低马赫数下圆球绕流的硬球-拟颗粒模拟  

Simulation of flow around a single sphere at low mach numbers by hard sphere/pseudo particle modeling(HS-PPM)

作　　者：马琳博 赵明璨 赵祺 崔丽杰 陈飞国[2] 葛蔚[2,3] MA Linbo;ZHAO Mingcan;ZHAO Qi;CUI Lijie;CHEN Feiguo;GE Wei(School of Chemical Sciences,University of Chinese Academy of Sciences(UCAS),Beijing 100049,China;State Key Laboratory of Multiphase Complex Systems,Institute of Process Engineering(IPE),Chinese Academy of Sciences(CAS),Beijing 100190,China;School of Chemical Engineering,University of Chinese Academy of Sciences(UCAS),Beijing 100049,China)

机构地区：[1]中国科学院大学化学科学学院,北京市100049 [2]中国科学院过程工程研究所多相复杂系统国家重点实验室,北京市100190 [3]中国科学院大学化学工程学院,北京市100049

出　　处：《计算机与应用化学》2019年第5期439-444,共6页Computers and Applied Chemistry

基　　金：国防基础科研科学挑战专题项目(编号:TZ2016001);国家自然科学基金资助项目(编号:91834303);中国科学院前沿科学重点研究项目(编号:QYZDJ-SSW-JSC029);中国科学院信息化专项课题(编号:XXH13506-301)

摘　　要：硬球-拟颗粒模拟(HS-PPM)能够描述流动的微观细节,已应用于反应-扩散耦合和超声速流动等的研究。但对过程工业中广泛存在的低马赫数(Ma<1.0)流动,HS-PPM的适用性还没有直接证据。本文以低雷诺数(Re≤10)和低马赫数(Ma<1.0)下的圆球绕流为实例探索了这种可行性。圆球表面以解析法描述以保证光滑性,并采用回弹模型保证无滑移边界条件,所有方向上采用周期性边界条件。当Ma<0.1时,分析了模拟体系固含率、模拟区域的形状以及努森数对曳力系数的影响。结果表明,曳力系数随固含率的提高而增加;低固含率下的曳力系数与无限大流场中的单颗粒绕流接近;低努森数下得到的曳力系数更高。采用时空平均得到的流场稳定、轴对称,且无明显的温度和密度梯度,符合公认的实验和模拟结果。Ma>0.1时的曳力系数随马赫数的变化符合前人报道。上述结果展示了HS-PPM用于低马赫数流动研究的可行性。Hard Sphere/Pseudo Particle Modeling(HS-PPM) can describe the micro-details of flow and has been applied to the study of reaction-diffusion coupling process and supersonic flow. However, there is no direct evidence for the applicability of HS-PPM for low Mach number(Ma<1.0) flows widely existing in process industries. In this study, the flow past a single sphere under low Reynolds number(≤10) and low Mach number(<1.0) was simulated with HS-PPM as test cases to explore its applicability. In the parallel program, the whole simulation domain was divided into several subdomains according to the distribution of computational load, and PPM was used for the information exchange between the subdomains. The sphere was described analytically to preserve the exact geometry, and at the surface of the sphere, no-slip boundary condition was satisfied and periodic boundary condition was imposed in all directions of the simulation domain. The effect of solid volume fraction, aspect ratio of the simulation domain and Knudsen number on the drag coefficient at Ma<0.1 and Ma>0.1 were investigated, respectively. When Ma<0.1, the results shown that the drag coefficient obtained at high solid volume fraction was larger than that of a single sphere in unbounded flow;which the drag coefficient obtained at low solid volume fraction were closer to the latter. The drag coefficient obtained at low Knudsen number was higher. The flow field obtained by time-space average was stable and nearly axis-symmetry, and there was no obvious temperature and density gradient, which was in good agreement with the classical results, though some signature of thermal fluctuation can still be noticed. When Ma>0.1, the variation of drag coefficient with Ma was found to be consistent with previous reports. Together with our earlier publications on HS-PPM simulation of supersonic flow, these results further demonstrated that the HS-PPM may be a general approach for more complex flow condition.

关 键 词：分子动力学模拟 硬球-拟颗粒模拟 圆球绕流 无滑移 曳力系数 

分 类 号：O35[理学—流体力学] TQ015[理学—力学]