A priori study of subgrid-scale flux of a passive scalar in isotropic homogeneous turbulence [electronic resource].

Published:: Washington, D.C. : United States. Dept. of Energy, 2008.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
Additional Creators:: Los Alamos National Laboratory, United States. Department of Energy, and United States. Department of Energy. Office of Scientific and Technical Information

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Summary:

We perform a direct numerical simulation (DNS) of forced homogeneous isotropic turbulence with a passive scalar that is forced by mean gradient. The DNS data are used to study the properties of subgrid-scale flux of a passive scalar in the framework of large eddy simulation (LES), such as alignment trends between the flux, resolved, and subgrid-scale flow structures. It is shown that the direction of the flux is strongly coupled with the subgrid-scale stress axes rather than the resolved flow quantities such as strain, vorticity, or scalar gradient. We derive an approximate transport equation for the subgrid-scale flux of a scalar and look at the relative importance of the terms in the transport equation. A particular form of LES tensor-viscosity model for the scalar flux is investigated, which includes the subgrid-scale stress. Effect of different models for the subgrid-scale stress on the model for the subgrid-scale flux is studied.

Report Numbers:

E 1.99:la-ur-08-04884
E 1.99: la-ur-08-4884
la-ur-08-4884
la-ur-08-04884

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Note:

Published through SciTech Connect.
01/01/2008.
"la-ur-08-04884"
" la-ur-08-4884"
Phys. Rev. E 78 3 ISSN 1539-3755 FT
Chumakov, Sergei.

Funding Information:

AC52-06NA25396

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