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Topic: Shear flow

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392

Jul 8, 2009
07/09

by
Powell, Gregory Merlin, 1949-

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Topics: Shear flow, Fluid dynamics

http://uf.catalog.fcla.edu/uf.jsp?st=UF030262946&ix=pm&I=0&V=D&pm=1

Topics: Shear flow, Fluid dynamics, Hydrodynamics.

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204

Jun 21, 2010
06/10

by
Horton, J. C.; King, H. M

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Fabrication of sintered impurity semiconductor brushes for electrical energy transfer

Topics: FLUID AMPLIFIERS, HYDRAULIC CONTROL, SHEAR FLOW, VORTICES

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Topics: Irreversible processes, Statistical mechanics, Hydrodynamics, Shear flow

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4.0

Jul 15, 2022
07/22

by
Burton, Ralph A

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x, 217 p. : 24 cm

Topics: Bearings (Machinery), Lubrication and lubricants, Heat -- Transmission, Shear flow

The ability to control a viscoelastic field is an essential concept that defines some important restrictions and potentials of the influenced material. This thesis investigates the controllability of three popular constitutive models under homogeneous extensional and shear flows via the Lie bracket method. The constitutive models are as follows: the Phan-Thien-Tanner model; the Johnson-Segalman model; and the Doi model. The effect of extensional flow on these models and the effect of shear flow...

Topics: Nonlinear systems, Control theory, Viscoelasticity, Linear systems, Shear flow, Non-Newtonian fluids

In this research, new Technique was developed to perform three different operations in the same stroke, namely conventional spinning, shear spinning (wall thickness reduction) and burnishing processes. Experimental work was conducted and confirmed the success of the presented technique. The response of the product quality and required load to process parameters such as rotational speed (46,76,150 and 230 rpm), axial feed (0.15,0.3,0.6 and 1.21 mm/rev), burnishing load (20, 25 and 30 KN),...

Topics: Combined Processes, Conventional Spinning, Shear Flow Forming, Ball Burnishing, Hardness &...

Based on the cutting experiments of a hydrogenated cylindrical shell material 2.25Cr-1Mo-0.25V steel, this paper analyses the dynamic mechanical properties of extremely heavy-duty cutting, studies the influence of dynamic mechanical properties on cutting tool failure during extremely heavy-duty cutting, and builds a dynamic shear mechanical model for the cutting zone. The results of those experiments show that the flow stress of dynamic shear in the zone has a greater influence on the fatigue...

Topics: Extremely Heavy-duty Cutting, Shear Flow Stress, Dynamic Cutting Force, Fatigue Rupture, Dynamic...

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283

Jun 21, 2010
06/10

by
Dugan, J. V., Jr

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Computation of cross sections for electron and heavy particle collisions and their plasma chemistry

Topics: DIELECTRIC PROPERTIES, ELLIPSOIDS, PARTICLE MOTION, SHEAR FLOW, PROBABILITY DISTRIBUTION FUNCTIONS,...

It is well-known that an incompressible sheared flow with an inflection point in the velocity profile will result in the formation of turbulent vortices. In the case of compressible plasma flow with velocity shear ion acoustic fluctuations in addition to vortices will be generated. We present a detailed analysis of the excitation of such low frequency oscillations in a compressible plasma flow with velocity shear. To examine the process of excitation and nonlinear saturation of low frequency...

Topics: DTIC Archive, NEVADA UNIV RENO DEPT OF PHYSICS, *TURBULENCE, *SHEAR FLOW, *ELECTROMAGNETIC...

We present a new method for stability and modal analysis of shear flows and their acoustic radiation. The Euler equations are modified and solved as a spatial initial value problem in which initial perturbations are specified at the ow inlet and propagated downstream by integration of the equations. The modified equations, which we call one-way Euler equations, differ from the usual Euler equations in that they do not support upstream acoustic waves. It is necessary to remove these modes from...

Topics: DTIC Archive, CALIFORNIA INST OF TECH PASADENA, *EULER EQUATIONS, MACH NUMBER, SHEAR FLOW,...

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xxi, 424 pages : 24 cm

Topics: Unsteady flow (Aerodynamics) -- Congresses, Turbulence -- Congresses, Shear flow -- Congresses,...

