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Thursday, December 3, 2020 | History

3 edition of Molecular study of turbulence in three dimensional cavity flow found in the catalog.

Molecular study of turbulence in three dimensional cavity flow

Donald Greenspan

Molecular study of turbulence in three dimensional cavity flow

  • 65 Want to read
  • 39 Currently reading

Published by Dept. of Mathematics, University of Texas at Arlington in Arlington .
Written in English

    Subjects:
  • Molecular emission cavity analysis,
  • Turbulence -- Mathematical models,
  • Molecular dynamics -- Mathematical models

  • Edition Notes

    StatementDonald Greenspan.
    SeriesTR -- #339., Technical report (University of Texas at Arlington. Dept. of Mathematics) -- no. 339.
    ContributionsUniversity of Texas at Arlington. Dept. of Mathematics.
    The Physical Object
    Pagination[24] leaves :
    Number of Pages24
    ID Numbers
    Open LibraryOL17596433M
    OCLC/WorldCa45179003

      The flow in the left cavity remains largely laminar in the anterior region, although there is evidence of transitional flow on the right side, especially around the breakdown of the nasal-valve jet (where the sagittal plane crosses plane 3). Flow in the cross-sectional planes 3 and 4 in the nose and at planes 9 and 10 in the descending airway. Molecular-based optical measurement techniques for transition the paths leading to the onset of fully turbulent flow must be well understood. This requires that including the presence of discrete two-dimensional and three-dimensional roughness elements, . The transition to unsteadiness and the dynamics of weakly turbulent natural convection, coupled to wall or gas radiation in a differentially heated cubical cavity with adiabatic lateral walls, are studied numerically. The working fluid is air with small contents of water vapor and carbon dioxide whose infrared spectral radiative properties are modelled by the absorption distribution function. the flow field and rotordynamic forces in a whirling, grooved liquid annular seal. To validate the capabilities of the CFD code for this class of problems, comparisons of basic fluid dynamic parameters are made to three-dimensional laser Doppler anemometer (LDA) measurements for a spinning, centered grooved seal. Predictions.

    Asako and M. Faghri, “Developing Laminar Flow and Heat Transfer in the Entrance Region of Regular Polygonal Ducts,” Int. J, Heat Mass Transfer, 31 (12), pp. , M. Faghri and Y. Asako, “Three-Dimensional Laminar Natural Convection in Horizontal Hexagonal Honeycomb Enclosure,” Numerical Heat Transfer, 15, pp. ,


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Molecular study of turbulence in three dimensional cavity flow by Donald Greenspan Download PDF EPUB FB2

Three-dimensional molecular cavity problems are formulated and solved numerically. The fluid considered is water at 15°C. The turbulent flows generated are characterized by strong cross-currents over the usual primary vortex : Donald Greenspan.

Three-dimensional molecular cavity problems are formulated and solved numerically. The fluid considered is water at 15°C. The turbulent flows generated are characterized by strong cross-currents Author: Donald Greenspan. V=, J=, T = Figure V =J =T = 7. TURBULENT FLOW Recall now that, usually, turbulent flows have two well-defined criteria.

(1) A strong current develops across the usual primary vortex direction [7]. (2) Many small vortices appear and disappear quickly [8]. Molecular Turbulence Figure Author: D. Greenspan. 16 hours ago  The aim of this paper is to investigate the influence of different turbulence models (k−ε, RNG k−ε, and SST k−ω) Molecular study of turbulence in three dimensional cavity flow book the numerical simulation of cavitating flow in thermosensitive fluid.

The filter-based model and density correction method were employed to correct the turbulent viscosity of the three turbulence models. A study of molecular turbulence throughthe cavity problem for air Article in Mathematical and Computer Modelling 40() August with 7 Reads How we measure 'reads'Author: Donald Greenspan.

Three-dimensional molecular cavity problems are formulated and solved numerically. The fluid considered is water at 15°C. The turbulent flows generated are characterized by strong cross-currents. Previous three-dimensional simulations of the lid-driven cavity flow have reproduced only the most general features of the flow.

Improvements to a finite difference code, REBUFFS, have made. Fig. 11 shows a direct, two-dimensional simulation of the flow in the YZ plane for wallsp J=25 and Δt= at T= The initial data are those for the molecules in the YZ plane in the three-dimensional example described above.

The flow is analyzed using the very same parameters as those used to display Molecular study of turbulence in three dimensional cavity flow book. ison of the results in Fig. 5 and those in Fig. To the authors' knowledge this is the first thorough study dealing with an inclined cavity containing a turbulent natural convection flow.

