Research progress of general Richtmyer-Meshkov instability

Richtmyer-Meshkov (RM) instability has attracted wide attention due to its academic significance and engineering application in many fields. Previous studies show majority of research on shock-induced interface instability dealt with the classic RM instability (referring to the uniform incident shock interacting with initially perturbed interface) which followed after Richtmyer's seminal work. In recent decades, much interest has been paid to the generalized RM instability (standing for the rippled incident shock interacting with material interface) and great progresses have been achieved through experimental and numerical investigations. In this article, we review the developments of methods used to study generalized RM instability. Three kinds of experimental method and three sets of numerical codes are introduced. Images obtained by those methods and post treatment analysis are presented, including the incident shock shape, shock strength, density ratio effects and physical mechanism and theoretical model on the evolution of generalized RM instability in both planar and convergent geometry cases. Finally, based on the limitation of current studies, we propose the following four directions for future study: comparison of turbulent mixing processes induced by general and classic RM instability; general RM experiment at extremes; advanced diagnostic techniques; theory, computation and underlying mechanism.