Two-dimensional simulation of instability growth due to shocks

The 2D Lagrangian calculations of impulsively driven instabilities in compressible fluids. The results of four problems are reported. In the first two, the first shock crosses the perturbed interface in a direction from heavy to light. During the shock passage, the interface thinks it is stable and starts to oscillate but once the shock has delivered its impuse and moved away, the interface realizes its error and the perturbation continues to grow with a constant velocity. The result of this is a phase reversal of the perturbation amplitude during the first shock. Following this is a succession of shocks which are different in the two problems due to a change in boundary conditions. In the last two problems, the first shock crosses the perturbed interface in a direction from light to heavy, and the perturbation amplitude grows with time after first being decreased by the shock compression. Later in time a heavy to light shock crosses the interface, and again the interface goes through a phase reversal.