the multiple-component fluid. A system for determining flow uses two of the inventive circuits, one of which is set at an angle that is not perpendicular to the direction of flow.

Ultrasonic fluid quality sensor system

DOEpatents

Gomm, Tyler J.; Kraft, Nancy C.; Phelps, Larry D.; Taylor, Steven C.

2002-10-08

A system for determining the composition of a multiple-component fluid and for determining linear flow comprising at least one sing-around circuit that determines the velocity of a signal in the multiple-component fluid and that is correlatable to a database for the multiple-component fluid. A system for determining flow uses two of the inventive circuits, one of which is set at an angle that is not perpendicular to the direction of flow.

Reduced viscosity interpreted for fluid/gas mixtures

NASA Technical Reports Server (NTRS)

Lewis, D. H.

1981-01-01

Analysis predicts decrease in fluid viscosity by comparing pressure profile of fluid/gas mixture with that of power-law fluid. Fluid is taken to be viscous, non-Newtonian, and incompressible; the gas to be ideal; the flow to be inertia-free, isothermal, and one dimensional. Analysis assists in design of flow systems for petroleum, coal, polymers, and other materials.

Network-Theoretic Modeling of Fluid Flow

DTIC Science & Technology

2015-07-29

Final Report STIR: Network-Theoretic Modeling of Fluid Flow ARO Grant W911NF-14-1-0386 Program manager: Dr. Samuel Stanton ( August 1, 2014–April 30...Morzyński, M., and Comte , P., “A finite-time thermodynamics of unsteady fluid flows,” Journal of Non-Equilibrium Thermody- namics, Vol. 33, No. 2

Apparatus and method for aerodynamic levitation

NASA Technical Reports Server (NTRS)

Williamson, John W. (Inventor); al-Darwish, Mohamad M. (Inventor); Cashen, Grant E. (Inventor)

1993-01-01

An apparatus for the levitation of a liquid drop by a fluid flow comprising a profile generator, a fluid flow supply means operatively connected to the profile generator. The profile generator includes an elongate cylindrical shell in which is contained a profiling means for configuring the velocity profile of the fluid flow exiting the profile generator.

Ultrasonic velocity profiling rheometry based on a widened circular Couette flow

NASA Astrophysics Data System (ADS)

Shiratori, Takahisa; Tasaka, Yuji; Oishi, Yoshihiko; Murai, Yuichi

2015-08-01

We propose a new rheometry for characterizing the rheological properties of fluids. The technique produces flow curves, which represent the relationship between the fluid shear rate and shear stress. Flow curves are obtained by measuring the circumferential velocity distribution of tested fluids in a circular Couette system, using an ultrasonic velocity profiling technique. By adopting a widened gap of concentric cylinders, a designed range of the shear rate is obtained so that velocity profile measurement along a single line directly acquires flow curves. To reduce the effect of ultrasonic noise on resultant flow curves, several fitting functions and variable transforms are examined to best approximate the velocity profile without introducing a priori rheological models. Silicone oil, polyacrylamide solution, and yogurt were used to evaluate the applicability of this technique. These substances are purposely targeted as examples of Newtonian fluids, shear thinning fluids, and opaque fluids with unknown rheological properties, respectively. We find that fourth-order Chebyshev polynomials provide the most accurate representation of flow curves in the context of model-free rheometry enabled by ultrasonic velocity profiling.

Effects of variable properties on MHD heat and mass transfer flow near a stagnation point towards a stretching sheet in a porous medium with thermal radiation

NASA Astrophysics Data System (ADS)

M. Salem, A.; Rania, Fathy

2012-05-01

The effect of variable viscosity and thermal conductivity on steady magnetohydrodynamic (MHD) heat and mass transfer flow of viscous and incompressible fluid near a stagnation point towards a permeable stretching sheet embedded in a porous medium are presented, taking into account thermal radiation and internal heat genberation/absorbtion. The stretching velocity and the ambient fluid velocity are assumed to vary linearly with the distance from the stagnation point. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing fundamental equations are first transformed into a system of ordinary differential equations using a scaling group of transformations and are solved numerically by using the fourth-order Rung—Kutta method with the shooting technique. A comparison with previously published work has been carried out and the results are found to be in good agreement. The results are analyzed for the effect of different physical parameters, such as the variable viscosity and thermal conductivity, the ratio of free stream velocity to stretching velocity, the magnetic field, the porosity, the radiation and suction/injection on the flow, and the heat and mass transfer characteristics. The results indicate that the inclusion of variable viscosity and thermal conductivity into the fluids of light and medium molecular weight is able to change the boundary-layer behavior for all values of the velocity ratio parameter λ except for λ = 1. In addition, the imposition of fluid suction increases both the rate of heat and mass transfer, whereas fluid injection shows the opposite effect.

Numerical schemes for anomalous diffusion of single-phase fluids in porous media

NASA Astrophysics Data System (ADS)

Awotunde, Abeeb A.; Ghanam, Ryad A.; Al-Homidan, Suliman S.; Tatar, Nasser-eddine

2016-10-01

Simulation of fluid flow in porous media is an indispensable part of oil and gas reservoir management. Accurate prediction of reservoir performance and profitability of investment rely on our ability to model the flow behavior of reservoir fluids. Over the years, numerical reservoir simulation models have been based mainly on solutions to the normal diffusion of fluids in the porous reservoir. Recently, however, it has been documented that fluid flow in porous media does not always follow strictly the normal diffusion process. Small deviations from normal diffusion, called anomalous diffusion, have been reported in some experimental studies. Such deviations can be caused by different factors such as the viscous state of the fluid, the fractal nature of the porous media and the pressure pulse in the system. In this work, we present explicit and implicit numerical solutions to the anomalous diffusion of single-phase fluids in heterogeneous reservoirs. An analytical solution is used to validate the numerical solution to the simple homogeneous case. The conventional wellbore flow model is modified to account for anomalous behavior. Example applications are used to show the behavior of wellbore and wellblock pressures during the single-phase anomalous flow of fluids in the reservoirs considered.

On the determination of a generalized Darcy equation for yield stress fluid in porous media using a LB TRT scheme

NASA Astrophysics Data System (ADS)

Talon, Laurent; Chevalier, Thibaud

2014-11-01

Non-Newtonian fluids have practical applications in very different domains. Indeed, polymer mixture, paints, slurries, colloidal suspensions, emulsions, foams or heavy oil present complex rheologies. Among the large number of different non-Newtonian fluids an important class of behavior is represented by the yield-stress fluids, viz. fluids that require a minimum of stress to flow. Yield stress fluids are usually modelled as a Bingham fluid or by the Herschel-Bulkley equation. However, simulating flow of a Bingham fluid in porous media still remains a challenging task as the yield stress may significantly alter the numerical stability and precision. In the present work, we use a Lattice-Boltzmann TRT scheme to determine this type of flow in a synthetic porous medium or fracture. Different pressure drops ΔP have been applied in order to derive a generalization of the Darcy's equation. Three different scaling regimes can be distinguished when plotting the dimensionless flow rate q as function of the distance to the critical pressure ΔP - ΔPc . In this presentation, we will investigate the importance of the heterogeneities on those flowing regimes. ANR-12-MONU-0011.

A Theoretical and Experimental Study for a Developing Flow in a Thin Fluid Gap

NASA Astrophysics Data System (ADS)

Wu, Qianhong; Lang, Ji; Jen, Kei-Peng; Nathan, Rungun; Vucbmss Team

2016-11-01

In this paper, we report a novel theoretical and experimental approach to examine a fast developing flow in a thin fluid gap. Although the phenomena are widely observed in industrial applications and biological systems, there is a lack of analytical approach that captures the instantaneous fluid response to a sudden impact. An experimental setup was developed that contains a piston instrumented with a laser displacement sensor and a pressure transducer. A sudden impact was imposed on the piston, creating a fast compaction on the thin fluid gap underneath. The motion of the piston was captured by the laser displacement sensor, and the fluid pressure build-up and relaxation was recorded by the pressure transducer. For this dynamic process, a novel analytical approach was developed. It starts with the inviscid limit when the viscous fluid effect has no time to appear. This short process is followed by a developing flow, in which the inviscid core flow region decreases and the viscous wall region increases until the entire fluid gap is filled with viscous fluid flow. A boundary layer integral method is used during the process. Lastly, the flow is completely viscous dominant featured by a typical squeeze flow in a thin gap. Excellent agreement between the theory and the experiment was achieved. The study presented herein, filling the gap in the literature, will have broad impact in industrial and biomedical applications. This research was supported by the National Science Foundation under Award #1511096.

Conjugate Compressible Fluid Flow and Heat Transfer in Ducts

NASA Technical Reports Server (NTRS)

Cross, M. F.

2011-01-01

A computational approach to modeling transient, compressible fluid flow with heat transfer in long, narrow ducts is presented. The primary application of the model is for analyzing fluid flow and heat transfer in solid propellant rocket motor nozzle joints during motor start-up, but the approach is relevant to a wide range of analyses involving rapid pressurization and filling of ducts. Fluid flow is modeled through solution of the spatially one-dimensional, transient Euler equations. Source terms are included in the governing equations to account for the effects of wall friction and heat transfer. The equation solver is fully-implicit, thus providing greater flexibility than an explicit solver. This approach allows for resolution of pressure wave effects on the flow as well as for fast calculation of the steady-state solution when a quasi-steady approach is sufficient. Solution of the one-dimensional Euler equations with source terms significantly reduces computational run times compared to general purpose computational fluid dynamics packages solving the Navier-Stokes equations with resolved boundary layers. In addition, conjugate heat transfer is more readily implemented using the approach described in this paper than with most general purpose computational fluid dynamics packages. The compressible flow code has been integrated with a transient heat transfer solver to analyze heat transfer between the fluid and surrounding structure. Conjugate fluid flow and heat transfer solutions are presented. The author is unaware of any previous work available in the open literature which uses the same approach described in this paper.

Stagnation point flow of wormlike micellar solutions in a microfluidic cross-slot device: effects of surfactant concentration and ionic environment.

PubMed

Haward, Simon J; McKinley, Gareth H

2012-03-01

We employ the techniques of microparticle image velocimetry and full-field birefringence microscopy combined with mechanical measurements of the pressure drop to perform a detailed characterization of the extensional rheology and elastic flow instabilities observed for a range of wormlike micellar solutions flowing through a microfluidic cross-slot device. As the flow rate through the device is increased, the flow first bifurcates from a steady symmetric to a steady asymmetric configuration characterized by a birefringent strand of highly aligned micellar chains oriented along the shear-free centerline of the flow field. At higher flow rates the flow becomes three dimensional and time dependent and is characterized by aperiodic spatiotemporal fluctuations of the birefringent strand. The extensional properties and critical conditions for the onset of flow instabilities in the fluids are highly dependent on the fluid formulation (surfactant concentration and ionic strength) and the resulting changes in the linear viscoelasticity and nonlinear shear rheology of the fluids. By combining the measurements of critical conditions for the flow transitions with the viscometric material properties and the degree of shear-thinning characterizing each test fluid, it is possible to construct a stability diagram for viscoelastic flow of complex fluids in the cross-slot geometry.

Fluid displacement during droplet formation at microfluidic flow-focusing junctions.

PubMed

Huang, Haishui; He, Xiaoming

2015-11-07

Microdroplets and microcapsules have been widely produced using microfluidic flow-focusing junctions for biomedical and chemical applications. However, the multiphase microfluidic flow at the flow-focusing junction has not been well investigated. In this study, the displacement of two (core and shell) aqueous fluids that disperse into droplets altogether in a carrier oil emulsion was investigated both numerically and experimentally. It was found that extensive displacement of the two aqueous fluids within the droplet during its formation could occur as a result of the shear effect of the carrier fluid and the capillary effect of interfacial tension. We further identified that the two mechanisms of fluid displacement can be evaluated by two dimensionless parameters. The quantitative relationship between the degree of fluid displacement and these two dimensionless parameters was determined experimentally. Finally, we demonstrated that the degree of fluid displacement could be controlled to generate hydrogel microparticles of different morphologies using planar or nonplanar flow-focusing junctions. These findings should provide useful guidance to the microfluidic production of microscale droplets or capsules for various biomedical and chemical applications.

System and method for improving performance of a fluid sensor for an internal combustion engine

DOEpatents

Kubinski, David [Canton, MI; Zawacki, Garry [Livonia, MI

2009-03-03

A system and method for improving sensor performance of an on-board vehicle sensor, such as an exhaust gas sensor, while sensing a predetermined substance in a fluid flowing through a pipe include a structure for extending into the pipe and having at least one inlet for receiving fluid flowing through the pipe and at least one outlet generally opposite the at least one inlet, wherein the structure redirects substantially all fluid flowing from the at least one inlet to the sensor to provide a representative sample of the fluid to the sensor before returning the fluid through the at least one outlet.

Computational fluid dynamics applications to improve crop production systems

USDA-ARS?s Scientific Manuscript database

Computational fluid dynamics (CFD), numerical analysis and simulation tools of fluid flow processes have emerged from the development stage and become nowadays a robust design tool. It is widely used to study various transport phenomena which involve fluid flow, heat and mass transfer, providing det...

Fuel cell membrane hydration and fluid metering

DOEpatents

Jones, Daniel O.; Walsh, Michael M.

2003-01-01

A hydration system includes fuel cell fluid flow plate(s) and injection port(s). Each plate has flow channel(s) with respective inlet(s) for receiving respective portion(s) of a given stream of reactant fluid for a fuel cell. Each injection port injects a portion of liquid water directly into its respective flow channel. This serves to hydrate at least corresponding part(s) of a given membrane of the corresponding fuel cell(s). The hydration system may be augmented by a metering system including flow regulator(s). Each flow regulator meters an injecting at inlet(s) of each plate of respective portions of liquid into respective portion(s) of a given stream of fluid by corresponding injection port(s).

Real-Time Maps of Fluid Flow Fields in Porous Biomaterials

PubMed Central

Mack, Julia J.; Youssef, Khalid; Noel, Onika D.V.; Lake, Michael P.; Wu, Ashley; Iruela-Arispe, M. Luisa; Bouchard, Louis-S.

2013-01-01

Mechanical forces such as fluid shear have been shown to enhance cell growth and differentiation, but knowledge of their mechanistic effect on cells is limited because the local flow patterns and associated metrics are not precisely known. Here we present real-time, noninvasive measures of local hydrodynamics in 3D biomaterials based on nuclear magnetic resonance. Microflow maps were further used to derive pressure, shear and fluid permeability fields. Finally, remodeling of collagen gels in response to precise fluid flow parameters was correlated with structural changes. It is anticipated that accurate flow maps within 3D matrices will be a critical step towards understanding cell behavior in response to controlled flow dynamics. PMID:23245922

One-group interfacial area transport in vertical air-water bubbly flow

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

Wu, Q.; Kim, S.; Ishii, M.

In the two-fluid model for two-phase flows, interfacial area concentration is one of the most important closure relations that should be obtained from careful mechanistic modeling. The objective of this study is to develop a one-group interfacial area transport equation together with the modeling of the source and sink terms due to bubble breakage and coalescence. For bubble coalescence, two mechanisms are considered to be dominant in vertical two-phase bubbly flow. These are the random collisions between bubbles due to turbulence in the flow field, and the wake entrainment process due to the relative motion of the bubbles in themore » wake region of a seeding bubble. For bubble breakup, the impact of turbulent eddies is considered. These phenomena are modeled individually, resulting in a one-group interfacial area concentration transport equation with certain parameters to be determined from experimental data. Compared to the measured axial distribution of the interfacial area concentration under various flow conditions, these parameters are obtained for the reduced one-group, one-dimensional transport equation. The results indicate that the proposed models for bubble breakup and coalescence are appropriate.« less

Intravenous fluid flow meter concept for zero gravity environment

NASA Technical Reports Server (NTRS)

Miller, C. G.

1972-01-01

Measuring chamber, included in infusion-set tubing, and peristaltic flow meter concept can be incorporated into flow meter that measures fluid flow rates between 100 and 600 cu cm per hour and at the same time maintains sterilization.

Thermal transient anemometer

DOEpatents

Bailey, J.L.; Vresk, J.

1989-07-18

A thermal transient anemometer is disclosed having a thermocouple probe which is utilized to measure the change in temperature over a period of time to provide a measure of fluid flow velocity. The thermocouple probe is located in the fluid flow path and pulsed to heat or cool the probe. The cooling of the heated probe or the heating of the cooled probe from the fluid flow over a period of time is measured to determine the fluid flow velocity. The probe is desired to be locally heated near the tip to increase the efficiency of devices incorporating the probe. 12 figs.

Verification of capillary pressure functions and relative permeability equations for gas production

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

Jang, Jaewon

The understanding of multiphase fluid flow in porous media is of great importance in many fields such as enhanced oil recovery, hydrology, CO 2 sequestration, contaminants cleanup and natural gas production from hydrate bearing sediments. However, there are many unanswered questions about the key parameters that characterize gas and water flows in porous media. The characteristics of multiphase fluid flow in porous media such as water retention curve, relative permeability, preferential fluid flow patterns and fluid-particle interaction should be taken into consideration for a fundamental understanding of the behavior of pore scale systems.

Self-similarity in incompressible Navier-Stokes equations.

PubMed

Ercan, Ali; Kavvas, M Levent

2015-12-01

The self-similarity conditions of the 3-dimensional (3D) incompressible Navier-Stokes equations are obtained by utilizing one-parameter Lie group of point scaling transformations. It is found that the scaling exponents of length dimensions in i = 1, 2, 3 coordinates in 3-dimensions are not arbitrary but equal for the self-similarity of 3D incompressible Navier-Stokes equations. It is also shown that the self-similarity in this particular flow process can be achieved in different time and space scales when the viscosity of the fluid is also scaled in addition to other flow variables. In other words, the self-similarity of Navier-Stokes equations is achievable under different fluid environments in the same or different gravity conditions. Self-similarity criteria due to initial and boundary conditions are also presented. Utilizing the proposed self-similarity conditions of the 3D hydrodynamic flow process, the value of a flow variable at a specified time and space can be scaled to a corresponding value in a self-similar domain at the corresponding time and space.

The physics of debris flows

NASA Astrophysics Data System (ADS)

Iverson, Richard M.

1997-08-01

Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ˜10 m³ of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate permeability of the debris. Realistic models of debris flows therefore require equations that simulate inertial motion of surges in which high-resistance fronts dominated by solid forces impede the motion of low-resistance tails more strongly influenced by fluid forces. Furthermore, because debris flows characteristically originate as nearly rigid sediment masses, transform at least partly to liquefied flows, and then transform again to nearly rigid deposits, acceptable models must simulate an evolution of material behavior without invoking preternatural changes in material properties. A simple model that satisfies most of these criteria uses depth-averaged equations of motion patterned after those of the Savage-Hutter theory for gravity-driven flow of dry granular masses but generalized to include the effects of viscous pore fluid with varying pressure. These equations can describe a spectrum of debris flow behaviors intermediate between those of wet rock avalanches and sediment-laden water floods. With appropriate pore pressure distributions the equations yield numerical solutions that successfully predict unsteady, nonuniform motion of experimental debris flows.

The physics of debris flows

USGS Publications Warehouse

Iverson, R.M.

1997-01-01

Recent advances in theory and experimentation motivate a thorough reassessment of the physics of debris flows. Analyses of flows of dry, granular solids and solid-fluid mixtures provide a foundation for a comprehensive debris flow theory, and experiments provide data that reveal the strengths and limitations of theoretical models. Both debris flow materials and dry granular materials can sustain shear stresses while remaining static; both can deform in a slow, tranquil mode characterized by enduring, frictional grain contacts; and both can flow in a more rapid, agitated mode characterized by brief, inelastic grain collisions. In debris flows, however, pore fluid that is highly viscous and nearly incompressible, composed of water with suspended silt and clay, can strongly mediate intergranular friction and collisions. Grain friction, grain collisions, and viscous fluid flow may transfer significant momentum simultaneously. Both the vibrational kinetic energy of solid grains (measured by a quantity termed the granular temperature) and the pressure of the intervening pore fluid facilitate motion of grains past one another, thereby enhancing debris flow mobility. Granular temperature arises from conversion of flow translational energy to grain vibrational energy, a process that depends on shear rates, grain properties, boundary conditions, and the ambient fluid viscosity and pressure. Pore fluid pressures that exceed static equilibrium pressures result from local or global debris contraction. Like larger, natural debris flows, experimental debris flows of ???10 m3 of poorly sorted, water-saturated sediment invariably move as an unsteady surge or series of surges. Measurements at the base of experimental flows show that coarse-grained surge fronts have little or no pore fluid pressure. In contrast, finer-grained, thoroughly saturated debris behind surge fronts is nearly liquefied by high pore pressure, which persists owing to the great compressibility and moderate permeability of the debris. Realistic models of debris flows therefore require equations that simulate inertial motion of surges in which high-resistance fronts dominated by solid forces impede the motion of low-resistance tails more strongly influenced by fluid forces. Furthermore, because debris flows characteristically originate as nearly rigid sediment masses, transform at least partly to liquefied flows, and then transform again to nearly rigid deposits, acceptable models must simulate an evolution of material behavior without invoking preternatural changes in material properties. A simple model that satisfies most of these criteria uses depth-averaged equations of motion patterned after those of the Savage-Hutter theory for gravity-driven flow of dry granular masses but generalized to include the effects of viscous pore fluid with varying pressure. These equations can describe a spectrum of debris flow behaviors intermediate between those of wet rock avalanches and sediment-laden water floods. With appropriate pore pressure distributions the equations yield numerical solutions that successfully predict unsteady, nonuniform motion of experimental debris flows.

Collective fluid mechanics of honeybee nest ventilation

NASA Astrophysics Data System (ADS)

Gravish, Nick; Combes, Stacey; Wood, Robert J.; Peters, Jacob

2014-11-01

Honeybees thermoregulate their brood in the warm summer months by collectively fanning their wings and creating air flow through the nest. During nest ventilation workers flap their wings in close proximity in which wings continuously operate in unsteady oncoming flows (i.e. the wake of neighboring worker bees) and near the ground. The fluid mechanics of this collective aerodynamic phenomena are unstudied and may play an important role in the physiology of colony life. We have performed field and laboratory observations of the nest ventilation wing kinematics and air flow generated by individuals and groups of honeybee workers. Inspired from these field observations we describe here a robotic model system to study collective flapping wing aerodynamics. We microfabricate arrays of 1.4 cm long flapping wings and observe the air flow generated by arrays of two or more fanning robotic wings. We vary phase, frequency, and separation distance among wings and find that net output flow is enhanced when wings operate at the appropriate phase-distance relationship to catch shed vortices from neighboring wings. These results suggest that by varying position within the fanning array honeybee workers may benefit from collective aerodynamic interactions during nest ventilation.

Direction dependence of displacement time for two-fluid electroosmotic flow.

PubMed

Lim, Chun Yee; Lam, Yee Cheong

2012-03-01

Electroosmotic flow that involves one fluid displacing another fluid is commonly encountered in various microfludic applications and experiments, for example, current monitoring technique to determine zeta potential of microchannel. There is experimentally observed anomaly in such flow, namely, the displacement time is flow direction dependent, i.e., it depends if it is a high concentration fluid displacing a low concentration fluid, or vice versa. Thus, this investigation focuses on the displacement flow of two fluids with various concentration differences. The displacement time was determined experimentally with current monitoring method. It is concluded that the time required for a high concentration solution to displace a low concentration solution is smaller than the time required for a low concentration solution to displace a high concentration solution. The percentage displacement time difference increases with increasing concentration difference and independent of the length or width of the channel and the voltage applied. Hitherto, no theoretical analysis or numerical simulation has been conducted to explain this phenomenon. A numerical model based on finite element method was developed to explain the experimental observations. Simulations showed that the velocity profile and ion distribution deviate significantly from a single fluid electroosmotic flow. The distortion of ion distribution near the electrical double layer is responsible for the displacement time difference for the two different flow directions. The trends obtained from simulations agree with the experimental findings.

Direction dependence of displacement time for two-fluid electroosmotic flow

PubMed Central

Lim, Chun Yee; Lam, Yee Cheong

2012-01-01

Electroosmotic flow that involves one fluid displacing another fluid is commonly encountered in various microfludic applications and experiments, for example, current monitoring technique to determine zeta potential of microchannel. There is experimentally observed anomaly in such flow, namely, the displacement time is flow direction dependent, i.e., it depends if it is a high concentration fluid displacing a low concentration fluid, or vice versa. Thus, this investigation focuses on the displacement flow of two fluids with various concentration differences. The displacement time was determined experimentally with current monitoring method. It is concluded that the time required for a high concentration solution to displace a low concentration solution is smaller than the time required for a low concentration solution to displace a high concentration solution. The percentage displacement time difference increases with increasing concentration difference and independent of the length or width of the channel and the voltage applied. Hitherto, no theoretical analysis or numerical simulation has been conducted to explain this phenomenon. A numerical model based on finite element method was developed to explain the experimental observations. Simulations showed that the velocity profile and ion distribution deviate significantly from a single fluid electroosmotic flow. The distortion of ion distribution near the electrical double layer is responsible for the displacement time difference for the two different flow directions. The trends obtained from simulations agree with the experimental findings. PMID:22662083

Interstitial Fluid Flow Increases Hepatocellular Carcinoma Cell Invasion through CXCR4/CXCL12 and MEK/ERK Signaling

PubMed Central

2015-01-01

Hepatocellular carcinoma (HCC) is the most common form of liver cancer (~80%), and it is one of the few cancer types with rising incidence in the United States. This highly invasive cancer is very difficult to detect until its later stages, resulting in limited treatment options and low survival rates. There is a dearth of knowledge regarding the mechanisms associated with the effects of biomechanical forces such as interstitial fluid flow (IFF) on hepatocellular carcinoma invasion. We hypothesized that interstitial fluid flow enhanced hepatocellular carcinoma cell invasion through chemokine-mediated autologous chemotaxis. Utilizing a 3D in vitro invasion assay, we demonstrated that interstitial fluid flow promoted invasion of hepatocellular carcinoma derived cell lines. Furthermore, we showed that autologous chemotaxis influences this interstitial fluid flow-induced invasion of hepatocellular carcinoma derived cell lines via the C-X-C chemokine receptor type 4 (CXCR4)/C-X-C motif chemokine 12 (CXCL12) signaling axis. We also demonstrated that mitogen-activated protein kinase (MEK)/extracellular signal-regulated kinase (ERK) signaling affects interstitial fluid flow-induced invasion; however, this pathway was separate from CXCR4/CXCL12 signaling. This study demonstrates, for the first time, the potential role of interstitial fluid flow in hepatocellular carcinoma invasion. Uncovering the mechanisms that control hepatocellular carcinoma invasion will aid in enhancing current liver cancer therapies and provide better treatment options for patients. PMID:26560447

Dynamic fluid connectivity during steady-state multiphase flow in a sandstone.

PubMed

Reynolds, Catriona A; Menke, Hannah; Andrew, Matthew; Blunt, Martin J; Krevor, Samuel

2017-08-01

The current conceptual picture of steady-state multiphase Darcy flow in porous media is that the fluid phases organize into separate flow pathways with stable interfaces. Here we demonstrate a previously unobserved type of steady-state flow behavior, which we term "dynamic connectivity," using fast pore-scale X-ray imaging. We image the flow of N 2 and brine through a permeable sandstone at subsurface reservoir conditions, and low capillary numbers, and at constant fluid saturation. At any instant, the network of pores filled with the nonwetting phase is not necessarily connected. Flow occurs along pathways that periodically reconnect, like cars controlled by traffic lights. This behavior is consistent with an energy balance, where some of the energy of the injected fluids is sporadically converted to create new interfaces.

Cooling system for electronic components

DOEpatents

Anderl, William James; Colgan, Evan George; Gerken, James Dorance; Marroquin, Christopher Michael; Tian, Shurong

2015-12-15

Embodiments of the present invention provide for non interruptive fluid cooling of an electronic enclosure. One or more electronic component packages may be removable from a circuit card having a fluid flow system. When installed, the electronic component packages are coincident to and in a thermal relationship with the fluid flow system. If a particular electronic component package becomes non-functional, it may be removed from the electronic enclosure without affecting either the fluid flow system or other neighboring electronic component packages.

Cooling system for electronic components

DOEpatents

Anderl, William James; Colgan, Evan George; Gerken, James Dorance; Marroquin, Christopher Michael; Tian, Shurong

2016-05-17

Embodiments of the present invention provide for non interruptive fluid cooling of an electronic enclosure. One or more electronic component packages may be removable from a circuit card having a fluid flow system. When installed, the electronic component packages are coincident to and in a thermal relationship with the fluid flow system. If a particular electronic component package becomes non-functional, it may be removed from the electronic enclosure without affecting either the fluid flow system or other neighboring electronic component packages.

Parametric study of fluid flow manipulation with piezoelectric macrofiber composite flaps

NASA Astrophysics Data System (ADS)

Sadeghi, O.; Tarazaga, P.; Stremler, M.; Shahab, S.

2017-04-01

Active Fluid Flow Control (AFFC) has received great research attention due to its significant potential in engineering applications. It is known that drag reduction, turbulence management, flow separation delay and noise suppression through active control can result in significantly increased efficiency of future commercial transport vehicles and gas turbine engines. In microfluidics systems, AFFC has mainly been used to manipulate fluid passing through the microfluidic device. We put forward a conceptual approach for fluid flow manipulation by coupling multiple vibrating structures through flow interactions in an otherwise quiescent fluid. Previous investigations of piezoelectric flaps interacting with a fluid have focused on a single flap. In this work, arrays of closely-spaced, free-standing piezoelectric flaps are attached perpendicular to the bottom surface of a tank. The coupling of vibrating flaps due to their interacting with the surrounding fluid is investigated in air (for calibration) and under water. Actuated flaps are driven with a harmonic input voltage, which results in bending vibration of the flaps that can work with or against the flow-induced bending. The size and spatial distribution of the attached flaps, and the phase and frequency of the input actuation voltage are the key parameters to be investigated in this work. Our analysis will characterize the electrohydroelastic dynamics of active, interacting flaps and the fluid motion induced by the system.

Validation of model predictions of pore-scale fluid distributions during two-phase flow

NASA Astrophysics Data System (ADS)

Bultreys, Tom; Lin, Qingyang; Gao, Ying; Raeini, Ali Q.; AlRatrout, Ahmed; Bijeljic, Branko; Blunt, Martin J.

2018-05-01

Pore-scale two-phase flow modeling is an important technology to study a rock's relative permeability behavior. To investigate if these models are predictive, the calculated pore-scale fluid distributions which determine the relative permeability need to be validated. In this work, we introduce a methodology to quantitatively compare models to experimental fluid distributions in flow experiments visualized with microcomputed tomography. First, we analyzed five repeated drainage-imbibition experiments on a single sample. In these experiments, the exact fluid distributions were not fully repeatable on a pore-by-pore basis, while the global properties of the fluid distribution were. Then two fractional flow experiments were used to validate a quasistatic pore network model. The model correctly predicted the fluid present in more than 75% of pores and throats in drainage and imbibition. To quantify what this means for the relevant global properties of the fluid distribution, we compare the main flow paths and the connectivity across the different pore sizes in the modeled and experimental fluid distributions. These essential topology characteristics matched well for drainage simulations, but not for imbibition. This suggests that the pore-filling rules in the network model we used need to be improved to make reliable predictions of imbibition. The presented analysis illustrates the potential of our methodology to systematically and robustly test two-phase flow models to aid in model development and calibration.

Salt tectonics and shallow subseafloor fluid convection: Models of coupled fluid-heat-salt transport

USGS Publications Warehouse

Wilson, A.; Ruppel, C.

