Large-eddy simulation and multiscale modelling of a Richtmyer–Meshkov instability with reshock

Abstract

Large-eddy simulations of the Richtmyer–Meshkov instability with reshock are pre- sented and the results are compared with experiments. Several configurations of shocks initially travelling from light (air) to heavy (sulfur hexafluoride, SF 6 ) have been simulated to match previous experiments and good agreement is found in the growth rates of the turbulent mixing zone (TMZ). The stretched-vortex subgrid model used in this study allows for subgrid continuation modelling, where statistics of the unresolved scales of the flow are estimated. In particular, this multiscale modelling allows the anisotropy of the flow to be extended to the dissipation scale, $\eta$ , and estimates to be formed for the subgrid probability density function of the mixture fraction of air/SF 6 based on the subgrid variance, including the effect of Schmidt number.