Experimental study of instability growth patterns of a shock- accelerated, thin fluid layer.

摘要

We have discovered a remarkable set of flow patterns induced by shock acceleration of two nearby, perturbed interfaces. Using planar laser-induced fluorescence (PLIF), we observe three distinct patterns in the nonlinear evolution of Richtmyer-Meshkov (RM) instabilities associated with this flow. We observe two patterns dominated by vortex pairs and one pattern showing no vortex pairing (until late time) for initial conditions that are indistinguishable by measurement techniques available for our work. The flow is initiated by spatially periodic perturbations imposed on a ''gas curtain'' interacting with a planar shock wave. These flow patterns are not predictable nor controllable in our experiments. Our measurements appear to be the first observations of a shock-driven flow exhibiting characteristics of bifurcation. Results were recently published, and more detailed results are forthcoming. We present here a brief description of the experiment, summary of results, and a vortex-based explanation of the phenomena.