A dynamic LES scheme for the vorticity transport equation: formulation and a-priori tests

Johns R. Mansfield 1, Omar Knio and Charles Meneveau
Department of Mechanical Engineering, The Johns Hopkins University Baltimore MD 21218 1, Present address: Department of Mechanical Engineering UCLA, Los Angeles CA 90024

ABSTRACT: This work aims at the development of a Lagrangian large eddy simulation (LES) scheme. The scheme is based on the filtered vorticity transport equation and on modeling the effects of subfilter scale (SFS) velocity and vorticity fluctuations using a dynamic eddy diffusivity model. The dynamic implementation of the model relies on multiple filtering in order to determine model coefficients from the resolved data. The performance of the dynamic SFS model is examined using a priori tests that are based on direct numerical simulations of forced, homogeneous, isotropic turbulence. The tests show a fair correlation of the model with SFS convection of vorticity. In addition, the computed value of the dynamic model coefficient is in good agreement with predictions based on enstrophy balances. Finally, the direct numerical simulation data is used to compare a particle representation of the model that is well suited for Lagrangian three- dimensional vortex element computation with spectral evaluations of the model. The tests show that when the particle representation is sufficiently resolved, the Lagrangian model predictions are in good agreement with spectral results.

J. Comp. Phys. 145 (1998), p.693

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