Subgrid-scale pressure field of scale-enriched large eddy simulations using Gabor modes

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.

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Neural networks based subgrid scale modeling in large eddy simulations

Computers & Fluids ◽

10.1016/s0045-7930(01)00098-6 ◽

2003 ◽

Vol 32 (1) ◽

pp. 97-108 ◽

Cited By ~ 42

Author(s):

F. Sarghini ◽

G. de Felice ◽

S. Santini

Keyword(s):

Neural Networks ◽

Large Eddy Simulations ◽

Subgrid Scale ◽

Scale Modeling ◽

Large Eddy ◽

Subgrid Scale Modeling

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

Physics of Fluids ◽

10.1063/1.1366668 ◽

2001 ◽

Vol 13 (6) ◽

pp. 1748-1754 ◽

Cited By ~ 100

Author(s):

C. Jiménez ◽

F. Ducros ◽

B. Cuenot ◽

B. Bédat

Keyword(s):

Scalar Field ◽

Large Eddy Simulations ◽

Subgrid Scale ◽

Large Eddy

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On the magnitude of the subgrid-scale eddy coefficient in large-eddy simulations of turbulent channel flow

Journal of Fluid Mechanics ◽

10.1017/s0022112086002112 ◽

1986 ◽

Vol 162 (-1) ◽

pp. 439 ◽

Cited By ~ 196

Author(s):

P. J. Mason ◽

N. S. Callen

Keyword(s):

Channel Flow ◽

Turbulent Channel Flow ◽

Large Eddy Simulations ◽

Subgrid Scale ◽

Large Eddy

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Subgrid-scale Modeling for Large Eddy Simulations of Dense-to-Dilute Multiphase Reacting Flows

2018 Joint Propulsion Conference ◽

10.2514/6.2018-4733 ◽

2018 ◽

Author(s):

Achyut Panchal ◽

Reetesh Ranjan ◽

Suresh Menon

Keyword(s):

Reacting Flows ◽

Large Eddy Simulations ◽

Subgrid Scale ◽

Scale Modeling ◽

Large Eddy ◽

Subgrid Scale Modeling

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Flat vs. curved rigid-lid LES computations of an open-channel confluence

Journal of Hydroinformatics ◽

10.2166/hydro.2019.109 ◽

2019 ◽

Vol 21 (2) ◽

pp. 318-334 ◽

Cited By ~ 4

Author(s):

Pedro Xavier Ramos ◽

Laurent Schindfessel ◽

João Pedro Pêgo ◽

Tom De Mulder

Keyword(s):

Free Surface ◽

Secondary Flow ◽

Open Channel ◽

Pressure Field ◽

Large Eddy Simulations ◽

Numerical Treatment ◽

Mean Flow ◽

Large Eddy ◽

Flow Case ◽

Channel Confluence

Abstract This paper describes the application of four Large Eddy Simulations (LES) to an open-channel confluence flow, making use of a frictionless rigid-lid to treat the free-surface. Three simulations are conducted with a flat rigid-lid, at different elevations. A fourth simulation is carried out with a curved rigid-lid which is a closer approximation to the real free-surface of the flow. The curved rigid-lid is obtained from the time-averaged pressure field on the flat rigid-lid from one of the initial three simulations. The aim is to investigate the limitations of the free-surface treatment by means of a rigid-lid in the simulation of an asymmetric confluence, showing the differences that both approaches produce in terms of mean flow, secondary flow and turbulence. After validation with experimental data, the predictions are used to understand the differences between adopting a flat and a curved rigid-lid onto the confluence hydrodynamics. For the present flow case, although it was characterized by a moderately low downstream Froude number (Fr ≈ 0.37), it was found that an oversimplification of the numerical treatment of the free-surface leads to a decreased accuracy of the predictions of the secondary flow and turbulent kinetic energy.

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

10.5194/gmd-2015-280 ◽

2016 ◽

Cited By ~ 1

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.

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