Large Eddy Simulations of Supersonic Turbulence

TL;DR

This paper introduces a subgrid scale model for simulating highly compressible supersonic turbulence using large eddy simulations, reducing bottleneck effects and enabling approximate scaling laws at lower resolutions.

Contribution

The paper presents a new subgrid scale model applicable to compressible turbulence and demonstrates its effectiveness in large eddy simulations of supersonic flows.

Findings

Bottleneck effect is significantly reduced with the new model.

Approximate scaling laws can be obtained at lower resolutions.

Velocity spectrum varies with forcing, indicating non-universality of scaling.

Abstract

Based on ideas by Woodward et al., a subgrid scale model that is applicable to highly compressible turbulence is presented. Applying the subgrid scale model in large eddy simulations of forced supersonic turbulence, the bottleneck effect is largely reduced and, thereby, approximate scaling laws can be obtained at relatively low numerical resolution. In agreement with previous results from PPM simulations without explicit subgrid scale model, it is found that the energy spectrum function for the velocity field with fractional density-weighing, rho^(1/3)u, varies substantially with the forcing, at least for the decade of wavenumbers next to the energy-containing range. Consequently, if universal scaling of compressible turbulence exists, it can be found on length scales much smaller than the forcing scale only.