Observation of the Development of Secondary Features in a Richtmyer–Meshkov Instability Driven Flow

Abstract

Richtmyer–Meshkov instability (RMI) has long been the subject of interest for analytical, numerical, and experimental studies. In comparing results of experiment with numerics, it is important to understand the limitations of experimental techniques inherent in the chosen method(s) of data acquisition. We discuss results of an experiment where a laminar, gravitydriven column of heavy gas is injected into surrounding light gas and accelerated by a planar shock. A popular and wellstudied method of flow visualization (using glycol droplet tracers) does not produce a flow pattern that matches the numerical model of the same conditions, while revealing the primary feature of the flow developing after shock acceleration: the pair of counterrotating vortex columns. However, visualization using fluorescent gaseous tracer confirms the presence of features suggested by the numerics; in particular, a central spike formed due to shock focusing in the heavygas column. Moreover, the streamwise growth rate of the spike appears to exhibit the same scaling with Mach number as that of the counterrotating vortex pair (CRVP).