2007-01-01

Thermohaline convection associated with salt domes has the potential to drive significant fluid flow and mass and heat transport in continental margins, but previous studies of fluid flow associated with salt structures have focused on continental settings or deep flow systems of importance to petroleum exploration. Motivated by recent geophysical and geochemical observations that suggest a convective pattern to near-seafloor pore fluid flow in the northern Gulf of Mexico (GoMex), we devise numerical models that fully couple thermal and chemical processes to quantify the effects of salt geometry and seafloor relief on fluid flow beneath the seafloor. Steady-state models that ignore halite dissolution demonstrate that seafloor relief plays an important role in the evolution of shallow geothermal convection cells and that salt at depth can contribute a thermal component to this convection. The inclusion of faults causes significant, but highly localized, increases in flow rates at seafloor discharge zones. Transient models that include halite dissolution show the evolution of flow during brine formation from early salt-driven convection to later geothermal convection, characteristics of which are controlled by the interplay of seafloor relief and salt geometry. Predicted flow rates are on the order of a few millimeters per year or less for homogeneous sediments with a permeability of 10−15 m2, comparable to compaction-driven flow rates. Sediment permeabilities likely fall below 10−15 m2 at depth in the GoMex basin, but such thermohaline convection can drive pervasive mass transport across the seafloor, affecting sediment diagenesis in shallow sediments. In more permeable settings, such flow could affect methane hydrate stability, seafloor chemosynthetic communities, and the longevity of fluid seeps.

Simulations of Bingham plastic flows with the multiple-relaxation-time lattice Boltzmann model

NASA Astrophysics Data System (ADS)

Chen, SongGui; Sun, QiCheng; Jin, Feng; Liu, JianGuo

2014-03-01

Fresh cement mortar is a type of workable paste, which can be well approximated as a Bingham plastic and whose flow behavior is of major concern in engineering. In this paper, Papanastasiou's model for Bingham fluids is solved by using the multiplerelaxation-time lattice Boltzmann model (MRT-LB). Analysis of the stress growth exponent m in Bingham fluid flow simulations shows that Papanastasiou's model provides a good approximation of realistic Bingham plastics for values of m > 108. For lower values of m, Papanastasiou's model is valid for fluids between Bingham and Newtonian fluids. The MRT-LB model is validated by two benchmark problems: 2D steady Poiseuille flows and lid-driven cavity flows. Comparing the numerical results of the velocity distributions with corresponding analytical solutions shows that the MRT-LB model is appropriate for studying Bingham fluids while also providing better numerical stability. We further apply the MRT-LB model to simulate flow through a sudden expansion channel and the flow surrounding a round particle. Besides the rich flow structures obtained in this work, the dynamics fluid force on the round particle is calculated. Results show that both the Reynolds number Re and the Bingham number Bn affect the drag coefficients C D , and a drag coefficient with Re and Bn being taken into account is proposed. The relationship of Bn and the ratio of unyielded zone thickness to particle diameter is also analyzed. Finally, the Bingham fluid flowing around a set of randomly dispersed particles is simulated to obtain the apparent viscosity and velocity fields. These results help simulation of fresh concrete flowing in porous media.

Application of a magnetic fluid seal to rotary blood pumps

NASA Astrophysics Data System (ADS)

Mitamura, Y.; Arioka, S.; Sakota, D.; Sekine, K.; Azegami, M.

2008-05-01

A magnetic fluid seal enables mechanical contact-free rotation of a shaft without frictional heat and material wear and hence has excellent durability. However, the durability of a magnetic fluid seal decreases in liquid. The life of a seal applied to a rotary blood pump is not known. We have developed a magnetic fluid seal that has a shield mechanism minimizing the influence of the rotary pump on the magnetic fluid. The developed magnetic fluid seal worked for over 286 days in a continuous flow condition, for 24 days (on-going) in a pulsatile flow condition and for 24 h (electively terminated) in blood flow. The magnetic fluid seal is promising as a shaft seal for rotary blood pumps.

Application of a magnetic fluid seal to rotary blood pumps.

PubMed

Mitamura, Y; Arioka, S; Sakota, D; Sekine, K; Azegami, M

2008-05-21

A magnetic fluid seal enables mechanical contact-free rotation of a shaft without frictional heat and material wear and hence has excellent durability. However, the durability of a magnetic fluid seal decreases in liquid. The life of a seal applied to a rotary blood pump is not known. We have developed a magnetic fluid seal that has a shield mechanism minimizing the influence of the rotary pump on the magnetic fluid. The developed magnetic fluid seal worked for over 286 days in a continuous flow condition, for 24 days (on-going) in a pulsatile flow condition and for 24 h (electively terminated) in blood flow. The magnetic fluid seal is promising as a shaft seal for rotary blood pumps.

Magnetic transit-time flowmeter

DOEpatents

Forster, George A.

1976-07-06

The flow rate of a conducting fluid in a stream is determined by disposing two permanent-magnet flowmeters in the stream, one downstream of the other. Flow of the conducting fluid causes the generation of both d-c and a-c electrical signals, the a-c comprising flow noise. Measurement of the time delay between similarities in the a-c signals by cross-correlation methods provides a measure of the rate of flow of the fluid.

Engineering Fracking Fluids with Computer Simulation

NASA Astrophysics Data System (ADS)

Shaqfeh, Eric

2015-11-01

There are no comprehensive simulation-based tools for engineering the flows of viscoelastic fluid-particle suspensions in fully three-dimensional geometries. On the other hand, the need for such a tool in engineering applications is immense. Suspensions of rigid particles in viscoelastic fluids play key roles in many energy applications. For example, in oil drilling the ``drilling mud'' is a very viscous, viscoelastic fluid designed to shear-thin during drilling, but thicken at stoppage so that the ``cuttings'' can remain suspended. In a related application known as hydraulic fracturing suspensions of solids called ``proppant'' are used to prop open the fracture by pumping them into the well. It is well-known that particle flow and settling in a viscoelastic fluid can be quite different from that which is observed in Newtonian fluids. First, it is now well known that the ``fluid particle split'' at bifurcation cracks is controlled by fluid rheology in a manner that is not understood. Second, in Newtonian fluids, the presence of an imposed shear flow in the direction perpendicular to gravity (which we term a cross or orthogonal shear flow) has no effect on the settling of a spherical particle in Stokes flow (i.e. at vanishingly small Reynolds number). By contrast, in a non-Newtonian liquid, the complex rheological properties induce a nonlinear coupling between the sedimentation and shear flow. Recent experimental data have shown both the shear thinning and the elasticity of the suspending polymeric solutions significantly affects the fluid-particle split at bifurcations, as well as the settling rate of the solids. In the present work, we use the Immersed Boundary Method to develop computer simulations of viscoelastic flow in suspensions of spheres to study these problems. These simulations allow us to understand the detailed physical mechanisms for the remarkable physical behavior seen in practice, and actually suggest design rules for creating new fluid recipes.

Portable device and method for determining permeability characteristics of earth formations

DOEpatents

Shuck, Lowell Z.

1977-01-01

The invention is directed to a device which is used for determining permeability characteristics of earth formations at the surface thereof. The determination of the maximum permeability direction and the magnitude of permeability are achieved by employing a device comprising a housing having a central fluid-injection port surrounded by a plurality of spaced-apart fluid flow and pressure monitoring ports radially extending from the central injection port. With the housing resting on the earth formation in a relatively fluid-tight manner as provided by an elastomeric pad disposed therebetween, fluid is injected through the central port into the earth formation and into registry with the fluid-monitoring ports disposed about the injection port. The fluid-monitoring ports are selectively opened and the flow of the fluid through the various fluid ports is measured so as to provide a measurement of flow rates and pressure distribution about the center hole which is indicative on the earth formation permeability direction and magnitude. For example, the azimuthal direction of the fluid-monitoring ports in the direction through which the greatest amount of injected fluid flows as determined by the lowest pressure distribution corresponds to the direction of maximum permeability in the earth formation.

Analytical and numerical study of the electro-osmotic annular flow of viscoelastic fluids.

PubMed

Ferrás, L L; Afonso, A M; Alves, M A; Nóbrega, J M; Pinho, F T

2014-04-15

In this work we present semi-analytical solutions for the electro-osmotic annular flow of viscoelastic fluids modeled by the Linear and Exponential PTT models. The viscoelastic fluid flows in the axial direction between two concentric cylinders under the combined influences of electrokinetic and pressure forcings. The analysis invokes the Debye-Hückel approximation and includes the limit case of pure electro-osmotic flow. The solution is valid for both no slip and slip velocity at the walls and the chosen slip boundary condition is the linear Navier slip velocity model. The combined effects of fluid rheology, electro-osmotic and pressure gradient forcings on the fluid velocity distribution are also discussed. Copyright © 2013 Elsevier Inc. All rights reserved.

Helmholtz-Smoluchowski velocity for viscoelastic electroosmotic flows.

PubMed

Park, H M; Lee, W M

2008-01-15

Many biofluids such as blood and DNA solutions are viscoelastic and exhibit extraordinary flow behaviors, not existing in Newtonian fluids. Adopting appropriate constitutive equations these exotic flow behaviors can be modeled and predicted reasonably using various numerical methods. However, the governing equations for viscoelastic flows are not easily solvable, especially for electroosmotic flows where the streamwise velocity varies rapidly from zero at the wall to a nearly uniform velocity at the outside of the very thin electric double layer. In the present investigation, we have devised a simple method to find the volumetric flow rate of viscoelastic electroosmotic flows through microchannels. It is based on the concept of the Helmholtz-Smoluchowski velocity which is widely adopted in the electroosmotic flows of Newtonian fluids. It is shown that the Helmholtz-Smoluchowski velocity for viscoelastic fluids can be found by solving a simple cubic algebraic equation. The volumetric flow rate obtained using this Helmholtz-Smoluchowski velocity is found to be almost the same as that obtained by solving the governing partial differential equations for various viscoelastic fluids.

Numerical simulation of heat transfer and fluid flow during double-sided laser beam welding of T-joints for aluminum aircraft fuselage panels

NASA Astrophysics Data System (ADS)

Yang, Zhibin; Tao, Wang; Li, Liqun; Chen, Yanbin; Shi, Chunyuan

2017-06-01

In comparison with conventional laser beam welding, double-sided laser beam welding has two laser heat sources simultaneously and symmetrically loaded from both sides makes it to be a more complicated coupled heat transport and fluid flow process. In this work, in order to understand the heat transfer and fluid flow, a three-dimensional model was developed and validated with the experimental results. The temperature field, fluid flow field, and keyhole characteristic were calculated using the developed model by FLUENT software. Calculated results indicated that the temperature and fluid flow fields were bilateral symmetry along the stringer center, and the molten pool maximum length was located near the keyhole intersection position. The skin side had higher temperature and faster cooling speed. Several characteristic flow patterns in the weld pool cross section, including the vortexes flows near the keyhole opening position, the convection flows above the keyhole intersection location, the regularity downward flows at the molten pool bottom. And in the lengthwise section, a distinct vortex flow below the keyhole, and the liquid metal behind the keyhole first flowed to near the molten pool maximum length location and then to the molten pool surface. Perpendicular to and along welding direction the keyhole liquid metal flowed to the weld molten pool surface and around the keyhole, respectively. The special temperature fields and fluid flow patterns were closely related to the effects of the double sides' laser energy coupling and enhancement. The calculated weld pool geometry basically in good agreement with the experimental results indicated that the developed model was validity and reasonable.

THE EFFECT OF RATE OF GLAND FUNCTION ON PAROTID FLUID URIC ACID LEVELS.

DTIC Science & Technology

Paired parotid fluid samples were collected without exogenous stimulation and at 5 different gustation-induced rates of flow. Enzymatic uric acid...diminished as flow rate increased. It is suggested that parotid fluid samples for uric acid analysis should be collected at flow rates of 0.7 ml./min. or more. (Author)

Phenomena of drag reduction on saltating sediment in shallow, supercritical flows

USDA-ARS?s Scientific Manuscript database

ABSTRACT: When a group of objects move through a fluid, it often exhibits coordinated behavior in which bodies in the wake of a leader generally experience reduced drag. Locomotion provides well known examples including the maneuvering and clustering of racing automobiles and bicyclists and queuing...

Polymer Fluid Dynamics.

ERIC Educational Resources Information Center

Bird, R. Byron

1980-01-01

Problems in polymer fluid dynamics are described, including development of constitutive equations, rheometry, kinetic theory, flow visualization, heat transfer studies, flows with phase change, two-phase flow, polymer unit operations, and drag reduction. (JN)

Numerical modeling of fluid migration in subduction zones

NASA Astrophysics Data System (ADS)

Walter, Marius J.; Quinteros, Javier; Sobolev, Stephan V.

2015-04-01

It is well known that fluids play a crucial role in subduction evolution. For example, excess mechanical weakening along tectonic interfaces, due to excess fluid pressure, may enable oceanic subduction. Hence, the fluid content seems to be a critical parameter for subduction initiation. Studies have also shown a correlation between the location of slab dehydration and intermediate seismic activity. Furthermore, expelled fluids from the subduction slab affect the melting temperature, consequently, contributing to partial melting in the wedge above the downgoing plate, and resulting in chemical changes in earth interior and extensive volcanism. In summary, fluids have a great impact on tectonic processes and therefore should be incorporated into geodynamic numerical models. Here we use existing approaches to couple and solve fluid flow equations in the SLIM-3D thermo-mechanical code. SLIM-3D is a three-dimensional thermo-mechanical code capable of simulating lithospheric deformation with elasto-visco-plastic rheology. It incorporates an arbitrary Lagrangian Eulerian formulation, free surface, and changes in density and viscosity, due to endothermic and exothermic phase transitions. It has been successfully applied to model geodynamic processes at different tectonic settings, including subduction zones. However, although SLIM-3D already includes many features, fluid migration has not been incorporated into the model yet. To this end, we coupled solid and fluid flow assuming that fluids flow through a porous and deformable solid. Thereby, we introduce a two-phase flow into the model, in which the Stokes flow is coupled with the Darcy law for fluid flow. This system of equations becomes, however, nonlinear, because the rheology and permeability are depended on the porosity (fluid fraction of the matrix). Ultimately, the evolution of porosity is governed by the compaction pressure and the advection of the porous solid. We show the details of our implementation of the fluid flow into the existing thermo-mechanical finite element code and present first results of benchmarks (e.g. solitary wave) and experiments. We are especially interested in the coupling of subduction processes and the evolution of the magmatic arc. Thereby, we focus on the key factors controlling magma emplacement and its influence on subduction processes.

Lecture Series "Boundary Layer Theory". Part I - Laminar Flows. Part 1; Laminar Flows

NASA Technical Reports Server (NTRS)

Schlichting, H.

1949-01-01

In the lecture series starting today author want to give a survey of a field of aerodynamics which has for a number of years been attracting an ever growing interest. The subject is the theory of flows with friction, and, within that field, particularly the theory of friction layers, or boundary layers. A great many considerations of aerodynamics are based on the ideal fluid, that is the frictionless incompressibility and fluid. By neglect of compressibility and friction the extensive mathematical theory of the ideal fluid, (potential theory) has been made possible. Actual liquids and gases satisfy the condition of incomressibility rather well if the velocities are not extremely high or, more accurately, if they are small in comparison with sonic velocity. For air, for instance, the change in volume due to compressibility amounts to about 1 percent for a velocity of 60 meters per second. The hypothesis of absence of friction is not satisfied by any actual fluid; however, it is true that most technically important fluids, for instance air and water, have a very small friction coefficient and therefore behave in many cases almost like the ideal frictionless fluid. Many flow phenomena, in particular most cases of lift, can be treated satisfactorily, - that is, the calculations are in good agreement with the test results, -under the assumption of frictionless fluid. However, the calculations with frictionless flow show a very serious deficiency; namely, the fact, known as d'Alembert's paradox, that in frictionless flow each body has zero drag whereas in actual flow each body experiences a drag of greater or smaller magnitude. For a long time the theory has been unable to bridge this gap between the theory of frictionless flow and the experimental findings about actual flow. The cause of this fundamental discrepancy is the viscosity which is neglected in the theory of ideal fluid; however, in spite of its extraordinary smallness it is decisive for the course of the flow phenomena.

Leveraging Understanding of Flow of Variable Complex Fluid to Design Better Absorbent Hygiene Products

NASA Astrophysics Data System (ADS)

Krautkramer, C.; Rend, R. R.

2014-12-01

Menstrual flow, which is a result of shedding of uterus endometrium, occurs periodically in sync with a women's hormonal cycle. Management of this flow while allowing women to pursue their normal daily lives is the purpose of many commercial products. Some of these products, e.g. feminine hygiene pads and tampons, utilize porous materials in achieving their goal. In this paper we will demonstrate different phenomena that have been observed in flow of menstrual fluid through these porous materials, share some of the advances made in experimental and analytical study of these phenomena, and also present some of the unsolved challenges and difficulties encountered while studying this kind of flow. Menstrual fluid is generally composed of four main components: blood plasma, blood cells, cervical mucus, and tissue debris. This non-homogeneous, multiphase fluid displays very complex rheological behavior, e. g., yield stress, thixotropy, and visco-elasticity, that varies throughout and between menstrual cycles and among women due to various factors. Flow rates are also highly variable during menstruation and across the population and the rheological properties of the fluid change during the flow into and through the product. In addition to these phenomena, changes to the structure of the porous medium within the product can also be seen due to fouling and/or swelling of the material. This paper will, also, share how the fluid components impact the flow and the consequences for computer simulation, the creation of a simulant fluid and testing methods, and for designing products that best meet consumer needs. We hope to bring to light the challenges of managing this complex flow to meet a basic need of women all over the world. An opportunity exists to apply learnings from research in other disciplines to improve the scientific knowledge related to the flow of this complex fluid through the porous medium that is a sanitary product.

Spheromak plasma flow injection into a torus chamber and the HIST plasmas

NASA Astrophysics Data System (ADS)

Hatuzaki, Akinori

2005-10-01

The importance of plasma flow or two-fluid effect is recognized in understanding the relaxed states of high-beta torus plasmas, start-up and current drive by non-coaxial helicity injection, magnetic reconnection and plasma dynamo in fusion, laboratory and space plasmas. As a new approach to create a flowing two-fluid plasma equilibrium, we have tried to inject tangentially the plasma flow with spheromak-type magnetic configurations into a torus vacuum chamber with an external toroidal magnetic field (TF) coil. In the initial experiments, the RFP-like configuration with helical magnetic structures was realized in the torus vessel. The ion flow measurement with Mach probes showed that the ion flow keeps the same direction despite the reversal of the toroidal current and the axial electric field. The ion fluid comes to flow in the opposite direction to the electron fluid by the reversal of TF. This result suggests that not only electron but also ion flow contributes significantly on the reversed toroidal current. In this case, the ratio of ui to the electron flow velocity ue is estimated as ui/ue ˜ 1/2. We also will inject the spheromak flow into the HIST spherical torus plasmas to examine the possibilities to embedding the two-fluid effect in the ST plasmas.

Implementation and effects of pulse-contour- automated SVV/CI guided goal directed fluid therapy algorithm for the routine management of pancreatic surgery patients.

PubMed

Kratz, Thomas; Simon, Christina; Fendrich, Volker; Schneider, Ralph; Wulf, Hinnerk; Kratz, Caroline; Efe, Turgay; Schüttler, Karl F; Zoremba, Martin

2016-11-14

Goal directed fluid management in major abdominal surgery has shown to reduce perioperative complications. The approach aims to optimize the intravascular fluid volume by use of minimally invasive devices which calculate flow-directed variables such as stroke volume (SV) and stroke volume variation (SVV). We aimed to show the feasibility of routinely implementing this type of hemodynamic monitoring during pancreatic surgery, and to evaluate its effects in terms of perioperative fluid management and postoperative outcomes. All patients undergoing pancreatic surgery at a university hospital during two successive 12 months periods were included in this retrospective cohort analysis. Twelve months after the implementation of a standard operating procedure for a goal directed therapy (GDT, N = 45) using a pulse contour automated hemodynamic device were compared with a similar period before its use (control, N = 31) regarding mortality, length of hospital and ICU stay, postoperative complications and the use of fluids and vasopressors. Overall, 76 patients were analysed. Significantly less crystalloids were used in the GDT group. Patients receiving GDT showed significantly fewer severe complications (insufficiency of intestinal anastomosis: 0 vs. 5 (P = 0.0053) and renal failure: 0 vs. 4 (P = 0.0133). Mortality for pancreatic surgery was 1 vs. 3 patients, (P = 0.142), and length of stay (LOS) in the intensive care unit (ICU) was 4.38 ± 3.63 vs. 6.87 ± 10.02 (P= 0.0964) days. Use of blood products was significantly less within the GDT group. Implementation of a SOP for a GDT in the daily routine using flow-related parameters is feasible and is associated with better outcomes in pancreatic surgery.

Fluid Flow Experiment for Undergraduate Laboratory.

ERIC Educational Resources Information Center

Vilimpochapornkul, Viroj; Obot, Nsima T.

1986-01-01

The undergraduate fluid mechanics laboratory at Clarkson University consists of three experiments: mixing; drag measurements; and fluid flow and pressure drop measurements. The latter experiment is described, considering equipment needed, procedures used, and typical results obtained. (JN)

TopoDrive and ParticleFlow--Two Computer Models for Simulation and Visualization of Ground-Water Flow and Transport of Fluid Particles in Two Dimensions

USGS Publications Warehouse

Hsieh, Paul A.

2001-01-01

This report serves as a user?s guide for two computer models: TopoDrive and ParticleFlow. These two-dimensional models are designed to simulate two ground-water processes: topography-driven flow and advective transport of fluid particles. To simulate topography-driven flow, the user may specify the shape of the water table, which bounds the top of the vertical flow section. To simulate transport of fluid particles, the model domain is a rectangle with overall flow from left to right. In both cases, the flow is under steady state, and the distribution of hydraulic conductivity may be specified by the user. The models compute hydraulic head, ground-water flow paths, and the movement of fluid particles. An interactive visual interface enables the user to easily and quickly explore model behavior, and thereby better understand ground-water flow processes. In this regard, TopoDrive and ParticleFlow are not intended to be comprehensive modeling tools, but are designed for modeling at the exploratory or conceptual level, for visual demonstration, and for educational purposes.

Friction factors of colloidal suspension containing silicon dioxide nanoparticles in water

NASA Astrophysics Data System (ADS)

Tang, Clement; Pant, Sarbottam; Sharif, Md. Tanveer

2015-11-01

The purpose of this study is to experimentally characterize the friction factor of a colloidal suspension flow in circular and square tubes. The suspension contained silicon dioxide nanoparticles dispersed in distilled water at 9.58% volume concentration. Rheological measurements indicated that the suspension exhibits non-Newtonian behavior, and could be modelled as a power-law generalized Newtonian fluid. The experimental study showed that, with proper characterization of the consistency and flow behavior indices, the suspension flow friction factors in circular and square tubes exhibit similarities with those of Newtonian fluid flow. In the laminar fully-developed flow region, the Poiseuille numbers are similar to those established for Newtonian fluid flow. In the turbulent region, the Dodge and Metzner relation between the friction factor and a generalized Reynolds number can adequately describe the flow. The onsets of transition to turbulent flow for the suspension vary with the shape of the tube and differ from those of Newtonian fluid flow. The deviations suggest that the flow passage shape and the presence of nanoparticles affect the onset of transition to turbulent flow. Supported by North Dakota NASA EPSCoR.

Lattice Boltzmann computation of creeping fluid flow in roll-coating applications

NASA Astrophysics Data System (ADS)

Rajan, Isac; Kesana, Balashanker; Perumal, D. Arumuga

2018-04-01

Lattice Boltzmann Method (LBM) has advanced as a class of Computational Fluid Dynamics (CFD) methods used to solve complex fluid systems and heat transfer problems. It has ever-increasingly attracted the interest of researchers in computational physics to solve challenging problems of industrial and academic importance. In this current study, LBM is applied to simulate the creeping fluid flow phenomena commonly encountered in manufacturing technologies. In particular, we apply this novel method to simulate the fluid flow phenomena associated with the "meniscus roll coating" application. This prevalent industrial problem encountered in polymer processing and thin film coating applications is modelled as standard lid-driven cavity problem to which creeping flow analysis is applied. This incompressible viscous flow problem is studied in various speed ratios, the ratio of upper to lower lid speed in two different configurations of lid movement - parallel and anti-parallel wall motion. The flow exhibits interesting patterns which will help in design of roll coaters.

Effect of External Pressure and Catheter Gauge on Flow Rate, Kinetic Energy, and Endothelial Injury During Intravenous Fluid Administration in a Rabbit Model.

PubMed

Hu, Mei-Hua; Chan, Wei-Hung; Chen, Yao-Chang; Cherng, Chen-Hwan; Lin, Chih-Kung; Tsai, Chien-Sung; Chou, Yu-Ching; Huang, Go-Shine

2016-01-01

The effects of intravenous (IV) catheter gauge and pressurization of IV fluid (IVF) bags on fluid flow rate have been studied. However, the pressure needed to achieve a flow rate equivalent to that of a 16 gauge (G) catheter through smaller G catheters and the potential for endothelial damage from the increased kinetic energy produced by higher pressurization are unclear. Constant pressure on an IVF bag was maintained by an automatic adjustable pneumatic pressure regulator of our own design. Fluids running through 16 G, 18 G, 20 G, and 22 G catheters were assessed while using IV bag pressurization to achieve the flow rate equivalent to that of a 16 G catheter. We assessed flow rates, kinetic energy, and flow injury to rabbit inferior vena cava endothelium. By applying sufficient external constant pressure to an IVF bag, all fluids could be run through smaller (G) catheters at the flow rate in a 16 G catheter. However, the kinetic energy increased significantly as the catheter G increased. Damage to the venous endothelium was negligible or minimal/patchy cell loss. We designed a new rapid infusion system, which provides a constant pressure that compresses the fluid volume until it is free from visible residual fluid. When large-bore venous access cannot be obtained, multiple smaller catheters, external pressure, or both should be considered. However, caution should be exercised when fluid pressurized to reach a flow rate equivalent to that in a 16 G catheter is run through a smaller G catheter because of the profound increase in kinetic energy that can lead to venous endothelium injury.

Streaming Potential Modeling to Understand the Identification of Hydraulically Active Fractures and Fracture-Matrix Fluid Interactions Using the Self-Potential Method

NASA Astrophysics Data System (ADS)

Jougnot, D.; Roubinet, D.; Linde, N.; Irving, J.

2016-12-01

Quantifying fluid flow in fractured media is a critical challenge in a wide variety of research fields and applications. To this end, geophysics offers a variety of tools that can provide important information on subsurface physical properties in a noninvasive manner. Most geophysical techniques infer fluid flow by data or model differencing in time or space (i.e., they are not directly sensitive to flow occurring at the time of the measurements). An exception is the self-potential (SP) method. When water flows in the subsurface, an excess of charge in the pore water that counterbalances electric charges at the mineral-pore water interface gives rise to a streaming current and an associated streaming potential. The latter can be measured with the SP technique, meaning that the method is directly sensitive to fluid flow. Whereas numerous field experiments suggest that the SP method may allow for the detection of hydraulically active fractures, suitable tools for numerically modeling streaming potentials in fractured media do not exist. Here, we present a highly efficient two-dimensional discrete-dual-porosity approach for solving the fluid-flow and associated self-potential problems in fractured domains. Our approach is specifically designed for complex fracture networks that cannot be investigated using standard numerical methods due to computational limitations. We then simulate SP signals associated with pumping conditions for a number of examples to show that (i) accounting for matrix fluid flow is essential for accurate SP modeling and (ii) the sensitivity of SP to hydraulically active fractures is intimately linked with fracture-matrix fluid interactions. This implies that fractures associated with strong SP amplitudes are likely to be hydraulically conductive, attracting fluid flow from the surrounding matrix.

Lattice Boltzmann heat transfer model for permeable voxels

NASA Astrophysics Data System (ADS)

Pereira, Gerald G.; Wu, Bisheng; Ahmed, Shakil

2017-12-01

We develop a gray-scale lattice Boltzmann (LB) model to study fluid flow combined with heat transfer for flow through porous media where voxels may be partially solid (or void). Heat transfer in rocks may lead to deformation, which in turn can modulate the fluid flow and so has significant contribution to rock permeability. The LB temperature field is compared to a finite difference solution of the continuum partial differential equations for fluid flow in a channel. Excellent quantitative agreement is found for both Poiseuille channel flow and Brinkman flow. The LB model is then applied to sample porous media such as packed beds and also more realistic sandstone rock sample, and both the convective and diffusive regimes are recovered when varying the thermal diffusivity. It is found that while the rock permeability can be comparatively small (order milli-Darcy), the temperature field can show significant variation depending on the thermal convection of the fluid. This LB method has significant advantages over other numerical methods such as finite and boundary element methods in dealing with coupled fluid flow and heat transfer in rocks which have irregular and nonsmooth pore spaces.

Wave dispersion of carbon nanotubes conveying fluid supported on linear viscoelastic two-parameter foundation including thermal and small-scale effects

NASA Astrophysics Data System (ADS)

Sina, Nima; Moosavi, Hassan; Aghaei, Hosein; Afrand, Masoud; Wongwises, Somchai

2017-01-01

In this paper, for the first time, a nonlocal Timoshenko beam model is employed for studying the wave dispersion of a fluid-conveying single-walled carbon nanotube on Viscoelastic Pasternak foundation under high and low temperature change. In addition, the phase and group velocity for the nanotube are discussed, respectively. The influences of Winkler and Pasternak modulus, homogenous temperature change, steady flow velocity and damping factor of viscoelastic foundation on wave dispersion of carbon nanotubes are investigated. It was observed that the characteristic of the wave for carbon nanotubes conveying fluid is the normal dispersion. Moreover, implying viscoelastic foundation leads to increasing the wave frequencies.

The Fluids RAP

NASA Astrophysics Data System (ADS)

Nedyalkov, Ivaylo

2016-11-01

After fifteen years of experience in rap, and ten in fluid mechanics, "I am coming here with high-Reynolds-number stamina; I can beat these rap folks whose flows are... laminar." The rap relates fluid flows to rap flows. The fluid concepts presented in the song have varying complexity and the listeners/viewers will be encouraged to read the explanations on a site dedicated to the rap. The music video will provide an opportunity to share high-quality fluid visualizations with a general audience. This talk will present the rap lyrics, the vision for the video, and the strategy for outreach. Suggestions and comments will be welcomed.

Application of wave mechanics theory to fluid dynamics problems: Boundary layer on a circular cylinder including turbulence

NASA Technical Reports Server (NTRS)

Krzywoblocki, M. Z. V.

1974-01-01

The application of the elements of quantum (wave) mechanics to some special problems in the field of macroscopic fluid dynamics is discussed. Emphasis is placed on the flow of a viscous, incompressible fluid around a circular cylinder. The following subjects are considered: (1) the flow of a nonviscous fluid around a circular cylinder, (2) the restrictions imposed the stream function by the number of dimensions of space, and (3) the flow past three dimensional bodies in a viscous fluid, particularly past a circular cylinder in the symmetrical case.

