Particle Lag Effects in Shock-Driven Multiphase Instability with Solid Particles*

The Shock-Driven Multiphase Instability (SDMI) occurs when a multiphase (particle-gas) medium is

instantaneously accelerated by the passage of a shock-wave. At the macro-scale, shock-driven multiphase mixing

(cloud-mixing) occurs when vorticity is deposited at an interface between two multiphase mixtures of differing

properties. In the limit of small, fast-reacting particles the interface evolves like the classic Richtmyer-Meshkov

Instability; however, as particle velocity equilibration times grow the vorticity deposition is reduced. Due to this, a

deeper understanding of the particle response time effects to better predict the level of mixing generated.

Experiments are performed in a shock tube facility to investigate shock-driven multiphase mixing for different

particle velocity equilibration times. A multiphase interface consisting of solid particles and carrier gas is

impulsively accelerated by a shock wave. The particle size distribution and concentration are characterized ex-situ

and in-situ utilizing Phase Doppler Anemometry and particle mass retention. The particle response time was studied

while maintaining the same effective Atwood by controlling the concentration, particle size, and material properties.

The multiphase interface development was captured through an ensemble of Mie-scattering images. These

measurements allow for the characterization of the vorticity deposition. Results are compared with theoretical for

the RMI and a SDMI vorticity deposition model is proposed.