scholarly journals Study on Three-Dimensional Turbulent Shear Flow Structure over Sand Ridges by Direct Numerical Simulation

2001 ◽  
Vol 4 ◽  
pp. 591-600
Author(s):  
Syunichiro HAYASHI ◽  
Terunori OHMOTO ◽  
Kiyoshi TAKIKAWA
Keyword(s):  
Numerical Simulation ◽  
Shear Flow ◽  
Direct Numerical Simulation ◽  
Flow Structure ◽  
Three Dimensional ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Sand Ridges

scholarly journals The effect of compressibility on turbulent shear flow: a rapid-distortion-theory and direct-numerical-simulation study

1997 ◽  
Vol 330 ◽  
pp. 307-338 ◽  
Author(s):  
A. SIMONE ◽  
G.N. COLEMAN ◽  
C. CAMBON
Keyword(s):  
Numerical Simulation ◽  
Mach Number ◽  
Kinetic Energy ◽  
Shear Flow ◽  
Direct Numerical Simulation ◽  
Pure Shear ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Rapid Distortion Theory ◽  
The Mean

The influence of compressibility upon the structure of homogeneous sheared turbulence is investigated. For the case in which the rate of shear is much larger than the rate of nonlinear interactions of the turbulence, the modification caused by compressibility to the amplification of turbulent kinetic energy by the mean shear is found to be primarily reflected in pressure–strain correlations and related to the anisotropy of the Reynolds stress tensor, rather than in explicit dilatational terms such as the pressure–dilatation correlation or the dilatational dissipation. The central role of a ‘distortion Mach number’ Md =  S[lscr ]/a, where S is the mean strain or shear rate, [lscr ] a lengthscale of energetic structures, and a the sonic speed, is demonstrated. This parameter has appeared in previous rapid-distortion-theory (RDT) and direct-numerical-simulation (DNS) studies; in order to generalize the previous analyses, the quasi-isentropic compressible RDT equations are numerically solved for homogeneous turbulence subjected to spherical (isotropic) compression, one-dimensional (axial) compression and pure shear. For pure-shear flow at finite Mach number, the RDT results display qualitatively different behaviour at large and small non-dimensional times St: when St < 4 the kinetic energy growth rate increases as the distortion Mach number increases; for St > 4 the inverse occurs, which is consistent with the frequently observed tendency for compressibility to stabilize a turbulent shear flow. This ‘crossover’ behaviour, which is not present when the mean distortion is irrotational, is due to the kinematic distortion and the mean-shear-induced linear coupling of the dilatational and solenoidal fields. The relevance of the RDT is illustrated by comparison to the recent DNS results of Sarkar (1995), as well as new DNS data, both of which were obtained by solving the fully nonlinear compressible Navier–Stokes equations. The linear quasi-isentropic RDT and nonlinear non-isentropic DNS solutions are in good general agreement over a wide range of parameters; this agreement gives new insight into the stabilizing and destabilizing effects of compressibility, and reveals the extent to which linear processes are responsible for modifying the structure of compressible turbulence.

The Effect of Compressibility on Turbulent Shear Flow: Direct Numerical Simulation Study

2013 ◽  
Vol 135 (10) ◽  
Author(s):  
Aicha Hanafi ◽  
Hechmi Khlifi ◽  
Taieb Lili
Keyword(s):  
Numerical Simulation ◽  
Shear Flow ◽  
Direct Numerical Simulation ◽  
Reynolds Stress ◽  
Simulation Study ◽  
Structural Evolution ◽  
Second Order ◽  
Turbulent Shear ◽  
Turbulent Shear Flow ◽  
Wide Range

The study of the phenomenon of compressibility for modeling to second order has been made by several authors, and they concluded that models of the pressure-strain are not able to predict the structural evolution of the Reynolds stress. In particular studies and Simone Sarkar et al., a wide range of initial values of the parameters of the problem are covered. The observation of Sarkar was confirmed by the study of Simone et al. (1997,“The Effect of Compressibility on Turbulent Shear Flow: A Rapid Distortion Theory and Direct Numerical Simulation Study,” J. Fluid Mech., 330, p. 307;“Etude Théorique et Simulation Numérique de la Turbulence Compressible en Présence de Cisaillement où de Variation de Volume à Grande Échelle” thése, École Centrale de Lyon, France). We will then use the data provided by the direct simulations of Simone to discuss the implications for modeling to second order. The performance of different variants of the modeling results will be compared with DNS results.

Numerical Simulation of Particulate Motion in Turbulent Gas-Solid Channel Flow

1979 ◽  
Vol 101 (3) ◽  
pp. 319-325 ◽  
Author(s):  
R. L. Peskin ◽  
C. J. Kau
Keyword(s):  
Numerical Simulation ◽  
Shear Flow ◽  
Three Dimensional ◽  
Turbulent Shear ◽  
Large Reynolds Number ◽  
Turbulent Shear Flow ◽  
Time Dependency ◽  
Linear Dependency ◽  
Wall Boundary Conditions ◽  
Schmidt Numbers

A three-dimensional numerical model for turbulent shear flow in a channel with large Reynolds number is employed for the investigation of turbulent diffusion of finite inertia particulates. A stochastic nonlinear equation describing the motion of particles is integrated to obtain Lagrangian information. Special attention is paid to the effects of shear flow and wall boundary conditions. The results of these studies are compared to previous theoretical and empirical results. A cubic time dependency for separation is found at intermediate values of time while linear dependency is observed at large times. Schmidt numbers are always found to be smaller than one in the non-homogeneous region. It was concluded that special attention must be paid to appropriate computation times necessary to obtain a statistical equilibrium.

Direct Numerical Simulation of Drops in Three Dimensional Viscoelastic Simple Shear Flows

2001 ◽  
Author(s):  
Shriram B. Pillapakkam ◽  
Pushpendra Singh
Keyword(s):  
Numerical Simulation ◽  
Shear Flow ◽  
Direct Numerical Simulation ◽  
Viscoelastic Fluid ◽  
Simple Shear ◽  
Polymer Concentration ◽  
Three Dimensional ◽  
Simple Shear Flow ◽  
Splitting Technique

Abstract A three dimensional finite element scheme for Direct Numerical Simulation (DNS) of viscoelastic two phase flows is implemented. The scheme uses the Level Set Method to track the interface and the Marchuk-Yanenko operator splitting technique to decouple the difficulties associated with the governing equations. Using this numerical scheme, the shape of Newtonian drops in a simple shear flow of viscoelastic fluid and vice versa are analyzed as a function of Capillary number, Deborah number and polymer concentration. The viscoelastic fluid is modeled via the Oldroyd-B model. The role of viscoelastic stresses in deformation of a drop subjected to simple shear flow and its effect on the steady state shape is analyzed. Our results compare favorably with existing experimental data and also help in understanding the role of viscoelastic stresses in drop deformation.

A Study on the Structure of Turbulent Shear Flow by Numerical Simulation

1986 ◽  
Vol 29 (251) ◽  
pp. 1455-1461
Author(s):  
Yutaka MIYAKE ◽  
Takeo KAJISHIMA
Keyword(s):  
Numerical Simulation ◽  
Shear Flow ◽  
Turbulent Shear ◽  
Turbulent Shear Flow
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