Onset of the Crow instability from the late-time Richtmyer-Meshkov instability

The Crow instability is a vortex-line instability that leads to the three-dimensional growth of perturbations in counter-rotating vortices, with pinch-off leading to the generation of vortex rings at late-time. Classically, two incompressible, inviscid vortices are studied in this context; in the present work we use numerical simulations to demonstrate that the cores which are generated from the compressible multi-material Richtmyer-Meshkov instability are subject to the Crow instability. Thus, the onset of the Crow instability from the Richtmyer-Meshkov-induced cores can act as a mechanism for transitioning a nominally two-dimensional Richtymer-Meshkov flow to three dimensions. Further, the vortex rings produced when pinch-off occurs can enhance material mixing near the interface via their self-propulsion. We demonstrate that the Crow growth rates measured from numerical simulations match well with classical Crow theory with simple scaling, despite the compressible, multi-material nature of the flow.