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138

Jun 2, 2011
06/11

by
Singh, Hanwant B.; Eilers, Jame

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The enormous growth in aviation has given rise to concerns that emissions from aircraft may be modifying the atmosphere in important ways. SONEX (Subsonic Assessment Ozone Nitrogen Oxide Experiment), a NASA-sponsored DC-8 aircraft mission, was conducted in October-November 1997 in the vicinity of the North Atlantic flight corridor to study the effect of aircraft emissions on the nitrogen oxide families (NOx), and ozone (O3). SONEX was managed by Ames Research Center. The major SONEX science...

Topics: K-EPSILON TURBULENCE MODEL, K-OMEGA TURBULENCE MODEL, AERODYNAMICS, SHEAR FLOW, BOUNDARY LAYER...

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201

May 21, 2011
05/11

by
Chatterjee, Siddhartha; Gilbert, John R.; Schreiber, Rober

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Implementing a data-parallel language such as Fortran 90 on a distributed-memory parallel computer requires distributing aggregate data objects (such as arrays) among the memory modules attached to the processors. The mapping of objects to the machine determines the amount of residual communication needed to bring operands of parallel operations into alignment with each other. We present a program representation called the alignment distribution graph that makes these communication requirements...

Topics: FLOW STABILITY, FLUID DYNAMICS, INCOMPRESSIBLE FLOW, INCOMPRESSIBLE FLUIDS, SHEAR FLOW, TURBULENT...

LONG TERM GOALS: To study the dynamic processes of tropical cyclone (TC) development in the western North Pacific through field observational data and theoretical modeling. The objectives are: (1) to study the convection and vorticity generations in the vortex environment that may lead to the development and intensification of TC; (2) to study the development and evolution of deep moist mesoscale convective system subject to strain effect due to the horizontal shear associated with the vortex...

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF METEOROLOGY, *CYCLOGENESIS, CONVECTION,...

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379

Jun 11, 2011
06/11

by
Golombek, M. P

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The Spirit rover landed successfully in a low albedo portion of Gusev crater at 14.5692 deg S, 175.4729 deg E on January 3, 2004 and has traversed about 3.5 km over 180 sols through cratered plains to Bonneville crater and the Columbia Hills. Gusev, a 160 km diameter Noachian crater that lies at the terminus of the 900 km long Ma'adim Vallis, was selected as a landing site to search for evidence of previous liquid water flow and/or ponding. Although no clear evidence of fluvial or lacustrine...

Topics: AEROACOUSTICS, CONFERENCES, NUMERICAL ANALYSIS, SOUND WAVES, BOUNDARY CONDITIONS, AIRCRAFT NOISE,...

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183

May 28, 2011
05/11

by
Goodman, Jindr

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Minor constituents play an important role in atmospheric chemistry and serve as tracers in transport and mixing studies in tropospheric-stratospheric exchange processes. Measurements of trace gases are essential to an understanding of the mechanisms by which minor constituents originating in the troposphere, both naturally occurring and anthropogenic, reach the stratosphere. Many of these gases are sources of species directly involved in the chemistry of ozone depletion in the stratosphere and...

Topics: SOUND PROPAGATION, LININGS, DUCTS, AXISYMMETRIC FLOW, EMISSION, COMPUTATION, TURBULENT FLOW,...

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198

Sep 20, 2010
09/10

by
Bennett, Gary L

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The topics covered are presented in viewgraph form and include the following: Office of Aeronautics and Space Technology; space research and technology (R&T); space R&T mission statement; Space R&T program development; R&T strategy; Office of Space Science and Applications (OSSA) technology needs; transportation technology; and space platforms technology.

Topics: COST REDUCTION, FLOW MEASUREMENT, FREQUENCY RESPONSE, HOT-FILM ANEMOMETERS, COMPRESSIBLE BOUNDARY...

In the present work, an investigation has been made about the shape change and movement phenomena of liquid droplet over a horizontal solid surface under shear flow with adiabatic boundary condition. Finite Volume Method (FVM) with 3D Volume of Fluid (VOF) model has been used to formulate/simulate the complex interface in multiphase flow. The effect of important factors which govern the drop dynamics on a solid surface (like fluid properties: density, surface tension, viscosity and the surface...

