Volume-Fraction Distribution of Moderately Dense Particles in Re-Shocked Richtmyer-Meshkov Flow

Re-shocked Richtmyer-Meshkov flow laden with particles is extensively observed in supernova explosions and laser-driven inertial confinement fusion experiments. Studies on the dispersal of particles are fundamental in this topic, and the most intuitive quantity used to denote dispersal is the volume-fraction distribution. Previous studies on dilute particles have shown that the volume-fraction distribution deviates from the initially uniform distribution after re-shock. However, the dispersal of moderately dense particles remains an open question. To address this problem, we conducted three-dimensional simulations using the well-verified compressible multiphase particle-in-cell (CMP-PIC) method. We initially distributed the particles uniformly in a planar shock tube with an Air/ SF ₆ interface, setting different initial volume fractions for the particles, and compared the one-dimensional profile of particle velocity and volume fractions. Our findings reveal that the peak of the velocity profile is consistently located at the interface, and its magnitude decreases slightly as particle becomes denser. Moreover, the volume fraction distribution reveals an intriguing phenomenon in which particles tend to concentrate near the reflection wall after re-shock, with denser particles exhibiting a stronger tendency towards clustering. This study enhances our understanding of the following behaviors of particles under the coupled effect of interface instability and shock wave propagation.