Modeling and simulations of radiative blast wave driven Rayleigh-Taylor instability experiments

Recent experiments at the National Ignition Facility measured the growth of Rayleigh-Taylor RT instabilities driven by radiative blast waves, relevant to astrophysics and other HEDP systems. We constructed a new Buoyancy-Drag (BD) model, which accounts for the ablation effect on both bubble and spike. This ablation effect is accounted for by using the potential flow model ]Oron et al PoP 1998], adding another term to the classical BD formalism: $\beta $\textit{Du}$_{A}/u$, where $\beta $ the Takabe constant, $D$ the drag term, $u_{A}$ the ablation velocity and $u $the instability growth velocity. The model results are compared with the results of experiments and 2D simulations using the CRASH code, with nominal radiation or reduced foam opacity (by a factor of 1000). The ablation constant of the model, $\beta_{b/s}$, for the bubble and for the spike fronts, are calibrated using the results of the radiative shock experiments.