A-priori testing of alpha regularisation models as subgrid-scale closures for large-eddy simulations

2013 ◽  
Vol 14 (6) ◽  
pp. 1-20 ◽  
Author(s):  
Denis F. Hinz ◽  
Tae-Yeon Kim ◽  
James J. Riley ◽  
Eliot Fried
Keyword(s):  
A Priori ◽  
Large Eddy Simulations ◽  
Subgrid Scale ◽  
Large Eddy

Subgrid-scale models for large-eddy simulations of compressible wall bounded flows

AIAA Journal ◽  
2000 ◽  
Vol 38 ◽  
pp. 1340-1350 ◽  
Author(s):  
E. Lenormand ◽  
P. Sagaut ◽  
L. Ta Phuoc ◽  
P. Comte
Keyword(s):  
Large Eddy Simulations ◽  
Subgrid Scale ◽  
Scale Models ◽  
Large Eddy ◽  
Wall Bounded Flows

scholarly journals Statistical ensemble of large-eddy simulations

2002 ◽  
Vol 455 ◽  
pp. 195-212 ◽  
Author(s):  
DANIELE CARATI ◽  
MICHAEL M. ROGERS ◽  
ALAN A. WRAY
Keyword(s):  
Large Scale ◽  
Isotropic Turbulence ◽  
Velocity Fields ◽  
Large Eddy Simulations ◽  
Statistical Ensemble ◽  
Model Parameters ◽  
Spatial Averaging ◽  
Subgrid Scale ◽  
Large Eddy ◽  
New Models

A statistical ensemble of large-eddy simulations (LES) is run simultaneously for the same flow. The information provided by the different large-scale velocity fields is used in an ensemble-averaged version of the dynamic model. This produces local model parameters that only depend on the statistical properties of the flow. An important property of the ensemble-averaged dynamic procedure is that it does not require any spatial averaging and can thus be used in fully inhomogeneous flows. Also, the ensemble of LES provides statistics of the large-scale velocity that can be used for building new models for the subgrid-scale stress tensor. The ensemble-averaged dynamic procedure has been implemented with various models for three flows: decaying isotropic turbulence, forced isotropic turbulence, and the time-developing plane wake. It is found that the results are almost independent of the number of LES in the statistical ensemble provided that the ensemble contains at least 16 realizations.

Subgrid scale variance and dissipation of a scalar field in large eddy simulations

2001 ◽  
Vol 13 (6) ◽  
pp. 1748-1754 ◽  
Author(s):  
C. Jiménez ◽  
F. Ducros ◽  
B. Cuenot ◽  
B. Bédat
Keyword(s):  
Scalar Field ◽  
Large Eddy Simulations ◽  
Subgrid Scale ◽  
Large Eddy

scholarly journals A new subgrid-scale representation of hydrometeor fields using a multivariate PDF

2016 ◽  
Author(s):  
Brian M. Griffin ◽  
Vincent E. Larson
Keyword(s):  
Probability Density Function ◽  
Probability Density ◽  
Density Function ◽  
Vertical Velocity ◽  
Lognormal Distribution ◽  
Large Eddy Simulations ◽  
Subgrid Scale ◽  
Microphysical Process ◽  
Large Eddy ◽  
Probability Density Function Pdf

Abstract. The subgrid-scale representation of hydrometeor fields is important for calculating microphysical process rates. In order to represent subgrid-scale variability, the Cloud Layers Unified By Binormals (CLUBB) parameterization uses a multivariate Probability Density Function (PDF). In addition to vertical velocity, temperature, and moisture fields, the PDF includes hydrometeor fields. Previously, each hydrometeor field was assumed to follow a multivariate single lognormal distribution. Now, in order to better represent the distribution of hydrometeors, two new multivariate PDFs are formulated and introduced. The new PDFs represent hydrometeors using either a delta-lognormal or a delta-double-lognormal shape. The two new PDF distributions, plus the previous single lognormal shape, are compared to histograms of data taken from Large-Eddy Simulations (LES) of a precipitating cumulus case, a drizzling stratocumulus case, and a deep convective case. Finally, the warm microphysical process rates produced by the different hydrometeor PDFs are compared to the same process rates produced by the LES.

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

Sign in / Sign up

Export Citation Format

Share Document