This paper characterizes the refraction of a triple-shock configuration at planar fast–slow gas interfaces. The primary objective is to reveal the wave configurations and elucidate the mechanisms governing circulation deposition and velocity perturbation on the interface caused by triple-shock refraction. The incident triple-shock configuration is generated by diffracting a planar shock around a rigid cylinder, and four interfaces with various $Z_{{r}}$ (i.e. acoustic impedance ratio across the interface) are considered. An analytical model describing the triple-shock refraction is developed, which accurately predicts both the wave configurations as well as circulation deposition and velocity perturbation. Depending on $Z_{{r}}$ , three distinct patterns of transmitted waves can be anticipated: a triple-shock configuration; a four-shock configuration; a four-wave configuration. The underlying mechanism for the formation of these wave configurations is elucidated through shock polar analysis. A novel physical insight into the contribution of triple-shock refraction to the interface perturbation growth is provided. The results indicate that the reflected shock in an incident triple-shock configuration makes significant negative contribution to both circulation deposition and velocity perturbation. This investigation elucidates the underlying mechanism responsible for the relatively insignificant contribution of baroclinic circulation to the Richtmyer–Meshkov-like instability induced by a non-uniform shock, and provides an explanation for the decrease in growth rate of interface perturbation amplitude with increasing Atwood number.

中文翻译：

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平面快慢气体界面处三重激波配置的折射

本文描述了平面快慢气体界面处三重激波配置的折射。主要目标是揭示波的结构并阐明三重激波折射引起的界面上循环沉积和速度扰动的控制机制。入射三重激波配置是通过围绕刚性圆柱体衍射平面激波而生成的，并且具有不同的四个界面 $Z_{{r}}$ （即界面上的声阻抗比）被考虑。开发了描述三重激波折射的分析模型，该模型可以准确预测波的配置以及环流沉积和速度扰动。根据 $Z_{{r}}$ ，可以预期三种不同的发射波模式： 三重冲击配置；四冲击配置；四波配置。通过激波极性分析阐明了形成这些波配置的基本机制。提供了关于三重激波折射对界面微扰增长的贡献的新颖的物理见解。结果表明，入射三重激波配置中的反射激波对环流沉积和速度扰动均产生显着的负贡献。这项研究阐明了斜压环流对非均匀激波引起的 Richtmyer-Meshkov 类不稳定性的贡献相对较小的潜在机制，并解释了界面扰动幅度的增长率随着阿特伍德数的增加而降低。