Fluidic angular velocity sensor

NASA Technical Reports Server (NTRS)

Berdahl, C. M. (Inventor)

1986-01-01

A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

Damage Response in Fluid Flow Networks

NASA Astrophysics Data System (ADS)

Gavrilchenko, Tatyana; Katifori, Eleni

The networks found in biological fluid flow systems such as leaf venation and animal vasculature are characterized by hierarchically nested loops. This structure allows the system to be resilient against fluctuations in the flow of fluid and to be robust against damage. We analytically and computationally investigate how this loopy hierarchy determines the extent of disruption in fluid flow in the vicinity of a damage site. Perturbing the network with the removal of a single edge results in the differential flow as a function of distance from the perturbation decaying as a power law. The power law exponent is generally around -2 in 2D, but we find that it varies due to edge effects, initial edge conductivity, and local topology. We expect that these network flow findings, directly applicable to plant and animal veins, will have analogues in electrical grids, traffic flow and other transport networks.

Purely-elastic flow instabilities and elastic turbulence in microfluidic cross-slot devices

PubMed Central

Sousa, P. C.; Pinho, F. T.

2018-01-01

We experimentally investigate the dynamics of viscoelastic fluid flows in cross-slot microgeometries under creeping flow conditions. We focus on the unsteady flow regime observed at high Weissenberg numbers (Wi) with the purpose of understanding the underlying flow signature of elastic turbulence. The effects of the device aspect ratio and fluid rheology on the unsteady flow state are investigated. Visualization of the flow patterns and time-resolved micro-particle image velocimetry were carried out to study the fluid flow behavior for a wide range of Weissenberg numbers. A periodic flow behavior is observed at low Weissenberg numbers followed by a more complex dynamics as Wi increases, eventually leading to the onset of elastic turbulence for very high Weissenberg numbers. PMID:29376533

A two-fluid model for avalanche and debris flows.

PubMed

Pitman, E Bruce; Le, Long

2005-07-15

Geophysical mass flows--debris flows, avalanches, landslides--can contain O(10(6)-10(10)) m(3) or more of material, often a mixture of soil and rocks with a significant quantity of interstitial fluid. These flows can be tens of meters in depth and hundreds of meters in length. The range of scales and the rheology of this mixture presents significant modelling and computational challenges. This paper describes a depth-averaged 'thin layer' model of geophysical mass flows containing a mixture of solid material and fluid. The model is derived from a 'two-phase' or 'two-fluid' system of equations commonly used in engineering research. Phenomenological modelling and depth averaging combine to yield a tractable set of equations, a hyperbolic system that describes the motion of the two constituent phases. If the fluid inertia is small, a reduced model system that is easier to solve may be derived.

Curved film cooling admission tube

NASA Astrophysics Data System (ADS)

Graham, R. W.; Papell, S. S.

1980-10-01

Effective film cooling to protect a wall surface from a hot fluid which impinges on or flows along the surface is provided. A film of cooling fluid having increased area is provided by changing the direction of a stream of cooling fluid through an angle of from 135 deg. to 165 deg. before injecting it through the wall into the hot flowing gas. The 1, cooling fluid is injected from an orifice through a wall into a hot flowing gas at an angle to form a cooling fluid film. Cooling fluid is supplied to the orifice from a cooling fluid source via a turbulence control passageway having a curved portion between two straight portions. The angle through which the direction of the cooling fluid is turned results in less mixing of the cooling fluid with the hot gas, thereby substantially increasing the length of the film in a downstream direction.

Curved film cooling admission tube

NASA Technical Reports Server (NTRS)

Graham, R. W.; Papell, S. S. (Inventor)

1980-01-01

Effective film cooling to protect a wall surface from a hot fluid which impinges on or flows along the surface is provided. A film of cooling fluid having increased area is provided by changing the direction of a stream of cooling fluid through an angle of from 135 deg. to 165 deg. before injecting it through the wall into the hot flowing gas. The 1, cooling fluid is injected from an orifice through a wall into a hot flowing gas at an angle to form a cooling fluid film. Cooling fluid is supplied to the orifice from a cooling fluid source via a turbulence control passageway having a curved portion between two straight portions. The angle through which the direction of the cooling fluid is turned results in less mixing of the cooling fluid with the hot gas, thereby substantially increasing the length of the film in a downstream direction.

Stability of Gas Hydrates on Continental Margins: Implications of Subsurface Fluid Flow

NASA Astrophysics Data System (ADS)

Nunn, J. A.

2008-12-01

Gas hydrates are found at or just below the sediment-ocean interface in continental margins settings throughout the world. They are also found on land in high latitude regions such as the north slope of Alaska. While gas hydrate occurrence is common, gas hydrates are stable under a fairly restricted range of temperatures and pressures. In a purely conductive thermal regime, near surface temperatures depend on basal heat flow, thermal conductivity of sediments, and temperature at the sediment-water or sediment-air interface. Thermal conductivity depends on porosity and sediment composition. Gas hydrates are most stable in areas of low heat flow and high thermal conductivity which produce low temperature gradients. Older margins with thin continental crust and coarse grained sediments would tend to be colder. Another potentially important control on subsurface temperatures is advective heat transport by recharge/discharge of groundwater. Upward fluid flow depresses temperature gradients over a purely conductive regime with the same heat flow which would make gas hydrates more stable. Downward fluid flow would have the opposite effect. However, regional scale fluid flow may substantially increase heat flow in discharge areas which would destabilize gas hydrates. For example, discharge of topographically driven groundwater along the coast in the Central North Slope of Alaska has increased surface heat flow in some areas by more than 50% over a purely conductive thermal regime. Fluid flow also alters the pressure regime which can affect gas hydrate stability. Modeling results suggest a positive feedback between gas hydrate formation/disassociation and fluid flow. Disassociation of gas hydrates or permafrost due to global warming could increase permeability. This could enhance fluid flow and associated heat transport causing a more rapid and/or more spatially extensive gas hydrate disassociation than predicted solely from conductive propagation of temporal changes in surface or water bottom temperature. Model results from both the North Slope of Alaska and the Gulf of Mexico are compared.

Choked flow of fluid nitrogen with emphasis on the thermodynamic critical region

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Simoneau, R. J.; Ehlers, R. C.

1972-01-01

Experimental measurements of critical flow rate and pressure ratio for nitrogen flowing through a nozzle are presented. Data for selected stagnation isotherms from 87.5 to 234 K with pressures to 9.3 MN/m2 are compared to an equilibrium model with real fluid properties and also a nonequilibrium model. Critical flow pressure ratio along an isotherm tends to peak while the flow rate indicates an inflection. The point is closely associated with the transposed critical temperature and represents a change in the fluid structure.

Estimating Vibrational Powers Of Parts In Fluid Machinery

NASA Technical Reports Server (NTRS)

Harvey, S. A.; Kwok, L. C.

1995-01-01

In new method of estimating vibrational power associated with component of fluid-machinery system, physics of flow through (or in vicinity of) component regarded as governing vibrations. Devised to generate scaling estimates for design of new parts of rocket engines (e.g., pumps, combustors, nozzles) but applicable to terrestrial pumps, turbines, and other machinery in which turbulent flows and vibrations caused by such flows are significant. Validity of method depends on assumption that fluid flows quasi-steadily and that flow gives rise to uncorrelated acoustic powers in different parts of pump.

Time-Dependent Thermally-Driven Interfacial Flows in Multilayered Fluid Structures

NASA Technical Reports Server (NTRS)

Haj-Hariri, Hossein; Borhan, A.

1996-01-01

A computational study of thermally-driven convection in multilayered fluid structures will be performed to examine the effect of interactions among deformable fluid-fluid interfaces on the structure of time-dependent flow in these systems. Multilayered fluid structures in two models configurations will be considered: the differentially heated rectangular cavity with a free surface, and the encapsulated cylindrical liquid bridge. An extension of a numerical method developed as part of our recent NASA Fluid Physics grant will be used to account for finite deformations of fluid-fluid interfaces.

Coherent structure coloring: identification of coherent structures from sparse flow trajectories using graph theory

NASA Astrophysics Data System (ADS)

Schlueter, Kristy; Dabiri, John

2016-11-01

Coherent structure identification is important in many fluid dynamics applications, including transport phenomena in ocean flows and mixing and diffusion in turbulence. However, many of the techniques currently available for measuring such flows, including ocean drifter datasets and particle tracking velocimetry, only result in sparse velocity data. This is often insufficient for the use of current coherent structure detection algorithms based on analysis of the deformation gradient. Here, we present a frame-invariant method for detecting coherent structures from Lagrangian flow trajectories that can be sparse in number. The method, based on principles used in graph coloring algorithms, examines a measure of the kinematic dissimilarity of all pairs of flow trajectories, either measured experimentally, e.g. using particle tracking velocimetry; or numerically, by advecting fluid particles in the Eulerian velocity field. Coherence is assigned to groups of particles whose kinematics remain similar throughout the time interval for which trajectory data is available, regardless of their physical proximity to one another. Through the use of several analytical and experimental validation cases, this algorithm is shown to robustly detect coherent structures using significantly less flow data than is required by existing methods. This research was supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate Fellowship (NDSEG) Program.

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

Isa, Sharena Mohamad; Ali, Anati

In this paper, the hydromagnetic flow of dusty fluid over a vertical stretching sheet with thermal radiation is investigated. The governing partial differential equations are reduced to nonlinear ordinary differential equations using similarity transformation. These nonlinear ordinary differential equations are solved numerically using Runge-Kutta Fehlberg fourth-fifth order method (RKF45 Method). The behavior of velocity and temperature profiles of hydromagnetic fluid flow of dusty fluid is analyzed and discussed for different parameters of interest such as unsteady parameter, fluid-particle interaction parameter, the magnetic parameter, radiation parameter and Prandtl number on the flow.

Unsteady Boundary-Layer Flow over Jerked Plate Moving in a Free Stream of Viscoelastic Fluid

PubMed Central

Mehmood, Ahmer; Ali, Asif; Saleem, Najma

2014-01-01

This study aims to investigate the unsteady boundary-layer flow of a viscoelastic non-Newtonian fluid over a flat surface. The plate is suddenly jerked to move with uniform velocity in a uniform stream of non-Newtonian fluid. Purely analytic solution to governing nonlinear equation is obtained. The solution is highly accurate and valid for all values of the dimensionless time 0 ≤ τ < ∞. Flow properties of the viscoelastic fluid are discussed through graphs. PMID:24892060

Understanding Angiography-Based Aneurysm Flow Fields through Comparison with Computational Fluid Dynamics.

PubMed

Cebral, J R; Mut, F; Chung, B J; Spelle, L; Moret, J; van Nijnatten, F; Ruijters, D

2017-06-01

Hemodynamics is thought to be an important factor for aneurysm progression and rupture. Our aim was to evaluate whether flow fields reconstructed from dynamic angiography data can be used to realistically represent the main flow structures in intracranial aneurysms. DSA-based flow reconstructions, obtained during interventional treatment, were compared qualitatively with flow fields obtained from patient-specific computational fluid dynamics models and quantitatively with projections of the computational fluid dynamics fields (by computing a directional similarity of the vector fields) in 15 cerebral aneurysms. The average similarity between the DSA and the projected computational fluid dynamics flow fields was 78% in the parent artery, while it was only 30% in the aneurysm region. Qualitatively, both the DSA and projected computational fluid dynamics flow fields captured the location of the inflow jet, the main vortex structure, the intrasaccular flow split, and the main rotation direction in approximately 60% of the cases. Several factors affect the reconstruction of 2D flow fields from dynamic angiography sequences. The most important factors are the 3-dimensionality of the intrasaccular flow patterns and inflow jets, the alignment of the main vortex structure with the line of sight, the overlapping of surrounding vessels, and possibly frame rate undersampling. Flow visualization with DSA from >1 projection is required for understanding of the 3D intrasaccular flow patterns. Although these DSA-based flow quantification techniques do not capture swirling or secondary flows in the parent artery, they still provide a good representation of the mean axial flow and the corresponding flow rate. © 2017 by American Journal of Neuroradiology.

Spinning fluids reactor

DOEpatents

Miller, Jan D; Hupka, Jan; Aranowski, Robert

2012-11-20

A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

ACE-1 experiment

NASA Image and Video Library

2013-06-24

ISS036-E-019783 (24 June 2013) --- In the International Space Station’s Destiny laboratory, a fisheye lens attached to an electronic still camera was used to capture this image of NASA astronaut Karen Nyberg, Expedition 36 flight engineer, as she conducts a session with the Advanced Colloids Experiment (ACE)-1 sample preparation at the Light Microscopy Module (LMM) in the Fluids Integrated Rack / Fluids Combustion Facility (FIR/FCF). ACE-1 is a series of microscopic imaging investigations that uses the microgravity environment to examine flow characteristics and the evolution and ordering effects within a group of colloidal materials.

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

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

Physically-Based Modelling and Real-Time Simulation of Fluids.

NASA Astrophysics Data System (ADS)

Chen, Jim Xiong

1995-01-01

Simulating physically realistic complex fluid behaviors presents an extremely challenging problem for computer graphics researchers. Such behaviors include the effects of driving boats through water, blending differently colored fluids, rain falling and flowing on a terrain, fluids interacting in a Distributed Interactive Simulation (DIS), etc. Such capabilities are useful in computer art, advertising, education, entertainment, and training. We present a new method for physically-based modeling and real-time simulation of fluids in computer graphics and dynamic virtual environments. By solving the 2D Navier -Stokes equations using a CFD method, we map the surface into 3D using the corresponding pressures in the fluid flow field. This achieves realistic real-time fluid surface behaviors by employing the physical governing laws of fluids but avoiding extensive 3D fluid dynamics computations. To complement the surface behaviors, we calculate fluid volume and external boundary changes separately to achieve full 3D general fluid flow. To simulate physical activities in a DIS, we introduce a mechanism which uses a uniform time scale proportional to the clock-time and variable time-slicing to synchronize physical models such as fluids in the networked environment. Our approach can simulate many different fluid behaviors by changing the internal or external boundary conditions. It can model different kinds of fluids by varying the Reynolds number. It can simulate objects moving or floating in fluids. It can also produce synchronized general fluid flows in a DIS. Our model can serve as a testbed to simulate many other fluid phenomena which have never been successfully modeled previously.

Computational analysis of plane and parabolic flow of MHD Carreau fluid with buoyancy and exponential heat source effects

NASA Astrophysics Data System (ADS)

Krishna, P. Mohan; Sandeep, N.; Sharma, Ram Prakash

2017-05-01

This paper presents the two-dimensional magnetohydrodynamic Carreau fluid flow over a plane and parabolic regions in the form of buoyancy and exponential heat source effects. Soret and Dufour effects are used to examine the heat and mass transfer process. The system of ODE's is obtained by utilizing similarity transformations. The RK-based shooting process is employed to generate the numerical solutions. The impact of different parameters of interest on fluid flow, concentration and thermal fields is characterized graphically. Tabular results are presented to discuss the wall friction, reduced Nusselt and Sherwood numbers. It is seen that the flow, thermal and concentration boundary layers of the plane and parabolic flows of Carreau fluid are non-uniform.

On approximation of non-Newtonian fluid flow by the finite element method

NASA Astrophysics Data System (ADS)

Svácek, Petr

2008-08-01

In this paper the problem of numerical approximation of non-Newtonian fluid flow with free surface is considered. Namely, the flow of fresh concrete is addressed. Industrial mixtures often behaves like non-Newtonian fluids exhibiting a yield stress that needs to be overcome for the flow to take place, cf. [R.B. Bird, R.C. Armstrong, O. Hassager, Dynamics of Polymeric Liquids, vol. 1, Fluid Mechanics, Wiley, New York, 1987; R.P. Chhabra, J.F. Richardson, Non-Newtonian Flow in the Process Industries, Butterworth-Heinemann, London, 1999]. The main interest is paid to the mathematical formulation of the problem and to discretization with the aid of finite element method. The described numerical procedure is applied onto the solution of several problems.

Density and Cavitating Flow Results from a Full-Scale Optical Multiphase Cryogenic Flowmeter

NASA Technical Reports Server (NTRS)

Korman, Valentin

2007-01-01

Liquid propulsion systems are hampered by poor flow measurements. The measurement of flow directly impacts safe motor operations, performance parameters as well as providing feedback from ground testing and developmental work. NASA Marshall Space Flight Center, in an effort to improve propulsion sensor technology, has developed an all optical flow meter that directly measures the density of the fluid. The full-scale sensor was tested in a transient, multiphase liquid nitrogen fluid environment. Comparison with traditional density models shows excellent agreement with fluid density with an error of approximately 0.8%. Further evaluation shows the sensor is able to detect cavitation or bubbles in the flow stream and separate out their resulting effects in fluid density.

The dynamic two-fluid model OLGA; Theory and application

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

Bendiksen, K.H.; Maines, D.; Moe, R.

1991-05-01

Dynamic two-fluid models have found a wide range of application in the simulation of two-phase-flow systems, particularly for the analysis of steam/water flow in the core of a nuclear reactor. Until quite recently, however, very few attempts have been made to use such models in the simulation of two-phase oil and gas flow in pipelines. This paper presents a dynamic two-fluid model, OLGA, in detail, stressing the basic equations and the two-fluid models applied. Predictions of steady-state pressure drop, liquid hold-up, and flow-regime transitions are compared with data from the SINTEF Two-Phase Flow Laboratory and from the literature. Comparisons withmore » evaluated field data are also presented.« less

Slip analysis of squeezing flow using doubly stratified fluid

NASA Astrophysics Data System (ADS)

Ahmad, S.; Farooq, M.; Javed, M.; Anjum, Aisha

2018-06-01

The non-isothermal flow is modeled and explored for squeezed fluid. The influence of velocity, thermal and solutal slip effects on transport features of squeezed fluid are analyzed through Darcy porous channel when fluid is moving due to squeezing of upper plate towards the stretchable lower plate. Dual stratification effects are illustrated in transport equations. A similarity analysis is performed and reduced governing flow equations are solved using moderated and an efficient convergent approach i.e. Homotopic technique. The significant effects of physical emerging parameters on flow velocity, temperature and fluid concentration are reporting through various plots. Graphical explanations for drag force, Nusselt and Sherwood numbers are stated and examined. The results reveal that minimum velocity field occurs near the plate, whereas it increases far away from the plate for strong velocity slip parameter. Furthermore, temperature and fluid concentration significantly decreases with increased slip effects. The current analysis is applicable in some advanced technological processes and industrial fluid mechanics.

Electromagnetic probe technique for fluid flow measurements

NASA Technical Reports Server (NTRS)

Arndt, G. D.; Carl, J. R.

1994-01-01

The probes described herein, in various configurations, permit the measurement of the volume fraction of two or more fluids flowing through a pipe. Each probe measures the instantaneous relative dielectric constant of the fluid in immediate proximity. As long as separation of the relative dielectric constant of the fluid is possible, several or even many fluids can be measured in the same flow stream. By using multiple probes, the velocity of each fluid can generally be determined as well as the distribution of each constituent in the pipe. The values are determined by statistical computation. There are many potential applications for probes of this type in industry and government. Possible NASA applications include measurements of helium/hydrazine flow during rocket tests at White Sands, liquid/gas flow in hydrogen or oxygen lines in Orbiter engines, and liquid/gaseous Freon flow in zero gravity tests with the KS135 aircraft at JSC. Much interest has been shown recently by the oil industry. In this a good method is needed to measure the fractions of oil, water, and natural gas flowing in a pipeline and the velocity of each. This particular problem involves an extension of what has been developed to date and our plans to solve this problem will be discussed herein.

FLOWMETER

DOEpatents

November, G.S.; Schute, F.

1962-02-20

A fluid flowmeter is designed in which a standing pressure wave is established. The amplitude of this standing wave is a function of the fluid flow rate so that pressure sensing devices may be used to indicate fluid flow and variations thereof. (AEC)

XFEM modeling of hydraulic fracture in porous rocks with natural fractures

NASA Astrophysics Data System (ADS)

Wang, Tao; Liu, ZhanLi; Zeng, QingLei; Gao, Yue; Zhuang, Zhuo

2017-08-01

Hydraulic fracture (HF) in porous rocks is a complex multi-physics coupling process which involves fluid flow, diffusion and solid deformation. In this paper, the extended finite element method (XFEM) coupling with Biot theory is developed to study the HF in permeable rocks with natural fractures (NFs). In the recent XFEM based computational HF models, the fluid flow in fractures and interstitials of the porous media are mostly solved separately, which brings difficulties in dealing with complex fracture morphology. In our new model the fluid flow is solved in a unified framework by considering the fractures as a kind of special porous media and introducing Poiseuille-type flow inside them instead of Darcy-type flow. The most advantage is that it is very convenient to deal with fluid flow inside the complex fracture network, which is important in shale gas extraction. The weak formulation for the new coupled model is derived based on virtual work principle, which includes the XFEM formulation for multiple fractures and fractures intersection in porous media and finite element formulation for the unified fluid flow. Then the plane strain Kristianovic-Geertsma-de Klerk (KGD) model and the fluid flow inside the fracture network are simulated to validate the accuracy and applicability of this method. The numerical results show that large injection rate, low rock permeability and isotropic in-situ stresses tend to lead to a more uniform and productive fracture network.

Microfluidic device and methods for focusing fluid streams using electroosmotically induced pressures

DOEpatents

Jacobson, Stephen C.; Ramsey, J. Michael

2010-06-01

A microfabricated device employing a bridging membrane and methods for electrokinetic transport of a liquid phase biological or chemical material using the same are described. The bridging membrane is deployed in or adjacent to a microchannel and permits either electric current flow or the transport of gas species, while inhibiting the bulk flow of material. The use of bridging membranes in accordance with this invention is applicable to electrokinetically inducing fluid flow to confine a selected material in a region of a microchannel that is not influenced by an electric field. Other structures for inducing fluid flow in accordance with this invention include nanochannel bridging membranes and alternating current fluid pumping devices. Applications of the bridging membranes according to this invention include the separation of species from a sample material, valving of fluids in a microchannel network, mixing of different materials in a microchannel, and the pumping of fluids.

Feedback regulated induction heater for a flowing fluid

DOEpatents

Migliori, Albert; Swift, Gregory W.

1985-01-01

A regulated induction heater for heating a stream of flowing fluid to a predetermined desired temperature. The heater includes a radiofrequency induction coil which surrounds a glass tube through which the fluid flows. A heating element consisting of a bundle of approximately 200 stainless steel capillary tubes located within the glass tube couples the output of the induction coil to the fluid. The temperature of the fluid downstream from the heating element is sensed with a platinum resistance thermometer, the output of which is applied to an adjustable proportional and integral feedback control circuit which regulates the power applied to the induction coil. The heater regulates the fluid temperature to within 0.005.degree. C. at a flow rate of 50 cm.sup.3 /second with a response time of less than 0.1 second, and can accommodate changes in heat load up to 1500 watts.

Feedback regulated induction heater for a flowing fluid

DOEpatents

Migliori, A.; Swift, G.W.

1984-06-13

A regulated induction heater for heating a stream of flowing fluid to a predetermined desired temperature. The heater includes a radiofrequency induction coil which surrounds a glass tube through which the fluid flows. A heating element consisting of a bundle of approximately 200 stainless steel capillary tubes located within the glass tube couples the output of the induction coil to the fluid. The temperature of the fluid downstream from the heating element is sensed with a platinum resistance thermometer, the output of which is applied to an adjustable porportional and integral feedback control circuit which regulates the power applied to the induction coil. The heater regulates the fluid temperature to within 0.005/sup 0/C at a flow rate of 50 cm/sup 3//sec with a response time of less than 0.1 second, and can accommodate changes in heat load up to 1500 watts.

Apparatus for irradiating a continuously flowing stream of fluid. [For neutron activation analysis

DOEpatents

Speir, L.G.; Adams, E.L.

1982-05-13

An apparatus for irradiating a continuously flowing stream of fluid is disclosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4..pi.. radiation geometry. The irradiation source, for example a /sup 252/Cf neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

Apparatus for irradiating a continuously flowing stream of fluid

DOEpatents

Speir, Leslie G.; Adams, Edwin L.

1984-01-01

An apparatus for irradiating a continuously flowing stream of fluid is diosed. The apparatus consists of a housing having a spherical cavity and a spherical moderator containing a radiation source positioned within the spherical cavity. The spherical moderator is of lesser diameter than the spherical cavity so as to define a spherical annular volume around the moderator. The housing includes fluid intake and output conduits which open onto the spherical cavity at diametrically opposite positions. Fluid flows through the cavity around the spherical moderator and is uniformly irradiated due to the 4.pi. radiation geometry. The irradiation source, for example a .sup.252 CF neutron source, is removable from the spherical moderator through a radial bore which extends outwardly to an opening on the outside of the housing. The radiation source may be routinely removed without interrupting the flow of fluid or breaching the containment of the fluid.

14 CFR 23.1095 - Carburetor deicing fluid flow rate.

Code of Federal Regulations, 2010 CFR

2010-01-01

.... (b) The fluid must be introduced into the air induction system— (1) Close to, and upstream of, the carburetor; and (2) So that it is equally distributed over the entire cross section of the induction system... Induction System § 23.1095 Carburetor deicing fluid flow rate. (a) If a carburetor deicing fluid system is...

Fracture Flow Characterization from Seismic and Electric Properties: Insight from Experimental and Numerical Approaches

NASA Astrophysics Data System (ADS)

Sawayama, K.; Kitamura, K.; Tsuji, T.; Fujimitsu, Y.

2017-12-01

The estimation of fluid flow and its distribution in the fracture is essential to evaluate subsurface fluid (e.g., geothermal water, ground water, oil and gas). Recently, fluid flow in the geothermal reservoir has been attracting attention to develop EGS (enhanced geothermal system) technique. To detect the fluid distribution under the ground, geophysical exploration such as seismic and electromagnetic methods have been broadly applied. For better interpretation of these exploration data, more detailed investigation about the effect of fluid on seismic and electric properties of fracture is required. In this study, we measured and calculated seismic and electric properties of a cracked rock to discuss the effect of water distribution and saturation on them as well as fluid flow. For the experimental observation, we developed the technique to measure electrical impedance, P-wave velocity and water saturation simultaneously during the fluid-flow test. The test has been conducted as follows; a cracked andesite core sample was filled with nitrogen gas (Pp = 10 MPa) under 20 MPa of confining pressure and then, brine (1wt.%-KCl, 1.75 S/m) was injected into the sample to replace the gas. During the test, water saturation, permeability, electrical impedance and P-wave velocity were measured. As a result of this experimental study, electrical impedance dramatically decreased from 105 to 103 Ω and P-wave velocity increased by 2% due to the brine injection. This remarkable change of the electrical impedance could be due to the replacement of pre-filled nitrogen gas to the brine in the broad fracture. After the brine injection, electrical impedance decreased with injection pressure by up to 40% while P-wave velocity was almost constant. This decrease of electrical impedance could be related to the flow to the narrow path (microcrack) which cannot be detected by P-wave velocity. These two types of fluid flow mechanism were also suggested from other parameters such as permeability, water saturation and saturation exponent of Archie's law. To quantify the fluid flow and its distribution in the fracture, we applied fluid flow simulation by LBM (Lattice Boltzmann Method). From this result, we calculate physical parameters by FEM and FDM and then discuss effect of fluid on them as well as their comparison with experimental results.

Inhibition of the expression of aquaporin‑1 by RNA interference in pulmonary epithelial cells and its effects on water transport.

PubMed

Zhang, Qiuyue; Fu, Jianhua; Xue, Xindong

2016-01-01

In the present study, the effect of aquaporin‑1 (AQP1) on fluid transportation in pulmonary epithelial cells, and the role of AQP1 in alveolar fluid clearance were investigated to provide an experimental foundation to elucidate the pathogenesis of hyperoxic lung edema. An siRNA transfection technique was used to silence AQP1 in the A549 cell line. The transfected cells were randomized into a hyperoxia exposure and an air control group, with a negative control group set for each group. Cell volume was determined using flow cytometry, and Pf values were used to determine osmotic water permeability. Cell volume was found to be reduced in the AQP1‑silenced A549 cells, compared with the negative control group 72 h following air exposure. In addition, cell volume was reduced in the AQP1‑silenced A549 cells, compared with the negative control group 48 and 72 h following hyperoxia exposure. The osmotic water permeability of the AQP1‑silenced cells was reduced in the air control and hyperoxia exposure groups, compared with the negative control group 48 and 72 h following exposure. The volume and cell membrane osmotic water permeability of the A549 cells were reduced, compared with those in the control group following AQP1‑silencing, which indicated that the downregulation of AQP1 impedes extracellular to intracellular fluid transportation. Therefore, the disturbance in alveolar fluid clearance resulting from the downregulation of AQP1 following hyperoxia exposure may be one of the key mechanisms responsible for hyperoxic lung edema.

Interfacial gauge methods for incompressible fluid dynamics

PubMed Central

Saye, Robert

2016-01-01

Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of “gauge freedom” to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work, high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena. PMID:27386567

Generalized Fluid System Simulation Program (GFSSP) - Version 6

NASA Technical Reports Server (NTRS)

Majumdar, Alok; LeClair, Andre; Moore, Ric; Schallhorn, Paul

2015-01-01

The Generalized Fluid System Simulation Program (GFSSP) is a finite-volume based general-purpose computer program for analyzing steady state and time-dependent flow rates, pressures, temperatures, and concentrations in a complex flow network. The program is capable of modeling real fluids with phase changes, compressibility, mixture thermodynamics, conjugate heat transfer between solid and fluid, fluid transients, pumps, compressors, flow control valves and external body forces such as gravity and centrifugal. The thermo-fluid system to be analyzed is discretized into nodes, branches, and conductors. The scalar properties such as pressure, temperature, and concentrations are calculated at nodes. Mass flow rates and heat transfer rates are computed in branches and conductors. The graphical user interface allows users to build their models using the 'point, drag, and click' method; the users can also run their models and post-process the results in the same environment. The integrated fluid library supplies thermodynamic and thermo-physical properties of 36 fluids, and 24 different resistance/source options are provided for modeling momentum sources or sinks in the branches. Users can introduce new physics, non-linear and time-dependent boundary conditions through user-subroutine.

Directed Fluid Transport and Mixing with Biomimetic Cilia Arrays

NASA Astrophysics Data System (ADS)

Shields, A. R.; Evans, B. A.; Carstens, B. L.; Falvo, M. R.; Washburn, S.; Superfine, R.

2009-03-01

We present results on the long-range, directed fluid transport and fluidic mixing produced by the collective beating of arrays of biomimetic cilia. These artificial cilia are arrays of free-standing nanorods roughly the size of biological cilia, which we fabricate from a polymer-magnetic nanoparticle composite material and actuate with permanent magnets to mimic biological cilia. Biological cilia have evolved to produce microscale fluid transport and are increasingly being recognized as critical components in a wide range of biological systems. However, despite much effort cilia generated fluid flows remain an area of active study. In the last decade, cilia-driven fluid flow in the embryonic node of vertebrates has been implicated as the initial left-right symmetry breaking event in these embryos. With silia we generate directional fluid transport by mimicking the tilted conical beating of these nodal cilia. By seeding fluorescent microparticles into the fluid we have noted the existence of two distinct flow regimes. The fluid flow is directional and coherent above the cilia tips, while between the cilia tips and the floor particle motion is complicated and suggestive of chaotic advection.

A design methodology of magentorheological fluid damper using Herschel-Bulkley model

NASA Astrophysics Data System (ADS)

Liao, Linqing; Liao, Changrong; Cao, Jianguo; Fu, L. J.