Results for the flow struc- tures and temperature distribution have been dis- cussed for all interesting angles of inclination of the cavity. Experimental study of supersonic flow over cavity with aft wall offset and cavity floor injection. Control of Three-Dimensional Cavity Flow Using Leading-Edge Slot Blowing.

turbulent cavity flows. Progress in Aerospace Sciences, Vol. 47, No. We demonstrate how the self-sustained oscillation of a confined jet in a thin cavity can be quantitatively described by a zero-dimensional model of the delay differential equation type with two a priori predicted model constants.

This model describes the three phases in self-sustained oscillations: (i) pressure driven growth of the oscillation, (ii) amplitude limitation by geometry, and (iii. A Three-Dimensional Hybrid LES-Acoustic Analogy Method for Predicting Open-Cavity Noise 28 February | Flow, Turbulence and Combustion, Vol.

79, No. 1 Spectral Multi-Domain Methods for BiGlobal Instability Analysis of Complex Flows over Open Cavity Configurations.

Turbulence has also been inferred from direct measurements of power spectra in molecular clouds across a wide range of scales (Heyer & Brunt ). While turbulence can provide an isotropic pressure to support the cloud against self-gravity, both hydrodynamic and MHD turbulence decay quickly (Stone et al.

; Mac Low ). Thus if clouds are. DeepDyve is the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Yeh, L. Ukeiley, L. Cattafesta, and K.

Taira, "Unsteady Control of Supersonic Turbulent Cavity Flow Based on Resolvent Resolution Analysis of Three-Dimensional Turbulent Channel Flow," Japan Society of Mechanical Three-Dimensional Wake Flow," Active Flow Control Conference II, (Springer book chapter.

Within the spiral core zone, a nested zone of spiral flow exists with opposite rotational directions in the inner and outer layers. The flow in a V-shaped stepped spillway is three-dimensional, unlike that in a traditional stepped spillway. Additionally, the k-ϵ turbulence model was used to study the flow structure of a V-shaped stepped spillway.

A schematic illustration of a two dimensional supersonic cavity flow is presented in Fig. 1, where the coordinate origin is located at the cavity leading edge with the horizontal direction of x and the vertical direction of cavity has a length-to-depth ratio (L/D) of 4, and its depth is 5 supersonic incoming flow with Ma> 1 has an initial boundary layer.

In this study, tomographic PIV measurements are deployed to obtain the complex three-dimensional vortical structures generated by the interaction of plasma synthetic jets with a crossflow turbulent boundary layer. This investigation focuses on the unsteadiness and turbulent characteristics of the flow.

At the moderate Reynolds number (Re = ) where the cavity flow is fully laminar, a direct numerical simulation (DNS) is used whereas large-eddy simulation (LES) methodology is adopted to predict the cavity flow at the higher Reynolds number (Re = ).

Large-eddy simulations of a subsonic three-dimensional cavity flow with self-sustaining oscillations are carried out for a Reynolds number based on the length of the cavity equal to 7 × Three dimensional, steady, turbulent flow RANS simulations are carried out to study the near flow field characteristics of a particle laden coaxial water jet.

Spherical glass particles of micron diameter are added to the central jet flow at two mass loading ratios of % and %.

The three-dimensional characteristics of the unsteady wall-pressure in a low-Mach-number rectangular cavity flow with Rossiter model oscillation 2 August | Experiments in Fluids, Vol.

58, No. 9 Numerical investigation of cavity self-oscillation and noise radiation induced by turbulent flow at non-zero inclination angle. As a three-dimensional hydrofoil is used at moderate velocities, the sides of the attached cavity can be locally suppressed as the flow remains laminar, so roughness elements of μ m were applied at the leading edge (4% chord length) as a turbulence tripping mechanism.

The roughness elements can lead to local streaks of cavitation appearing. Three-dimensional compressible–incompressible turbulent flow simulation using a pressure-based algorithm Computers & Fluids, Vol. 37, No. 6 Numerical Investigation of Methane and Air Mixing in a Shcramjet Inlet.

Investigation of Three-Dimensional Unsteady Flows in a Two-Stage Shrouded Axial Turbine Using Stereoscopic PIV—Kinematics of Shroud Cavity Flow J.

Turbomach (January, ) Differential Equation-Based Specification of Turbulence Integral Length Scales for Cavity Flows. The present study performs two-dimensional (2-D) and three-dimensional (3- D) simulations of steady turbulent (K-e) flow in bifurcated nozzles, using a finite-element (FIDAP) model, which has been verified previously with water model experiments.

For the purpose of improving the transport capability of the mixed transport pump, a new self-made three-stage deep-sea multiphase pump was taken as the research object.

