Measurements of Velocity in the Turbulent Stage of Gaseous Mixtures Induced by Shock Waves

Abstract

We study the mixing of two gases of different densities arising from the shock wave-induced Richtmyer-Meshkov instability (RMI). The RMI appears when a shock wave impulsively accelerates two gases separated by an interface generally parallel to the shock plane but presenting small perturbations. The RMI is a manifestation of the baroclinic instability: the production of voracity is proportional to the vector product of pressure gradient of the shock and the density gradient of the interface. It leads to an amplification of the interface perturbations, hence to the interpenetration of the two gases and eventually to the formation of a turbulent mixing zone. We seek to characterize the turbulent stage of the RMI in order to improve the modelization of this phenomenon. Measurements of mixing zone thickness and density profiles have already been performed in discontinuous heavy-light interfaces, where such a stage is observed [1] (see also the book of abstracts). Now, we try more direct measurements of turbulence, using laser Doppler velocimetry (LDV).