Insights into coupling effects of double light square bubbles on shocked hydrodynamic instability

Abstract

This study investigates the coupling effects of double light square bubbles on the evolution of Richtmyer–Meshkov instability under shock interactions. Using high-fidelity numerical simulations based on a high-order modal discontinuous Galerkin solver, we analyze the influence of initial separation distance, Atwood number, and Mach number on bubble interactions, vortex formation, and instability growth. The results reveal that the coupling strength between the bubbles increases significantly as the separation distance decreases, leading to enhanced vorticity production, strong coupling jets, and intensified mixing. At larger separations, the bubbles evolve independently with minimal interaction, whereas at smaller separations, the merging of inner vortex rings and rapid enstrophy growth characterize the flow. The study further establishes a scaling law to quantify the dependence of coupling strength on separation distance, Atwood number, and Mach number, providing predictive insights into peak enstrophy generation and turbulence enhancement. The findings have important implications for understanding shock-driven hydrodynamic instabilities in inertial confinement fusion, astrophysical flows, and high-energy-density physics.