Convergence of High-Order and Low-Order Accuracy Simulations for Richtmyer-Meshkov Instability

Simulations of variable density mixing induced by the interaction between a Mach 1.45 shock and subsequent re-shock with the interface between two ideal gases at high Atwood number (sulphur hexafluoride and air) contain a wide range of spatial scales. Sixth-order spatially accurate shock-capturing simulations of this flow for a series of grid resolutions demonstrated excellent agreement of global quantities such as mixing layer width and slower but eventual convergence of quantities sensitive to the smallest scales of motion such as total dissipation [Wong et al., Phys. Rev. Fl., 2022]. Simulations of a similar configuration with the same spatial resolutions are performed with the lower-order multiphysics hydrocode xRage with two different hydrodynamics schemes to assess the convergence. The convergence within the first shock and reshocked regimes are addressed and the ability of lower order code to predict the salient features and detailed statistics of the flow is assessed.