The multiscale formulation of large eddy simulation: Decay of homogeneous isotropic turbulence

2001 ◽  
Vol 13 (2) ◽  
pp. 505-512 ◽  
Author(s):  
Thomas J. R. Hughes ◽  
Luca Mazzei ◽  
Assad A. Oberai ◽  
Alan A. Wray
Keyword(s):  
Large Eddy Simulation ◽  
Isotropic Turbulence ◽  
Homogeneous Isotropic Turbulence ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals Performance of the Finite Element and Finite Volume Methods for Large Eddy Simulation in Homogeneous Isotropic Turbulence

2010 ◽  
Vol 2 (2) ◽  
pp. 237-249 ◽  
Author(s):  
M. A. Uddin ◽  
C. Kato ◽  
N. Oshima ◽  
M. Tanahashi ◽  
T. Miyauchi
Keyword(s):  
Finite Element ◽  
Large Eddy Simulation ◽  
Finite Volume ◽  
Isotropic Turbulence ◽  
Finite Volume Methods ◽  
Homogeneous Isotropic Turbulence ◽  
Smagorinsky Model ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Better Than

Large eddy simulation (LES) in homogeneous isotropic turbulence is performed by using the Finite element method (FEM) and Finite volume vethod (FVM) and the results are compared to show the performance of FEM and FVM numerical solvers. The validation tests are done by using the standard Smagorinsky model (SSM) and dynamic Smagorinsky model (DSM) for subgrid-scale modeling. LES is performed on a uniformly distributed 643 grids and the Reynolds number is low enough that the computational grid is capable of resolving all the turbulence scales. The LES results are compared with those from direct numerical simulation (DNS) which is calculated by a spectral method in order to assess its spectral accuracy. It is shown that the performance of FEM results is better than FVM results in this simulation. It is also shown that DSM performs better than SSM for both FEM and FVM simulations and it gives good agreement with DNS results in terms of both spatial spectra and decay of the turbulence statistics. Visualization of second invariant, Q, in LES data for both FEM and FVM reveals the existence of distinct, coherent, and tube-like vortical structures somewhat similar to those found in instantaneous flow field computed by the DNS. Keywords: Large eddy simulation; Validation; Smagorinsky model; Dynamic Smagorinsky model; Tube-like vortical structure; Homogeneous isotropic turbulence. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v2i2.2582              J. Sci. Res. 2 (2), 237-249 (2010) 

Implicit Large-Eddy Simulation of Transition and Turbulence Decay

2019 ◽  
Author(s):  
Fernando F. Grinstein
Keyword(s):  
Large Eddy Simulation ◽  
Isotropic Turbulence ◽  
Navier Stokes ◽  
Homogeneous Isotropic Turbulence ◽  
Eddy Simulation ◽  
Numerical Hydrodynamics ◽  
Geometrical Complexity ◽  
Turbulence Decay ◽  
Large Eddy ◽  
Implicit Large Eddy Simulation

Abstract Accurate predictions with quantifiable uncertainties are essential to many practical turbulent flow applications exhibiting extreme geometrical complexity and broad ranges of length and time scales. Under-resolved computer simulations are typically unavoidable in such applications, and implicit large-eddy simulation (ILES) often becomes the effective strategy. We focus on ILES initialized with well-characterized 2563 homogeneous isotropic turbulence datasets generated with direct numerical simulation (DNS). ILES is based on the LANL xRAGE code, and solutions are examined as function of resolution for 643, 1283, 2563, and 5123 grids. The ILES performance of new directionally-unsplit high-order numerical hydrodynamics algorithms in xRAGE is examined. Compared to the initial 2563 DNS, we find longer inertial subranges and higher turbulence Re for directional-split 2563 & 5123 xRAGE — attributed to having linked DNS (Navier-Stokes based) solutions to nominally inviscid (higher Re) Euler based ILES solutions. Alternatively — for fixed resolution, we find that significantly higher simulated turbulence Re can be achieved with unsplit (vs. split) discretizations.

scholarly journals Comparative Study of the Grid-Scale and Subgrid-Scale Velocity Fields - A Priori Test

1970 ◽  
Vol 30 ◽  
pp. 19-31
Author(s):  
M Ashraf Uddin ◽  
M Matiar Rahman ◽  
M Saiful Islam Mallik
Keyword(s):  
Isotropic Turbulence ◽  
A Priori ◽  
Velocity Fields ◽  
Subgrid Scale ◽  
Homogeneous Isotropic Turbulence ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Spatial Spectra ◽  
Sharp Cutoff ◽  
Better Than

Generation of grid-scale (GS) and subgrid-scale (SGS) velocity fields is performed by direct filtering of DNS (Direct Numerical Simulation) data at a low Reynolds number in homogeneous isotropic turbulence in order to assess the spectral accuracy as well as the performance of filter functions for LES (Large Eddy Simulation). The filtering is performed using three classical filter functions: Gaussian, Tophat and Sharp cutoff filters and in all three cases the results are compared with three different filter widths for LES. Comparing the distributions of GS and SGS velocities, and the decay of turbulence with those from DNS fields through out the whole calculation we have found that among the three filter functions, the performance of Sharp cutoff filter is better than that of the other two filter functions in terms of both spatial spectra and the distribution of velocities. Furthermore, it is shown that the accuracy of the filtering approach does not depend only on the filter functions but also on the filter widths for LES. GANIT J. Bangladesh Math. Soc. (ISSN 1606-3694) 30 (2010) 19-31   DOI: http://dx.doi.org/10.3329/ganit.v30i0.8499

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