Topics: Multiphase flow, Droplet, Interface, Volume of Fluid (VOF), Finite Volume Method (FVM), Contact...

An account is given herein of an investigation conducted to determine the feasibility of artificially thickening a turbulent boundary layer on a flat plate. A description is given of several methods used to thicken artificially the boundary layer. It is shown that it is possible to do substantial thickening and obtain a fully developed turbulent boundary layer, which is free from any distortions introduced by the thickening process, and, as such, is a suitable medium for fundamental research....

Topics: DTIC Archive, Klebanoff, P S, NATIONAL BUREAU OF STANDARDS GAITHERSBURG MD, *TURBULENT BOUNDARY...

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269

Jul 9, 2010
07/10

by
Chen, C.; Fan, M

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The performance of command and telemetry systems, useful in deep-space communications, is frequently affected by the radio-frequency phase error which is introduced at the point of reception by means of the carrier tracking loop. In low data rate communications, this phase error may vary rapidly over the duration of the signaling interval. In this paper such phase variation is characterized by a sinusoidal input phase, K sin (omega sub o t, pi/6), which models a typical phase variation in...

Topics: AIR FLOW, BOUNDARY LAYER SEPARATION, FLOW CHARACTERISTICS, FLOW EQUATIONS, VISCOUS FLOW,...

Four boundary value problems in unsteady simple shear flow are considered. Solutions for the second-order fluid approximation are listed, including a solution which seems to be new. For the third-order fluid approximation solutions are obtained for the linearized versions of the various problems. The Second Law of Thermodynamics, reduced to the requirement that the rate of deformation work be non-negative, is applied to these solutions. The signs of the pertinent second-order material constant...

Topics: DTIC Archive, Leigh, D C, PRINCETON UNIV NJ, *THERMODYNAMICS, *BOUNDARY VALUE PROBLEMS, UNSTEADY...

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266

Sep 20, 2010
09/10

by
Payne, Barr

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The opportunities for improved training and checking by using helicopter simulators are greater than they are for airplane pilot training. Simulators permit the safe creation of training environments that are conducive to the development of pilot decision-making, situational awareness, and cockpit management. This paper defines specific attributes required in a simulator to meet a typical helicopter operator's training and checking objectives.

Topics: AIR FLOW, JET AIRCRAFT NOISE, MIXING LAYERS (FLUIDS), NOISE REDUCTION, S WAVES, SOUND WAVES, FLOW...

Research under this grant, an extension of Grant number N00014-98-1-08l3 that supported the completion of the Ph.D. thesis of Christopher L. Wolfe, focused primarily on computations of unstable nonlinear periodic solutions, time-dependent normal modes (Floquet vectors) and singular vectors in a two-layer quasi-geostrophic channel model. The model was studied in a strongly nonlinear regime, in which small disturbances to an unstable, steady, zonal, baroclinic shear flow grow to finite amplitude...

Topics: DTIC Archive, Samelson, Roger M, OREGON STATE UNIV CORVALLIS, *COMPUTATIONS, *TIME DEPENDENCE,...

Our goal is to elucidate the fluid dynamical processes associated with stratified flow over topography including the establishment of such flows, effects due to strong forcing and the generation of internal solitary waves.

Topics: DTIC Archive, SCRIPPS INSTITUTION OF OCEANOGRAPHY LA JOLLA CA, *FLUID DYNAMICS, *INTERNAL WAVES,...

The flow field of a vortex in a viscous shear flow is found by constructing a uniformly valid asymptotic expansion consisting of an inner solution field represented, to lowest order, by a two dimensional, nonliner, inviscid Stuart vortex and an outer solution field represented, to lowest order, by either a two dimensional parallel or self similar viscous flow. The technique involves scaling both the transverse and streamwise coordinates in the vicinity of the vortex as well as allowing for a...

Topics: NASA Technical Reports Server (NTRS), SHEAR FLOW, VISCOUS FLOW, VORTICES, ASYMPTOTIC METHODS,...

