Computations in 3D for shock-induced distortion of a light spherical gas inhomogeneity

Results are presented from a series of 3D numerical simulations for shock-bubble interactions, for a spherical helium bubble in air or nitrogen initially at atmospheric pressure (A≈ -0.75), accelerated by a planar shock wave of Mach number M = 1.45, 2.08, or 2.95. The simulations are carried out using a multifluid, adaptive Eulerian Godunov code at a fine-grid resolution of R 100. The computed solutions clearly resolve well-known shock refraction and vortex formation processes. Further, distinct, counter-rotating secondary vortex rings are observed to form in the flowfield as a result of irregular shock refraction effects. The temporal development of the the bubble’s streamwise dimension and the mixing of bubble and ambient fluid are shown to collapse onto nearly self-similar trends on timescales based on a 1D gasdynamics analysis.