Shock-driven flow physics of Richtmyer–Meshkov instability in tandem light cylindrical interfaces

The Richtmyer–Meshkov instability (RMI) arises when a shock wave impulsively accelerates a perturbed density interface, generating baroclinic vorticity and driving complex interface evolution. This study presents high-fidelity numerical simulations of shock-driven RMI in tandem light cylindrical interfaces, examining the influence of center-to-center spacing, shock Mach number, and interface size. An in-house high-order modal discontinuous Galerkin solver is employed to resolve multi-scale wave interactions, vortex dynamics, and deformation processes. The results show that reduced spacing strongly enhances instability growth, vorticity generation, and mixing through interfacial coupling, with baroclinic vorticity dominating at late times. Increasing Mach number amplifies both dilatational and baroclinic contributions, accelerating transition to small-scale turbulence. Interface-size variations not only reveal that larger radii strengthen initial vortex generation but also alter downstream response via shock focusing and flow deflection. Comparative analyses with single-interface cases confirm that multi-interface coupling sustains instability growth, modifies circulation dynamics, and enhances turbulent mixing. Furthermore, comparisons between tandem light- and heavy-gas configurations highlight reversed baroclinic vorticity deposition and distinct coupling pathways in light gases, leading to earlier turbulence onset and enhanced small-scale structures. These findings highlight tandem light-cylinder RMI as a distinct regime with implications for shock-driven mixing layers, supersonic combustion, and inertial confinement fusion.