First, Mumford & Son's "Little Lion Man" is amazing. Listen. Purchase. Bonus points for accidentally starting two or more copies and noticing it sounds excellent in a round. Found it on thesixtyone.com, which is a great source for day-to-day working music and occasionally emits gems like this one.
Second, the Richtmyer-Meshkov setup I've been mucking with for two days is working. In it, a shock wave interacts with a perturbed, constant pressure interface between two different densities (details). Courtesy of gnuplot and gifsicle, here's an animated gif showing density evolution for a problem that's periodic in y and reflective at both x boundaries (click to view animation, 3.2M):
Just a roll up?
The reflective condition at the left boundary causes a re-reshock, which isn't usually what folks are interested in for these problems. I'm not entirely sure how to enforce a strict inflow condition for compressible simulations like these-- presumably such an inflow condition would eat the outgoing characteristics and stop the re-reshock seen here.