Vorticity Dynamics of the Richtmyer-Meshkov Instability

The interaction between a shock wave and a material interface separating two fluids of different densities gives rise to the Richtmyer-Meshkov instability, ubiquitous in both nature and engineering applications, such as high energy density physics and scramjet combustion. The initial baroclinic vorticity deposited along the interface by the incoming shock is the dominant and driving mechanism of the evolution of the interface in time. This study explores the evolution of an initially perturbed interface dominated by the vorticity dynamics of the interface. The use of a vortex-sheet approach allows us to identify the mechanisms responsible for the dynamics of the interfacial vorticity, and enhances our understanding of the vortex cores behavior. We identify three consecutive phases for the temporal evolution of the circulation, and quantify secondary vorticity appearing in the non-linear regime. A scaling analysis of the secondary vorticity is performed based on the parameters of the problem.