Self-similar bubble-front evolutions of ablative Rayleigh-Taylor instability seeded by localized perturbations

Abstract

Two-dimensional numerical simulations are carried out to investigate the nonlinear bubble growth of ablative Rayleigh-Taylor instability (ARTI) seeded by localized perturbations (LPs), where the LPs are described by a Gaussian mode. It is found that the nonlinear bubble-front penetration of LP-seeded ARTI follows the self-similar scaling law α b A T(∫ √gdt)2, different from the classical case, where the self-similar behavior is not observed. It is also found that the quadratic growth coefficient α b in the LP-seeded ARTI mainly depends on the initial perturbation amplitude and initial perturbation width. When the perturbation amplitude is small, α b has a value of ∼0.03, which is not sensitive to the perturbation width. As the perturbation amplitude increases, the value of α b increases, and the phenomenon is more significant when the perturbation width is narrower. It is shown that the increase in α b is due to the spike-induced upward jet and the ablation-generated vorticity inside the bubble.