Large eddy simulation on unstructured grids using explicit differential filtering: A case study of Taylor-Green vortex

Abstract

The application of an approximate deconvolution model was extended for large eddy simulation (LES) on unstructured grids by further developing a three dimensional explicit differential filter. Decaying isotropic homogeneous turbulence at a Reynolds number 3,400 was modeled on both structured and unstructured grids. Results were compared to a reference direct numerical simulation and other results reported in the literature. A Taylor-Green vortex at a Reynolds number of 1,600 was also studied as it is a canonical problem for laminar to turbulent transitional flow. Investigative studies on the ADM order and under-relaxation coefficient, the degree of anisotropy of the grid, and the grid resolution were performed to benchmark the filter performance in conjunction with ADM. Finally, a large eddy simulation on a fully unstructured grid was performed to demonstrate the range of applications of the proposed filter. All numerical results showed strong LES numerical stability when the explicit differential filter was used.