Shock-driven gas-particle flows exist in a wide variety of physical systems, covering the range from dilute to dense regime. There are a lot of fundamental questions remaining to be answered, like the evolutions of flow instability, two-phase interactions, and inter-particle collision effects. In this work, the Eulerian-Lagrangian approach with gas-particle four-way coupling is applied to model two-dimensional shock-driven gas-particle flow under the moderately dense regime. For the gas flow, the formation mechanism of primary and secondary vortexes is discussed. The primary vortex is caused by the roll-up of slip line, while the secondary vortexes are induced by the velocity and density difference between the penetrating flow of particle-laden zone and the outside mainstream. Parametric studies of different Mach numbers, particle diameters and initial volume fractions have been performed to investigate the effects on shock behaviours and slip line instabilities. For the particle phase, a high-volume-fraction compression region forms at the upstream cloud zone, which blocks the penetrating gas, and results in the formation of slip line. The cloud tail is mainly composed of the upstream edge particles. The inter-particle collisions have impact on the particle distributions, and greatly affect the slip line stability at the upstream cloud edge. This work provides valuable insights into the instability mechanism of compressible gas-solid flow and the particle dispersion behaviours. However, it is important to note that our analysis is based on a two-dimensional configuration. In a real three-dimensional context, the generation of vortices is likely to differ, and may affect the particle dynamics to a certain degree.

中文翻译：

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受事件冲击影响的圆形中等密度粒子云的不稳定性

冲击驱动的气体粒子流存在于各种物理系统中，涵盖从稀流到稠密的范围。还有许多基本问题有待解答，例如流动不稳定性的演变、两相相互作用和粒子间碰撞效应。在这项工作中，采用具有气体-粒子四向耦合的欧拉-拉格朗日方法来模拟中等密度状态下二维激波驱动的气体-粒子流。对于气流，讨论了初级涡流和次级涡流的形成机制。初级涡是由滑移线卷起引起的，次级涡是由颗粒填充区穿透流与外部主流之间的速度和密度差引起的。对不同马赫数、颗粒直径和初始体积分数进行了参数研究，以研究其对冲击行为和滑移线不稳定性的影响。对于颗粒相，上游云区形成高体积分数压缩区，阻挡气体穿透，导致滑移线的形成。云尾主要由上游边缘粒子组成。粒子间碰撞对粒子分布产生影响，并且极大地影响上游云缘滑移线的稳定性。这项工作为可压缩气固流的不稳定机制和颗粒分散行为提供了有价值的见解。然而，值得注意的是，我们的分析是基于二维配置。在真实的三维环境中，涡流的产生可能会有所不同，并且可能在一定程度上影响粒子动力学。