Potential flow models of Rayleigh–Taylor and Richtmyer– Meshkov bubble fronts

Abstract. A new realization of the two-phase flow approach is presented and applied for the Rayleigh-Taylor (RT) and Richtmyer-Meshkov (RM) instabilities. The mixing zone fronts and interior are treated separately, yielding a physically motivated model that is easier to implement numer-ically than standard two-phase flow treatments. In the model, the evolu-tion of the mixing zone boundaries is given by point equations, based on the physics of large-scale structure at the fronts. The inner zone mixing is governed by a diffusive scheme that simplifies standard two-phase flow equations. The mixing-model parameters are determined by comparison to theoretical models. The linear stage and late-time growth scaling laws, for both RT and RM cases, as well as the mixing profiles, are obtained in good agreement with full-scale numerical simulations.