Richtmyer-Meshkov instability growth: experiment, simulation and theory

Richtmyer-Meshkov instability is investigated for negative Atwood number an d two-dimensional sinusoidal perturbations by comparing experiments, numeri cal simulations and analytic theories. The experiments were conducted on th e NOVA laser with strong radiatively driven shocks with Mach numbers greate r than 10. Three different hydrodynamics codes (RAGE, PROMETHEUS and FroriT ier) reproduce the amplitude evolution and the gross features in the experi ment while the fine-scale features differ in the different numerical techni ques. Linearized theories correctly calculate the growth rates at small amp litude and early time, but fail at large amplitude and late time. A nonline ar theory using asymptotic matching between the linear theory and a potenti al flow model shows much better agreement with the late-time and large-ampl itude growth rates found in the experiments and simulations. We vary the in cident shock strength and initial perturbation amplitude to study the behav iour of the simulations and theory and to study the effects of compression and nonlinearity.