Explosion-driven interfacial instabilities of granular media

This paper investigates the evolution of a Richtmyer-Meshkov (RM)-like instability on the internal surface of particle rings impinged by divergent blast waves. Despite the signature spike-bubble instability structure analogous to the hydrodynamic RM instability, the growth of the perturbation amplitude in granular media undergoes an exponential phase followed by a linear phase, markedly differing from the hydrodynamic RM instability and indicating a fundamentally different mechanism. The granular RM-like instability arises from the incipient transverse granular flows induced by hydrodynamic effects upon the shock interaction. Substantial perturbation growth is initiated by the ensuing rarefaction dilation when the hydrodynamic effects are small. It is found that the interplay between the localized transverse and radial granular flows sustains the persistent perturbation growth and drives the corresponding morphological changes in the instability pattern.