Drag force on spherical particle moving near a plane wall in highly rarefied gas
Drag force on spherical particle moving near a plane wall in highly rarefied gas
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DOI：
10.1017/jfm.2019.921
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发表时间：
2020-01-25
影响因子：
3.7
通讯作者：
Klar, A.
中科院分区：
文献类型：
--
作者：
Goswami, P.;Baier, T.;Klar, A.
在大克努森数和小马赫（以及斯特劳哈尔）数的极限情况下，假设等温条件以及气体分子在壁面上的漫反射，对一个球体在与平面壁相切和法向运动时的阻力进行了评估。在自由分子流的极限情况下，利用一组耦合的弗雷德霍姆积分方程对气体的分子分布函数进行了评估。将结果与直接模拟蒙特卡罗计算进行了比较，并扩展到有限克努森数的情况。在所有情况下，都发现与切向运动相比，法向运动时力对间隙宽度的依赖性更强。当间隙内的流动本质上可被视为基本无碰撞时，在有限克努森数的情况下，观察到力对间隙宽度的依赖性与自由分子情况类似。
The drag force on a sphere in tangential and normal motion to a plane wall is evaluated in the limit of large Knudsen number and small Mach (and Strouhal) number assuming isothermal conditions and diffuse reflection of gas molecules on walls. In the limit of free molecular flow, the molecular distribution function of the gas is evaluated using a set of coupled Fredholm integral equations. The results are compared with direct simulation Monte Carlo calculations and extended for finite Knudsen numbers. In all cases stronger dependence of the force on the width of the gap is found for normal compared to tangential motion. When the flow within the gap can be considered as essentially collisionless in nature, a similar dependence of the force on the gap width is observed at finite Knudsen numbers as in the free molecular case.