Numerical Study of Multiple Shock-Bubble Interactions*

We have performed numerical simulations of interactions of a low-density bubble with multiple shocks, including a planar incident shock and subsequent shocks reflected from channel walls. The compressible fluid dynamics is described by Euler and Navier-Stokes equations solved by a high-order method combined with a front-tracking algorithm to maintain the sharp interface between the bubble and the background gas. Simulation results were interpreted using Fourier analysis of vorticity and kinetic energy. The analysis shows that the Richtmyer- Meshkov instability resulting from repeated shock-interface interactions generates vorticity on multiple scales. Vorticity and energy spectra for the high-speed flow dominated by shock- interface interaction are very different from those expected for an equilibrium Kolmogorov-type turbulence. These results can also be extended to high-speed turbulent combustion dominated by shock-flame interactions.