High-amplitude effect on Richtmyer–Meshkov instability at a single-mode heavy–light interface

An experimental study is conducted to explore the high-amplitude effect on Richtmyer–Meshkov instability (RMI) at a single-mode heavy–light interface. A wide range of scaled initial amplitude (ka0, where k and a0 are perturbation wavenumber and initial amplitude, respectively) is considered. Qualitatively, nonstandard (standard) indirect phase inversion occurs in experiments with high (low and moderate) ka0. The nonstandard indirect phase inversion exhibits a complex process, and the interface mixing width does not reduce to near zero. Quantitatively, the linear model poorly (accurately) predicts the post-phase-inversion linear amplitude growth rate when ka0 is high (low and moderate). Additionally, a representative theoretical reduction factor fortuitously evaluates the high-amplitude effect on the post-phase-inversion linear amplitude growth rate well. The high-amplitude effect significantly alters the nonlinear evolution law, which differs from the case of RMI at a light–heavy interface. None of the considered nonlinear models can accurately predict the amplitude evolution under all ka0 conditions, regardless of whether their expressions are related to ka0 or not. Based on the current experimental results, an empirical nonlinear model is proposed to describe RMI at a single-mode heavy–light interface across a wide range of ka0 conditions.