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551

Jul 23, 2010
07/10

by
Schach, W

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The deflection of a flat water jet on a flat plate perpendicular and oblique to the flow direction can be determined with the Prandtl hodograph method. The outer jet shape of the circular water jet for perpendicular impact on a flat plate was measured in tests by Reich and was represented by an empirical equation. The problem can also be discussed mathematically, if the flow to be axisymmetric potential flow is to be considered. For this purpose, the same method which Trefftz established for...

Topics: HOMOGENEOUS TURBULENCE, ISOTROPIC TURBULENCE, LAGRANGE SIMILARITY HYPOTHESIS, NUMERICAL ANALYSIS,...

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361

Jun 1, 2011
06/11

by
Brown, W. Byron; Monroe, William R

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A theoretical analysis of the temperature distribution through the trailing portion of a blade near the coolant passages of liquid cooled gas turbines was made. The analysis was applied to obtain the hot spot temperatures at the trailing edge and influence of design variables. The effective gas temperature was varied from 2000 degrees to 5000 degrees F in each investigation.

Topics: NAVIER-STOKES EQUATION, VISCOUS FLUIDS, FRICTION, STRESS ANALYSIS, SHEAR FLOW, ONE DIMENSIONAL...

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245

May 31, 2011
05/11

by
Reid, Mark J

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Our program, funded by a NASA/SARA 3-yr grant, is designed to measure distances directly with accuracies of 5% to three anchor points in the Local Universe. We are attacking this problem on three fronts, using Very Long Baseline Interferometry (VLBI) observations of NGC 4258, M 33, and Sgr A. We plan to provide distance estimates, with a minimum of systematic uncertainty, that can be used to re-calibrate several 'standard candles,' such as Cepheid and RR Lyrae variables. This will place the...

Topics: STRATIFIED FLOW, TURBULENT FLOW, SHEAR FLOW, INTERNAL WAVES, GRAVITY WAVES, PHASE SHIFT, DENSITY...

The low-frequency free-stream disturbances penetrate boundary layer despite the sheltering ability of the mean shear. These disturbances form streaks via the lift-up mechanism. The streaks subsequently become unstable and breakdown to turbulence. The stability of laminar boundary layers is examined in presence of a thin wall-film, of different viscosity. The influence of the film on the evolution of free-stream vortical modes and the generation of boundary layer streaks is solved analytically....

Topics: DTIC Archive, IMPERIAL COLL LONDON (UNITED KINGDOM), *BOUNDARY LAYER TRANSITION, *VISCOSITY,...

A Galilean invariant weak-equilbrium hypothesis that is sensitive to streamline curvature is proposed. The hypothesis leads to an algebraic Reynolds stress model for curved flows that is fully explicit and self-consistent. The model is tested in curved homogeneous shear flow: the agreement is excellent with Reynolds stress closure model and adequate with available experimental data.

Topics: NASA Technical Reports Server (NTRS), TURBULENCE MODELS, MATHEMATICAL MODELS, REYNOLDS STRESS,...

The Eulerian mapping closure approach is developed for uncertainty propagation in computational fluid mechanics. The approach is used to study the Probability Density Function (PDF) for the concentration of species advected by a random shear flow. An analytical argument shows that fluctuation of the concentration field at one point in space is non-Gaussian and exhibits stretched exponential form. An Eulerian mapping approach provides an appropriate approximation to both convection and diffusion...

Topics: NASA Technical Reports Server (NTRS), PROBABILITY THEORY, DENSITY, COMPUTATIONAL FLUID DYNAMICS,...

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Jul 6, 2010
07/10

by
Ceresuela, R

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Problems in the aerodynamics of sustained hypersonic flight including maximal lift/drag ratios and longitudinal and lateral stabilities related to large volume engines are discussed. The compatibility of internal and external flows is examined for highly deformed intakes and exhausts.

Topics: ATMOSPHERIC MODELS, CLEAR AIR TURBULENCE, FLOW STABILITY, COMPUTER PROGRAMS, FLUID MECHANICS, LEE...