2003-09-01

Magnetorheological fluid (MR fluid) is highly concentrated suspension of very small magnetic particle in inorganic oil. The essential behavior of MR fluid is its ability to reversibly change from free-flowing, linear viscous liquids to semi-solids having controllable yield strength in milliseconds when exposed to magnetic field. This feature provides simple, quiet, rapid-response interfaces between electronic controls and mechanical systems. In this paper, a mini-bus MR fluid damper based on plate Poiseuille flow mode is typically analyzed using Herschel-Bulkley model, which can be used to account for post-yield shear thinning or thickening under the quasi-steady flow condition. In the light of various value of flow behavior index, the influences of post-yield shear thinning or thickening on flow velocity profiles of MR fluid in annular damping orifice are examined numerically. Analytical damping coefficient predictions also are compared via the nonlinear Bingham plastic model and Herschel-Bulkley constitutive model. A MR fluid damper, which is designed and fabricated according to design method presented in this paper, has tested by electro-hydraulic servo vibrator and its control system in National Center for Test and Supervision of Coach Quality. The experimental results reveal that the analysis methodology and design theory are reasonable and MR fluid damper can be designed according to the design methodology.

A soft porous drop in linear flows

NASA Astrophysics Data System (ADS)

Young, Yuan-Nan; Miksis, Michael; Mori, Yoichiro; Shelley, Michael

2017-11-01

The cellular cytoplasm consists a viscous fluid filled with fibrous networks that also have their own dynamics. Such fluid-structure interactions have been modeled as a soft porous material immersed in a viscous fluid. In this talk we focus on the hydrodynamics of a viscous drop filled with soft porous material inside. Suspended in a Stokes flow, such a porous viscous drop is allowed to deform, both the drop interface and the porous structures inside. Special focus is on the deformation dynamics of both the porosity and the shape of the drop under simple flows such as a uniform streaming flow and linear flows. We examine the effects of flow boundary conditions at interface between the porous drop and the surrounding viscous fluid. We also examine the dynamics of a porous drop with active stress from the porous network.

Go with the Flow: Cerebrospinal Fluid Flow Regulates Neural Stem Cell Proliferation.

PubMed

Kaneko, Naoko; Sawamoto, Kazunobu

2018-06-01

Adult neural stem cells in the wall of brain ventricles make direct contact with cerebrospinal fluid. In this issue of Cell Stem Cell, Petrik et al. (2018) demonstrate that these neural stem cells sense the flow of cerebrospinal fluid through a transmembrane sodium channel, ENaC, which regulates their proliferation. Copyright © 2018 Elsevier Inc. All rights reserved.

Topology optimization of unsteady flow problems using the lattice Boltzmann method

NASA Astrophysics Data System (ADS)

Nørgaard, Sebastian; Sigmund, Ole; Lazarov, Boyan

2016-02-01

This article demonstrates and discusses topology optimization for unsteady incompressible fluid flows. The fluid flows are simulated using the lattice Boltzmann method, and a partial bounceback model is implemented to model the transition between fluid and solid phases in the optimization problems. The optimization problem is solved with a gradient based method, and the design sensitivities are computed by solving the discrete adjoint problem. For moderate Reynolds number flows, it is demonstrated that topology optimization can successfully account for unsteady effects such as vortex shedding and time-varying boundary conditions. Such effects are relevant in several engineering applications, i.e. fluid pumps and control valves.

AC Electric-Field-Induced Fluid Flow in Microelectrodes.

PubMed

Ramos; Morgan; Green; Castellanos

1999-09-15

During the AC electrokinetic manipulation of particles in suspension on microelectrode structures, strong frequency-dependent fluid flow is observed. The fluid movement is predominant at frequencies below the reciprocal charge relaxation time, with a reproducible pattern occurring close to and across the electrode surface. This paper reports measurements of the fluid velocity as a function of frequency and position across the electrode. Evidence is presented indicating that the flow occurs due to electroosmotic stress arising from the interaction of the electric field and the electrical double layer on the electrodes. The electrode polarization plays a significant role in controlling the frequency dependence of the flow. Copyright 1999 Academic Press.

Smoothed Particle Hydrodynamics: A consistent model for interfacial multiphase fluid flow simulations

NASA Astrophysics Data System (ADS)

Krimi, Abdelkader; Rezoug, Mehdi; Khelladi, Sofiane; Nogueira, Xesús; Deligant, Michael; Ramírez, Luis

2018-04-01

In this work, a consistent Smoothed Particle Hydrodynamics (SPH) model to deal with interfacial multiphase fluid flows simulation is proposed. A modification to the Continuum Stress Surface formulation (CSS) [1] to enhance the stability near the fluid interface is developed in the framework of the SPH method. A non-conservative first-order consistency operator is used to compute the divergence of stress surface tensor. This formulation benefits of all the advantages of the one proposed by Adami et al. [2] and, in addition, it can be applied to more than two phases fluid flow simulations. Moreover, the generalized wall boundary conditions [3] are modified in order to be well adapted to multiphase fluid flows with different density and viscosity. In order to allow the application of this technique to wall-bounded multiphase flows, a modification of generalized wall boundary conditions is presented here for using the SPH method. In this work we also present a particle redistribution strategy as an extension of the damping technique presented in [3] to smooth the initial transient phase of gravitational multiphase fluid flow simulations. Several computational tests are investigated to show the accuracy, convergence and applicability of the proposed SPH interfacial multiphase model.

Lagrangian averaging with geodesic mean

NASA Astrophysics Data System (ADS)

Oliver, Marcel

2017-11-01

This paper revisits the derivation of the Lagrangian averaged Euler (LAE), or Euler-α equations in the light of an intrinsic definition of the averaged flow map as the geodesic mean on the volume-preserving diffeomorphism group. Under the additional assumption that first-order fluctuations are statistically isotropic and transported by the mean flow as a vector field, averaging of the kinetic energy Lagrangian of an ideal fluid yields the LAE Lagrangian. The derivation presented here assumes a Euclidean spatial domain without boundaries.

Lagrangian averaging with geodesic mean.

PubMed

Oliver, Marcel

2017-11-01

This paper revisits the derivation of the Lagrangian averaged Euler (LAE), or Euler- α equations in the light of an intrinsic definition of the averaged flow map as the geodesic mean on the volume-preserving diffeomorphism group. Under the additional assumption that first-order fluctuations are statistically isotropic and transported by the mean flow as a vector field, averaging of the kinetic energy Lagrangian of an ideal fluid yields the LAE Lagrangian. The derivation presented here assumes a Euclidean spatial domain without boundaries.

Medical and Scientific Evaluations aboard the KC-135. Microgravity-Compatible Flow Cytometer

NASA Technical Reports Server (NTRS)

Crucian, Brian; Nelman-Gonzalez, Mayra; Sams, Clarence

2005-01-01

A spaceflight-compatible flow cytometer would be useful for the diagnosis of astronaut illness during long duration spaceflight and for conducting in-flight research to evaluate the effects of microgravity on human physiology. Until recently, the primary limitations preventing the development of a spaceflight compatible flow cytometer have been largely mechanical. Standard commercially available flow cytometers are large, complex instruments that use high-energy lasers and require significant training to operate. Standard flow cytometers function by suspending the particles to be analyzed inside a sheath fluid for analysis. This requires the presence of several liters of sheath fluid for operation, and generates a corresponding amount of liquid hazardous waste. The particles are then passed through a flow cell which uses the fluid mechanical property of hydrodynamic focusing to place the cells in single-file (laminar flow) as they pass through a laser beam for scanning and evaluation. Many spaceflight experiments have demonstrated that fluid physics is dramatically altered in microgravity (MSF [Manned Space Flight] Fluid Physics Data Sheet-August 1997) and previous studies have shown that sheath-fluid based hydrodynamic focusing may also be altered during microgravity (Crucian et al, 2000). For these reasons it is likely that any spaceflight compatible design for a flow cytometer would abandon the sheath fluid requirement. The elimination of sheath fluid would remove both the problems of weight associated with large volumes of liquids as well as the large volume of liquid waste generated. It would also create the need for a method to create laminar particle flow distinct from the standard sheath-fluid based method. The spaceflight prototype instrument is based on a recently developed commercial flow cytometer possessing a novel flow cell design that creates single-particle laser scanning and evaluation without the need for sheath-fluid based hydrodynamic focusing. This instrument also possesses a number of design advances that make it conditionally microgravity compatible: it is highly miniaturized and lightweight, uses a low energy diode laser, has a small number of moving parts, does not use sheath fluid and does not generate significant liquid waste. Although possessing certain limitations, the commercial cytometer functions operationally like a standard bench top laboratory flow cytometer, aspirating liquid particle samples and generating histogram or dot-plot data in standard FCS file format. In its current configuration however, the cytometer is limited to three parameter/two-color capability (two color PMTs + forward scatter), does not allow compensation between colors, does not allow linear analysis and is operated by rather inflexible software with limited capabilities. This is due to the fact that the cytometer has been designed and marketed as an instrument specific to a few particular assays, not as a multipurpose cytometer.

Goal-directed fluid therapy in major elective rectal surgery.

PubMed

Srinivasa, Sanket; Taylor, Matthew H G; Singh, Primal P; Lemanu, Daniel P; MacCormick, Andrew D; Hill, Andrew G

2014-12-01

Goal-Directed Fluid Therapy (GDFT) has been previously shown to decrease complications and hospital length of stay in major colorectal surgery but the data are not specific to rectal surgery and may be potentially outdated. This study investigated whether GDFT provides clinical benefits in patients undergoing major elective rectal surgery. There were 81 consecutive patients in this cohort study. Twenty-seven patients were allotted to GDFT using the Oesophageal Doppler Monitor (ODM) and received boluses of colloid fluid based on corrected flow time and stroke volume. These patients were compared with a historical cohort of the previous 54 patients managed without the ODM. The primary endpoint of the study was 30-day total complications which were defined and graded. Secondary endpoints included hospital length of stay (LOS) and fluid volumes administered. There were no differences at baseline between the two groups. Patients in the treatment group received a higher volume of colloid fluids (1000 mL vs. 500 mL; p < 0.01) but there were no differences in overall fluid volumes administered intraoperatively (3000 mL vs. 3000 mL; p = 0.41). A non-significant trend (p = 0.06) suggested that patients allotted to GDFT had decreased fluid requirement in the first 24 h after surgery. There were no differences in median total fluid volumes (12700 mL vs. 10407 mL; p = 0.95), total complications (22 [81%] vs. 44 [81%]; p = 1.00) or median hospital LOS (9 days vs. 10 days; p = 0.92) between the two groups. Intraoperative GDFT did not improve clinical outcomes following major elective rectal surgery. Copyright © 2014 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

Calculation of incompressible fluid flow through cambered blades

NASA Technical Reports Server (NTRS)

Hsu, C. C.

1970-01-01

Conformal mapping technique yields linear, approximate solutions for calculating flow of an incompressible fluid through staggered array of cambered blades for the cases of flow with partial cavitation and supercavitation. Lift and drag coefficients, cavitation number, cavity shape, and exit flow conditions can be determined.

Numerical Modeling of Conjugate Heat Transfer in Fluid Network

NASA Technical Reports Server (NTRS)

Majumdar, Alok

2004-01-01

Fluid network modeling with conjugate heat transfer has many applications in Aerospace engineering. In modeling unsteady flow with heat transfer, it is important to know the variation of wall temperature in time and space to calculate heat transfer between solid to fluid. Since wall temperature is a function of flow, a coupled analysis of temperature of solid and fluid is necessary. In cryogenic applications, modeling of conjugate heat transfer is of great importance to correctly predict boil-off rate in propellant tanks and chill down of transfer lines. In TFAWS 2003, the present author delivered a paper to describe a general-purpose computer program, GFSSP (Generalized Fluid System Simulation Program). GFSSP calculates flow distribution in complex flow circuit for compressible/incompressible, with or without heat transfer or phase change in all real fluids or mixtures. The flow circuit constitutes of fluid nodes and branches. The mass, energy and specie conservation equations are solved at the nodes where as momentum conservation equations are solved at the branches. The proposed paper describes the extension of GFSSP to model conjugate heat transfer. The network also includes solid nodes and conductors in addition to fluid nodes and branches. The energy conservation equations for solid nodes solves to determine the temperatures of the solid nodes simultaneously with all conservation equations governing fluid flow. The numerical scheme accounts for conduction, convection and radiation heat transfer. The paper will also describe the applications of the code to predict chill down of cryogenic transfer line and boil-off rate of cryogenic propellant storage tank.

Acquisition of Turbulence Data Using the DST Group Constant-Temperature Hot-Wire Anemometer System

DTIC Science & Technology

2015-10-01

fluctuations in the low-speed wind tunnel at DST Group. The use of both single- wire and crossed- wire (2 wire ) probes is described. Areas covered include a...fluid-flow studies, including testing of models of aircraft, ships and submarines in wind and water tunnels. Hot- wire anemometers and associated hot...spectra of velocity fluctuations in the low-speed wind tunnel at DST Group. The use of both single- wire and crossed- wire (2 wires ) probes is

Missile Aerodynamics: Conference Proceedings of Symposium of the Fluid Dynamics Panel Held in Friedrichshafen, Germany on 23-26 April 1990

DTIC Science & Technology

1990-10-01

closely to the four groups of launch Mach numbers used two independent planar motions. The addition of con- in the range firings. A representative...the geometrical configuration. In a recent past, the AGARD Working Group 08 made a rather thorough review of afterbody flow studies by examining both...NUMBER OF COLOR PAGES WHICH DO NOT REPRODUCE LEGIBLY ON BLACK AND WHITE MICROFICHE. AGARD-CP-493 NORTH ATLANTIC TREATY ORGANIZATION ADVISORY GROUP FOR

EFFECT OF AN ADDITIONAL HYDROPHILIC VERSUS HYDROPHOBIC COAT ON THE QUALITY OF DENTINAL SEALING PROVIDED BY TWO-STEP ETCH-AND-RINSE ADHESIVES

PubMed Central

Silva, Safira Marques de Andrade; Carrilho, Marcela Rocha de Oliveira; Marquezini, Luiz; Garcia, Fernanda Cristina Pimentel; Manso, Adriana Pigozzo; Alves, Marcelo Corrêa; de Carvalho, Ricardo Marins

2009-01-01

Objective: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. Material and Methods: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. Results: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. Conclusions: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent. PMID:19466248

Influence of mechanical rock properties and fracture healing rate on crustal fluid flow dynamics

NASA Astrophysics Data System (ADS)

Sachau, Till; Bons, Paul; Gomez-Rivas, Enrique; Koehn, Daniel; de Riese, Tamara

2016-04-01

Fluid flow in the Earth's crust is very slow over extended periods of time, during which it occurs within the connected pore space of rocks. If the fluid production rate exceeds a certain threshold, matrix permeability alone is insufficient to drain the fluid volume and fluid pressure builds up, thereby reducing the effective stress supported by the rock matrix. Hydraulic fractures form once the effective pressure exceeds the tensile strength of the rock matrix and act subsequently as highly effective fluid conduits. Once local fluid pressure is sufficiently low again, flow ceases and fractures begin to heal. Since fluid flow is controlled by the alternation of fracture permeability and matrix permeability, the flow rate in the system is strongly discontinuous and occurs in intermittent pulses. Resulting hydraulic fracture networks are largely self-organized: opening and subsequent healing of hydraulic fractures depends on the local fluid pressure and on the time-span between fluid pulses. We simulate this process with a computer model and describe the resulting dynamics statistically. Special interest is given to a) the spatially and temporally discontinuous formation and closure of fractures and fracture networks and b) the total flow rate over time. The computer model consists of a crustal-scale dual-porosity setup. Control parameters are the pressure- and time-dependent fracture healing rate, and the strength and the permeability of the intact rock. Statistical analysis involves determination of the multifractal properties and of the power spectral density of the temporal development of the total drainage rate and hydraulic fractures. References Bons, P. D. (2001). The formation of large quartz veins by rapid ascent of fluids in mobile hydrofractures. Tectonophysics, 336, 1-17. Miller, S. a., & Nur, A. (2000). Permeability as a toggle switch in fluid-controlled crustal processes. Earth and Planetary Science Letters, 183(1-2), 133-146. Sachau, T., Bons, P. D., & Gomez-Rivas, E. (2015). Transport efficiency and dynamics of hydraulic fracture networks. Frontiers in Physics, 3.

Group invariant solution for a pre-existing fluid-driven fracture in impermeable rock

NASA Astrophysics Data System (ADS)

Fitt, A. D.; Mason, D. P.; Moss, E. A.

2007-11-01

The propagation of a two-dimensional fluid-driven fracture in impermeable rock is considered. The fluid flow in the fracture is laminar. By applying lubrication theory a partial differential equation relating the half-width of the fracture to the fluid pressure is derived. To close the model the PKN formulation is adopted in which the fluid pressure is proportional to the half-width of the fracture. By considering a linear combination of the Lie point symmetries of the resulting non-linear diffusion equation the boundary value problem is expressed in a form appropriate for a similarity solution. The boundary value problem is reformulated as two initial value problems which are readily solved numerically. The similarity solution describes a preexisting fracture since both the total volume and length of the fracture are initially finite and non-zero. Applications in which the rate of fluid injection into the fracture and the pressure at the fracture entry are independent of time are considered.

Voltage-Rectified Current and Fluid Flow in Conical Nanopores.

PubMed

Lan, Wen-Jie; Edwards, Martin A; Luo, Long; Perera, Rukshan T; Wu, Xiaojian; Martin, Charles R; White, Henry S

2016-11-15

Ion current rectification (ICR) refers to the asymmetric potential-dependent rate of the passage of solution ions through a nanopore, giving rise to electrical current-voltage characteristics that mimic those of a solid-state electrical diode. Since the discovery of ICR in quartz nanopipettes two decades ago, synthetic nanopores and nanochannels of various geometries, fabricated in membranes and on wafers, have been extensively investigated to understand fundamental aspects of ion transport in highly confined geometries. It is now generally accepted that ICR requires an asymmetric electrical double layer within the nanopore, producing an accumulation or depletion of charge-carrying ions at opposite voltage polarities. Our research groups have recently explored how the voltage-dependent ion distributions and ICR within nanopores can induce novel nanoscale flow phenomena that have applications in understanding ionics in porous materials used in energy storage devices, chemical sensing, and low-cost electrical pumping of fluids. In this Account, we review our most recent investigations on this topic, based on experiments using conical nanopores (10-300 nm tip opening) fabricated in thin glass, mica, and polymer membranes. Measurable fluid flow in nanopores can be induced either using external pressure forces, electrically via electroosmotic forces, or by a combination of these two forces. We demonstrate that pressure-driven flow can greatly alter the electrical properties of nanopores and, vice versa, that the nonlinear electrical properties of conical nanopores can impart novel and useful flow phenomena. Electroosmotic flow (EOF), which depends on the magnitude of the ion fluxes within the double layer of the nanopore, is strongly coupled to the accumulation/depletion of ions. Thus, the same underlying cause of ICR also leads to EOF rectification, i.e., unequal flows occurring for the same voltage but opposite polarities. EOF rectification can be used to electrically pump fluids with very precise control across membranes containing conical pores via the application of a symmetric sinusoidal voltage. The combination of pressure and asymmetric EOF can also provide a means to generate new nanopore electrical behaviors, including negative differential resistance (NDR), in which the current through a conical pore decreases with increasing driving force (applied voltage), similar to solid-state tunnel diodes. NDR results from a positive feedback mechanism between the ion distributions and EOF, yielding a true bistability in both fluid flow and electrical current at a critical applied voltage. Nanopore-based NDR is extremely sensitive to the surface charge near the nanopore opening, suggesting possible applications in chemical sensing.

A simplified model to evaluate the effect of fluid rheology on non-Newtonian flow in variable aperture fractures

NASA Astrophysics Data System (ADS)

Felisa, Giada; Ciriello, Valentina; Longo, Sandro; Di Federico, Vittorio

2017-04-01

Modeling of non-Newtonian flow in fractured media is essential in hydraulic fracturing operations, largely used for optimal exploitation of oil, gas and thermal reservoirs. Complex fluids interact with pre-existing rock fractures also during drilling operations, enhanced oil recovery, environmental remediation, and other natural phenomena such as magma and sand intrusions, and mud volcanoes. A first step in the modeling effort is a detailed understanding of flow in a single fracture, as the fracture aperture is typically spatially variable. A large bibliography exists on Newtonian flow in single, variable aperture fractures. Ultimately, stochastic modeling of aperture variability at the single fracture scale leads to determination of the flowrate under a given pressure gradient as a function of the parameters describing the variability of the aperture field and the fluid rheological behaviour. From the flowrate, a flow, or 'hydraulic', aperture can then be derived. The equivalent flow aperture for non-Newtonian fluids of power-law nature in single, variable aperture fractures has been obtained in the past both for deterministic and stochastic variations. Detailed numerical modeling of power-law fluid flow in a variable aperture fracture demonstrated that pronounced channelization effects are associated to a nonlinear fluid rheology. The availability of an equivalent flow aperture as a function of the parameters describing the fluid rheology and the aperture variability is enticing, as it allows taking their interaction into account when modeling flow in fracture networks at a larger scale. A relevant issue in non-Newtonian fracture flow is the rheological nature of the fluid. The constitutive model routinely used for hydro-fracturing modeling is the simple, two-parameter power-law. Yet this model does not characterize real fluids at low and high shear rates, as it implies, for shear-thinning fluids, an apparent viscosity which becomes unbounded for zero shear rate and tends to zero for infinite shear rate. On the contrary, the four-parameter Carreau constitutive equation includes asymptotic values of the apparent viscosity at those limits; in turn, the Carreau rheological equation is well approximated by the more tractable truncated power-law model. Results for flow of such fluids between parallel walls are already available. This study extends the adoption of the truncated power-law model to variable aperture fractures, with the aim of understanding the joint influence of rheology and aperture spatial variability. The aperture variation, modeled within a stochastic or deterministic framework, is taken to be one-dimensional and perpendicular to the flow direction; for stochastic modeling, the influence of different distribution functions is examined. Results are then compared with those obtained for pure power-law fluids for different combinations of model parameters. It is seen that the adoption of the pure power law model leads to significant overestimation of the flowrate with respect to the truncated model, more so for large external pressure gradient and/or aperture variability.

Levitation of heavy particles against gravity in asymptotically downward flows.

PubMed

Angilella, Jean-Régis; Case, Daniel J; Motter, Adilson E

2017-03-01

In the fluid transport of particles, it is generally expected that heavy particles carried by a laminar fluid flow moving downward will also move downward. We establish a theory to show, however, that particles can be dynamically levitated and lifted by interacting vortices in such flows, thereby moving against gravity and the asymptotic direction of the flow, even when they are orders of magnitude denser than the fluid. The particle levitation is rigorously demonstrated for potential flows and supported by simulations for viscous flows. We suggest that this counterintuitive effect has potential implications for the air-transport of water droplets and the lifting of sediments in water.

Levitation of heavy particles against gravity in asymptotically downward flows

NASA Astrophysics Data System (ADS)

Angilella, Jean-Régis; Case, Daniel J.; Motter, Adilson E.

2017-03-01

In the fluid transport of particles, it is generally expected that heavy particles carried by a laminar fluid flow moving downward will also move downward. We establish a theory to show, however, that particles can be dynamically levitated and lifted by interacting vortices in such flows, thereby moving against gravity and the asymptotic direction of the flow, even when they are orders of magnitude denser than the fluid. The particle levitation is rigorously demonstrated for potential flows and supported by simulations for viscous flows. We suggest that this counterintuitive effect has potential implications for the air-transport of water droplets and the lifting of sediments in water.

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

Bolenbaugh, Jonathan M.; Naqi, Syed

A method to operate a clutch device in an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and at least one electric machine includes, in response to a failure condition detected within a flow control device configured to facilitate flow of hydraulic fluid for operating the clutch device, selectively preventing the flow of hydraulic fluid from entering the flow control device and feeding the clutch device. Synchronization of the clutch device is initiated when the clutch device is intended for activation, and only if the clutch device is synchronized, the flow of hydraulic fluid is selectively permitted to entermore » the flow control device to activate the clutch device.« less

Turbulence coefficients and stability studies for the coaxial flow or dissimiliar fluids. [gaseous core nuclear reactors

NASA Technical Reports Server (NTRS)

Weinstein, H.; Lavan, Z.

1975-01-01

Analytical investigations of fluid dynamics problems of relevance to the gaseous core nuclear reactor program are presented. The vortex type flow which appears in the nuclear light bulb concept is analyzed along with the fluid flow in the fuel inlet region for the coaxial flow gaseous core nuclear reactor concept. The development of numerical methods for the solution of the Navier-Stokes equations for appropriate geometries is extended to the case of rotating flows and almost completes the gas core program requirements in this area. The investigations demonstrate that the conceptual design of the coaxial flow reactor needs further development.

Paleozoic fluid history of the Michigan Basin: Evidence from dolomite geochemistry in the Middle Ordovician St. Peter Sandstone

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

Winter, B.L.; Johnson, C.M.; Simo, J.A.

1995-04-03

The isotope (Sr and O) and elemental (Mg, Ca, Mn, Fe, and Sr) compositions of the various dolomites in the Middle Ordovician St. Peter Sandstone in the Michigan Basin are determined and the variations are modeled in terms of fluid-rock interaction or as mixing relations. These geochemical models, combined with the paragenetic sequence of the dolomites and late anhydrite cement, suggest the existence of at least four distinct diagenetic fluids in the St. Peter Sandstone during the paleozoic. Fluid 1 has a composition consistent with a modified older (pre-Middle Ordovician) seawater origin, which indicates that the flow path for thismore » fluid had a major upward component. This fluid resulted in the first and volumetrically most important burial dolomitization event, producing dolomite in both carbonate and quartz sandstone lithofacies in the St. Peter Sandstone. Fluid 2 has a composition consistent with a modified Middle to early Late Ordovician seawater origin, suggesting a major downward component for fluid flow. Fluid 2 produced dolomite cement in the carbonate lithofacies that postdates Fluid 1 dolomite. The composition of Fluid 3 is best interpreted to reflect a heated, deep basinal brine that had previously interacted with the K-feldspar-rich rocks near the Cambrian-Precambrian unconformity in the Michigan Basin, indicating a major upward component for fluid flow. Fluid 3 produced dolomite cement in quartz sandstone lithofacies that postdates Fluid 1 dolomite. Fluid 4 resulted in precipitation of late anhydrite in fractures. The {sup 87}Sr/{sup 86}Sr ratio of the anhydrite is consistent with Fluid 4 originating as a dilute fluid that interacted extensively with Silurian gypsum in the Michigan Basin; this indicates that the flow path of Fluid 4 had a major downward component.« less

Vortex locking in direct numerical simulations of quantum turbulence.

PubMed

Morris, Karla; Koplik, Joel; Rouson, Damian W I

2008-07-04

Direct numerical simulations are used to examine the locking of quantized superfluid vortices and normal fluid vorticity in evolving turbulent flows. The superfluid is driven by the normal fluid, which undergoes either a decaying Taylor-Green flow or a linearly forced homogeneous isotropic turbulent flow, although the back reaction of the superfluid on the normal fluid flow is omitted. Using correlation functions and wavelet transforms, we present numerical and visual evidence for vortex locking on length scales above the intervortex spacing.

Method and apparatus for controlling cross contamination of microfluid channels

DOEpatents

Hasselbrink, Jr., Ernest F.; Rehm, Jason E [Alameda, CA; Paul, Phillip H [Livermore, CA; Arnold, Don W [Livermore, CA

2006-02-07

A method for controlling fluid flow at junctions in microchannel systems. Control of fluid flow is accomplished generally by providing increased resistance to electric-field and pressure-driven flow in the form of regions of reduced effective cross-sectional area within the microchannels and proximate a channel junction. By controlling these flows in the region of a microchannel junction it is possible to eliminate sample dispersion and cross contamination and inject well-defined volumes of fluid from one channel to another.

Detailed computational procedure for design of cascade blades with prescribed velocity distributions in compressible potential flows

NASA Technical Reports Server (NTRS)

Costello, George R; Cummings, Robert L; Sinnette, John T , Jr

1952-01-01

A detailed step-by-step computational outline is presented for the design of two-dimensional cascade blades having a prescribed velocity distribution on the blade in a potential flow of the usual compressible fluid. The outline is based on the assumption that the magnitude of the velocity in the flow of the usual compressible nonviscous fluid is proportional to the magnitude of the velocity in the flow of a compressible nonviscous fluid with linear pressure-volume relation.

Hemodynamics in a giant intracranial aneurysm characterized by in vitro 4D flow MRI

PubMed Central

Schiavazzi, Daniele; Moen, Sean; Jagadeesan, Bharathi; Van de Moortele, Pierre-François; Coletti, Filippo

2018-01-01

Experimental and computational data suggest that hemodynamics play a critical role in the development, growth, and rupture of cerebral aneurysms. The flow structure, especially in aneurysms with a large sac, is highly complex and three-dimensional. Therefore, volumetric and time-resolved measurements of the flow properties are crucial to fully characterize the hemodynamics. In this study, phase-contrast Magnetic Resonance Imaging is used to assess the fluid dynamics inside a 3D-printed replica of a giant intracranial aneurysm, whose hemodynamics was previously simulated by multiple research groups. The physiological inflow waveform is imposed in a flow circuit with realistic cardiovascular impedance. Measurements are acquired with sub-millimeter spatial resolution for 16 time steps over a cardiac cycle, allowing for the detailed reconstruction of the flow evolution. Moreover, the three-dimensional and time-resolved pressure distribution is calculated from the velocity field by integrating the fluid dynamics equations, and is validated against differential pressure measurements using precision transducers. The flow structure is characterized by vortical motions that persist within the aneurysm sac for most of the cardiac cycle. All the main flow statistics including velocity, vorticity, pressure, and wall shear stress suggest that the flow pattern is dictated by the aneurysm morphology and is largely independent of the pulsatility of the inflow, at least for the flow regimes investigated here. Comparisons are carried out with previous computational simulations that used the same geometry and inflow conditions, both in terms of cycle-averaged and systolic quantities. PMID:29300738

Abrupt contraction flow of magnetorheological fluids

NASA Astrophysics Data System (ADS)

Kuzhir, P.; López-López, M. T.; Bossis, G.

2009-05-01

Contraction and expansion flows of magnetorheological fluids occur in a variety of smart devices. It is important therefore to learn how these flows can be controlled by means of applied magnetic fields. This paper presents a first investigation into the axisymmetric flow of a magnetorheological fluid through an orifice (so-called abrupt contraction flow). The effect of an external magnetic field, longitudinal or transverse to the flow, is examined. In experiments, the pressure-flow rate curves were measured, and the excess pressure drop (associated with entrance and exit losses) was derived from experimental data through the Bagley correction procedure. The effect of the longitudinal magnetic field is manifested through a significant increase in the slope of the pressure-flow rate curves, while no discernible yield stress occurs. This behavior, observed at shear Mason numbers 10

A closed-form analytical model for predicting 3D boundary layer displacement thickness for the validation of viscous flow solvers

NASA Astrophysics Data System (ADS)

Kumar, V. R. Sanal; Sankar, Vigneshwaran; Chandrasekaran, Nichith; Saravanan, Vignesh; Natarajan, Vishnu; Padmanabhan, Sathyan; Sukumaran, Ajith; Mani, Sivabalan; Rameshkumar, Tharikaa; Nagaraju Doddi, Hema Sai; Vysaprasad, Krithika; Sharan, Sharad; Murugesh, Pavithra; Shankar, S. Ganesh; Nejaamtheen, Mohammed Niyasdeen; Baskaran, Roshan Vignesh; Rahman Mohamed Rafic, Sulthan Ariff; Harisrinivasan, Ukeshkumar; Srinivasan, Vivek

2018-02-01

A closed-form analytical model is developed for estimating the 3D boundary-layer-displacement thickness of an internal flow system at the Sanal flow choking condition for adiabatic flows obeying the physics of compressible viscous fluids. At this unique condition the boundary-layer blockage induced fluid-throat choking and the adiabatic wall-friction persuaded flow choking occur at a single sonic-fluid-throat location. The beauty and novelty of this model is that without missing the flow physics we could predict the exact boundary-layer blockage of both 2D and 3D cases at the sonic-fluid-throat from the known values of the inlet Mach number, the adiabatic index of the gas and the inlet port diameter of the internal flow system. We found that the 3D blockage factor is 47.33 % lower than the 2D blockage factor with air as the working fluid. We concluded that the exact prediction of the boundary-layer-displacement thickness at the sonic-fluid-throat provides a means to correctly pinpoint the causes of errors of the viscous flow solvers. The methodology presented herein with state-of-the-art will play pivotal roles in future physical and biological sciences for a credible verification, calibration and validation of various viscous flow solvers for high-fidelity 2D/3D numerical simulations of real-world flows. Furthermore, our closed-form analytical model will be useful for the solid and hybrid rocket designers for the grain-port-geometry optimization of new generation single-stage-to-orbit dual-thrust-motors with the highest promising propellant loading density within the given envelope without manifestation of the Sanal flow choking leading to possible shock waves causing catastrophic failures.

