Numerical Simulation of Non-Stationary Turbulent Flows Using Double Exponential Dynamic Time Filtering Technique

2020 ◽  
Author(s):  
Tausif Jamal ◽  
Shanti Bhushan ◽  
D. Keith Walters
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flows ◽  
Model Performance ◽  
Navier Stokes ◽  
Time Averaging ◽  
Suitable Alternative ◽  
Double Exponential ◽  
Reynolds Averaged Navier Stokes ◽  
Dynamic Hybrid ◽  
Dynamic Time

Abstract Temporally varying turbulent flows are of considerable interest in complex engineering problems such as combustion, hydrodynamics, and hemodynamics. These types of flows are often associated with complex flow physics such as varying mean pressure gradients, interactions of different scales of motion, and complex boundary layer separations. Hybrid Reynolds-averaged Navier-Stokes (RANS)/Large-Eddy Simulation (LES) methods have recently shown promise for accurate and computationally efficient simulation of these flows. One such method is the dyanamic hybrid RANS-LES (DHRL) model which has been demonstrated for numerous statistically stationary turbulent flows. More recently, it has been shown that Exponential Time-Averaging (ETA) and Dynamic Time Filtering (DTF) methods for obtaining resolved flow statistics have significantly improved the predictive capabilities of the Dynamic Hybrid RANS-LES (DHRL) model performance for a non-stationary turbulent flows with periodically time-varying statistics. However, for non-periodic temporally evolving flows with monotonically varying statistics, a more suitable alternative is desired. In this study, the performance of the Dynamic Hybrid RANS-LES (DHRL) model with a double exponential dynamic time filtering (DDTF) methodology is evaluated against a Reynolds-Averaged Navier-Stokes (RANS) model, a conventional Hybrid RANS-LES (HRL) model, implicit LES, and the DHRL model with DTF for a pulsating channel and a temporally-varying turbulent mixing layer. Model performance is evaluated based on comparisons to existing experimental and Direct Numerical Simulation (DNS) results. A comprehensive analysis of the results highlights key similarities and differences between the models and indicates that the use of a double exponential DTF technique improves the accuracy of the baseline DHRL model. It is concluded that the DDTF is a useful alternative to simulate unsteady non-periodic temporally evolving turbulent flows.

Study of turbulent flow past a square cylinder using partially-averaged Navier–Stokes method in OpenFOAM

2020 ◽  
Vol 234 (14) ◽  
pp. 2821-2832 ◽  
Author(s):  
Arnab Chakraborty ◽  
HV Warrior
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Turbulent Flow ◽  
Turbulent Flows ◽  
Normal Direction ◽  
Navier Stokes ◽  
Square Cylinder ◽  
Mean Velocity ◽  
Wide Range ◽  
Reynolds Averaged Navier Stokes

The present paper reports numerical simulation of turbulent flow over a square cylinder using a novel scale resolving computational fluid dynamics technique named Partially-Averaged Navier–Stokes (PANS), which bridges Reynolds-Averaged Navier–Stokes (RANS) with Direct Numerical Simulation (DNS) in a seamless manner. All stream-wise and wall normal mean velocity components, turbulent stresses behavior have been computed along the flow (streamwise) as well as in transverse (wall normal) direction. The measurement locations are chosen based on the previous studies so that results could be compared. However, the Reynolds number ( Re) of the flow is maintained at 21,400 and K– ω turbulence model is considered for the present case. All the computations are performed in OpenFOAM framework using a finite volume solver. Additionally, turbulent kinetic energy variations are presented over a wide range of measurement planes in order to explain the energy transfer process in highly unsteady turbulent flow field. The fluctuating root mean square velocities in the streamwise as well as in the wall normal direction have been discussed in the present work. It has been found that Partially-Averaged Navier–Stokes (PANS) model is capable of capturing the properties of highly unsteady turbulent flows and gives better results than Reynolds-Averaged Navier–Stokes (RANS). The results obtained using Partially-Averaged Navier–Stokes (PANS) are quite comparable with Large Eddy Simulation (LES) and Direct Numerical Simulation (DNS) data available in literature. The partially-averaged Navier–Stokes results are compared with our simulated Reynolds-Averaged Navier–Stokes (RANS) results, available experimental as well as numerical results in literature and it is found to be good in agreement.

On Direct Numerical Simulation of Turbulent Flows

2011 ◽  
Vol 64 (2) ◽  
Author(s):  
Giancarlo Alfonsi
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
High Performance Computing ◽  
Turbulent Flows ◽  
High Performance ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Turbulent Shear ◽  
Navier Stokes Equations ◽  
Performance Computing

The direct numerical simulation of turbulence (DNS) has become a method of outmost importance for the investigation of turbulence physics, and its relevance is constantly growing due to the increasing popularity of high-performance-computing techniques. In the present work, the DNS approach is discussed mainly with regard to turbulent shear flows of incompressible fluids with constant properties. A body of literature is reviewed, dealing with the numerical integration of the Navier-Stokes equations, results obtained from the simulations, and appropriate use of the numerical databases for a better understanding of turbulence physics. Overall, it appears that high-performance computing is the only way to advance in turbulence research through the front of the direct numerical simulation.

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.

Pressure–strain correlation modelling of complex turbulent flows

2000 ◽  
Vol 422 ◽  
pp. 91-123 ◽  
Author(s):  
SHARATH S. GIRIMAJI
Keyword(s):  
Fixed Point ◽  
Turbulent Flows ◽  
Standard Form ◽  
Model Performance ◽  
Variable Coefficients ◽  
Navier Stokes ◽  
Bench Mark ◽  
New Model ◽  
Equilibrium Limit ◽  
Point Analysis

A methodology for deriving a pressure–strain correlation model with variable coefficients is developed. The methodology is based on two important premises: (i) the extreme states of turbulence – the rapid distortion and equilibrium limits – are more amenable to mathematically rigorous modelling because of significant simplifications not possible at other states; and (ii) the models of the extreme states collectively contain all of the relevant physics so that models for any intermediate state can be obtained by suitable interpolation. A pressure–strain model of the standard form is considered and the coefficients are determined from linear analysis in the rapid distortion limit and from a fixed point analysis in the equilibrium limit. The model coefficients, which depend on the mean deformation and turbulence state, vary from flow to flow in a manner consistent with Navier–Stokes physics.The exact causal relationship between the model coefficients and the model's equilibrium behaviour is established by fixed point analysis performed using representation theory. Then, the equilibrium values of the model coefficients are chosen to yield the observed equilibrium behaviour. The values of the model coefficients in the rapid distortion limit are determined by enforcing consistency with the Crow constraint. The new variable-coefficient model reduces to the traditional constant-coefficient model in strain-dominated turbulent flows near equilibrium. The model performance in bench-mark turbulent flows, in which the traditional models have been calibrated extensively, is preserved intact. The new model is significantly different from the traditional one in mean vorticity-dominated and non-equilibrium turbulence. These two important classes of flows, in which traditional models fail, are successfully captured by the new model.

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