Variable sphere molecular model for inverse power law and Lennard-Jones potentials in Monte Carlo simulations
Variable sphere molecular model for inverse power law and Lennard-Jones potentials in Monte Carlo simulations
复制标题
蒙特卡罗模拟中逆幂律和 Lennard-Jones 势的变球分子模型
DOI：
10.1063/1.1517602
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发表时间：
2002
影响因子：
4.6
通讯作者：
H. Matsumoto
中科院分区：
文献类型：
--
作者：
H. Matsumoto
介绍了用于稀薄气体流动的Monte Carlo模拟的可变球（VS）分子模型，以提供与任何现实分子间势的扩散和粘性截面的一致性。然后将其应用于逆幂律（IPL）和Lennard-Jones（LJ）势。VS模型具有比可变硬球（VHS）或可变软球（VSS）模型更简单的散射规律，而且，它具有与VHS和VSS模型几乎相同的计算效率。为了验证VS模型的有效性，对均匀空间中的速度弛豫进行了模拟，并对均匀热浴气体中的分子扩散和单原子气体中的正激波结构进行了比较模拟。松弛麦克斯韦分布函数和均分之间的所有自由度建立良好;良好的协议显示在VS模型和IPL和LJ电位之间的分子扩散和冲击波结构。将VS模型与统计非弹性截面（SICS）模型相结合，应用于均匀空间中平移和转动能量弛豫的模拟。VS模型显示了麦克斯韦和玻尔兹曼分布函数的松弛以及所有自由度之间的均分。对氮气正激波中的转动弛豫进行了VS模型与SICS模型（VS-SICS）和VSS模型与SICS模型（VSS-SICS）的对比计算。VS-SICS模型和VS-SICS模型在激波结构和旋转能量分布函数方面表现出很好的一致性。这项研究表明，扩散和粘度截面，而不是每个分子碰撞的散射规律，影响宏观输运现象。
The variable sphere (VS) molecular model for the Monte Carlo simulation of rarefied gas flow is introduced to provide consistency for diffusion and viscosity cross-sections with those of any realistic intermolecular potential. It is then applied to the inverse power law (IPL) and Lennard-Jones (LJ) potentials. The VS model has a much simpler scattering law than either the variable hard sphere (VHS) or variable soft sphere (VSS) models; also, it has almost the same computational efficiency as the VHS and VSS models. A simulation of velocity relaxation in a homogeneous space and two comparative simulations of molecular diffusion in a homogeneous heat-bath gas and normal shock wave structure in a monatomic gas are made to examine VS model validity. The relaxation to a Maxwelliandistribution function and equipartition between all degrees of freedom are well established; good agreement is shown in the molecular diffusion and shock wave structure between the VS model and the IPL and LJ potentials. The VS model is combined with the statistical inelastic cross-section (SICS) model and applied to simulation of translational and rotational energy relaxation in a homogeneous space. The VS model shows the relaxation of Maxwellian and Boltzmanndistribution functions and equipartition between all degrees of freedom. Comparative calculation between the VS model with the SICS (VS-SICS) model and the VSS model with the SICS (VSS-SICS) model is made for rotational relaxation in a nitrogen normal shock wave. Good agreement is shown in the shock wave structure and rotational energy distribution function between the VS-SICS model and the VSS-SICS model. This study demonstrates that diffusion and viscosity cross-sections, rather than the scattering law of each molecular collision, affect macroscopic transport phenomena.