Modeling of Shock Tube Experiments of a Perturbed Diffuse Interface Subjected to the Richtmyer-Meshkov Instability

When a shock wave impinges upon a perturbed interface separating two fluids of different densities, any perturbations along the interface grow due to the Richtmyer-Meshkov instability, possibly leading to a turbulent mixing region. In this study, we discuss the modeling of experiments performed at the Vertical Shock Tube facility at Los Alamos of a single-mode perturbation along an air/SF6 interface impulsively accelerated by a shock (shock Mach number Ms=1.2). In particular, using the radiation-hydrodynamics code xRAGE, we consider a diffuse interface between the air and SF6, and investigate the effects of the diffusion layer on the flow evolution. From experimental measurements, we accurately estimate the initial size of the diffusion layer and use it to initialize our simulations, allowing us to compare the perturbation growth with the experiments. Using the velocity and density fields from these measurements, we further estimate the turbulence parameters required to initialize a Besnard-Harlow-Rauenzhan (BHR) turbulence model, greatly improving our ability to model the experiments.