SHOCK CAVITY IMPLOSION MORPHOLOGIES AND VORTICAL PROJECTILE GENERATION IN AXISYMMETRICAL SHOCK-SPHERICAL FAST SLOW BUBBLE INTERACTIONS/

Collapsing shock-bounded cavities in fast/slow (F/S) spherical and nea r-spherical configurations give rise to expelled jets and vortex rings . In this paper, we simulate with the Euler equations planar shocks in teracting with an R12 axisymmetric spherical bubble. We visualize and quantify results that show evolving upstream and downstream complex wa ve patterns and emphasize the appearance of vortex rings. We examine h ow the magnitude of these structures scales with Mach number. The coll apsing shock cavity within the bubble causes secondary shock refractio ns on the interface and an expelled weak jet at low Mach number. At hi gher Mach numbers (e.g. M = 2.5) 'vortical projectiles' (VP) appear on the downstream side of the bubble. The primary VP arises from the del ayed conical vortex layer generated at the Mach disk which forms as a result of the interaction of the curved incoming shock waves that coll ide on the downstream side of the bubble. These rings grow in a self-s imilar manner and their circulation is a function of the incoming shoc k Mach number. At M = 5.0, it is of the same order of magnitude as the primary negative circulation deposited on the bubble interface. Also at M = 2.5 and 5.0 a double vortex layer arises near the apex of the b ubble and moves off the interface. It evolves into a VP, an asymmetric diffuse double ring, and moves radially beyond the apex of the bubble . Our simulations of the Euler equations were done with a second-order -accurate Harten-Yee-type upwind TVD scheme with an approximate Rieman n Solver on mesh resolution of 803 x 123 with a bubble of radius 55 zo nes.