Hydrodynamic simulations of rippled shock wave driven by laser ablation and initial pressure discontinuity

When lasers irradiate a target with a rippled surface, the ablation pressure launches a rippled shock induced by the initial target surface. We study the evolution of a rippled shock driven by an ablation surface and the associated flow field using inviscid hydrodynamic simulations in FLASH. For strong shocks (O(100 GPa)), the shock separates from the ablation surface at very long times. Hence, the reverberations of pressure waves in the region between the shock front and the ablation surface can interact and modify the rippled shock evolution. We compare the evolution of the decaying amplitude of a rippled shock driven by: 1) laser-driven ablation and 2) initial pressure discontinuity across an interface separated by two media. First, we match the zeroth order flow profiles in the shock-compressed region in both the cases by driving a steady planar shock of equal strength. Next, we conduct simulations on sinusoidally-perturbed target surface (interface) of multiple wavelengths. Finally, we analyze the effect of including dynamic viscosity and compare our results with previous theoretical models of Miller et al. (1991) and Ishizaki et al. (1996).