Strontium isotope constraints on fluid flow in the sheeted dike complex of fast spreading crust: Pervasive fluid flow at Pito Deep

NASA Astrophysics Data System (ADS)

Barker, A. K.; Coogan, L. A.; Gillis, K. M.; Weis, D.

2008-06-01

Fluid flow through the axial hydrothermal system at fast spreading ridges is investigated using the Sr-isotopic composition of upper crustal samples recovered from a tectonic window at Pito Deep (NE Easter microplate). Samples from the sheeted dike complex collected away from macroscopic evidence of channelized fluid flow, such as faults and centimeter-scale hydrothermal veins, show a range of 87Sr/86Sr from 0.7025 to 0.7030 averaging 0.70276 relative to a protolith with 87Sr/86Sr of ˜0.7024. There is no systematic variation in 87Sr/86Sr with depth in the sheeted dike complex. Comparison of these new data with the two other localities that similar data sets exist for (ODP Hole 504B and the Hess Deep tectonic window) reveals that the extent of Sr-isotope exchange is similar in all of these locations. Models that assume that fluid-rock reaction occurs during one-dimensional (recharge) flow lead to significant decreases in the predicted extent of isotopic modification of the rock with depth in the crust. These model results show systematic misfits when compared with the data that can only be avoided if the fluid flow is assumed to be focused in isolated channels with very slow fluid-rock exchange. In this scenario the fluid at the base of the crust is little modified in 87Sr/86Sr from seawater and thus unlike vent fluids. Additionally, this model predicts that some rocks should show no change from the fresh-rock 87Sr/86Sr, but this is not observed. Alternatively, models in which fluid-rock reaction occurs during upflow (discharge) as well as downflow, or in which fluids are recirculated within the hydrothermal system, can reproduce the observed lack of variation in 87Sr/86Sr with depth in the crust. Minimum time-integrated fluid fluxes, calculated from mass balance, are between 1.5 and 2.6 × 106 kg m-2 for all areas studied to date. However, new evidence from both the rocks and a compilation of vent fluid compositions demonstrates that some Sr is leached from the crust. Because this leaching lowers the fluid 87Sr/86Sr without changing the rock 87Sr/86Sr, these mass balance models must underestimate the time-integrated fluid flux. Additionally, these values do not account for fluid flow that is channelized within the crust.

Highly resolved fluid flows: "liquid plasmas" at the kinetic level.

PubMed

Morfill, Gregor E; Rubin-Zuzic, Milenko; Rothermel, Hermann; Ivlev, Alexei V; Klumov, Boris A; Thomas, Hubertus M; Konopka, Uwe; Steinberg, Victor

2004-04-30

Fluid flow around an obstacle was observed at the kinetic (individual particle) level using "complex (dusty) plasmas" in their liquid state. These "liquid plasmas" have bulk properties similar to water (e.g., viscosity), and a comparison in terms of similarity parameters suggests that they can provide a unique tool to model classical fluids. This allows us to study "nanofluidics" at the most elementary-the particle-level, including the transition from fluid behavior to purely kinetic transport. In this (first) experimental investigation we describe the kinetic flow topology, discuss our observations in terms of fluid theories, and follow this up with numerical simulations.

Existence of the passage to the limit of an inviscid fluid.

PubMed

Goldobin, Denis S

2017-11-24

In the dynamics of a viscous fluid, the case of vanishing kinematic viscosity is actually equivalent to the Reynolds number tending to infinity. Hence, in the limit of vanishing viscosity the fluid flow is essentially turbulent. On the other hand, the Euler equation, which is conventionally adopted for the description of the flow of an inviscid fluid, does not possess proper turbulent behaviour. This raises the question of the existence of the passage to the limit of an inviscid fluid for real low-viscosity fluids. To address this question, one should employ the theory of turbulent boundary layer near an inflexible boundary (e.g., rigid wall). On the basis of this theory, one can see how the solutions to the Euler equation become relevant for the description of the flow of low-viscosity fluids, and obtain the small parameter quantifying accuracy of this description for real fluids.

Introducing Non-Newtonian Fluid Mechanics Computations with Mathematica in the Undergraduate Curriculum

ERIC Educational Resources Information Center

Binous, Housam

2007-01-01

We study four non-Newtonian fluid mechanics problems using Mathematica[R]. Constitutive equations describing the behavior of power-law, Bingham and Carreau models are recalled. The velocity profile is obtained for the horizontal flow of power-law fluids in pipes and annuli. For the vertical laminar film flow of a Bingham fluid we determine the…

Viscoelastic flow past mono- and bidisperse random arrays of cylinders: flow resistance, topology and normal stress distribution.

PubMed

De, S; Kuipers, J A M; Peters, E A J F; Padding, J T

2017-12-13

We investigate creeping viscoelastic fluid flow through two-dimensional porous media consisting of random arrangements of monodisperse and bidisperse cylinders, using our finite volume-immersed boundary method introduced in S. De, et al., J. Non-Newtonian Fluid Mech., 2016, 232, 67-76. The viscoelastic fluid is modeled with a FENE-P model. The simulations show an increased flow resistance with increase in flow rate, even though the bulk response of the fluid to shear flow is shear thinning. We show that if the square root of the permeability is chosen as the characteristic length scale in the determination of the dimensionless Deborah number (De), then all flow resistance curves collapse to a single master curve, irrespective of the pore geometry. Our study reveals how viscoelastic stresses and flow topologies (rotation, shear and extension) are distributed through the porous media, and how they evolve with increasing De. We correlate the local viscoelastic first normal stress differences with the local flow topology and show that the largest normal stress differences are located in shear flow dominated regions and not in extensional flow dominated regions at higher viscoelasticity. The study shows that normal stress differences in shear flow regions may play a crucial role in the increase of flow resistance for viscoelastic flow through such porous media.

Falkner-Skan Boundary Layer Flow of a Sisko Fluid

NASA Astrophysics Data System (ADS)

Khan, Masood; Shahzad, Azeem

2012-09-01

In this paper, we investigate the steady boundary layer flow of a non-Newtonian fluid, represented by a Sisko fluid, over a wedge in a moving fluid. The equations of motion are derived for boundary layer flow of an incompressible Sisko fluid using appropriate similarity variables. The governing equations are reduced to a single third-order highly nonlinear ordinary differential equation in the dimensionless stream function, which is then solved analytically using the homotopy analysis method. Some important parameters have been discussed by this study, which include the power law index n, the material parameter A, the wedge shape factor b, and the skin friction coefficient Cf. A comprehensive study is made between the results of the Sisko and the power-law fluids.

Fluid permeability measurement system and method

DOEpatents

Hallman, Jr., Russell Louis; Renner, Michael John [Oak Ridge, TN

2008-02-05

A system for measuring the permeance of a material. The permeability of the material may also be derived. The system provides a liquid or high concentration fluid bath on one side of a material test sample, and a gas flow across the opposing side of the material test sample. The mass flow rate of permeated fluid as a fraction of the combined mass flow rate of gas and permeated fluid is used to calculate the permeance of the material. The material test sample may be a sheet, a tube, or a solid shape. Operational test conditions may be varied, including concentration of the fluid, temperature of the fluid, strain profile of the material test sample, and differential pressure across the material test sample.

System and method for networking electrochemical devices

DOEpatents

Williams, Mark C.; Wimer, John G.; Archer, David H.

1995-01-01

An improved electrochemically active system and method including a plurality of electrochemical devices, such as fuel cells and fluid separation devices, in which the anode and cathode process-fluid flow chambers are connected in fluid-flow arrangements so that the operating parameters of each of said plurality of electrochemical devices which are dependent upon process-fluid parameters may be individually controlled to provide improved operating efficiency. The improvements in operation include improved power efficiency and improved fuel utilization in fuel cell power generating systems and reduced power consumption in fluid separation devices and the like through interstage process fluid parameter control for series networked electrochemical devices. The improved networking method includes recycling of various process flows to enhance the overall control scheme.

Stability of flow of a thermoviscoelastic fluid between rotating coaxial circular cylinders

NASA Technical Reports Server (NTRS)

Ghandour, N. N.; Narasimhan, M. N. L.

1976-01-01

The stability problem of thermoviscoelastic fluid flow between rotating coaxial cylinders is investigated using nonlinear thermoviscoelastic constitutive equations due to Eringen and Koh. The velocity field is found to be identical with that of the classical viscous case and the case of the viscoelastic fluid, but the temperature and pressure fields are found to be different. By imposing some physically reasonable mechanical and geometrical restrictions on the flow, and by a suitable mathematical analysis, the problem is reduced to a characteristic value problem. The resulting problem is solved and stability criteria are obtained in terms of critical Taylor numbers. In general, it is found that thermoviscoelastic fluids are more stable than classical viscous fluids and viscoinelastic fluids under similar conditions.

Fluid delivery control system

DOEpatents

Hoff, Brian D.; Johnson, Kris William; Algrain, Marcelo C.; Akasam, Sivaprasad

2006-06-06

A method of controlling the delivery of fluid to an engine includes receiving a fuel flow rate signal. An electric pump is arranged to deliver fluid to the engine. The speed of the electric pump is controlled based on the fuel flow rate signal.

SALIVA SPECIFIC GRAVITY.

DTIC Science & Technology

Four experiments were carried out to investigate the effect of flow rate on parotid fluid specific gravity at different levels of stimulation and to...compare parotid fluid to submaxillo-sublingual fluid in this regard. A strong positive correlation was found between parotid flow rate and specific

Method and apparatus for chemically altering fluids in continuous flow

DOEpatents

Heath, W.O.; Virden, J.W. Jr.; Richardson, R.L.; Bergsman, T.M.

1993-10-19

The present invention relates to a continuous flow fluid reactor for chemically altering fluids. The reactor operates on standard frequency (50 to 60 Hz) electricity. The fluid reactor contains particles that are energized by the electricity to form a corona throughout the volume of the reactor and subsequently a non-equilibrium plasma that interacts with the fluid. Particles may form a fixed bed or a fluid bed. Electricity may be provided through electrodes or through an inductive coil. Fluids include gases containing exhaust products and organic fuels requiring oxidation. 4 figures.

Method and apparatus for chemically altering fluids in continuous flow

DOEpatents

Heath, William O.; Virden, Jr., Judson W.; Richardson, R. L.; Bergsman, Theresa M.

1993-01-01

The present invention relates to a continuous flow fluid reactor for chemically altering fluids. The reactor operates on standard frequency (50 to 60 Hz) electricity. The fluid reactor contains particles that are energized by the electricity to form a corona throughout the volume of the reactor and subsequently a non-equilibrium plasma that interacts with the fluid. Particles may form a fixed bed or a fluid bed. Electricity may be provided through electrodes or through an inductive coil. Fluids include gases containing exhaust products and organic fuels requiring oxidation.

Current Results and Proposed Activities in Microgravity Fluid Dynamics

NASA Technical Reports Server (NTRS)

Polezhaev, V. I.

1996-01-01

The Institute for Problems in Mechanics' Laboratory work in mathematical and physical modelling of fluid mechanics develops models, methods, and software for analysis of fluid flow, instability analysis, direct numerical modelling and semi-empirical models of turbulence, as well as experimental research and verification of these models and their applications in technological fluid dynamics, microgravity fluid mechanics, geophysics, and a number of engineering problems. This paper presents an overview of the results in microgravity fluid dynamics research during the last two years. Nonlinear problems of weakly compressible and compressible fluid flows are discussed.

Theoretical Exploration of Exponential Heat Source and Thermal Stratification Effects on The Motion of 3-Dimensional Flow of Casson Fluid Over a Low Heat Energy Surface at Initial Unsteady Stage

NASA Astrophysics Data System (ADS)

Sandeep, N.; Animasaun, I. L.

2017-06-01

Within the last few decades, experts and scientists dealing with the flow of non-Newtonian fluids (most especially Casson fluid) have confirmed the existence of such flow on a stretchable surface with low heat energy (i.e. absolute zero of temperature). This article presents the motion of a three-dimensional of such fluid. Influence of uniform space dependent internal heat source on the intermolecular forces holding the molecules of Casson fluid is investigated. It is assumed that the stagnation flow was induced by an external force (pressure gradient) together with impulsive. Based on these assumptions, variable thermophysical properties are most suitable; hence modified kinematic viscosity model is presented. The system of governing equations of 3-dimensional unsteady Casson fluid was non-dimensionalized using suitable similarity transformation which unravels the behavior of the flow at full fledge short period. The numerical solution of the corresponding boundary value problem (ODE) was obtained using Runge-Kutta fourth order along with shooting technique. The intermolecular forces holding the molecules of Casson fluid flow in both horizontal directions when magnitude of velocity ratio parameters are greater than unity breaks continuously with an increase in Casson parameter and this leads to an increase in velocity profiles in both directions.

Method and device for producing a tactile display using an electrorheological fluid

NASA Technical Reports Server (NTRS)

Garner, H. Douglas (Inventor)

1996-01-01

A tactile display device utilizes an electrorheological fluid to activate a plurality of tactile dots. A voltage is selectively produced uniformly across an electrorheological fluid flowing between a common ground electrode and a plurality of conductive dot electrodes, thereby producing an increase in the fluid's viscosity to the extent that fluid flow between the two electrodes is restricted. The flow restriction produces a build-up of electrorheological fluid in a corresponding dot actuator chamber. The resulting pressure increase in the chamber displaces an elastic diaphragm fixed to a display surface to form a lump which can be perceived by the reader as one dot in a Braille character cell. A flow regulation system provides a continually pressurized flow system and provides for free flow of the electrorheological fluid through the plurality of dot actuator chambers when they are not activated. The device is adaptable to printed circuit techniques and can simultaneously display tactile dots representative of a full page of Braille characters stored on a medium such as a tape cassette or to display tactile dots representative of non-Braille data appearing on a computer monitor or contained on another data storage medium. In an alternate embodiment, the elastic diaphragm drives a plurality of spring-loaded pins provided with positive stops to maintain consistent displacements of the pins in both their actuated and nonactuated positions.

Numerical solution of chemically reactive non-Newtonian fluid flow: Dual stratification

NASA Astrophysics Data System (ADS)

Rehman, Khalil Ur; Malik, M. Y.; Khan, Abid Ali; Zehra, Iffat; Zahri, Mostafa; Tahir, M.

2017-12-01

We have found that only a few attempts are available in the literature relatively to the tangent hyperbolic fluid flow induced by stretching cylindrical surfaces. In particular, temperature and concentration stratification effects have not been investigated until now with respect to the tangent hyperbolic fluid model. Therefore, we have considered the tangent hyperbolic fluid flow induced by an acutely inclined cylindrical surface in the presence of both temperature and concentration stratification effects. To be more specific, the fluid flow is attained with the no slip condition, which implies that the bulk motion of the fluid particles is the same as the stretching velocity of a cylindrical surface. Additionally, the flow field situation is manifested with heat generation, mixed convection and chemical reaction effects. The flow partial differential equations give a complete description of the present problem. Therefore, to trace out the solution, a set of suitable transformations is introduced to convert these equations into ordinary differential equations. In addition, a self-coded computational algorithm is executed to inspect the numerical solution of these reduced equations. The effect logs of the involved parameters are provided graphically. Furthermore, the variations of the physical quantities are examined and given with the aid of tables. It is observed that the fluid temperature is a decreasing function of the thermal stratification parameter and a similar trend is noticed for the concentration via the solutal stratification parameter.

Tactile display device using an electrorheological fluid

NASA Technical Reports Server (NTRS)

Garner, H. Douglas (Inventor)

1994-01-01

A tactile display device utilizes an electrorheological fluid to activate a plurality of tactile dots. A voltage is selectively produced uniformly across an electrorheological fluid flowing between a common ground electrode and a plurality of conductive dot electrodes, thereby producing an increase in the fluid's viscosity to the extent that fluid flow between the two electrodes is restricted. The flow restriction produces a build-up of electrorheological fluid in a corresponding dot actuator chamber. The resulting pressure increase in the chamber displaces an elastic diaphragm fixed to a display surface to form a lump which can be perceived by the reader as one dot in a Braille character cell. A flow regulation system provides a continually pressurized flow system and provides for free flow of the electrorheological fluid through the plurality of dot actuator chambers when they are not activated. The device is adaptable to printed circuit techniques and can simultaneously display tactile dots representative of a full page of Braille characters stored on a medium such as a tape cassette or to display tactile dots representative of non-Braille data appearing on a computer monitor or contained on another data storage medium. In an alternate embodiment, the elastic diaphragm drives a plurality of spring-loaded pins provided with positive stops to maintain consistent displacements of the pins in both their actuated and nonactuated positions.

Interfacing a General Purpose Fluid Network Flow Program with the SINDA/G Thermal Analysis Program

NASA Technical Reports Server (NTRS)

Schallhorn, Paul; Popok, Daniel

1999-01-01

A general purpose, one dimensional fluid flow code is currently being interfaced with the thermal analysis program Systems Improved Numerical Differencing Analyzer/Gaski (SINDA/G). The flow code, Generalized Fluid System Simulation Program (GFSSP), is capable of analyzing steady state and transient flow in a complex network. The flow code is capable of modeling several physical phenomena including compressibility effects, phase changes, body forces (such as gravity and centrifugal) and mixture thermodynamics for multiple species. The addition of GFSSP to SINDA/G provides a significant improvement in convective heat transfer modeling for SINDA/G. The interface development is conducted in multiple phases. This paper describes the first phase of the interface which allows for steady and quasi-steady (unsteady solid, steady fluid) conjugate heat transfer modeling.

Theoretical investigation on exciplex pumped alkali vapor lasers with sonic-level gas flow

NASA Astrophysics Data System (ADS)

Xu, Xingqi; Shen, Binglin; Huang, Jinghua; Xia, Chunsheng; Pan, Bailiang

2017-07-01

Considering the effects of higher excited and ion energy states and utilizing the methodology in the fluid mechanics, a modified model of exciplex pumped alkali vapor lasers with sonic-level flowing gas is established. A comparison of output characters between subsonic flow and supersonic flow is made. In this model, higher excited and ion energy states are included as well, which modifies the analysis of the kinetic process and introduces larger heat loading in an operating CW exciplex-pumped alkali vapor laser. The results of our calculations predict that subsonic flow has an advantage over supersonic flow under the same fluid parameters, and stimulated emission in the supersonic flow would be quenched while the pump power reaching a threshold value of the fluid choking effect. However, by eliminating the influence of fluid characters, better thermal management and higher optical conversion efficiency can be obtained in supersonic flow. In addition, we make use of the "nozzle-diffuser" to build up the closed-circle flowing experimental device and gather some useful simulated results.

Interrogation cradle and insertable containment fixture for detecting birefringent microcrystals in bile

DOEpatents

Darrow, Chris; Seger, Tino

2003-09-30

A transparent flow channel fluidly communicates a fluid source and a collection reservoir. An interrogating light beam passes through a first polarizer having a first plane of polarization. The flow channel is orthogonal to the light beam. The light beam passes through a fluid sample as it flows through the flow channel, and is then filtered through a second polarizer having a second plane of polarization rotated 90.degree. from the first plane of polarization. An electronic photo-detector is aligned with the light beam, and signals the presence of birefringent microcrystals in the fluid sample by generating voltage pulses. A disposable containment fixture includes the flow channel and the collection reservoir. The fixture is adapted for removable insertion into an interrogation cradle that includes optical and data processing components. The cradle rigidly positions the centerline of the flow channel orthogonal to the light beam.

Mathematical modeling of fluid flow in aluminum ladles for degasification with impeller - injector

NASA Astrophysics Data System (ADS)

Ramos-Gómez, E.; González-Rivera, C.; Ramírez-Argáez, M. A.

2012-09-01

In this work a fundamental Eulerian mathematical model was developed to simulate fluid flow in a water physical model of an aluminum ladle equipped with impeller for degassing treatment. The effect of critical process parameters such as rotor speed, gas flow rate on the fluid flow and vortex formation was analyzed with this model. Commercial CFD code PHOENICS 3.4 was used to solve all conservation equations governing the process for this twophase fluid flow system. The mathematical model was successfully validated against experimentally measured liquid velocity and turbulent profiles in a physical model. From the results it was concluded that the angular speed of the impeller is the most important parameter promoting better stirred baths. Pumping effect of the impeller is increased as impeller rotation speed increases. Gas flow rate is detrimental on bath stirring and diminishes pumping effect of impeller.

On compressible and piezo-viscous flow in thin porous media.

PubMed

Pérez-Ràfols, F; Wall, P; Almqvist, A

2018-01-01

In this paper, we study flow through thin porous media as in, e.g. seals or fractures. It is often useful to know the permeability of such systems. In the context of incompressible and iso-viscous fluids, the permeability is the constant of proportionality relating the total flow through the media to the pressure drop. In this work, we show that it is also relevant to define a constant permeability when compressible and/or piezo-viscous fluids are considered. More precisely, we show that the corresponding nonlinear equation describing the flow of any compressible and piezo-viscous fluid can be transformed into a single linear equation. Indeed, this linear equation is the same as the one describing the flow of an incompressible and iso-viscous fluid. By this transformation, the total flow can be expressed as the product of the permeability and a nonlinear function of pressure, which represents a generalized pressure drop.

Toward an optimal design principle in symmetric and asymmetric tree flow networks.

PubMed

Miguel, Antonio F

2016-01-21

Fluid flow in tree-shaped networks plays an important role in both natural and engineered systems. This paper focuses on laminar flows of Newtonian and non-Newtonian power law fluids in symmetric and asymmetric bifurcating trees. Based on the constructal law, we predict the tree-shaped architecture that provides greater access to the flow subjected to the total network volume constraint. The relationships between the sizes of parent and daughter tubes are presented both for symmetric and asymmetric branching tubes. We also approach the wall-shear stresses and the flow resistance in terms of first tube size, degree of asymmetry between daughter branches, and rheological behavior of the fluid. The influence of tubes obstructing the fluid flow is also accounted for. The predictions obtained by our theory-driven approach find clear support in the findings of previous experimental studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

A Generalized Fluid System Simulation Program to Model Flow Distribution in Fluid Networks

NASA Technical Reports Server (NTRS)

Majumdar, Alok; Bailey, John W.; Schallhorn, Paul; Steadman, Todd

1998-01-01

This paper describes a general purpose computer program for analyzing steady state and transient flow in a complex network. The program is capable of modeling phase changes, compressibility, mixture thermodynamics and external body forces such as gravity and centrifugal. The program's preprocessor allows the user to interactively develop a fluid network simulation consisting of nodes and branches. Mass, energy and specie conservation equations are solved at the nodes; the momentum conservation equations are solved in the branches. The program contains subroutines for computing "real fluid" thermodynamic and thermophysical properties for 33 fluids. The fluids are: helium, methane, neon, nitrogen, carbon monoxide, oxygen, argon, carbon dioxide, fluorine, hydrogen, parahydrogen, water, kerosene (RP-1), isobutane, butane, deuterium, ethane, ethylene, hydrogen sulfide, krypton, propane, xenon, R-11, R-12, R-22, R-32, R-123, R-124, R-125, R-134A, R-152A, nitrogen trifluoride and ammonia. The program also provides the options of using any incompressible fluid with constant density and viscosity or ideal gas. Seventeen different resistance/source options are provided for modeling momentum sources or sinks in the branches. These options include: pipe flow, flow through a restriction, non-circular duct, pipe flow with entrance and/or exit losses, thin sharp orifice, thick orifice, square edge reduction, square edge expansion, rotating annular duct, rotating radial duct, labyrinth seal, parallel plates, common fittings and valves, pump characteristics, pump power, valve with a given loss coefficient, and a Joule-Thompson device. The system of equations describing the fluid network is solved by a hybrid numerical method that is a combination of the Newton-Raphson and successive substitution methods. This paper also illustrates the application and verification of the code by comparison with Hardy Cross method for steady state flow and analytical solution for unsteady flow.

Economic method for measuring ultra-low flow rates of fluids

NASA Technical Reports Server (NTRS)

Bogdanovic, J. A.; Keller, W. F.

1970-01-01

Capillary tube flowmeter measures ultra-low flows of very corrosive fluids /such as chlorine trifluoride and liquid fluorine/ and other liquids with reasonable accuracy. Flowmeter utilizes differential pressure transducer and operates on the principle that for laminar flow in the tube, pressure drop is proportional to flow rate.

Infusion pressure and pain during microneedle injection into skin of human subjects.

PubMed

Gupta, Jyoti; Park, Sohyun S; Bondy, Brian; Felner, Eric I; Prausnitz, Mark R

2011-10-01

Infusion into skin using hollow microneedles offers an attractive alternative to hypodermic needle injections. However, the fluid mechanics and pain associated with injection into skin using a microneedle have not been studied in detail before. Here, we report on the effect of microneedle insertion depth into skin, partial needle retraction, fluid infusion flow rate and the co-administration of hyaluronidase on infusion pressure during microneedle-based saline infusion, as well as on associated pain in human subjects. Infusion of up to a few hundred microliters of fluid required pressures of a few hundred mmHg, caused little to no pain, and showed weak dependence on infusion parameters. Infusion of larger volumes up to 1 mL required pressures up to a few thousand mmHg, but still usually caused little pain. In general, injection of larger volumes of fluid required larger pressures and application of larger pressures caused more pain, although other experimental parameters also played a significant role. Among the intradermal microneedle groups, microneedle length had little effect; microneedle retraction lowered infusion pressure but increased pain; lower flow rate reduced infusion pressure and kept pain low; and use of hyaluronidase also lowered infusion pressure and kept pain low. We conclude that microneedles offer a simple method to infuse fluid into the skin that can be carried out with little to no pain. Copyright © 2011 Elsevier Ltd. All rights reserved.

Surface tension driven flow in glass melts and model fluids

NASA Technical Reports Server (NTRS)

Mcneil, T. J.; Cole, R.; Subramanian, R. S.

1982-01-01

Surface tension driven flow has been investigated analytically and experimentally using an apparatus where a free column of molten glass or model fluids was supported at its top and bottom faces by solid surfaces. The glass used in the experiments was sodium diborate, and the model fluids were silicone oils. In both the model fluid and glass melt experiments, conclusive evidence was obtained to prove that the observed flow was driven primarily by surface tension forces. The experimental observations are in qualitative agreement with predictions from the theoretical model.

Magnetorheological rotational flow with viscous dissipation

NASA Astrophysics Data System (ADS)

Ashrafi, Nariman

2017-11-01

Effects of a magnetic field and fluid nonlinearity are investigated for the rotational flow of the Carreau-type fluid while viscous dissipation is taken into account. The governing motion and energy balance equations are coupled, adding complexity to the already highly correlated set of differential equations. The numerical solution is obtained for the narrow-gap limit and steady-state base flow. Magnetic field effect on local entropy generation due to steady two-dimensional laminar forced convection flow was investigated. This study was focused on the entropy generation characteristics and its dependency on various dimensionless parameters. The effects of the Hartmann number, the Brinkman number, and the Deborah number on the stability of the flow were investigated. The introduction of the magnetic field induces a resistive force acting in the opposite direction of the flow, thus causing its deceleration. Moreover, the study shows that the presence of magnetic field tends to slow down the fluid motion. It, however, increases the fluid temperature. Moreover, the total entropy generation number decreases as the Hartmann number and fluid elasticity increase and increases with increasing Brinkman number.

Seminar in Flow Visualization at Lafayette College: Variations on the Hertzberg Effect

NASA Astrophysics Data System (ADS)

Rossmann, Jenn Stroud

2013-11-01

Flow visualization reveals an invisible world of fluid dynamics, blending scientific investigation and artistic exploration. The resulting images have inspired, and in some cases themselves become appreciated as, art. At Lafayette College, a sophomore-level seminar in The Art and Science of Flow Visualization exposes students to these techniques and the science of fluid mechanics, and to the photographic methods needed to create effective images that are successful both scientifically and artistically. Unlike other courses in flow visualization, this course assumes no a priori familiarity with fluid flow or with photography. The fundamentals of both are taught and practiced in a studio setting. Students are engaged in an interdisciplinary discourse about fluids and physics, photography, scientific ethics, and historical societal responses to science and art. Relevant texts from several disciplines are read, discussed, and responded to in student writing. This seminar approach makes flow visualization and fluid dynamics a natural part of a liberal education. The development, implementation, and assessment of this team-taught course at Lafayette College will be discussed. Support provided by National Science Foundation.

Computational modeling of unsteady third-grade fluid flow over a vertical cylinder: A study of heat transfer visualization

NASA Astrophysics Data System (ADS)

Reddy, G. Janardhana; Hiremath, Ashwini; Kumar, Mahesh

2018-03-01

The present paper aims to investigate the effect of Prandtl number for unsteady third-grade fluid flow over a uniformly heated vertical cylinder using Bejan's heat function concept. The mathematical model of this problem is given by highly time-dependent non-linear coupled equations and are resolved by an efficient unconditionally stable implicit scheme. The time histories of average values of momentum and heat transport coefficients as well as the steady-state flow variables are displayed graphically for distinct values of non-dimensional control parameters arising in the system. As the non-dimensional parameter value gets amplified, the time taken for the fluid flow variables to attain the time-independent state is decreasing. The dimensionless heat function values are closely associated with an overall rate of heat transfer. Thermal energy transfer visualization implies that the heat function contours are compact in the neighborhood of the leading edge of the hot cylindrical wall. It is noticed that the deviations of flow-field variables from the hot wall for a non-Newtonian third-grade fluid flow are significant compared to the usual Newtonian fluid flow.

Nonlinear flow response of soft hair beds

NASA Astrophysics Data System (ADS)

Alvarado, José; Comtet, Jean; de Langre, Emmanuel; Hosoi, A. E.

2017-10-01

We are `hairy' on the inside: beds of passive fibres anchored to a surface and immersed in fluids are prevalent in many biological systems, including intestines, tongues, and blood vessels. These hairs are soft enough to deform in response to stresses from fluid flows. Yet fluid stresses are in turn affected by hair deformation, leading to a coupled elastoviscous problem that is poorly understood. Here we investigate a biomimetic model system of elastomer hair beds subject to shear-driven Stokes flows. We characterize this system with a theoretical model that accounts for the large-deformation flow response of hair beds. Hair bending results in a drag-reducing nonlinearity because the hair tip lowers towards the base, widening the gap through which fluid flows. When hairs are cantilevered at an angle subnormal to the surface, flow against the grain bends hairs away from the base, narrowing the gap. The flow response of angled hair beds is axially asymmetric and amounts to a rectification nonlinearity. We identify an elastoviscous parameter that controls nonlinear behaviour. Our study raises the hypothesis that biological hairy surfaces function to reduce fluid drag. Furthermore, angled hairs may be incorporated in the design of integrated microfluidic components, such as diodes and pumps.

