High-amplitude single-mode perturbation evolution at the Richtmyer-Meshkov instability

The single-mode Richtmyer-Meshkov hydrodynamic instability at light/heavy (air/SF6 and air/CO2), close density (air/N2), and heavy/light (air/He) interfaces has been experimentally studied for a low incident shock wave Mach number. Two identical 2D half sinusoidal initial perturbations, with a relatively high initial amplitude, were considered in order to rapidly reach the nonlinear regime and check the reduction of the initial growth rate compared to that predicted by the small-amplitude theory. The growth rate measurements for the air/SF6 and air/CO2 cases are in excellent agreement with the nonlinear model of Sadot et al. coupled with a reduction factor suggested by Rikanati et al. In the air/N2 case, the reversal phase can be precisely described by the linear theory. Finally, the heavy/light experiment is well described by the Vandenboomgaerde model also coupled with a smaller reduction factor.