Ross White

Numerical Simulation of a Shock-Accelerated Multiphase Fluid Interface

A Richtmyer-Meshkov Instability (RMI) [1, 2] is generated when an interface between two different fluids is impulsively accelerated. The instability develops due to misalignment of the density and pressure interfaces. This misalignment results in the deposition of vorticity, causing the formation of an instability that grows nonlinearly with time and eventually may transition to fully turbulent flow. It has been recently shown that a similar class of instability can evolve in a multi-phase flow [3], where the density gradient is caused by a second, non-fluid phase.

Vortex deposition in shock-accelerated gas with particle/droplet seeding

We present an experimental and numerical study of post-shock evolution of gas initially seeded with small droplets or particles. In two-phase media with gas being the embedding phase occupying most of the volume, shock acceleration can lead to vortex formation. The physical mechanism responsible for the vorticity deposition in this case is different from that of Richtmyer-Meshkov instability that would emerge on a gas-gas density interface. After the shock passage, the particles or droplets lag behind the surrounding gas. Momentum exchange between the embedded phase and the embedding phase leads to non-uniform local equilibrium velocity distribution, and thus to shear and vortex formation. Here we investigate shock interaction with a cylindrical particle-seeded column (with and without reshock).