Unsteady flow of fractional Oldroyd-B fluids through rotating annulus

NASA Astrophysics Data System (ADS)

Tahir, Madeeha; Naeem, Muhammad Nawaz; Javaid, Maria; Younas, Muhammad; Imran, Muhammad; Sadiq, Naeem; Safdar, Rabia

2018-04-01

In this paper exact solutions corresponding to the rotational flow of a fractional Oldroyd-B fluid, in an annulus, are determined by applying integral transforms. The fluid starts moving after t = 0+ when pipes start rotating about their axis. The final solutions are presented in the form of usual Bessel and hypergeometric functions, true for initial and boundary conditions. The limiting cases for the solutions for ordinary Oldroyd-B, fractional Maxwell and Maxwell and Newtonian fluids are obtained. Moreover, the solution is obtained for the fluid when one pipe is rotating and the other one is at rest. At the end of this paper some characteristics of fluid motion, the effect of the physical parameters on the flow and a correlation between different fluid models are discussed. Finally, graphical representations confirm the above affirmation.

Duration of mineralization and fluid-flow history of the Upper Mississippi Valley zinc-lead district

USGS Publications Warehouse

Rowan, E.L.; Goldhaber, M.B.

1995-01-01

Studies of fluid inclusions in sphalerite and biomarkers from the Upper Mississippi Valley zinc district show homogenization temperatures to be primarily between 90 and 150??C, yet show relatively low levels of thermal maturity. Numerical calculations are used to simulate fluid and heat flow through fracture-controlled ore zones and heat transfer to the adjacent rocks. Combining a best-fit path through fluid-inclusion data with measured thermal alteration of biomarkers, the time interval during which mineralizing fluids circulated through the Upper Mississippi Valley district was calculated to be on the order of 200 ka. Cambrian and Ordovician aquifers underlying the district, principally the St. Peter and Mt. Simon Sandstones, were the source of the mineralizing fluid. The duration of mineralization thus reflects the fluid-flow history of these regional aquifers. -from Authors

Peritoneal fluid transport in CAPD patients with different transport rates of small solutes.

PubMed

Sobiecka, Danuta; Waniewski, Jacek; Weryński, Andrzej; Lindholm, Bengt

2004-01-01

Continuous ambulatory peritoneal dialysis (CAPD) patients with high peritoneal solute transport rate often have inadequate peritoneal fluid transport. It is not known whether this inadequate fluid transport is due solely to a too rapid fall of osmotic pressure, or if the decreased effectiveness of fluid transport is also a contributing factor. To analyze fluid transport parameters and the effectiveness of dialysis fluid osmotic pressure in the induction of fluid flow in CAPD patients with different small solute transport rates. 44 CAPD patients were placed in low (n = 6), low-average (n = 13), high-average (n = 19), and high (n = 6) transport groups according to a modified peritoneal equilibration test (PET). The study involved a 6-hour peritoneal dialysis dwell with 2 L 3.86% glucose dialysis fluid for each patient. Radioisotopically labeled serum albumin was added as a volume marker.The fluid transport parameters (osmotic conductance and fluid absorption rate) were estimated using three mathematical models of fluid transport: (1) Pyle model (model P), which describes ultrafiltration rate as an exponential function of time; (2) model OS, which is based on the linear relationship of ultrafiltration rate and overall osmolality gradient between dialysis fluid and blood; and (3) model G, which is based on the linear relationship between ultrafiltration rate and glucose concentration gradient between dialysis fluid and blood. Diffusive mass transport coefficients (K(BD)) for glucose, urea, creatinine, potassium, and sodium were estimated using the modified Babb-Randerson-Farrell model. The high transport group had significantly lower dialysate volume and glucose and osmolality gradients between dialysate and blood, but significantly higher K(BD) for small solutes compared with the other transport groups. Osmotic conductance, fluid absorption rate, and initial ultrafiltration rate did not differ among the transport groups for model OS and model P. Model G yielded unrealistic values of fluid transport parameters that differed from those estimated by models OS and P. The K(BD) values for small solutes were significantly different among the groups, and did not correlate with fluid transport parameters for model OS. The difference in fluid transport between the different transport groups was due only to the differences in the rate of disappearance of the overall osmotic pressure of the dialysate, which was a combined result of the transport rate of glucose and other small solutes. Although the glucose gradient is the major factor influencing ultrafiltration rate, other solutes, such as urea, are also of importance. The counteractive effect of plasma small solutes on transcapillary ultrafiltration was found to be especially notable in low transport patients. Thus, glucose gradient alone should not be considered the only force that shapes the ultrafiltration profile during peritoneal dialysis. We did not find any correlations between diffusive mass transport coefficients for small solutes and fluid transport parameters such as osmotic conductance or fluid and volume marker absorption. We may thus conclude that the pathway(s) for fluid transport appears to be partly independent from the pathway(s) for small solute transport, which supports the hypothesis of different pore types for fluid and solute transport.

Biocompatibility of peritoneal dialysis fluids: long-term exposure of nonuremic rats.

PubMed

Musi, Barbara; Braide, Magnus; Carlsson, Ola; Wieslander, Anders; Albrektsson, Ann; Ketteler, Markus; Westenfeld, Ralf; Floege, Jürgen; Rippe, Bengt

2004-01-01

Long-term peritoneal dialysis (PD) leads to structural and functional changes in the peritoneum. The aim of the present study was to investigate the long-term effects of PD fluid components, glucose and glucose degradation products (GDP), and lactate-buffered solution on morphology and transport characteristics in a nonuremic rat model. Rats were subjected to two daily intraperitoneal injections (20 mL/day) during 12 weeks of one of the following: commercial PD fluid (Gambrosol, 4%; Gambro AB, Lund, Sweden), commercial PD fluid with low GDP levels (Gambrosol trio, 4%; Gambro AB), sterile-filtered PD fluid (4%) without GDP, or a glucose-free lactate-buffered PD fluid. Punctured and untreated controls were used. Following exposure, the rats underwent a single 4-hour PD dwell (30 mL, 4% glucose) to determine peritoneal function. Additionally, submesothelial tissue thickness, percentage of high mesothelial cells (perpendicular diameter > 2 microm), vascular density, vascular endothelial growth factor (VEGF), and transforming growth factor (TGF) beta1 mRNA expression were determined. Submesothelial collagen concentration was estimated by van Gieson staining. Submesothelial tissue thickness and vascular density, mediated by VEGF and TGFbeta production, in the diaphragmatic peritoneum increased significantly in rats exposed to any PD fluid. Gambrosol induced a marked increased fibrosis of the hepatic peritoneum. A significant increase in high mesothelial cells was observed in the Gambrosol group only. Net ultrafiltration was reduced in the Gambrosol and in the glucose-free groups compared to untreated controls. Small solute transport was unchanged, but all groups exposed to fluids showed significantly increased lymph flow. Our results show that long-term exposure to different components of PD fluids leads to mesothelial cell damage, submesothelial fibrosis, and neoangiogenesis. Mesothelial cell damage could be connected to the presence of GDP; the other changes were similar for all fluids. Peritoneal transport characteristics did not change in any consistent way and the neoangiogenesis observed was not paralleled by increased solute transport.

Error and Uncertainty Quantification in the Numerical Simulation of Complex Fluid Flows

NASA Technical Reports Server (NTRS)

Barth, Timothy J.

2010-01-01

The failure of numerical simulation to predict physical reality is often a direct consequence of the compounding effects of numerical error arising from finite-dimensional approximation and physical model uncertainty resulting from inexact knowledge and/or statistical representation. In this topical lecture, we briefly review systematic theories for quantifying numerical errors and restricted forms of model uncertainty occurring in simulations of fluid flow. A goal of this lecture is to elucidate both positive and negative aspects of applying these theories to practical fluid flow problems. Finite-element and finite-volume calculations of subsonic and hypersonic fluid flow are presented to contrast the differing roles of numerical error and model uncertainty. for these problems.

Effect of horizontal heat and fluid flow on the vertical temperature distribution in a semiconfining layer

USGS Publications Warehouse

Lu, Ning; Ge, Shemin

1996-01-01

By including the constant flow of heat and fluid in the horizontal direction, we develop an analytical solution for the vertical temperature distribution within the semiconfining layer of a typical aquifer system. The solution is an extension of the previous one-dimensional theory by Bredehoeft and Papadopulos [1965]. It provides a quantitative tool for analyzing the uncertainty of the horizontal heat and fluid flow. The analytical results demonstrate that horizontal flow of heat and fluid, if at values much smaller than those of the vertical, has a negligible effect on the vertical temperature distribution but becomes significant when it is comparable to the vertical.

Pore scale simulations for the extension of the Darcy-Forchheimer law to shear thinning fluids

NASA Astrophysics Data System (ADS)

Tosco, Tiziana; Marchisio, Daniele; Lince, Federica; Boccardo, Gianluca; Sethi, Rajandrea

2014-05-01

Flow of non-Newtonian fluids through porous media at high Reynolds numbers is often encountered in chemical, pharmaceutical and food as well as petroleum and groundwater engineering and in many other industrial applications (1 - 2). In particular, the use of shear thinning polymeric solutions has been recently proposed to improve colloidal stability of micro- and nanoscale zerovalent iron particles (MZVI and NZVI) for groundwater remediation. In all abovementioned applications, it is of paramount importance to correctly predict the pressure drop resulting from non-Newtonian fluid flow through the porous medium. For small Reynolds numbers, usually up to 1, typical of laboratory column tests, the extended Darcy law is known to be applicable also to non Newtonian fluids, provided that all non-Newtonian effects are lumped together into a proper viscosity parameter (1,3). For higher Reynolds numbers (eg. close to the injection wells) non linearities between pressure drop and flow rate arise, and the Darcy-Forchheimer law holds for Newtonian fluids, while for non-Newtonian fluids, it has been demonstrated that, at least for simple rheological models (eg. power law fluids) a generalized Forchheimer law can be applied, even if the determination of the flow parameters (permeability K, inertial coefficient β, and equivalent viscosity) is not straightforward. This work (co-funded by European Union project AQUAREHAB FP7 - Grant Agreement Nr. 226565) aims at proposing an extended formulation of the Darcy-Forchheimer law also for shear-thinning fluids, and validating it against results of pore-scale simulations via computational fluid dynamics (4). Flow simulations were performed using Fluent 12.0 on four different 2D porous domains for Newtonian and non-Newtonian fluids (Cross, Ellis and Carreau models). The micro-scale flow simulation results are analyzed in terms of 'macroscale' pressure drop between inlet and outlet of the model domain as a function of flow rate. The results of flow simulations show the superposition of two contributions to pressure drops: one, strictly related to the non-Newtonian properties of the fluid, dominates at low Reynolds numbers, while a quadratic one, arising at higher Reynolds numbers, is dependent only on the porous medium properties. The results suggest that, for Newtonian flow, the porous medium can be fully described by two macroscopic parameters, namely permeability K and inertial coefficient β. Conversely, for non-Newtonian flow, an additional parameter is required, represented by the shift factor α, which depends on the properties of both porous medium and fluid, which is not easy to be determined in laboratory tests, but can be in turn calculated from 2D or 3D pore-scale flow simulations, following the approach which was adopted in this work. References 1. Sorbie, K.S. Polymer-improved oil recovery; Blackie ; CRC Press: Glasgow, Boca Raton, Fla., 1991. 2. Xue, D.; Sethi, R. Viscoelastic gels of guar and xanthan gum mixtures provide long-term stabilization of iron micro- and nanoparticles. J Nanopart Res 2012, 14(11). 3. Bird, R.B.; Armstrong, R.C.; Hassager, O. Dynamics of polymeric liquids. Volume 1. Fluid mechanics; John Wiley and Sons Inc.: New York - NY, 1977. 4. Tosco, T.; Marchisio, D.L.; Lince, F.; Sethi, R. Extension of the Darcy-Forchheimer Law for Shear-Thinning Fluids and Validation via Pore-Scale Flow Simulations. Transport in Porous Media 2013, 96(1), 1-20.

Proliferation of CD4CD25Foxp3 regulatory T lymphocytes in ex vivo expanded ascitic fluid from primary and recurrent ovarian carcinoma.

PubMed

Lee, Shin Wha; Kim, Yong-Man; Lee, Ha-Young; Kim, Dae-Yeon; Kim, Jong-Hyeok; Nam, Joo-Hyun; Kim, Young-Tak

2010-03-01

Regulatory T lymphocytes evoke the immune tolerance by suppressing and inactivating cytotoxic T lymphocytes. The objective of this study was to compare the proportion of regulatory T lymphocytes, precisely defined as CD4(+)CD25(high+)Foxp3(+) T lymphocytes, in primary and recurrent ovarian carcinoma before and after ex vivo expansion of ascites with interleukin-2 (IL-2). Ascitic fluid samples were obtained from 26 patients with ovarian carcinoma. Lymphocytes were isolated from ascites and cell markers were analyzed by flow cytometry using anti-CD3/CD4/CD8/CD16/CD56/CD25 and anti-Foxp3 antibodies. Lymphocytes were incubated for 2 to 3 weeks and expanded ex vivo by IL-2 stimulation and their phenotypes were analyzed by flow cytometry. Following ex vivo expansion, ascitic fluid lymphocytes increased by a greater extent in the recurrent group than in the primary group. The proportion of ex vivo-expanded lymphocytes changed as follows; CD4(+) T lymphocytes increased, CD8(+) T lymphocytes decreased, and the proportion of CD3(-)CD16(+)56(+) NK cells was unchanged. The proportion of CD4(+)CD25(high+)Foxp3(+) regulatory T lymphocytes in CD4(+) T lymphocytes increased after ex vivo expansion in both groups, but to a greater degree in the recurrent group. This study showed that regulatory T lymphocytes, neither cytotoxic T lymphocytes nor NK cells, were extensively increased after ex vivo expansion, especially in recurrent ovarian carcinoma. These results may provide information that helps to guide the future development of adoptive immunotherapy against ovarian carcinoma.

Metagenomic Assessment of a Dynamic Microbial Population from Subseafloor Aquifer Fluids in the Cold, Oxygenated Crust

NASA Astrophysics Data System (ADS)

Tully, B. J.; Heidelberg, J. F.; Kraft, B.; Girguis, P. R.; Huber, J. A.

2016-12-01

The oceanic crust contains the largest aquifer on Earth with a volume approximately 2% of the global ocean. Ongoing research at the North Pond (NP) site, west of the Mid-Atlantic Ridge, provides an environment representative of oxygenated crustal aquifers beneath oligotrophic surface waters. Using subseafloor CORK observatories for multiple sampling depths beneath the seafloor, crustal fluids were sampled along the predicted aquifer fluid flow path over a two-year period. DNA was extracted and sequenced for metagenomic analysis from 22 crustal fluid samples, along with the overlying bottom. At broad taxonomic groupings, the aquifer system is highly dynamic over time and space, with shifts in dominant taxa and "blooms" of transient groups that appear at discreet time points and sample depths. We were able to reconstruct 194 high-quality, low-contamination bacterial and archaeal metagenomic-assembled genomes (MAGs) with estimated completeness >50% (429 MAGs >20% complete). Environmental genomes were assigned to phylogenies from the major bacterial phyla, putative novel groups, and poorly sampled phylogenetic groups, including the Marinimicrobia, Candidate Phyla Radiation, and Planctomycetes. Biogeochemically relevant processes were assigned to MAGs, including denitrification, dissimilatory sulfur and hydrogen cycling, and carbon fixation. Collectively, the oxic NP aquifer system represents a diverse, dynamic microbial habitat with the metabolic potential to impact multiple globally relevant biogeochemical cycles, including nitrogen, sulfur, and carbon.

Experimental study of the solid-liquid interface in a yield-stress fluid flow upstream of a step

NASA Astrophysics Data System (ADS)

Luu, Li-Hua; Pierre, Philippe; Guillaume, Chambon

2014-11-01

We present an experimental study where a yield-stress fluid is implemented to carefully examine the interface between a liquid-like unyielded region and a solid-like yielded region. The studied hydrodynamics consists of a rectangular pipe-flow disturbed by the presence of a step. Upstream of the step, a solid-liquid interface between a dead zone and a flow zone appears. This configuration can both model geophysical erosion phenomenon in debris flows or find applications for industrial extrusion processes. We aim to investigate the dominant physical mechanism underlying the formation of the static domain, by combining the rheological characterization of the yield-stress fluid with local measurements of the related hydrodynamic parameters. In this work, we use a model fluid, namely polymer micro-gel Carbopol, that exhibits a Hershel-Bulkley viscoplastic rheology. Exploiting the fluid transparency, the flow is monitored by Particle Image Velocimetry thanks to internal visualization technique. In particular, we demonstrate that the flow above the dead zone roughly behaves as a plug flow whose velocity profile can successfully be described by a Poiseuille equation including a Hershel-Bulkley rheology (PHB theory), with exception of a thin zone at the close vicinity of the static domain. The border inside the flow zone above which the so-called PHB flow starts, is found to be the same regardless of the flow rate and to move with a constant velocity that increases with the flow rate. We interpret this feature as a slip frontier.

Calibration, Data Acquisition, and Post Analysis of Turbulent Fluid Flow in a Calibration Jet Using Hot-wire Anemometry

NASA Technical Reports Server (NTRS)

Moreno, Michelle

2004-01-01

The Turbine Branch concentrates on the following areas: Computational Fluid Dynamics (CFD), and implementing experimental procedures to obtain physical modeling data. Hot-wire Anemometry is a valuable tool for obtaining physical modeling data. Hot-wire Anemometry is likely to remain the principal research tool for most turbulent air/gas flow studies. The Hot-wire anemometer consists of a fine wire heated by electric current. When placed in a fluid stream, the hot-wire loses heat to the fluid by forced convection. In forced convection, energy transfer is due to molecular motion imposed by an extraneous force moving fluid parcels. When the hot-wire is in "equilibrium", the rate of heat input to the wire is equal to the rate of heat loss at the wire ends. The equality between heat input and heat loss is the basis for King s equation, which relates the electrical parameters of the hot-wire to the flow parameters of the fluid. Hot-wire anemometry is based on convective heat transfer from a heated wire element placed in a fluid flow. Any change in the fluid flow condition that affects the heat transfer from the heated element will be detected virtually instantaneously by a constant-temperature Hot-wire anemometry system. The system implemented for this research is the IFA 300. The system is a fully-integrated, thermal anemometer-based system that measures mean and fluctuating velocity components in air, water, and other fluids. It also measures turbulence and makes localized temperature measurements. A constant-temperature anemometer is a bridge and amplifier circuit that controls a tiny wire at constant temperature. As a fluid flow passes over the heated sensor, the amplifier senses the bridge off-balance and adjusts the voltage to the top of the bridge, keeping the bridge in balance. The voltage on top of the bridge can then be related to the velocity of the flow. The bridge voltage is sensitive to temperature as well as velocity and so the built-in thermocouple circuit can be attached to a thermocouple that can measure the fluid temperature. Additional information is included in the original extended abstract.

Prize to a Faculty Member for Research in an Undergraduate: Chaotic mixing and front propagation

NASA Astrophysics Data System (ADS)

Solomon, Tom

2014-03-01

We present results from a series of experiments - all done with undergraduate students - on chaotic fluid mixing and the effects of fluid flows on the behavior of reaction systems. Simple, well-ordered laminar fluid flows can give rise to fluid mixing with complexity far beyond that of the underlying flow, with tracers that separate exponentially in time and invariant manifolds that act as barriers to transport. Recently, we have studied how fluid mixing affects the propagation of reaction fronts in a flow. This is an issue with applications to a wide range of systems including microfluidic chemical reactors, blooms of phytoplankton in the oceans, and the spreading of a disease in a moving population. To analyze and predict the behavior of the fronts, we generalize tools developed to describe passive mixing. In particular, the concept of an invariant manifold is expanded to account for reactive burning. ``Burning invariant manifolds'' (BIMs) are predicted and measured experimentally as structures in the flow that act as one-way barriers that block the motion of reaction fronts. We test these ideas experimentally in three fluid flows: (a) and chain of alternating vortices; (b) an extended, spatially-random pattern of vortices; and (c) a time-independent, three-dimensional, nested vortex flow. The reaction fronts are produced chemically with variations of the well-known Belousov-Zhabotinsky reaction. Supported by Research Corporation and the National Science Foundation.

Modeling the Migration of Fluids in Subduction Zones

NASA Astrophysics Data System (ADS)

Wilson, C. R.; Spiegelman, M.; Van Keken, P. E.; Vrijmoed, J. C.; Hacker, B. R.

2011-12-01

Fluids play a major role in the formation of arc volcanism and the generation of continental crust. Progressive dehydration reactions in the downgoing slab release fluids to the hot overlying mantle wedge, causing flux melting and the migration of melts to the volcanic front. While the qualitative concept is well established, the quantitative details of fluid release and especially that of fluid migration and generation of hydrous melting in the wedge is still poorly understood. Here we present new models of the fluid migration through the mantle wedge for subduction zones. We use an existing set of high resolution metamorphic models (van Keken et al, 2010) to predict the regions of water release from the sediments, upper and lower crust, and upper most mantle. We use this water flux as input for the fluid migration calculation based on new finite element models built on advanced computational libraries (FEniCS/PETSc) for efficient and flexible solution of coupled multi-physics problems. The first generation of one-way coupled models solves for the evolution of porosity and fluid-pressure/flux throughout the slab and wedge given solid flow, viscosity and thermal fields from separate solutions to the incompressible Stokes and energy equations in the mantle wedge. These solutions are verified by comparing to previous benchmark studies (van Keken et al, 2008) and global suites of thermal subduction models (Syracuse et al, 2010). Fluid flow depends on both permeability and the rheology of the slab-wedge system as interaction with rheological variability can induce additional pressure gradients that affect the fluid flow pathways. These non-linearities have been shown to explain laboratory-scale observations of melt band orientation in labratory experiments and numerical simulations of melt localization in shear bands (Katz et al 2006). Our second generation of models dispense with the pre-calculation of incompressible mantle flow and fully couple the now compressible system of mantle and fluid flow equations, introducing complex feedbacks between the rheology, temperature, permeability, strain rate and porosity. Using idealized subduction zone geometries we investigate the effects of this non-linearity and explore the sensitivity of fluid flow paths for a range of fluid flow parameters with emphasis on variability of the location of the volcanic arc with respect to flow paths. We also estimate the expected degrees of hydrous melting using a variety of wet-melting parameterizations (e.g., Katz et al, 2003, Kelley et al, 2010). The current models only include dehydration reactions but work continues on the next generation of models which will include both dehydration and hydration reactions as well as parameterized flux melting in a consistent reactive-flow framework.

Dynamics of dense granular flows of small-and-large-grain mixtures in an ambient fluid.

PubMed

Meruane, C; Tamburrino, A; Roche, O

2012-08-01

Dense grain flows in nature consist of a mixture of solid constituents that are immersed in an ambient fluid. In order to obtain a good representation of these flows, the interaction mechanisms between the different constituents of the mixture should be considered. In this article, we study the dynamics of a dense granular flow composed of a binary mixture of small and large grains immersed in an ambient fluid. In this context, we extend the two-phase approach proposed by Meruane et al. [J. Fluid Mech. 648, 381 (2010)] to the case of flowing dense binary mixtures of solid particles, by including in the momentum equations a constitutive relation that describes the interaction mechanisms between the solid constituents in a dense regime. These coupled equations are solved numerically and validated by comparing the numerical results with experimental measurements of the front speed of gravitational granular flows resulting from the collapse, in ambient air or water, of two-dimensional granular columns that consisted of mixtures of small and large spherical particles of equal mass density. Our results suggest that the model equations include the essential features that describe the dynamics of grains flows of binary mixtures in an ambient fluid. In particular, it is shown that segregation of small and large grains can increase the front speed because of the volumetric expansion of the flow. This increase in flow speed is damped by the interaction forces with the ambient fluid, and this behavior is more pronounced in water than in air.

Proceedings of the International Symposium on Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances

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

Faybishenko, B.

1999-02-01

This publication contains extended abstracts of papers presented at the International Symposium ''Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances'' held at Ernest Orlando Lawrence Berkeley National Laboratory on February 10-12, 1999. This Symposium is organized in Honor of the 80th Birthday of Paul A. Witherspoon, who initiated some of the early investigations on flow and transport in fractured rocks at the University of California, Berkeley, and at Lawrence Berkeley National Laboratory. He is a key figure in the development of basic concepts, modeling, and field measurements of fluid flow and contaminant transport in fractured rock systems. Themore » technical problems of assessing fluid flow, radionuclide transport, site characterization, modeling, and performance assessment in fractured rocks remain the most challenging aspects of subsurface flow and transport investigations. An understanding of these important aspects of hydrogeology is needed to assess disposal of nu clear wastes, development of geothermal resources, production of oil and gas resources, and remediation of contaminated sites. These Proceedings of more than 100 papers from 12 countries discuss recent scientific and practical developments and the status of our understanding of fluid flow and radionuclide transport in fractured rocks. The main topics of the papers are: Theoretical studies of fluid flow in fractured rocks; Multi-phase flow and reactive chemical transport in fractured rocks; Fracture/matrix interactions; Hydrogeological and transport testing; Fracture flow models; Vadose zone studies; Isotopic studies of flow in fractured systems; Fractures in geothermal systems; Remediation and colloid transport in fractured systems; and Nuclear waste disposal in fractured rocks.« less

Glossosoma nigrior (Trichoptera: Glossosomatidae) respiration in moving fluid.

PubMed

Morris, Mark W L; Hondzo, Miki

2013-08-15

Laboratory measurements of dissolved oxygen (DO) uptake by Glossosoma nigrior Banks were conducted in a sealed, recirculating flume under variable fluid flow velocities. Measurements were performed in similar water temperatures, DO concentrations and fluid flow velocities to field conditions in the stream where the larvae were obtained. Total oxygen uptake by both cased larvae and corresponding cases without larvae were quantified. An increased fluid flow velocity corresponded to an increased larval DO uptake rate. Oxygen uptake by the larval cases alone was not as sensitive to changes in the Peclet (Pe) number, the dimensionless ratio of advective to diffusive DO transport, as uptake by larvae themselves. The flux of DO to larvae and their cases was up to seven times larger in a moving fluid in comparison to non-moving fluid conditions in the proximity of larvae for 087, larvae typically remained in their cases. This indicates that oxygen delivery to the larvae at low Pe is insufficient to satisfy the respiratory demands of cased larvae.

Ceramic microparticles and capsules via microfluidic processing of a preceramic polymer

PubMed Central

Ye, Congwang; Chen, Anthony; Colombo, Paolo; Martinez, Carlos

2010-01-01

We have developed a robust technique to fabricate monodispersed solid and porous ceramic particles and capsules from single and double emulsion drops composed of silsesquioxane preceramic polymer. A microcapillary microfluidic device was used to generate the monodispersed drops. In this device, two round capillaries are aligned facing each other inside a square capillary. Three fluids are needed to generate the double emulsions. The inner fluid, which flows through the input capillary, and the middle fluid, which flows through the void space between the square and inner fluid capillaries, form a coaxial co-flow in a direction that is opposite to the flow of the outer fluid. As the three fluids are forced through the exit capillary, the inner and middle fluids break into monodispersed double emulsion drops in a single-step process, at rates of up to 2000 drops s−1. Once the drops are generated, the silsesquioxane is cross-linked in solution and the cross-linked particles are dried and pyrolysed in an inert atmosphere to form oxycarbide glass particles. Particles with diameters ranging from 30 to 180 µm, shell thicknesses ranging from 10 to 50 µm and shell pore diameters ranging from 1 to 10 µm were easily prepared by changing fluid flow rates, device dimensions and fluid composition. The produced particles and capsules can be used in their polymeric state or pyrolysed to ceramic. This technique can be extended to other preceramic polymers and can be used to generate unique core–shell multimaterial particles. PMID:20484226

Ceramic microparticles and capsules via microfluidic processing of a preceramic polymer.

PubMed

Ye, Congwang; Chen, Anthony; Colombo, Paolo; Martinez, Carlos

2010-08-06

We have developed a robust technique to fabricate monodispersed solid and porous ceramic particles and capsules from single and double emulsion drops composed of silsesquioxane preceramic polymer. A microcapillary microfluidic device was used to generate the monodispersed drops. In this device, two round capillaries are aligned facing each other inside a square capillary. Three fluids are needed to generate the double emulsions. The inner fluid, which flows through the input capillary, and the middle fluid, which flows through the void space between the square and inner fluid capillaries, form a coaxial co-flow in a direction that is opposite to the flow of the outer fluid. As the three fluids are forced through the exit capillary, the inner and middle fluids break into monodispersed double emulsion drops in a single-step process, at rates of up to 2000 drops s(-1). Once the drops are generated, the silsesquioxane is cross-linked in solution and the cross-linked particles are dried and pyrolysed in an inert atmosphere to form oxycarbide glass particles. Particles with diameters ranging from 30 to 180 microm, shell thicknesses ranging from 10 to 50 microm and shell pore diameters ranging from 1 to 10 microm were easily prepared by changing fluid flow rates, device dimensions and fluid composition. The produced particles and capsules can be used in their polymeric state or pyrolysed to ceramic. This technique can be extended to other preceramic polymers and can be used to generate unique core-shell multimaterial particles.

Two-Fluid Models and Interfacial Area Transport in Microgravity Condition

NASA Technical Reports Server (NTRS)

Ishii, Mamoru; Sun, Xiao-Dong; Vasavada, Shilp

2004-01-01

The objective of the present study is to develop a two-fluid model formulation with interfacial area transport equation applicable for microgravity conditions. The new model is expected to make a leapfrog improvement by furnishing the constitutive relations for the interfacial interaction terms with the interfacial area transport equation, which can dynamically model the changes of the interfacial structures. In the first year of this three-year project supported by the U.S. NASA, Office of Biological and Physics Research, the primary focus is to design and construct a ground-based, microgravity two-phase flow simulation facility, in which two immiscible fluids with close density will be used. In predicting the two-phase flow behaviors in any two-phase flow system, the interfacial transfer terms are among the most essential factors in the modeling. These interfacial transfer terms in a two-fluid model specify the rate of phase change, momentum exchange, and energy transfer at the interface between the two phases. For the two-phase flow under the microgravity condition, the stability of the fluid particle interface and the interfacial structures are quite different from those under normal gravity condition. The flow structure may not reach an equilibrium condition and the two fluids may be loosely coupled such that the inertia terms of each fluid should be considered separately by use of the two-fluid model. Previous studies indicated that, unless phase-interaction terms are accurately modeled in the two-fluid model, the complex modeling does not necessarily warrant an accurate solution.

Flow monitoring and control system for injection wells

DOEpatents

Corey, John C.

1993-01-01

A system for monitoring and controlling the injection rate of fluid by an injection well of an in-situ remediation system for treating a contaminated groundwater plume. The well is fitted with a gated insert, substantially coaxial with the injection well. A plurality of openings, some or all of which are equipped with fluid flow sensors and gates, are spaced along the insert. The gates and sensors are connected to a surface controller. The insert may extend throughout part of, or substantially the entire length of the injection well. Alternatively, the insert may comprise one or more movable modules which can be positioned wherever desired along the well. The gates are opened part-way at the start of treatment. The sensors monitor and display the flow rate of fluid passing through each opening on a controller. As treatment continues, the gates are opened to increase flow in regions of lesser flow, and closed to decrease flow in regions of greater flow, thereby approximately equalizing the amount of fluid reaching each part of the plume.

Flow monitoring and control system for injection wells

DOEpatents

Corey, J.C.