The goal of this project is to develop a fundamental understanding of how fluid flows, electric fields, and surface patterning affect polyelectrolyte adsorption, self-assembly, and transport near solid surfaces. Polyelectrolytes are charged polymers whose behavior is central to Army-relevant technologies (e.g., biochemical sensors, surface functionalization) but poorly understood. Brownian dynamics simulations---a coarse-grained simulation method suitable for describing non-equilibrium polymer...

Topics: DTIC Archive, MINNESOTA UNIV MINNEAPOLIS, *BROWNIAN MOTION, *ADSORPTION, *ELECTROPHORESIS,...

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473

Jul 11, 2010
07/10

by
Rosenlieb, J. W

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An analysis and system study was performed to provide design information regarding lubricant and coolant flow rates and flow paths for effective utilization of the lubricant and coolant in a once-through oil-mist (microfog) and coolant air system. A system was designed, manufactured, coupled with an existing rig and evaluation tests were performed using 46 mm bore split-inner angular-contact ball bearings under 1779N (400 lb.) thrust load. An emergency lubrication aspirator system was also...

Topics: ATMOSPHERIC ENTRY SIMULATION, MONTE CARLO METHOD, TURBULENT BOUNDARY LAYER, WALL PRESSURE, DRAG...

The long term goal of this work is to understand the physics of turbulent stratified shear flows as might be found in coastal regions and estuaries where both shear and stratification are strong. Because these regions are characterized by strong gradients in water characteristics (temperature, salinity and turbidity), the dynamics are influenced by the interaction of tidally-driven flows with the local density field both vertical and horizontal gradients. We anticipate that such an...

Topics: DTIC Archive, CALIFORNIA UNIV BERKELEY DEPT OF CIVIL AND ENVIRONMENTAL ENGINEERING, *DISSIPATION,...

This memorandum records the proceedings of a four-part seminar series on turbulence and its control sponsored by the Naval Undersea Warfare Center Division, Newport, Rl, during the summer of 1992. The Naval Undersea Warfare Center Division, Newport, RI, organized a four-part seminar series titled Turbulence and Its Control during the summer of 1992 . One seminar was held in June, one in July, and two in August. These seminars were an activity of NUWC's Hydrodynamics Sphere of Excellence, which...

Topics: DTIC Archive, NAVAL UNDERSEA WARFARE CENTER DIV NEWPORT RI, *SHEAR FLOW, *TURBULENT BOUNDARY LAYER,...

We provide a comprehensive study on the planar (2D) orientational distributions of nematic polymers under an imposed shear flow of arbitrary strength. We extend previous analysis for persistence of equilibria in steady shear and for transitions to unsteady limit cycles, from closure models [21] to the Doi-Hess 2D kinetic equation. A variation on the Boltzmann distribution analysis of Constantin et al. [3, 4, 5] and others [8, 22, 23] for potential flow is developed to solve for all persistent...

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA, *LIQUID CRYSTALS, *SHEAR FLOW, *POLYMERS,...

Capillary rheometry is effectively used with thermosets. Most important is providing a uniform temperature in the barrel. This was successfully accomplished by using a circulating hot oil system. Standard capillary rheometry methods provide the dependence of thermoset apparent viscosity on shear rate, temperature and time. Such information is very useful in evaluating resin processability and in setting preliminary fabrication conditions.

Topics: NASA Technical Reports Server (NTRS), SHEAR FLOW, THERMOSETTING RESINS, VISCOSITY, CAPILLARY FLOW,...

The classical theories for turbulent shear flow are the momentum transfer theory of Prandtl, the vorticity transfer theory of Taylor, and the similarity theory of Von Karman. The two transfer theories both involve a mixture length, which must be given by an additional assumption. On the other hand, the similarity theory is a more determinate scheme, because it makes a more definite hypothesis about the nature of the turbulent fluctuations. Goldstein, however, introduced an alternative form of...

Topics: DTIC Archive, Lin, C C, MASSACHUSETTS INST OF TECH CAMBRIDGE, *TURBULENT FLOW, *COMPRESSIBLE FLOW,...

