Lin Chuandong, Luo Kai H, Xu Aiguo, Gan Yanbiao, Lai Huilin
Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-Sen University, Zhuhai 519082, China.
Department of Mechanical Engineering, University College London, Torrington Place, London WC1E 7JE, United Kingdom.
Phys Rev E. 2021 Jan;103(1-1):013305. doi: 10.1103/PhysRevE.103.013305.
A multiple-relaxation-time discrete Boltzmann model (DBM) is proposed for multicomponent mixtures, where compressible, hydrodynamic, and thermodynamic nonequilibrium effects are taken into account. It allows the specific heat ratio and the Prandtl number to be adjustable, and is suitable for both low and high speed fluid flows. From the physical side, besides being consistent with the multicomponent Navier-Stokes equations, Fick's law, and Stefan-Maxwell diffusion equation in the hydrodynamic limit, the DBM provides more kinetic information about the nonequilibrium effects. The physical capability of DBM to describe the nonequilibrium flows, beyond the Navier-Stokes representation, enables the study of the entropy production mechanism in complex flows, especially in multicomponent mixtures. Moreover, the current kinetic model is employed to investigate nonequilibrium behaviors of the compressible Kelvin-Helmholtz instability (KHI). The entropy of mixing, the mixing area, the mixing width, the kinetic and internal energies, and the maximum and minimum temperatures are investigated during the dynamic KHI process. It is found that the mixing degree and fluid flow are similar in the KHI process for cases with various thermal conductivity and initial temperature configurations, while the maximum and minimum temperatures show different trends in cases with or without initial temperature gradients. Physically, both heat conduction and temperature exert slight influences on the formation and evolution of the KHI morphological structure.
针对多组分混合物提出了一种多松弛时间离散玻尔兹曼模型（DBM），该模型考虑了可压缩、流体动力学和热力学非平衡效应。它允许比热容比和普朗特数可调，适用于低速和高速流体流动。从物理角度来看，除了在流体动力学极限下与多组分纳维-斯托克斯方程、菲克定律和斯特凡-麦克斯韦扩散方程一致外，DBM还提供了更多关于非平衡效应的动力学信息。DBM描述非平衡流动的物理能力超越了纳维-斯托克斯表示，能够研究复杂流动中的熵产生机制，特别是在多组分混合物中。此外，采用当前的动力学模型研究可压缩开尔文-亥姆霍兹不稳定性（KHI）的非平衡行为。在动态KHI过程中研究了混合熵、混合面积、混合宽度、动能和内能以及最高和最低温度。结果发现，在具有不同热导率和初始温度配置的情况下，KHI过程中的混合程度和流体流动相似，而在有或没有初始温度梯度的情况下，最高和最低温度呈现不同的趋势。从物理上讲，热传导和温度对KHI形态结构的形成和演化都有轻微影响。