Based on the Euler-Euler heterogeneous flow model, liquid (water) and gas (air) are used as the mixed media to study the external characteristics and internal flow identities of the mixed pump under different gas volume. In naval hydrodynamics, many computational studies on cavitation have been carried out using incompressible flow solvers.

Rhee et al. [] studied cavity inception and shape around a marine and Rhee [] simulated the unsteady cavitating flow around a wedge-shaped cavitator and r et al. [] investigated the natural super-cavitating flow around three-dimensional cavitators.

MEB/3/GI 4 Laminar vs. Turbulent Flow Laminar Flow Turbulent Flow The flow is dominated by the object shape and dimension (large scale) and by the motion and evolution of small eddies (small scales) Challenging to compute The flow is dominated by the object shape and dimension (large scale) Easy to compute.

Three-Dimensional Experimental Study of Compressibility Effects on Turbulent Free Shear Layers. 3 February | Flow, Turbulence and Combustion, Vol. 83, No.

Turbulent molecular mixing in fully-developed planar shear flows. Terence Meyer. A numerical simulation of three-dimensional flow around rectangular prisms (two dimensional) of different aspect ratios, ranging from tois conducted at a Reynolds number of 10 5, using large eddy study identifies the influence of aspect ratio on the flow field around prisms and the attendant aerodynamics.

The turbulence closure was provided by two algebraic eddy-viscosity models. The three-dimensional turbulent flow field and the transport of a neutrally-buoyant solute in a compound channel were modelled.

The numerical results were compared with experimental data. In the simulation, they used two values of Sc t: and one. With the latter. The instantaneous turbulent velocity field in a three-dimensional wall jet was estimated from the fluctuating wall pressure using a spectral linear stochastic estimation technique.

The wall jet investigated issued from a long square channel with Reynolds number of 90, The solutions of the three-dimensional steady Navier-Stokes and continuity equations were obtained using the commercial software package FLUENT (Ansys, Inc.).

As described in the Introduction, whether human nasal airflow during restful breathing (flow rate turbulent is. An unsteady numerical investigation on mixed convection in a two dimensional open ended cavity with different aspect ratios is carried out.

In this investigation, uniform temperature is set to the left and the right sides of the cavity while the other surfaces are adiabatic. The simulation is performed for a wide range of Reynolds numbers (Re = –) and Richardson numbers (Ri =   Large-eddy simulations of the flow over a deep cavity are performed.

The computations reproduce identically all the parameters of the experiment by Forestier and co-workers [J. Fluid Mech. (to be published)], including the high Reynolds number Re L =×10 5.

Spectra show an accurate prediction of the peak levels of the fundamental frequency and its first harmonics. In fluid dynamics, turbulence or turbulent flow is fluid motion characterized by chaotic changes in pressure and flow is in contrast to a laminar flow, which occurs when a fluid flows in parallel layers, with no disruption between those layers.

Turbulence is commonly observed in everyday phenomena such as surf, fast flowing rivers, billowing storm clouds, or smoke from a chimney. Abstract: A numerical prediction of the natural convection of air in an enclosed tall differentially heated rectangular cavity of × × m is detailed in this present paper.

Two differential temperatures between the lateral plates are considered, of respectively, C and C, corresponding to low and high Rayleigh numbers, i.e., × 10 6 and × 10 6.

The mean. (3) turbulence modeling While for the first two elements precise mathematical theories exist, the concept of turbulence modeling is far less precise due to the complex nature of turbulent flow.

Turbulence is three-dimensional and time-dependent, and a great deal of information is required to describe all of the mechanics of the flow. A Laser-Doppler Velocimetry Study of the Ensemble-Averaged Characteristics of the Turbulent Wake of a Square Cylinder On the Unsteady and Turbulent Characteristics of Three-Dimensional Shear-Driven Cavity Flow,” Prasad, A.

K., and. Kosef, J. R.,“ Reynolds Number and End-Wall Effects on a Lid-Driven Cavity Flow,” Phys. Turbulent Flow in a Lid-Driven Cavity - Here we consider a square two-dimensional cavity in 2: y with mean flow being two-dimensional also.

The exact geometry and the corresponding spectral element mesh is Fig. 1 Spectral Element Mesh employed for the simulation of £10w in a lid~riven cavity .Two-dimensional PIV was used to observe the turbulent flow along the symmetry plane denoted by the shaded red region in Fig.

2, where the flow is expected to be two dimensional. In multiple tests, the height ratio between the upwind building and downwind building (H u / H d) was varied from 3 to   The four cases under investigation are natural convection in a tall cavity, forced convection in a model room with partitions, mixed convection in a square cavity, and strong buoyancy flow in a model fire room.

The first three cases are benchmark cases that represent the most basic flow features in an enclosed environment.