开式空腔流动的蒙特卡罗直接模拟

Flow Simulation in Open Cavity by Direct Simulation Monte-Carlo Method

蒙特卡罗直接模拟(Direct Simulation Monte-Carlo)方法是一种基于分子动力论的随机性数值模拟方法,它在各类稀薄气体流动模拟中得到了广泛应用。本文首先讨论了DSMC方法的基本原理,引用文献结果论述了DSMC方法与Boltzmann方程的内在一致性,采用DSMC方法从分子运动论层次对过渡区开式空腔流动进行精细模拟,再现空腔内旋涡的形成及发展过程,了解复杂流场的流场特性。模拟和分析了空腔的形状(展弦比)、壁温以及Knudsen数(稀薄性)等因素对空腔内流动和旋涡结构的影响。研究表明,空腔的展弦比、壁面温度以及流动Knudsen数等因素对空腔内旋涡的大小、形状、位置、个数都有极大的影响,应用DSMC方法可以真实再现稀薄条件下的开式空腔流动。

Direct Simulation Monte-Carlo method is a random numerical simulation method based on the molecular kinetic theory, which is widely used in a variety of rarefied fluid flow simulation. In this paper, firstly the elements of DSMC method was discussed, and the inherent consistency between DSMC method and Boltzmann equation was discussed according with the results in references, then the transitional fluid flow in the open cavity was simulated elaborately by DSMC method in the arrangement of molecular motion theory. The simulation reappeared the process of the development of the vortex in the cavity and made the complicated characteristic of the flow known well. The influence of the span-chord ratios of the cavity, wall temperature and Knudsen number on the flow and the vortex structure in the cavity were also discussed. The study indicates that the factors above have great influence on the size, shape, location and number of vortex in the open cavity, and the DSMC method is a good method to simulate the rarefied gas flow in the open cavity.