Discrete Filters for Large Eddy Simulation of Forced Compressible MHD Turbulence

Abstract

In present study, we discuss results of applicability of discrete filters for large eddy simulation (LES) method of forced compressible magnetohydrodynamic (MHD) turbulent flows with the scale-similarity model. Influences and effects of discrete filter shapes on the scale-similarity model are examined in physical space using a finite-difference numerical schemes. We restrict ourselves to the Gaussian filter and the top-hat filter. Representations of this subgrid-scale model which correspond to various 3- and 5-point approximations of both Gaussian and top-hat filters for different values of parameter $\epsilon$ (the ratio of the mesh size to the cut-off lengthscale of the filter) are investigated. Discrete filters produce more discrepancies for magnetic field. It is shown that the Gaussian filter is more sensitive to the parameter $\epsilon$ than the top-hat filter in compressible forced MHD turbulence. The 3-point filters at $\epsilon=2$ and $\epsilon=3$ give the least accurate results and the 5-point Gaussian filter shows the best results at $\epsilon=2$.