The propagation of spinning mode sound was considered for a cylindrical duct with sheared steady flow. Calculations concentrated on the determination of the wall optimum acoustic impedance and the maximum possible attenuation. Both the least attenuated and higher radial modes for spinning lobe patterns were considered. A parametric study was conducted over a wide range of Mach numbers, spinning lobe numbers, sound frequency, and boundary layer thickness. A correlation equation was developed...

Topics: NASA Technical Reports Server (NTRS), ACOUSTIC PROPAGATION, CYLINDRICAL BODIES, DUCTS, SHEAR FLOW,...

Partial contents: Vortex generation by suction in a rotating tank; Viscous splitting of the Navier-Stokes equation with boundaries; A Particle in Cell Method for the compressible Euler equation; A hybrid vortex method with deterministic diffusion; 3D vortex dynamic in a free shear flows; Dynamics of vortex tubes in 3D turbulence.

Topics: DTIC Archive, GRENOBLE UNIV (FRANCE), *VORTICES, *NUMERICAL METHODS AND PROCEDURES, TURBULENCE,...

The effects of varying freestream core turbulence on the evolution of a circular jet with and without tonal excitation are examined. Measurements are made on an 8.8 cm diameter jet at a Mach number of 0.3. The jet is excitated by plane waves at Strouhal number 0.5. For the excited and unexcited cases the turbulence level is varied by screens and grids placed upstream of the nozzle exit. The experiment results are compared with a theoretical model which incorporates a variable core turbulence...

Topics: NASA Technical Reports Server (NTRS), CORE FLOW, EXCITATION, JET FLOW, TURBULENCE, SHEAR FLOW,...

This report describes a data analysis effort to understand high-altitude turbulence measurements made on an EGRETT aircraft flown in Southern Australia.

Topics: DTIC Archive, Wroblewski, Donald, DEW CONSULTING WELLESELY MA, *HIGH ALTITUDE, *CLEAR AIR...

Endovascular embolisation technique using a tubular shaped stent is currently used to treat the aneurysm with a wide neck. In order to clarify the hemodynamic changes caused by a stent, the flow fields inside the fusiform aneurysm models were measured using a flow visualization technique incorporating photochomic dye. The flow fields in the non-stented model and those in the stented models with different porosities were compared. A strong inflow motion from the distal neck of aneurysm and a...

Topics: DTIC Archive, Rhee, K, MYONGII UNIV YONGIN (KOREA), *FLOW VISUALIZATION, *CARDIOVASCULAR DISEASES,...

To study the dynamic processes of tropical cyclone (TC) development in the western North Pacific through field observational data and theoretical modeling.

Topics: DTIC Archive, NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF METEOROLOGY, *TROPICAL CYCLONES,...

The major points are described of a turbulent transport model of the classical, gradient transport, eddy viscosity type. The relationship is discussed of the developed model to the Prandtl (jet mixing) model, the Schlichting (wake) model, and the Clauser (boundary layer) model. Limitations of the model and test cases are summarized.

Topics: NASA Technical Reports Server (NTRS), MATHEMATICAL MODELS, TURBULENT MIXING, EDDY VISCOSITY, FREE...

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226

Jul 12, 2010
07/10

by
Keyser, G. L., Jr

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Both the advent of electronic displays for cockpit applications and the availability of high-capacity data transmission systems, linking aicraft with ATC ground computers, offer the opportunity of expanding the pilots' role in the distributive management process. A critical element in this process is believed to be the presentation to the pilot of his traffic situation. A representative cockpit display of traffic information (CDTI) system is presented as viewed from the pilot in the cockpit,...

Topics: DENSITY DISTRIBUTION, PRESSURE GRADIENTS, FLOW VISUALIZATION, SHEAR FLOW, SMALL PERTURBATION FLOW,...

Leslie's perturbative treatment of the direct interaction approximation for shear turbulence (Modern Developments in the Theory of Turbulence, 1972) is applied to derive a time dependent model for the Reynolds stresses. The stresses are decomposed into tensor components which satisfy coupled linear relaxation equations; the present theory therefore differs from phenomenological Reynolds stress closures in which the time derivatives of the stresses are expressed in terms of the stresses...

Topics: NASA Technical Reports Server (NTRS), RELAXATION (MECHANICS), REYNOLDS STRESS, SHEAR FLOW,...