Turbulent dispersion in a non-homogeneous field

1999 ◽  
Vol 392 ◽  
pp. 45-71 ◽  
Author(s):  
ILIAS ILIOPOULOS ◽  
THOMAS J. HANRATTY
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Stochastic Model ◽  
Point Source ◽  
Time Scales ◽  
Langevin Equation ◽  
Turbulent Dispersion ◽  
Homogeneous Field ◽  
Fully Developed Flow ◽  
Good Agreement

Dispersion of fluid particles in non-homogeneous turbulence was studied for fully developed flow in a channel. A point source at a distance of 40 wall units from the wall is considered. Data obtained by carrying out experiments in a direct numerical simulation (DNS) are used to test a stochastic model which utilized a modified Langevin equation. All of the parameters, with the exception of the time scales, are obtained from Eulerian statistics. Good agreement is obtained by making simple assumptions about the spatial variation of the time scales.

scholarly journals Numerical investigation of particles turbulent dispersion in channel flow

2012 ◽  
Vol 16 (5) ◽  
pp. 1510-1514
Author(s):  
Tian Li ◽  
Li-Hao Zhao ◽  
Xiao-Ke Ku ◽  
Helge Andersson ◽  
Terese Lovas
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Numerical Investigation ◽  
Channel Flow ◽  
Particle Distribution ◽  
Turbulent Dispersion ◽  
Wall Turbulence ◽  
Navier Stokes ◽  
Reynolds Averaged Navier Stokes ◽  
Over Time

This paper investigates the performance of Reynolds-averaged Navier-Stokes model on dispersion of particles in wall turbulence. A direct numerical simulation of wall-bounded channel flow with particles suspensions was set as a benchmark. The standard k-? model coupled with two different eddy interaction models was used in Reynolds-averaged Navier-Stokes model and compared to the direct numerical simulation. Detailed comparisons between direct numerical simulation and Reynolds-averaged Navier-Stokes model on particle distribution evolving over time were carried out.

scholarly journals Direct Numerical Simulation of separated turbulent flow in axisymmetric diffuser

2021 ◽  
Vol 2103 (1) ◽  
pp. 012214
Author(s):  
A S Stabnikov ◽  
D K Kolmogorov ◽  
A V Garbaruk ◽  
F R Menter
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Eddy Viscosity ◽  
Separated Flow ◽  
Model Improvement ◽  
Good Agreement

Abstract Direct numerical simulation (DNS) of the separated flow in axisymmetric CS0 diffuser is conducted. The obtained results are in a good agreement with experimental data of Driver and substantially supplement them. Along with other data, eddy viscosity extracted from performed DNS could be used for RANS turbulence model improvement.

scholarly journals Direct numerical simulation of turbulent dispersion of evaporative aerosol clouds produced by an intense expiratory event

2021 ◽  
Vol 33 (3) ◽  
pp. 033329
Author(s):  
Alexandre Fabregat ◽  
Ferran Gisbert ◽  
Anton Vernet ◽  
Josep Anton Ferré ◽  
Ketan Mittal ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Dispersion

scholarly journals Inertial drag on a sphere settling in a stratified fluid

2018 ◽  
Vol 855 ◽  
pp. 1074-1087 ◽  
Author(s):  
R. Mehaddi ◽  
F. Candelier ◽  
B. Mehlig
Keyword(s):  
Numerical Simulation ◽  
Perturbation Theory ◽  
Direct Numerical Simulation ◽  
Drag Force ◽  
Stratified Fluid ◽  
Simulation Studies ◽  
Fluid Density ◽  
Settling Particle ◽  
Inertial Terms ◽  
Good Agreement

We compute the drag force on a sphere settling slowly in a quiescent, linearly stratified fluid. Stratification can significantly enhance the drag experienced by the settling particle. The magnitude of this effect depends on whether fluid-density transport around the settling particle is due to diffusion, to advection by the disturbance flow caused by the particle or due to both. It therefore matters how efficiently the fluid disturbance is convected away from the particle by fluid-inertial terms. When these terms dominate, the Oseen drag force must be recovered. We compute by perturbation theory how the Oseen drag is modified by diffusion and stratification. Our results are in good agreement with recent direct numerical simulation studies of the problem.

scholarly journals Direct Numerical Simulation and Visualization of Subcooled Pool Boiling

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
Tomoaki Kunugi ◽  
Yasuo Ose
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
High Speed ◽  
High Performance ◽  
High Spatial Resolution ◽  
Pool Boiling ◽  
Numerical Results ◽  
Condensation Model ◽  
High Performance Computers ◽  
Good Agreement

A direct numerical simulation of the boiling phenomena is one of the promising approaches in order to clarify their heat transfer characteristics and discuss the mechanism. During these decades, many DNS procedures have been developed according to the recent high performance computers and computational technologies. In this paper, the state of the art of direct numerical simulation of the pool boiling phenomena during mostly two decades is briefly summarized at first, and then the nonempirical boiling and condensation model proposed by the authors is introduced into the MARS (MultiInterface Advection and Reconstruction Solver developed by the authors). On the other hand, in order to clarify the boiling bubble behaviors under the subcooled conditions, the subcooled pool boiling experiments are also performed by using a high speed and high spatial resolution camera with a highly magnified telescope. Resulting from the numerical simulations of the subcooled pool boiling phenomena, the numerical results obtained by the MARS are validated by being compared to the experimental ones and the existing analytical solutions. The numerical results regarding the time evolution of the boiling bubble departure process under the subcooled conditions show a very good agreement with the experimental results. In conclusion, it can be said that the proposed nonempirical boiling and condensation model combined with the MARS has been validated.

scholarly journals Response of a stratified boundary layer on a tilted wall to surface undulations

2014 ◽  
Vol 751 ◽  
pp. 663-684 ◽  
Author(s):  
Pierre-Yves Passaggia ◽  
Patrice Meunier ◽  
Stéphane Le Dizès
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Direct Numerical Simulation ◽  
Spatial Structure ◽  
Transverse Velocity ◽  
Critical Layer ◽  
Velocity Response ◽  
Viscous Solution ◽  
Simulation Results ◽  
Good Agreement

AbstractThe structure of a stratified boundary layer over a tilted bottom with a small streamwise undulation is studied theoretically and numerically. We show that the tilt of the boundary can induce strong density variations and wall-transverse velocities in the critical layer when the frequency of the forcing by the topography $\def \xmlpi #1{}\def \mathsfbi #1{\boldsymbol {\mathsf {#1}}}\let \le =\leqslant \let \leq =\leqslant \let \ge =\geqslant \let \geq =\geqslant \def \Pr {\mathit {Pr}}\def \Fr {\mathit {Fr}}\def \Rey {\mathit {Re}}kU(z_c)$ is equal to the transverse Brunt–Väisälä frequency $N \sin \alpha $ ($N$ being the vertical Brunt–Väisälä frequency). The viscous solution in the critical layer, obtained and compared with direct numerical simulation results, is in good agreement for both the scaling and the spatial structure. The amplitude of the transverse velocity response is also shown to exhibit quasi-resonance peaks when the stratification strength is varied.

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