Multispecies Hybrid Model Applied to Species Mixing

The assumptions behind hydrodynamic models can break down in certain regimes (e.g. shocks). Alternatively, kinetic models provide more accurate solutions, but require many more degrees of freedom. A hybrid model combines both hydro and kinetic models into a single system of equations and applies kinetic models where needed. We present a new hybrid model for multispecies plasmas which generalizes Degond’s [1] smooth transition model from a single species to a multi-species model. Specifically, it combines multispecies Euler with Haack, Hauck, Murillo’s [2] recently formulated moment conserving, entropic multispecies kinetic model. We apply this method to study species mixing in inertial confinement fusion experiments [3] . Simulation results indicate that more than one momentum equation is required to capture mixing. We determine which physical regions require multiple momentum equations using the Chapman-Enskog closure of the kinetic model in conjunction with numerical estimates of the Knudsen number.