1993-02-16

A system for monitoring and controlling the injection rate of fluid by an injection well of an in-situ remediation system for treating a contaminated groundwater plume. The well is fitted with a gated insert, substantially coaxial with the injection well. A plurality of openings, some or all of which are equipped with fluid flow sensors and gates, are spaced along the insert. The gates and sensors are connected to a surface controller. The insert may extend throughout part of, or substantially the entire length of the injection well. Alternatively, the insert may comprise one or more movable modules which can be positioned wherever desired along the well. The gates are opened part-way at the start of treatment. The sensors monitor and display the flow rate of fluid passing through each opening on a controller. As treatment continues, the gates are opened to increase flow in regions of lesser flow, and closed to decrease flow in regions of greater flow, thereby approximately equalizing the amount of fluid reaching each part of the plume.

Numerical Modeling of Interstitial Fluid Flow Coupled with Blood Flow through a Remodeled Solid Tumor Microvascular Network

PubMed Central

Soltani, M.; Chen, P.

2013-01-01

Modeling of interstitial fluid flow involves processes such as fluid diffusion, convective transport in extracellular matrix, and extravasation from blood vessels. To date, majority of microvascular flow modeling has been done at different levels and scales mostly on simple tumor shapes with their capillaries. However, with our proposed numerical model, more complex and realistic tumor shapes and capillary networks can be studied. Both blood flow through a capillary network, which is induced by a solid tumor, and fluid flow in tumor’s surrounding tissue are formulated. First, governing equations of angiogenesis are implemented to specify the different domains for the network and interstitium. Then, governing equations for flow modeling are introduced for different domains. The conservation laws for mass and momentum (including continuity equation, Darcy’s law for tissue, and simplified Navier–Stokes equation for blood flow through capillaries) are used for simulating interstitial and intravascular flows and Starling’s law is used for closing this system of equations and coupling the intravascular and extravascular flows. This is the first study of flow modeling in solid tumors to naturalistically couple intravascular and extravascular flow through a network. This network is generated by sprouting angiogenesis and consisting of one parent vessel connected to the network while taking into account the non-continuous behavior of blood, adaptability of capillary diameter to hemodynamics and metabolic stimuli, non-Newtonian blood flow, and phase separation of blood flow in capillary bifurcation. The incorporation of the outlined components beyond the previous models provides a more realistic prediction of interstitial fluid flow pattern in solid tumors and surrounding tissues. Results predict higher interstitial pressure, almost two times, for realistic model compared to the simplified model. PMID:23840579

GPU accelerated simulations of three-dimensional flow of power-law fluids in a driven cube

NASA Astrophysics Data System (ADS)

Jin, K.; Vanka, S. P.; Agarwal, R. K.; Thomas, B. G.

2017-01-01

Newtonian fluid flow in two- and three-dimensional cavities with a moving wall has been studied extensively in a number of previous works. However, relatively a fewer number of studies have considered the motion of non-Newtonian fluids such as shear thinning and shear thickening power law fluids. In this paper, we have simulated the three-dimensional, non-Newtonian flow of a power law fluid in a cubic cavity driven by shear from the top wall. We have used an in-house developed fractional step code, implemented on a Graphics Processor Unit. Three Reynolds numbers have been studied with power law index set to 0.5, 1.0 and 1.5. The flow patterns, viscosity distributions and velocity profiles are presented for Reynolds numbers of 100, 400 and 1000. All three Reynolds numbers are found to yield steady state flows. Tabulated values of velocity are given for the nine cases studied, including the Newtonian cases.

Unsteady free convection flow of viscous fluids with analytical results by employing time-fractional Caputo-Fabrizio derivative (without singular kernel)

NASA Astrophysics Data System (ADS)

Ali Shah, Nehad; Mahsud, Yasir; Ali Zafar, Azhar

2017-10-01

This article introduces a theoretical study for unsteady free convection flow of an incompressible viscous fluid. The fluid flows near an isothermal vertical plate. The plate has a translational motion with time-dependent velocity. The equations governing the fluid flow are expressed in fractional differential equations by using a newly defined time-fractional Caputo-Fabrizio derivative without singular kernel. Explicit solutions for velocity, temperature and solute concentration are obtained by applying the Laplace transform technique. As the fractional parameter approaches to one, solutions for the ordinary fluid model are extracted from the general solutions of the fractional model. The results showed that, for the fractional model, the obtained solutions for velocity, temperature and concentration exhibit stationary jumps discontinuity across the plane at t=0 , while the solutions are continuous functions in the case of the ordinary model. Finally, numerical results for flow features at small-time are illustrated through graphs for various pertinent parameters.

A thermodynamically consistent model for granular-fluid mixtures considering pore pressure evolution and hypoplastic behavior

NASA Astrophysics Data System (ADS)

Hess, Julian; Wang, Yongqi

2016-11-01

A new mixture model for granular-fluid flows, which is thermodynamically consistent with the entropy principle, is presented. The extra pore pressure described by a pressure diffusion equation and the hypoplastic material behavior obeying a transport equation are taken into account. The model is applied to granular-fluid flows, using a closing assumption in conjunction with the dynamic fluid pressure to describe the pressure-like residual unknowns, hereby overcoming previous uncertainties in the modeling process. Besides the thermodynamically consistent modeling, numerical simulations are carried out and demonstrate physically reasonable results, including simple shear flow in order to investigate the vertical distribution of the physical quantities, and a mixture flow down an inclined plane by means of the depth-integrated model. Results presented give insight in the ability of the deduced model to capture the key characteristics of granular-fluid flows. We acknowledge the support of the Deutsche Forschungsgemeinschaft (DFG) for this work within the Project Number WA 2610/3-1.

Scaling and modeling of turbulent suspension flows

NASA Technical Reports Server (NTRS)

Chen, C. P.

1989-01-01

Scaling factors determining various aspects of particle-fluid interactions and the development of physical models to predict gas-solid turbulent suspension flow fields are discussed based on two-fluid, continua formulation. The modes of particle-fluid interactions are discussed based on the length and time scale ratio, which depends on the properties of the particles and the characteristics of the flow turbulence. For particle size smaller than or comparable with the Kolmogorov length scale and concentration low enough for neglecting direct particle-particle interaction, scaling rules can be established in various parameter ranges. The various particle-fluid interactions give rise to additional mechanisms which affect the fluid mechanics of the conveying gas phase. These extra mechanisms are incorporated into a turbulence modeling method based on the scaling rules. A multiple-scale two-phase turbulence model is developed, which gives reasonable predictions for dilute suspension flow. Much work still needs to be done to account for the poly-dispersed effects and the extension to dense suspension flows.

Capacitance probe for fluid flow and volume measurements

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

1995-01-01

Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a microgravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

Capacitance Probe for Fluid Flow and Volume Measurements

NASA Technical Reports Server (NTRS)

Arndt, G. Dickey (Inventor); Nguyen, Thanh X. (Inventor); Carl, James R. (Inventor)

1997-01-01

Method and apparatus for making measurements on fluids are disclosed, including the use of a capacitive probe for measuring the flow volume of a material within a flow stream. The capacitance probe has at least two elongate electrodes and, in a specific embodiment of the invention, has three parallel elongate electrodes with the center electrode being an extension of the center conductor of a co-axial cable. A conductance probe is also provided to provide more accurate flow volume data in response to conductivity of the material within the flow stream. A preferred embodiment of the present invention provides for a gas flow stream through a micro-gravity environment that allows for monitoring a flow volume of a fluid sample, such as a urine sample, that is entrained within the gas flow stream.

Investigation of the fluid flow dynamic parameters for Newtonian and non-Newtonian materials: an approach to understanding the fluid flow-like structures within fault zones

NASA Astrophysics Data System (ADS)

Tanaka, H.; Shiomi, Y.; Ma, K.-F.

2017-11-01

To understand the fault zone fluid flow-like structure, namely the ductile deformation structure, often observed in the geological field (e.g., Ramsay and Huber The techniques of modern structure geology, vol. 1: strain analysis, Academia Press, London, 1983; Hobbs and Ord Structure geology: the mechanics of deforming metamorphic rocks, Vol. I: principles, Elsevier, Amsterdam, 2015), we applied a theoretical approach to estimate the rate of deformation, the shear stress and the time to form a streak-line pattern in the boundary layer of viscous fluids. We model the dynamics of streak lines in laminar boundary layers for Newtonian and pseudoplastic fluids and compare the results to those obtained via laboratory experiments. The structure of deformed streak lines obtained using our model is consistent with experimental observations, indicating that our model is appropriate for understanding the shear rate, flow time and shear stress based on the profile of deformed streak lines in the boundary layer in Newtonian and pseudoplastic viscous materials. This study improves our understanding of the transportation processes in fluids and of the transformation processes in fluid-like materials. Further application of this model could facilitate understanding the shear stress and time history of the fluid flow-like structure of fault zones observed in the field.[Figure not available: see fulltext.

Electrostatically frequency tunable micro-beam-based piezoelectric fluid flow energy harvester

NASA Astrophysics Data System (ADS)

Rezaee, Mousa; Sharafkhani, Naser

2017-07-01

This research investigates the dynamic behavior of a sandwich micro-beam based piezoelectric energy harvester with electrostatically adjustable resonance frequency. The system consists of a cantilever micro-beam immersed in a fluid domain and is subjected to the simultaneous action of cross fluid flow and nonlinear electrostatic force. Two parallel piezoelectric laminates are extended along the length of the micro-beam and connected to an external electric circuit which generates an output power as a result of the micro-beam oscillations. The fluid-coupled structure is modeled using Euler-Bernoulli beam theory and the equivalent force terms for the fluid flow. Fluid induced forces comprise the added inertia force which is evaluated using equivalent added mass and the drag and lift forces which are evaluated using relative velocity and Van der Pol equation. In addition to flow velocity and fluid density, the influence of several design parameters such as external electrical resistance, piezo layer position, and dc voltage on the generated power are investigated by using Galerkin and step by step linearization method. It is shown that for given flowing fluid parameters, i.e., density and velocity, one can adjust the applied dc voltage to tune resonance frequency so that the lock-in phenomenon with steady large amplitude oscillations happens, also by adjusting the harvester parameters including the mechanical and electrical ones, the maximal output power of the harvester becomes possible.

Self-actuating and locking control for nuclear reactor

DOEpatents

Chung, Dong K.

1982-01-01

A self-actuating, self-locking flow cutoff valve particularly suited for use in a nuclear reactor of the type which utilizes a plurality of fluid support neutron absorber elements to provide for the safe shutdown of the reactor. The valve comprises a substantially vertical elongated housing and an aperture plate located in the housing for the flow of fluid therethrough, a substantially vertical elongated nozzle member located in the housing and affixed to the housing with an opening in the bottom for receiving fluid and apertures adjacent a top end for discharging fluid. The nozzle further includes two sealing means, one located above and the other below the apertures. Also located in the housing and having walls surrounding the nozzle is a flow cutoff sleeve having a fluid opening adjacent an upper end of the sleeve, the sleeve being moveable between an upper open position wherein the nozzle apertures are substantially unobstructed and a closed position wherein the sleeve and nozzle sealing surfaces are mated such that the flow of fluid through the apertures is obstructed. It is a particular feature of the present invention that the valve further includes a means for utilizing any increase in fluid pressure to maintain the cutoff sleeve in a closed position. It is another feature of the invention that there is provided a means for automatically closing the valve whenever the flow of fluid drops below a predetermined level.

Metamorphic assemblages and the direction of flow of metamorphic fluids in four instances of serpentinization

USGS Publications Warehouse

Barnes, I.; Rapp, J.B.; O'Neil, J.R.; Sheppard, R.A.; Gude, A.J.

1972-01-01

Fluids related to Serpentinization are of at least three types. The first reported (Barnes and O'Neil, 1969) is a fluid of local meteoric origin, the chemical and thermodynamic properties of which are entirely controlled by olivine, orthopyroxene, brucite, and serpentine reactions. It is a Ca+2-OH-1 type and is shown experimentally to be capable of reacting with albite to yield calcium hydroxy silicates. Rodingites may form where the Ca+2-OH-1 type waters flow across the ultramafic contact and react with siliceous country rock. The second type of fluid has its chemical composition largely controlled before it enters the ultramafic rocks, but reactions within the ultramafic rocks fix the thermodynamic properties by reactions of orthopyroxene, olivine, calcite, brucite, and serpentine. The precipitation of brucite from this fluid clearly shows that fluid flow allows reaction products to be deposited at a distance from the point of solution. Thus, textural evidence for volume relations during Serpentinization may not be valid. The third type of fluid has its chemical properties fixed in part before the reactions with ultramafic rocks, in part by the reactions of orthopyroxene, olivine, and serpentine and in part by reactions with siliceous country rock at the contact. The reactions of the ultramafic rock and country rock with the fluid must be contemporaneous and require flow to be along the contact. This third type of fluid is grossly supersaturated with talc and tremolite, both found along the contact. The occurrence of magadiite, kenyaite, mountainite, and rhodesite along the contact is probably due to a late stage low-temperature reaction of fluids of the same thermodynamic properties as those that formed the talc and tremolite at higher temperatures. Oxygen isotope analyses of some of these minerals supports this conclusion. Rodingites form from Ca+2-rich fluids flowing across the contact; talc and tremolite form from silica-rich fluids flowing along the contact. Isotopic analyses of the fluids indicate varied origins including unaltered local meteoric water and connate water. Complexion Spring water may be a sample of only slightly altered Jurassic or Cretaceous sea water. ?? 1972 Springer-Verlag.

Flowmeter for Clear and Translucent Fluids

NASA Technical Reports Server (NTRS)

White, P. R.

1985-01-01

Transducer with only three moving parts senses flow of clear or translucent fluid. Displacement of diaphragm by force of flow detected electrooptically and displayed by panel meter or other device. Transducer used to measure flow of gasoline to automobile engine.

Review of numerical models of cavitating flows with the use of the homogeneous approach

NASA Astrophysics Data System (ADS)

Niedźwiedzka, Agnieszka; Schnerr, Günter H.; Sobieski, Wojciech

2016-06-01

The focus of research works on cavitation has changed since the 1960s; the behaviour of a single bubble is no more the area of interest for most scientists. Its place was taken by the cavitating flow considered as a whole. Many numerical models of cavitating flows came into being within the space of the last fifty years. They can be divided into two groups: multi-fluid and homogeneous (i.e., single-fluid) models. The group of homogenous models contains two subgroups: models based on transport equation and pressure based models. Several works tried to order particular approaches and presented short reviews of selected studies. However, these classifications are too rough to be treated as sufficiently accurate. The aim of this paper is to present the development paths of numerical investigations of cavitating flows with the use of homogeneous approach in order of publication year and with relatively detailed description. Each of the presented model is accompanied by examples of the application area. This review focuses not only on the list of the most significant existing models to predict sheet and cloud cavitation, but also on presenting their advantages and disadvantages. Moreover, it shows the reasons which inspired present authors to look for new ways of more accurate numerical predictions and dimensions of cavitation. The article includes also the division of source terms of presented models based on the transport equation with the use of standardized symbols.

Characterization of the paleo-hydrothermal fluids flow in the geothermal province of Limagne. (French Massif Central).

NASA Astrophysics Data System (ADS)

Fréville, K.; Sizaret, S.

2017-12-01

Exploitation of the geothermal energy is a prime target to future energy supply. Understanding the nature and the flow of geothermal fluids is a key objective for describe the functioning of current hydrothermal systems. Located in the French Massif Central, the Limagne basin is a tertiary hemi-graben characterized by a high thermal gradient with numerous occurrences of CO2-rich thermo-mineral waters. This basin has potential for high-temperature geothermal energy, expressed by numerous natural high temperature water sources, as well as at Royat and Vichy were the surface temperature of the water can reach 33°C and 27°C, respectively. In order to better localize this potential, the geological evolution has to be deciphered. In this aim we study the flow processes of the paleo-fluids and estimate the direction and the velocity of the hydrothermal flow from the studies of the growth bands of comb quartz grain localized in vein. In a second time, the studies fluids inclusions within the quartz grain are used to characterize the nature of the fluids involved. Preliminary results show that the flow is discontinuous over the time with changes in velocities and directions during the growth of a single quartz grain. Two main flows were identified, i) a relatively fast upward flow at 10-6,-5 m.s-1; ii) a downward flow at about 10-5,-4 m.s-1. The results allow: (i) to discuss the processes controlling the fluids flow in the Limagne basin; and (ii) to suggest to delimitate the areas with high geothermal potential which integrate the flow variation in time.

Fluid dynamics following flow shut-off in bottle filling

NASA Astrophysics Data System (ADS)

Thete, Sumeet; Appathurai, Santosh; Gao, Haijing; Basaran, Osman

2012-11-01

Bottle filling is ubiquitous in industry. Examples include filling of bottles with shampoos and cleaners, engine oil and pharmaceuticals. In these examples, fluid flows out of a nozzle to fill bottles in an assembly line. Once the required volume of fluid has flowed out of the nozzle, the flow is shut off. However, an evolving fluid thread or string may remain suspended from the nozzle following flow shut-off and persist. This stringing phenomenon can be detrimental to a bottle filling operation because it can adversely affect line speed and filling accuracy by causing uncertainty in fill volume, product loss and undesirable marring of the bottles' exterior surfaces. The dynamics of stringing are studied numerically primarily by using the 1D, slender-jet approximation of the flow equations. A novel feature entails development and use of a new boundary condition downstream of the nozzle exit to expedite the computations. While the emphasis is on stringing of Newtonian fluids and use of 1D approximations, results will also be presented for situations where (a) the fluids are non-Newtonian and (b) the full set of equations are solved without invoking the 1D approximation. Phase diagrams will be presented that identify conditions for which stringing can be problematic.

Electroosmotic flow of Phan-Thien-Tanner fluids at high zeta potentials: An exact analytical solution

NASA Astrophysics Data System (ADS)

Sarma, Rajkumar; Deka, Nabajit; Sarma, Kuldeep; Mondal, Pranab Kumar

2018-06-01

We present a mathematical model to study the electroosmotic flow of a viscoelastic fluid in a parallel plate microchannel with a high zeta potential, taking hydrodynamic slippage at the walls into account in the underlying analysis. We use the simplified Phan-Thien-Tanner (s-PTT) constitutive relationships to describe the rheological behavior of the viscoelastic fluid, while Navier's slip law is employed to model the interfacial hydrodynamic slip. Here, we derive analytical solutions for the potential distribution, flow velocity, and volumetric flow rate based on the complete Poisson-Boltzmann equation (without considering the frequently used Debye-Hückel linear approximation). For the underlying electrokinetic transport, this investigation primarily reveals the influence of fluid rheology, wall zeta potential as modulated by the interfacial electrochemistry and interfacial slip on the velocity distribution, volumetric flow rate, and fluid stress, as well as the apparent viscosity. We show that combined with the viscoelasticity of the fluid, a higher wall zeta potential and slip coefficient lead to a phenomenal enhancement in the volumetric flow rate. We believe that this analysis, besides providing a deep theoretical insight to interpret the transport process, will also serve as a fundamental design tool for microfluidic devices/systems under electrokinetic influence.

Technical characterization of dialysis fluid flow and mass transfer rate in dialyzers with various filtration coefficients using dimensionless correlation equation.

PubMed

Fukuda, Makoto; Yoshimura, Kengo; Namekawa, Koki; Sakai, Kiyotaka

2017-06-01

The objective of the present study is to evaluate the effect of filtration coefficient and internal filtration on dialysis fluid flow and mass transfer coefficient in dialyzers using dimensionless mass transfer correlation equations. Aqueous solution of vitamin B 12 clearances were obtained for REXEED-15L as a low flux dialyzer, and APS-15EA and APS-15UA as high flux dialyzers. All the other design specifications were identical for these dialyzers except for filtration coefficient. The overall mass transfer coefficient was calculated, moreover, the exponents of Reynolds number (Re) and film mass transfer coefficient of the dialysis-side fluid (k D ) for each flow rate were derived from the Wilson plot and dimensionless correlation equation. The exponents of Re were 0.4 for the low flux dialyzer whereas 0.5 for the high flux dialyzers. Dialysis fluid of the low flux dialyzer was close to laminar flow because of its low filtration coefficient. On the other hand, dialysis fluid of the high flux dialyzers was assumed to be orthogonal flow. Higher filtration coefficient was associated with higher k D influenced by mass transfer rate through diffusion and internal filtration. Higher filtration coefficient of dialyzers and internal filtration affect orthogonal flow of dialysis fluid.

Interfacial gauge methods for incompressible fluid dynamics

DOE PAGES

Saye, R.

2016-06-10

Designing numerical methods for incompressible fluid flow involving moving interfaces, for example, in the computational modeling of bubble dynamics, swimming organisms, or surface waves, presents challenges due to the coupling of interfacial forces with incompressibility constraints. A class of methods, denoted interfacial gauge methods, is introduced for computing solutions to the corresponding incompressible Navier-Stokes equations. These methods use a type of "gauge freedom" to reduce the numerical coupling between fluid velocity, pressure, and interface position, allowing high-order accurate numerical methods to be developed more easily. Making use of an implicit mesh discontinuous Galerkin framework, developed in tandem with this work,more » high-order results are demonstrated, including surface tension dynamics in which fluid velocity, pressure, and interface geometry are computed with fourth-order spatial accuracy in the maximum norm. Applications are demonstrated with two-phase fluid flow displaying fine-scaled capillary wave dynamics, rigid body fluid-structure interaction, and a fluid-jet free surface flow problem exhibiting vortex shedding induced by a type of Plateau-Rayleigh instability. The developed methods can be generalized to other types of interfacial flow and facilitate precise computation of complex fluid interface phenomena.« less

Directed Fluid Transport with Biomimetic ``Silia'' Arrays

NASA Astrophysics Data System (ADS)

Shields, A. R.; Evans, B. A.; Carstens, B. L.; Falvo, M. R.; Washburn, S.; Superfine, R.

2008-10-01

We present results on the long-range, directed fluid transport produced by the collective beating of arrays of biomimetic ``silia.'' Silia are arrays of free-standing nanorods roughly the size of biological cilia, which we fabricate from a polymer-magnetic nanoparticle composite material. With external permanent magnets we actuate our silia such that their motion mimics the beating of biological cilia. Biological cilia have evolved to produce microscale fluid transport and are increasingly being recognized as critical components in a wide range of biological systems. However, despite much effort cilia generated fluid flows remain an area of active study. In the last decade, cilia-driven fluid flow in the embryonic node of vertebrates has been implicated as the initial left-right symmetry breaking event in these embryos. With silia we generate directional fluid transport by mimicking the tilted conical beating of these nodal cilia and seek to answer open questions about the nature of particle advection in such a system. By seeding fluorescent microparticles into the fluid we have noted the existence of two distinct flow regimes. The fluid flow is directional and coherent above the tips of the silia, while between the silia tips and floor particle motion is complicated and suggestive of chaotic advection.

Heat-sterilized PD fluid blocks leukocyte adhesion and increases flow velocity in rat peritoneal venules.

PubMed

Jonasson, P; Bagge, U; Wieslander, A; Braide, M

1996-01-01

Data from cell culture experiments indicate that heat sterilization of peritoneal dialysis (PD) fluids produces cytotoxic glucose degradation products. The present vital microscopic study investigated the effects of different sterilization methods on the biocompatibility of PD fluids. Thus, heat-sterilized (commercially obtained and experimentally produced) and filter-sterilized PD fluids (pH = 5.30-5.40; 1.5% glucose) were compared with Tyrode buffer, with respect to the effects on microvascular blood flow velocity and leukocyte adhesion in the rat mesentery. Exteriorization of the mesentery produced a mild inflammation, known from the literature and characterized by the adhesive rolling of leukocytes along venular walls. Superfusion of the mesentery with filter-sterilized PD fluid had no significant effects on leukocyte rolling or flow velocity in venules 25-40 microns in diameter compared with buffer superfusion. Heat-sterilized PD fluid decreased the concentration of rolling leukocytes and increased flow velocity significantly, as compared with buffer and filter-sterilized PD fluid. The results indicate that heat sterilization of PD fluids produces substances that interact with microvascular tone and leukocyte-endothelial adhesion, which hypothetically could impair the acute, granulocyte-mediated defense against bacterial infections.

Ca, Sr, O and D isotope approach to defining the chemical evolution of hydrothermal fluids: example from Long Valley, CA, USA

USGS Publications Warehouse

Brown, Shaun T.; Kennedy, B. Mack; DePaolo, Donald J.; Hurwitz, Shaul; Evans, William C.

2013-01-01

We present chemical and isotopic data for fluids, minerals and rocks from the Long Valley meteoric-hydrothermal system. The samples encompass the presumed hydrothermal upwelling zone in the west moat of the caldera, the Casa Diablo geothermal field, and a series of wells defining a nearly linear, ∼16 km long, west-to-east trend along the likely fluid flow path. Fluid samples were analyzed for the isotopes of water, Sr, and Ca, the concentrations of major cations and anions, alkalinity, and total CO2. Water isotope data conform to trends documented in earlier studies, interpreted as indicating a single hydrothermal fluid mixing with local groundwater. Sr isotopes show subtle changes along the flow path, which requires rapid fluid flow and minimal reaction between the channelized fluids and the wallrocks. Sr and O isotopes are used to calculate fracture spacing using a dual porosity model. Calculated fracture spacing and temperature data for hydrothermal fluids indicate the system is (approximately) at steady-state. Correlated variations among total CO2, and the concentration and isotopic composition of Ca suggest progressive fluid degassing (loss of CO2), which drives calcite precipitation as the fluid flows west-to-east and cools. The shifts in Ca isotopes require that calcite precipitated at temperatures of 150–180 °C is fractionated by ca. −0.3‰ to −0.5‰ relative to aqueous species. Our data are the first evidence that Ca isotopes undergo kinetic fractionation at high temperatures (>100 °C) and can be used to trace calcite precipitation along hydrothermal fluid flow paths.

[Comparison of atrio-ventricular and total cavo-pulmonary connections versus atrio-pulmonary anastomosis for repair of tricuspid atresia in dogs].

PubMed

Yu, C; Liu, Y; Zhu, X; Li, Y; Li, Y

2000-03-01

To compare the hemodynamic effect and energy loss of atrio-ventricular and total cavo-pulmonary connections versus atrio-pulmonary anastomosis for modified Fontan in dogs. Fifteen adult mongrel dogs were divided into three groups. Group I underwent right atrium to right ventricle (using 50% and 25% right ventricular chamber, respectively) connection with the flap of valved homo-pulmonary artery (modified Bjoerk procedure). Group II underwent total cavo-pulmonary connection. Group III received atrio-pulmonary anastomosis. Right atrium pressure, pulmonary artery pressure, and cardiac output were measured by Swan-Ganz catheter. The volumes of the right pulmonary artery, left pulmonary artery, superior vena cava and inferior vena cava were measured by electromagnetic flowmeter. The flow-rate of the right pulmonary artery, left pulmonary artery, superior vena cava and inferior vena cava were measured echocardiographically. The fluid energy loss was calculated. The postoperative right atrium pressure in group I was lower than in group III (P < 0.05). The postoperative stroke index in group I and group II was higher than in group III (P < 0.01). The fluid energy loss was decreased when 50% or 25% right ventricle chamber was used (P < 0.01) and the fluid energy less in group II was less than in group III. Our experience suggested that atrio-ventricular connection and total cavo-pulmonary connection would be better than atrio-pulmonary anastomosis for modified Fontan repair of tricuspid valve atresia.

Study of two-phase flow in helical and spiral coils

NASA Technical Reports Server (NTRS)

Keshock, Edward G.; Yan, AN; Omrani, Adel

1990-01-01

The principal purposes of the present study were to: (1) observe and develop a fundamental understanding of the flow regimes and their transitions occurring in helical and spiral coils; and (2) obtain pressure drop measurements of such flows, and, if possible, develop a method for predicting pressure drop in these flow geometries. Elaborating upon the above, the general intent is to develop criteria (preferably generalized) for establishing the nature of the flow dynamics (e.g. flow patterns) and the magnitude of the pressure drop in such configurations over a range of flow rates and fluid properties. Additionally, the visualization and identification of flow patterns were a fundamental objective of the study. From a practical standpoint, the conditions under which an annular flow pattern exists is of particular practical importance. In the possible practical applications which would implement these geometries, the working fluids are likely to be refrigerant fluids. In the present study the working fluids were an air-water mixture, and refrigerant 113 (R-113). In order to obtain records of flow patterns and their transitions, video photography was employed extensively. Pressure drop measurements were made using pressure differential transducers connected across pressure taps in lines immediately preceding and following the various test sections.

Messinian Salinity Crisis and basin fluid flow

NASA Astrophysics Data System (ADS)

Bertoni, Claudia; Cartwight, Joe

2014-05-01

Syn- and post-depositional movement of fluids through sediments is one of the least understood aspects in the evolution of a basin. The conventional hydrostratigraphic view on marine sedimentary basins assumes that compactional and meteoric groundwater fluid circulation drives fluid movement and defines its timing. However, in the past few years, several examples of instantaneous and catastrophic release of fluids have been observed even through low-permeability sediments. A particularly complex case-study involves the presence of giant salt bodies in the depocentres of marine basins. Evaporites dramatically change the hydrostratigraphy and fluid-dynamics of the basin, and influence the P/T regimes, e.g. through changes in the geothermal gradient and in the compaction of underlying sediments. Our paper reviews the impact of the Messinian Salinity Crisis (MSC) and evaporites on fluid flow in the Mediterranean sub-basins. The analysis of geological and geophysical sub-surface data provides examples from this basin, and the comparison with analogues in other well-known evaporitic provinces. During the MSC, massive sea-level changes occurred in a relatively limited time interval, and affected the balance of fluid dynamics, e.g. with sudden release or unusual trapping of fluids. Fluid expulsion events are here analysed and classified in relation to the long and short-term effects of the MSC. Our main aim is to build a framework for the correct identification of the fluid flow-related events, and their genetic mechanisms. On basin margins, where evaporites are thin or absent, the sea-level changes associated with the MSC force a rapid basinward shift of the mixing zone of meteoric/gravity flow and saline/compactional flow, 100s-km away from its pre-MSC position. This phenomenon changes the geometry of converging flows, creates hydraulic traps for fluids, and triggers specific diagenetic reactions in pre-MSC deep marine sediments. In basin-centre settings, unloading and re-loading of water associated to the sea-level changes leads to the sudden release of focused fluids, enhancing pockmark formation, evaporite dissolution, gas-hydrate dissociation and methane venting. After the MSC, and in the long-term basin evolution, the aquitard effect of the thick evaporites also created favourable condition for the development of overpressures in the pre-MSC sediments. However, the traditional view of saline giants as impermeable barriers to fluid flow has been challenged in recent years, by the documented evidence of fluid migration pathways through thick evaporites. Ultimately, these events can lead not only to fluid, but also to sediment remobilisation. The review here presented has applications as a tool for identifying, quantifying and understanding controls and timing of fluid dynamics in marine basins hosting extensive evaporitic series.

