Numerical investigation of compressibility effects in turbulent channel flows using large eddy simulation

The large eddy simulation (LES) of compressible turbulent channel flows at three different Mach numbers is performed in the present work, by extending the dynamic mixed subgrid-scale (SGS) model to compressible flows. The turbulent statistics agree well with those from the existing direct numerical simulation (DNS) results, indicating that the LES method established in the present work is reliable. The analysis of the turbulent fluctuations computed by the present LES reveals that the flows considered in this work follow the Morkovin’s hypothesis. Thus, the compressibility effects are dominated by the mean field properties, and the relevant statistical ratios are invariant to the variation of Mach number. The near-wall streamwise streaks are more coherent and the spacing between streaks is wider as the Mach number increases. This can be regarded as a direct feature characterized by the compressibility effects. The restrained influences of compressibility effects on the production and dissipation of the turbulence kinetic energy are also identified based on the present LES results.