A fluid-dynamical subgrid scale model for highly compressible astrophysical turbulence

Subgrid-scale modeling for Large-eddy simulations of compressible turbulence

We present two phenonmenological subgrid-scale (SGS) models for large-eddy simulations (LES) of compressible turbulent flows. A nonlinear model and a stretched-vortex model are tested in LES of compressible decaying isotropic turbulence. Results of LES at 32 resolution are compared to corresponding 256 direct numerical simulations (DNS). We use numerical schemes based on compact differences and...

A localised subgrid scale model for fluid dynamical simulations in astrophysics I: Theory and numerical tests

We present a one-equation subgrid scale model that evolves the turbulence energy corresponding to unresolved velocity fluctuations in large eddy simulations. The model is derived in the context of the Germano consistent decomposition of the hydrodynamical equations. The eddy-viscosity closure for the rate of energy transfer from resolved toward subgrid scales is localised by means of a dynamica...

A modified-Leray-α subgrid scale model of turbulence

Inspired by the remarkable performance of the Leray-α (and the Navier–Stokes alpha (NS-α), also known as the viscous Camassa–Holm) subgrid scale model of turbulence as a closure model to Reynolds averaged equations (RANS) for flows in turbulent channels and pipes, we introduce in this paper another subgrid scale model of turbulence, the modified Leray-α (ML-α) subgrid scale model of turbulence....

A Discrete Dynamical System Subgrid-Scale Model of Turbulent Convection

Subgrid-scale modeling of isotropic turbulence in compressible magnetohydrodynamic large eddy simulations

Despite the ever increasing availability of computational resources, fully resolved simulations of magnetohydrodynamic (MHD) turbulence are not going to be feasible for quite some time. For this reason, large eddy simulations (LES) have been introduced that only resolve large scales. In LES a low-pass filter is applied to the evolution equations, which introduces additional unknown terms. These...