Ye Haiyan, Lai Huilin, Li Demei, Gan Yanbiao, Lin Chuandong, Chen Lu, Xu Aiguo
College of Mathematics and Informatics, FJKLMAA, Fujian Normal University, Fuzhou 350117, China.
North China Institute of Aerospace Engineering, Langfang 065000, China.
Entropy (Basel). 2020 Apr 26;22(5):500. doi: 10.3390/e22050500.
Based on the framework of our previous work [H.L. Lai et al., Phys. Rev. E, , 023106 (2016)], we continue to study the effects of Knudsen number on two-dimensional Rayleigh-Taylor (RT) instability in compressible fluid via the discrete Boltzmann method. It is found that the Knudsen number effects strongly inhibit the RT instability but always enormously strengthen both the global hydrodynamic non-equilibrium (HNE) and thermodynamic non-equilibrium (TNE) effects. Moreover, when Knudsen number increases, the Kelvin-Helmholtz instability induced by the development of the RT instability is difficult to sufficiently develop in the later stage. Different from the traditional computational fluid dynamics, the discrete Boltzmann method further presents a wealth of non-equilibrium information. Specifically, the two-dimensional TNE quantities demonstrate that, far from the disturbance interface, the value of TNE strength is basically zero; the TNE effects are mainly concentrated on both sides of the interface, which is closely related to the gradient of macroscopic quantities. The global TNE first decreases then increases with evolution. The relevant physical mechanisms are analyzed and discussed.
基于我们之前工作的框架[H.L. Lai等人，《物理评论E》，，023106 (2016)]，我们继续通过离散玻尔兹曼方法研究克努森数对可压缩流体中二维瑞利 - 泰勒（RT）不稳定性的影响。研究发现，克努森数效应强烈抑制RT不稳定性，但总是极大地增强全局流体动力学非平衡（HNE）和热力学非平衡（TNE）效应。此外，当克努森数增加时，由RT不稳定性发展引起的开尔文 - 亥姆霍兹不稳定性在后期难以充分发展。与传统计算流体动力学不同，离散玻尔兹曼方法进一步呈现出丰富的非平衡信息。具体而言，二维TNE量表明，远离扰动界面时，TNE强度值基本为零；TNE效应主要集中在界面两侧，这与宏观量的梯度密切相关。全局TNE随演化先减小后增大。对相关物理机制进行了分析和讨论。
