Comparison of inclined and aligned interface Richtmyer-Meshkov instabilities

The classical Richtmyer-Meshkov instability arises from the interaction of a shock wave with a material interface that is nominally aligned with the shock. The problem is homogeneous in the directions perpendicular to the shock propagation direction. Shock interaction with a material interface that is nominally inclined with respect to the shock brings out the effects of inhomogeneity in the transverse direction. This creates large scale shear and large correlated vortex structures. The inclined interface RM simulations with a 1:1 crossectional domain target the experiment of McFarland et. al. (2014) and the aligned interface RM data is from Tritschler et. al. (2014). Turbulence energy budgets are characterized for both cases and compared. The inclined interface problem is found to have large scale shear that acts as a prolonged energy injection mechanism for the late time turbulent region while the turbulent kinetic energy decays in the aligned interface problem. Compressibility effects are characterized and are found to arise from coupling of the mixing region with the end wall. A scale decomposition analysis is also performed to assess the energetics of the problem as a function of scale.