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 αbAT∫gdt2, different from the classical case, where the self-similar behavior is not observed. It is also found that the quadratic growth coefficient αb in the LP-seeded ARTI mainly depends on the initial perturbation amplitude and initial perturbation width. When the perturbation amplitude is small, αb has a value of ∼0.03, which is not sensitive to the perturbation width. As the perturbation amplitude increases, the value of αb increases, and the phenomenon is more significant when the perturbation width is narrower. It is shown that the increase in αb is due to the spike-induced upward jet and the ablation-generated vorticity inside the bubble.