UWFDM-1301 Shock-Induced Instabilities on a Spherical Gas Bubble

Experiments studying the compression and unstable growth of an argon bubble in a nitrogen environment, subjected to planar shock wave (1.32 ≤ M < 4) are performed in a vertical shock tube of square internal cross section. In parallel with laboratory experiments, a computational investigation is carried out with the multi-fluid compressible hydrodynamics code raptor, using adaptive mesh refinement to achieve high resolution of the fluid interfaces. Experiments and computations confirm that the interaction of a planar shock wave propagating in nitrogen with a free-falling spherical soap bubble filled with argon first deforms the bubble into an oblate disk-like object and, subsequently, into a vortex ring. At later times, however, secondary features appear in the flow, which result from small-scale nonuniformities present in the initial condition. The evolution of the bubble is characterized, and integral length scale measurements are analyzed on a non-dimensional time scale for incident shocks within a range of Mach numbers.