The physical problem based on a shock-accelerated bubble has long been a fascinating subject in the study of the Richtmyer-Meshkov (RM) instability. In this study the behavior of a shock-accelerated heavy cylindrical bubble under the nonequilibrium conditions of diatomic and polyatomic gases is investigated numerically. For this purpose, a two-dimensional system of unsteady physical conservation laws derived from the Boltzmann-Curtiss kinetic equations is solved by employing an explicit mixed-type modal discontinuous Galerkin method with uniform meshes. For validation, the numerical results are compared with available experimental and computational results, and are found to be in good agreement. The results demonstrate that the effects of different physical properties, including thermal nonequilibrium and bulk viscosity associated with the viscous excess normal stress on diatomic and polyatomic gases, play a significant role in describing the RM instability during the interaction between a planar shock wave and a heavy bubble. The effects of diatomic and polyatomic gases result in a substantial change in the flow morphology with complex wave patterns, vortex creation, vorticity generation, and bubble deformation. In contrast to monatomic gas, the generation of larger rolled-up vortex chains, a different kind of outward jet formation, and a large mixing zone with strong and large expansion are observed in diatomic and polyatomic gases. A detailed study of the effects of diatomic and polyatomic gases is investigated through the vorticity generation, degree of nonequilibrium, the evolution of enstrophy, and dissipation rate. Furthermore, the time variations of the shock trajectories and the interface scales are investigated from the viewpoint of quantitative analysis. Finally, the effects of nonequilibrium parameters, including bulk viscosity and index of inverse power law, are also investigated. The present work can be seen as a supplement to the RM instability research to examine the nonequilibrium effects of diatomic and polyatomic gases on the dynamics of a shock-accelerated heavy cylindrical bubble.

中文翻译：

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在双原子和多原子气体的非平衡条件下，加速冲击的重圆柱气泡的行为

在Richtmyer-Meshkov（RM）不稳定性的研究中，基于冲击加速气泡的物理问题一直是一个引人入胜的主题。在这项研究中，数值研究了在双原子和多原子气体的非平衡条件下冲击加速的重圆柱气泡的行为。为此，通过采用具有均匀网格的显式混合型模态不连续伽勒金方法，解决了从玻尔兹曼-柯蒂斯动力学方程派生的二维非恒定物理守恒定律系统。为了进行验证，将数值结果与可用的实验和计算结果进行比较，并发现它们之间具有很好的一致性。结果表明，不同物理性质的影响，包括热不平衡和与双原子和多原子气体上的粘性过大法向应力相关的体粘度，在描述平面冲击波与重气泡之间相互作用期间的RM不稳定性方面起着重要作用。双原子和多原子气体的作用会导致流动形态发生实质性变化，具有复杂的波型，涡旋产生，涡旋产生和气泡变形。与单原子气体相反，在双原子气体和多原子气体中观察到了较大的卷起涡旋链的产生，不同类型的向外射流的形成以及具有强而大的膨胀的大混合区。通过涡度的产生，不平衡程度，涡旋的演变，和耗散率。此外，从定量分析的角度研究了冲击轨迹和界面尺度的时间变化。最后，还研究了非平衡参数的影响，包括体粘度和逆幂定律指数。目前的工作可以看作是对RM不稳定性研究的补充，以研究双原子和多原子气体对冲击加速的重圆柱气泡动力学的非平衡作用。