Turbulent mixing in multifluid vortex rings before & after shock interaction*

In the intermediate stages of Richtmyer-Meshkov instability development, prior to the development of turbulence, vortical flow structures are commonly observed at the outer extents of the mixing region. The behavior of these structures and their evolution upon reshock may play an important role in the tails of the mixedness distribution, but they are difficult to repeatably study because of the inherently unstable mixing process. 

To capture these vortex-shock interaction events in isolation, an ensemble of simultaneous planar laser-induced fluorescence/particle image velocimetry measurements were acquired following the firing of a small, open-ended shock tube filled with either argon, CF₄, or SF₆ upwards into ambient nitrogen. The density mismatch between the initially unmixed light and heavy gases corresponds to Atwood numbers of 0.19, 0.51, and 0.67, respectively. The measurements capture the initial propagation of the heavy-gas vortex ring as well as its perturbation upon M=1.8 shock interaction.