Unsteady Magnetized Flow and Heat Transfer of a Viscoelastic fluid over a Stretching Surface

NASA Astrophysics Data System (ADS)

Ghosh, Sushil Kumar

2017-12-01

This paper is to study the flow of heated ferro-fluid over a stretching sheet under the influence of magnetic field. The fluid considered in the present investigation is a mixture of blood as well as fluid-dispersed magnetic nano particles and under this context blood is found to be the appropriate choice of viscoelastic, Walter's B fluid. The objective of the present work is to study the effect of various parameters found in the mathematical analysis. Taking into account the blood has zero electrical conductivity, magnetization effect has been considered in the governing equation of the present study with the use of ferro-fluid dynamics principle. By introducing appropriate non-dimensional variables into the governing equations of unsteady two-dimensional flow of viscoelastic fluid with heat transfer are converted to a set of ordinary differential equations with appropriate boundary conditions. Newton's linearization technique has been employed for the solution of non-linear ordinary differential equations. Important results found in the present investigation are the substantial influence of ferro-magnetic parameter, Prandlt number and the parameter associated with the thermal conductivity on the flow and heat transfer. It is observed that the presence of magnetic dipole essentially reduces the flow velocity in the vertical direction and that helps to damage the cancer cells in the tumor region.

Flow of “stress power-law” fluids between parallel rotating discs with distinct axes

DOE PAGES

Srinivasan, Shriram; Karra, Satish

2015-04-16

The problem of flow between parallel rotating discs with distinct axes corresponds to the case of flow in an orthogonal rheometer and has been studied extensively for different fluids since the instrument's inception. All the prior studies presume a constitutive prescription of the fluid stress in terms of the kinematical variables. In this paper, we approach the problem from a different perspective, i.e., a constitutive specification of the symmetric part of the velocity gradient in terms of the Cauchy stress. Such an approach ensures that the boundary conditions can be incorporated in a manner quite faithful to real world experimentsmore » with the instrument. Interestingly, the choice of the boundary condition is critical to the solvability of the problem for the case of creeping/Stokes flow. Furthermore, when the no-slip condition is enforced at the boundaries, depending on the model parameters and axes offset, the fluid response can show non-uniqueness or unsolvability, features which are absent in a conventional constitutive specification. In case of creeping/Stokes flow with prescribed values of the stress, the fluid response is indeterminate. We also record the response of a particular case of the given “stress power-law” fluid; one that cannot be attained by the conventional power-law fluids.« less

Dynamic bulk and shear moduli due to grain-scale local fluid flow in fluid-saturated cracked poroelastic rocks: Theoretical model

NASA Astrophysics Data System (ADS)

Song, Yongjia; Hu, Hengshan; Rudnicki, John W.

2016-07-01

Grain-scale local fluid flow is an important loss mechanism for attenuating waves in cracked fluid-saturated poroelastic rocks. In this study, a dynamic elastic modulus model is developed to quantify local flow effect on wave attenuation and velocity dispersion in porous isotropic rocks. The Eshelby transform technique, inclusion-based effective medium model (the Mori-Tanaka scheme), fluid dynamics and mass conservation principle are combined to analyze pore-fluid pressure relaxation and its influences on overall elastic properties. The derivation gives fully analytic, frequency-dependent effective bulk and shear moduli of a fluid-saturated porous rock. It is shown that the derived bulk and shear moduli rigorously satisfy the Biot-Gassmann relationship of poroelasticity in the low-frequency limit, while they are consistent with isolated-pore effective medium theory in the high-frequency limit. In particular, a simplified model is proposed to quantify the squirt-flow dispersion for frequencies lower than stiff-pore relaxation frequency. The main advantage of the proposed model over previous models is its ability to predict the dispersion due to squirt flow between pores and cracks with distributed aspect ratio instead of flow in a simply conceptual double-porosity structure. Independent input parameters include pore aspect ratio distribution, fluid bulk modulus and viscosity, and bulk and shear moduli of the solid grain. Physical assumptions made in this model include (1) pores are inter-connected and (2) crack thickness is smaller than the viscous skin depth. This study is restricted to linear elastic, well-consolidated granular rocks.

Fluid outflows from Venus impact craters - Analysis from Magellan data

NASA Technical Reports Server (NTRS)

Asimow, Paul D.; Wood, John A.

1992-01-01

Many impact craters on Venus have unusual outflow features originating in or under the continuous ejecta blankets and continuing downhill into the surrounding terrain. These features clearly resulted from flow of low-viscosity fluids, but the identity of those fluids is not clear. In particular, it should not be assumed a priori that the fluid is an impact melt. A number of candidate processes by which impact events might generate the observed features are considered, and predictions are made concerning the rheological character of flows produce by each mechanism. A sample of outflows was analyzed using Magellan images and a model of unconstrained Bingham plastic flow on inclined planes, leading to estimates of viscosity and yield strength for the flow materials. It is argued that at least two different mechanisms have produced outflows on Venus: an erosive, channel-forming process and a depositional process. The erosive fluid is probably an impact melt, but the depositional fluid may consist of fluidized solid debris, vaporized material, and/or melt.

Topology optimization of thermal fluid flows with an adjoint Lattice Boltzmann Method

NASA Astrophysics Data System (ADS)

Dugast, Florian; Favennec, Yann; Josset, Christophe; Fan, Yilin; Luo, Lingai

2018-07-01

This paper presents an adjoint Lattice Boltzmann Method (LBM) coupled with the Level-Set Method (LSM) for topology optimization of thermal fluid flows. The adjoint-state formulation implies discrete velocity directions in order to take into account the LBM boundary conditions. These boundary conditions are introduced at the beginning of the adjoint-state method as the LBM residuals, so that the adjoint-state boundary conditions can appear directly during the adjoint-state equation formulation. The proposed method is tested with 3 numerical examples concerning thermal fluid flows, but with different objectives: minimization of the mean temperature in the domain, maximization of the heat evacuated by the fluid, and maximization of the heat exchange with heated solid parts. This latter example, treated in several articles, is used to validate our method. In these optimization problems, a limitation of the maximal pressure drop and of the porosity (number of fluid elements) is also applied. The obtained results demonstrate that the method is robust and effective for solving topology optimization of thermal fluid flows.

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

NASA Astrophysics Data System (ADS)

Kong, Bo; Fox, Rodney O.

2017-09-01

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

System and method measuring fluid flow in a conduit

DOEpatents

Ortiz, Marcos German; Kidd, Terrel G.

1999-01-01

A system for measuring fluid mass flow in a conduit in which there exists a pressure differential in the fluid between at least two spaced-apart locations in the conduit. The system includes a first pressure transducer disposed in the side of the conduit at a first location for measuring pressure of fluid at that location, a second or more pressure transducers disposed in the side of the conduit at a second location, for making multiple measurements of pressure of fluid in the conduit at that location, and a computer for computing the average pressure of the multiple measurements at the second location and for computing flow rate of fluid in the conduit from the pressure measurement by the first pressure transducer and from the average pressure calculation of the multiple measurements.

Microscale fluid transport using optically controlled marangoni effect

DOEpatents

Thundat, Thomas G [Knoxville, TN; Passian, Ali [Knoxville, TN; Farahi, Rubye H [Oak Ridge, TN

2011-05-10

Low energy light illumination and either a doped semiconductor surface or a surface-plasmon supporting surface are used in combination for manipulating a fluid on the surface in the absence of any applied electric fields or flow channels. Precise control of fluid flow is achieved by applying focused or tightly collimated low energy light to the surface-fluid interface. In the first embodiment, with an appropriate dopant level in the semiconductor substrate, optically excited charge carriers are made to move to the surface when illuminated. In a second embodiment, with a thin-film noble metal surface on a dispersive substrate, optically excited surface plasmons are created for fluid manipulation. This electrode-less optical control of the Marangoni effect provides re-configurable manipulations of fluid flow, thereby paving the way for reprogrammable microfluidic devices.

Is the Cochlear Amplifier a Fluid Pump?

NASA Astrophysics Data System (ADS)

Karavitaki, K. D.; Mountain, D. C.

2003-02-01

We have visualized and quantified the effects of electrically evoked motility of outer hair cells (OHCs) within the organ of Corti using an excised cochlear preparation. We found that OHC motility induces oscillatory fluid flow in the tunnel of Corti (TC) and this flow is present at physiologically relevant frequencies. We also show, using a simple one-dimensional hydromechanical model of the TC, that a fluid wave within the tunnel can travel without significant attenuation for distances larger than the wavelength of the cochlear traveling wave. These results in combination with a recent hypothesis that fluid flow within the tunnel is necessary for cochlear amplification suggest that the function of the OHCs is to act as a fluid pump.

Leptomeningeal metastases: a RANO proposal for response criteria

PubMed Central

Junck, Larry; Brandsma, Dieta; Soffietti, Riccardo; Rudà, Roberta; Raizer, Jeffrey; Boogerd, Willem; Taillibert, Sophie; Groves, Morris D.; Rhun, Emilie Le; Walker, Julie; van den Bent, Martin; Wen, Patrick Y.; Jaeckle, Kurt A.

2017-01-01

Abstract Leptomeningeal metastases (LM) currently lack standardization with respect to response assessment. A Response Assessment in Neuro-Oncology (RANO) working group with expertise in LM developed a consensus proposal for evaluating patients treated for this disease. Three basic elements in assessing response in LM are proposed: a standardized neurological examination, cerebral spinal fluid (CSF) cytology or flow cytometry, and radiographic evaluation. The group recommends that all patients enrolling in clinical trials undergo CSF analysis (cytology in all cancers; flow cytometry in hematologic cancers), complete contrast-enhanced neuraxis MRI, and in instances of planned intra-CSF therapy, radioisotope CSF flow studies. In conjunction with the RANO Neurological Assessment working group, a standardized instrument was created for assessing the neurological exam in patients with LM. Considering that most lesions in LM are nonmeasurable and that assessment of neuroimaging in LM is subjective, neuroimaging is graded as stable, progressive, or improved using a novel radiological LM response scorecard. Radiographic disease progression in isolation (ie, negative CSF cytology/flow cytometry and stable neurological assessment) would be defined as LM disease progression. The RANO LM working group has proposed a method of response evaluation for patients with LM that will require further testing, validation, and likely refinement with use. PMID:28039364

Multi-fluid CFD analysis in Process Engineering

NASA Astrophysics Data System (ADS)

Hjertager, B. H.

2017-12-01

An overview of modelling and simulation of flow processes in gas/particle and gas/liquid systems are presented. Particular emphasis is given to computational fluid dynamics (CFD) models that use the multi-dimensional multi-fluid techniques. Turbulence modelling strategies for gas/particle flows based on the kinetic theory for granular flows are given. Sub models for the interfacial transfer processes and chemical kinetics modelling are presented. Examples are shown for some gas/particle systems including flow and chemical reaction in risers as well as gas/liquid systems including bubble columns and stirred tanks.

Molecular tagging techniques and their applications to the study of complex thermal flow phenomena

NASA Astrophysics Data System (ADS)

Chen, Fang; Li, Haixing; Hu, Hui

2015-08-01

This review article reports the recent progress in the development of a new group of molecule-based flow diagnostic techniques, which include molecular tagging velocimetry (MTV) and molecular tagging thermometry (MTT), for both qualitative flow visualization of thermally induced flow structures and quantitative whole-field measurements of flow velocity and temperature distributions. The MTV and MTT techniques can also be easily combined to result in a so-called molecular tagging velocimetry and thermometry (MTV&T) technique, which is capble of achieving simultaneous measurements of flow velocity and temperature distribution in fluid flows. Instead of using tiny particles, the molecular tagging techniques (MTV, MTT, and MTV&T) use phosphorescent molecules, which can be turned into long-lasting glowing marks upon excitation by photons of appropriate wavelength, as the tracers for the flow velocity and temperature measurements. The unique attraction and implementation of the molecular tagging techniques are demonstrated by three application examples, which include: (1) to quantify the unsteady heat transfer process from a heated cylinder to the surrounding fluid flow in order to examine the thermal effects on the wake instabilities behind the heated cylinder operating in mixed and forced heat convection regimes, (2) to reveal the time evolution of unsteady heat transfer and phase changing process inside micro-sized, icing water droplets in order to elucidate the underlying physics pertinent to aircraft icing phenomena, and (3) to achieve simultaneous droplet size, velocity and temperature measurements of "in-flight" droplets to characterize the dynamic and thermodynamic behaviors of flying droplets in spray flows.

Novel Optical Technique Developed and Tested for Measuring Two-Point Velocity Correlations in Turbulent Flows

NASA Technical Reports Server (NTRS)

Zimmerli, Gregory A.; Goldburg, Walter I.

2002-01-01

A novel technique for characterizing turbulent flows was developed and tested at the NASA Glenn Research Center. The work is being done in collaboration with the University of Pittsburgh, through a grant from the NASA Microgravity Fluid Physics Program. The technique we are using, Homodyne Correlation Spectroscopy (HCS), is a laser-light-scattering technique that measures the Doppler frequency shift of light scattered from microscopic particles in the fluid flow. Whereas Laser Doppler Velocimetry gives a local (single-point) measurement of the fluid velocity, the HCS technique measures correlations between fluid velocities at two separate points in the flow at the same instant of time. Velocity correlations in the flow field are of fundamental interest to turbulence researchers and are of practical importance in many engineering applications, such as aeronautics.

Fuel cell membrane hydration and fluid metering

DOEpatents

Jones, Daniel O.; Walsh, Michael M.

1999-01-01

A hydration system includes fuel cell fluid flow plate(s) and injection port(s). Each plate has flow channel(s) with respective inlet(s) for receiving respective portion(s) of a given stream of reactant fluid for a fuel cell. Each injection port injects a portion of liquid water directly into its respective flow channel in order to mix its respective portion of liquid water with the corresponding portion of the stream. This serves to hydrate at least corresponding part(s) of a given membrane of the corresponding fuel cell(s). The hydration system may be augmented by a metering system including flow regulator(s). Each flow regulator meters an injecting at inlet(s) of each plate of respective portions of liquid into respective portion(s) of a given stream of fluid by corresponding injection port(s).

Impact of drag reducing polymers on the onset of instability in a pipe with reverse flow

NASA Astrophysics Data System (ADS)

Shashank, H. J.; Sreenivas, K. R.

2014-11-01

The objective of this study is to understand the mechanism by which drag reducing polymer (DRP) additives modify turbulent flow, so as to reduce turbulent drag. Reverse flow in a pipe occurs when the fluid close to the wall moves in an opposite direction to that of the core fluid. Reverse flow is established by using a piston-cylinder mechanism, the programmed motion of which imparts a known impulse to the fluid. When the piston is stopped at the end of the stroke, fluid inertia makes the core of the flow to continue in the same direction. In order to conserve mass, reverse flow is established close to the wall. An inflection point is thus formed, leading to flow instability above a critical Reynolds number. Dye and streak flow visualization experiments are performed to highlight the impact of DRP additives (polyethylene oxide, PEO, dissolved in water). The time of onset of the instability and the wavelength of the observed instability are studied in systems with and without DRP additives. This study will provide further insight into the phenomenon of turbulent polymer drag reduction.

Longitudinal vibration and instabilities of carbon nanotubes conveying fluid considering size effects of nanoflow and nanostructure

NASA Astrophysics Data System (ADS)

Oveissi, Soheil; Eftekhari, S. Ali; Toghraie, Davood

2016-09-01

In this study, the effects of small-scale of the both nanoflow and nanostructure on the vibrational response of fluid flowing single-walled carbon nanotubes are investigated. To this purpose, two various flowing fluids, the air-nano-flow and the water nano-flow using Knudsen number, and two different continuum theories, the nonlocal theory and the strain-inertia gradient theory are studied. Nano-rod model is used to model the fluid-structure interaction, and Galerkin method of weighted residual is utilizing to solve and discretize the governing obtained equations. It is found that the critical flow velocity decreases as the wave number increases, excluding the first mode divergence that it has the least value among of the other instabilities if the strain-inertia gradient theory is employed. Moreover, it is observed that Kn effect has considerable impact on the reduction of critical velocities especially for the air-flow flowing through the CNT. In addition, by increasing a nonlocal parameter and Knudsen number the critical flow velocity decreases but it increases as the characteristic length related to the strain-inertia gradient theory increases.

NASA/MSFC's Calculation for Test Case 1a of ATAC-FSDC Workshop on After-body and Nozzle Flows

NASA Technical Reports Server (NTRS)

Ruf, Joseph H.

2006-01-01

Mr. Ruf of NASA/MSFC executed the CHEM computational fluid dynamics (CFD) code to provide a prediction of the test case 1 a for the ATAC-FSDC Workshop on After-body and Nozzle Flows. CHEM is used extensively at MSFC for a wide variety of fluid dynamic problems. These problems include; injector element flows, nozzle flows, feed line flows, turbomachinery flows, solid rocket motor internal flows, plume vehicle flow interactions, etc.

Fast fluid-flow events within a subduction-related vein system in oceanic eclogite: implications for pore fluid pressure at the plate interface

NASA Astrophysics Data System (ADS)

Taetz, Stephan; John, Timm; Bröcker, Michael; Spandler, Carl; Stracke, Andreas

2017-04-01

A better understanding of the subduction zone fluid cycle and its mechanical feedback requires in-depth knowledge of how fluids flow within and out of the descending slabs. In order to develop reliable quantitative models of fluid flow, the general relationship between dehydration reactions, fluid pathway formation, and the dimensions and timescales of distinct fluid flow events have to be explored. The high-pressure/low-temperature metamorphic rocks of the Pouébo Eclogite Mélange in New Caledonia provide an excellent opportunity to study the fluid flux in a subduction zone setting. Fluid dynamics are recorded by high-pressure veins that cross-cut eclogite facies mélange blocks from this occurrence. Two types of garnet-quartz-phengite veins can be distinguished. These veins record both synmetamorphic internal fluid release by mineral breakdown reactions (type I veins) as well as infiltration of an external fluid (type II veins) and the associated formation of a reaction halo. The overall dehydration, fluid accumulation and fluid migration documented by the type I veins occurred on a timescale of 10^5-106 years that is mainly given by the geometry and convergence rate of the subduction system. In order to quantify the timeframe of fluid-rock interaction between the external fluid and the wall-rock, we have applied Li-isotope chronology. A continuous profile was sampled perpendicular to a type II vein including material from the vein, the reaction selvage and the immediate host rock. Additional drill cores were taken from parts of the outcrop that most likely remained completely unaffected by fluid infiltration-induced alteration. Different Li concentrations in the internal and external fluid reservoirs produced a distinct diffusion profile of decreasing Li concentration and increasing δ7Li as the reaction front propagated into the host-rock. Li-chronometric constraints indicate that fluid-rock interaction related to the formation of the type II veins and had been completed within ca. 3 years. The short-lived, pulse-like character of this process is in accordance with the notion that fluid flow related to oceanic crust dehydration at the blueschist-to-eclogite transition contributes to or even dominates episodic pore fluid pressure increases at the plate interface which may trigger slip events reported from many subduction zones.

The Computational Fluid Dynamics Rupture Challenge 2013—Phase I: prediction of rupture status in intracranial aneurysms.

PubMed

Janiga, G; Berg, P; Sugiyama, S; Kono, K; Steinman, D A

2015-03-01

Rupture risk assessment for intracranial aneurysms remains challenging, and risk factors, including wall shear stress, are discussed controversially. The primary purpose of the presented challenge was to determine how consistently aneurysm rupture status and rupture site could be identified on the basis of computational fluid dynamics. Two geometrically similar MCA aneurysms were selected, 1 ruptured, 1 unruptured. Participating computational fluid dynamics groups were blinded as to which case was ruptured. Participants were provided with digitally segmented lumen geometries and, for this phase of the challenge, were free to choose their own flow rates, blood rheologies, and so forth. Participants were asked to report which case had ruptured and the likely site of rupture. In parallel, lumen geometries were provided to a group of neurosurgeons for their predictions of rupture status and site. Of 26 participating computational fluid dynamics groups, 21 (81%) correctly identified the ruptured case. Although the known rupture site was associated with low and oscillatory wall shear stress, most groups identified other sites, some of which also experienced low and oscillatory shear. Of the 43 participating neurosurgeons, 39 (91%) identified the ruptured case. None correctly identified the rupture site. Geometric or hemodynamic considerations favor identification of rupture status; however, retrospective identification of the rupture site remains a challenge for both engineers and clinicians. A more precise understanding of the hemodynamic factors involved in aneurysm wall pathology is likely required for computational fluid dynamics to add value to current clinical decision-making regarding rupture risk. © 2015 by American Journal of Neuroradiology.

Modes of Fluid Expulsion and its Significance for Forearc Dewatering at Costa Rica Convergent Margin

NASA Astrophysics Data System (ADS)

Hensen, C.; Wallmann, K.; Ranero, C.; Rehder, G.; Brueckmann, W.; Grevemeyer, I.; Reston, T.

2005-12-01

The expulsion of chloride-depleted fluids is characteristic for vent sites at Costa Rica continental margin. Oxygen and hydrogen isotope ratios, thermogenic methane as well as elevated heat flow demonstrate that the fluid flow is initiated by mineral dehydration in subducting sediments at about 10-12 km depth. Conspicuous differences in the geochemical composition allow a subdivision of a southern and a northern type of fluids, which may reflect differences in the input or a general south to north decrease in flow rates. Fluids of the southern type are enriched in boron and typically rise at high rates. In contrast, the northern type of fluids is strongly enriched in calcium and barium, which points to significant alteration along the flow path. Fluid venting seems to be an important dewatering process as it occurs at a huge number of mound-like structures, which are carbonate-capped in many places and comprise of mixed types of mud extrusion features, along major slope failures caused by subducting seamounts and at fault-controlled slides. Convergence related seamount subduction and subduction-erosion are the primary reasons for slope instability, resulting in large-scale deformation structures. Fluid expulsion related to seamount subduction is largely unconstrained at present. Whereas seeps are rare at the top of the uplifted sediment bulge, massive discharge of methane-rich fluids is documented by lush tubeworm communities and significant methane plumes at the scarp planes. Recent estimates reveal that up to 65 Mg of methane per year may be released at a single structure, which may prove them as important as the mound structures in terms of fluid recycling. In order to improve our current understanding of fluid recycling, to constrain long-term estimates of fluid flow, to systematize the variability of fluid geochemistry, and to fully understand the role of seamounts in the forearc it is proposed to drill several key sites of the most prominent dewatering structures within IODP (proposal 633 full).

Systems and methods for thermal imaging technique for measuring mixing of fluids

DOEpatents

Booten, Charles; Tomerlin, Jeff; Winkler, Jon

2016-06-14

Systems and methods for thermal imaging for measuring mixing of fluids are provided. In one embodiment, a method for measuring mixing of gaseous fluids using thermal imaging comprises: positioning a thermal test medium parallel to a direction gaseous fluid flow from an outlet vent of a momentum source, wherein when the source is operating, the fluid flows across a surface of the medium; obtaining an ambient temperature value from a baseline thermal image of the surface; obtaining at least one operational thermal image of the surface when the fluid is flowing from the outlet vent across the surface, wherein the fluid has a temperature different than the ambient temperature; and calculating at least one temperature-difference fraction associated with at least a first position on the surface based on a difference between temperature measurements obtained from the at least one operational thermal image and the ambient temperature value.

Influence of thermal and velocity slip on the peristaltic flow of Cu-water nanofluid with magnetic field

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher

2016-03-01

The peristaltic flow of an incompressible viscous fluid containing copper nanoparticles in an asymmetric channel is discussed with thermal and velocity slip effects. The copper nanoparticles for the peristaltic flow water as base fluid is not explored so far. The equations for the purposed fluid model are developed first time in literature and simplified using long wavelength and low Reynolds number assumptions. Exact solutions have been calculated for velocity, pressure gradient, the solid volume fraction of the nanoparticles and temperature profile. The influence of various flow parameters on the flow and heat transfer characteristics is obtained.

Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

NASA Astrophysics Data System (ADS)

Krauter, N.; Stefani, F.

2017-10-01

Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.

Advanced Supercritical Carbon Dioxide Brayton Cycle Development

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

Anderson, Mark; Sienicki, James; Moisseytsev, Anton

2015-10-21

Fluids operating in the supercritical state have promising characteristics for future high efficiency power cycles. In order to develop power cycles using supercritical fluids, it is necessary to understand the flow characteristics of fluids under both supercritical and two-phase conditions. In this study, a Computational Fluid Dynamic (CFD) methodology was developed for supercritical fluids flowing through complex geometries. A real fluid property module was implemented to provide properties for different supercritical fluids. However, in each simulation case, there is only one species of fluid. As a result, the fluid property module provides properties for either supercritical CO 2 (S-CO 2)more » or supercritical water (SCW). The Homogeneous Equilibrium Model (HEM) was employed to model the two-phase flow. HEM assumes two phases have same velocity, pressure, and temperature, making it only applicable for the dilute dispersed two-phase flow situation. Three example geometries, including orifices, labyrinth seals, and valves, were used to validate this methodology with experimental data. For the first geometry, S-CO 2 and SCW flowing through orifices were simulated and compared with experimental data. The maximum difference between the mass flow rate predictions and experimental measurements is less than 5%. This is a significant improvement as previous works can only guarantee 10% error. In this research, several efforts were made to help this improvement. First, an accurate real fluid module was used to provide properties. Second, the upstream condition was determined by pressure and density, which determines supercritical states more precise than using pressure and temperature. For the second geometry, the flow through labyrinth seals was studied. After a successful validation, parametric studies were performed to study geometric effects on the leakage rate. Based on these parametric studies, an optimum design strategy for the see-through labyrinth seals was proposed. A stepped labyrinth seal, which mimics the behavior of the labyrinth seal used in the Sandia National Laboratory (SNL) S-CO 2 Brayton cycle, was also tested in the experiment along with simulations performed. The rest of this study demonstrates the difference of valves' behavior under supercritical fluid and normal fluid conditions. A small-scale valve was tested in the experiment facility using S-CO 2. Different percentages of opening valves were tested, and the measured mass flow rate agreed with simulation predictions. Two transients from a real S-CO 2 Brayton cycle design provided the data for valve selection. The selected valve was studied using numerical simulation, as experimental data is not available.« less

Using hydrogeologic data to evaluate geothermal potential in the eastern Great Basin

USGS Publications Warehouse

Masbruch, Melissa D.; Heilweil, Victor M.; Brooks, Lynette E.

2012-01-01

In support of a larger study to evaluate geothermal resource development of high-permeability stratigraphic units in sedimentary basins, this paper integrates groundwater and thermal data to evaluate heat and fluid flow within the eastern Great Basin. Previously published information from a hydrogeologic framework, a potentiometric-surface map, and groundwater budgets was compared to a surficial heat-flow map. Comparisons between regional groundwater flow patterns and surficial heat flow indicate a strong spatial relation between regional groundwater movement and surficial heat distribution. Combining aquifer geometry and heat-flow maps, a selected group of subareas within the eastern Great Basin are identified that have high surficial heat flow and are underlain by a sequence of thick basin-fill deposits and permeable carbonate aquifers. These regions may have potential for future geothermal resources development.

The Life and Legacy of G. I. Taylor

NASA Astrophysics Data System (ADS)

Batchelor, G. K.

1996-07-01

G.I. Taylor, one of the most distinguished physical scientists of this century, used his deep insight and originality to increase our understanding of phenomena such as the turbulent flow of fluids. His interest in the science of fluid flow was not confined to theory; he was one of the early pioneers of aeronautics, and designed a new type of anchor that was inspired by his passion for sailing. Taylor spent most of his working life in the Cavendish Laboratory in Cambridge, where he investigated the mechanics of fluid and solid materials; his discoveries and ideas have had application throughout mechanical, civil, and chemical engineering, meteorology, oceanography and materials science. He was also a noted research leader, and his group in Cambridge became one of the most productive centers for the study of fluid mechanics. How was Taylor able to be innovative in so many different ways? This interesting and unusual biography helps answer that question. Professor Batchelor, himself a student and close collaborator of Taylor, is ideally placed to describe Taylor's life, achievements and background. He does so without introducing any mathematical details, making this book enjoyable reading for a wide range of people--and especially those whose own interests have brought them into contact with the legacy of Taylor.

Viscosity and non-Newtonian features of thickened fluids used for dysphagia therapy.

PubMed

O'Leary, Mark; Hanson, Ben; Smith, Christina

2010-08-01

Thickening agents based primarily on granulated maize starch are widely used in the care of patients with swallowing difficulties, increasing viscosity of consumed fluids. This slows bolus flow during swallowing, allowing airway protection to be more properly engaged. Thickened fluids have been shown to exhibit time-varying behavior and are non-Newtonian, complicating assessment of fluid thickness, potentially compromising efficacy of therapy. This work aimed to quantify the flow properties of fluids produced with commercial thickeners at shear rates representative of slow tipping in a beaker to fast swallowing. Results were presented as indices calculated using a power-law model representing apparent viscosity (consistency index) and non-Newtonian nature of flow (flow behavior index). Immediately following mixing, 3 fluid thicknesses showed distinct consistency indices and decreasing flow behavior index with increasing thickener concentration. An increase in consistency index over 30 min was observed, but only for samples that were repeatedly sheared during acquisition. Three-hour measurements showed changes in consistency index across fluids with the largest being a 25% rise from initial value. This may have implications for efficacy of treatment, as fluids are not always consumed immediately upon mixing. Flow behavior indices were comparable across thickeners exhibiting similar rises over time. The indices were a more complete method of quantifying flow properties compared with single viscosity measurements, allowing an increased depth of analysis. The non-Newtonian nature of fluids perhaps renders them particularly suitable for use as dysphagia therapies, and such analysis may allow the possibility of altering these properties to optimize therapeutic efficacy to be explored. Practical Application: Effective treatment of swallowing disorders relies upon the appropriate choice and subsequent reproduction of drinks thickened to one of a number of predetermined levels. Currently there are no agreed methods of measuring the thickness of these drinks in use and the specifications are subjective, relying on descriptions such as "syrup" thick. This research aims to further understanding of the flow properties of thickened drinks and bring a quantified measure of thickness closer to being a practical reality.

Flow of variably fluidized granular masses across three-dimensional terrain I. Coulomb mixture theory

USGS Publications Warehouse

Iverson, R.M.; Denlinger, R.P.

2001-01-01

Rock avalanches, debris flows, and related phenomena consist of grain-fluid mixtures that move across three-dimensional terrain. In all these phenomena the same basic forces, govern motion, but differing mixture compositions, initial conditions, and boundary conditions yield varied dynamics and deposits. To predict motion of diverse grain-fluid masses from initiation to deposition, we develop a depth-averaged, threedimensional mathematical model that accounts explicitly for solid- and fluid-phase forces and interactions. Model input consists of initial conditions, path topography, basal and internal friction angles of solid grains, viscosity of pore fluid, mixture density, and a mixture diffusivity that controls pore pressure dissipation. Because these properties are constrained by independent measurements, the model requires little or no calibration and yields readily testable predictions. In the limit of vanishing Coulomb friction due to persistent high fluid pressure the model equations describe motion of viscous floods, and in the limit of vanishing fluid stress they describe one-phase granular avalanches. Analysis of intermediate phenomena such as debris flows and pyroclastic flows requires use of the full mixture equations, which can simulate interaction of high-friction surge fronts with more-fluid debris that follows. Special numerical methods (described in the companion paper) are necessary to solve the full equations, but exact analytical solutions of simplified equations provide critical insight. An analytical solution for translational motion of a Coulomb mixture accelerating from rest and descending a uniform slope demonstrates that steady flow can occur only asymptotically. A solution for the asymptotic limit of steady flow in a rectangular channel explains why shear may be concentrated in narrow marginal bands that border a plug of translating debris. Solutions for static equilibrium of source areas describe conditions of incipient slope instability, and other static solutions show that nonuniform distributions of pore fluid pressure produce bluntly tapered vertical profiles at the margins of deposits. Simplified equations and solutions may apply in additional situations identified by a scaling analysis. Assessment of dimensionless scaling parameters also reveals that miniature laboratory experiments poorly simulate the dynamics of full-scale flows in which fluid effects are significant. Therefore large geophysical flows can exhibit dynamics not evident at laboratory scales.