Freeze-out of perturbation growth of single-mode helium–air interface through reflected shock in Richtmyer–Meshkov flows

Abstract

‘Freeze-out’ of amplitude growth, i.e. the amplitude growth stagnation of a shocked helium–air interface, is realized through a reflected shock, which produces baroclinic vorticity of the opposite sign to that deposited by the first shock. Theoretically, a model is constructed to calculate the relations among the initial parameters for achieving freeze-out. In particular, if the amplitude growth is within the linear regime at the arrival of the reflected shock, the time interval between the impacts of two shock waves is linearly related to the initial perturbation wavelength, and is independent of the initial perturbation amplitude. Experimentally, an air–SF $_6$ (or air–argon) plane interface is adopted to produce a weak reflected shock. Seven experimental runs with specific initial conditions are examined. For all cases, freeze-out is achieved after the reflected shock impact under the designed conditions.

Experimental study on Richtmyer–Meshkov instability at a light–heavy interface over a wide range of Atwood numbers

“…Second, the initial distance between flat and single-mode interfaces is 105.00 mm, which ensures that the flat interface would not heavily affect the single-mode interface evolution within the effective experimental time (Chen et al. 2023). Third, gas components, and are obtained by matching the velocities of shocks and interface obtained from experiments and predicted by one-dimensional gas dynamics theory.…”

“…These issues remain unclear, which motivates the present study. The soap-film technique (Liu et al 2018;Liang et al 2019) enables the formation of well-defined desirable interfaces, while the gas-layer scheme (Liang & Luo 2021;Chen et al 2023) allows for a wide variation of A 1 , providing us with a rare opportunity to study RMI over a wide range of A 1 finely through experiments. In this work, by using the soap-film technique to generate initial interfaces and the gas-layer scheme to alter A 1 , first the evolution law of RMI under a wide range of A 1 conditions is obtained experimentally.…”

Effects of reverberating waves and interface coupling on a divergent Richtmyer–Meshkov instability

“…2022; Chen et al. 2023). More recently, this soap-film technique was extended to generate gas layers with controllable shape and thickness, which enables the experimental study on RM instability at various types of controllable gas layers (Liang & Luo 2021 a , 2022).…”

“…A series of elaborate experiments demonstrated that this technique can largely eliminate three-dimensionality and gas diffusion. In addition, the soap film was found to produce a negligible influence on the interface evolution at early to intermediate stages (Liang et al 2021;Guo et al 2022;Chen et al 2023). More recently, this soap-film technique was extended to generate gas layers with controllable shape and thickness, which enables the experimental study on RM instability at various types of controllable gas layers (Liang & Luo 2021a.…”

Attenuation of perturbation growth of single-mode SF6–air interface through reflected rarefaction waves

“…For a light-heavy interface, attenuation and freeze-out of the perturbation were realized through a weaker reflected shock in numerical simulations (Mikaelian 2010) and in shock-tube experiments (Chen et al 2023). However, in a traditional ICF capsule, the incident shock always travels from the heavy fluid to the light one (Lindl et al 2014).…”