Nedea S V, Frijns A J H, van Steenhoven A A, Markvoort A J, Hilbers P A J
Department of Mechanical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
Phys Rev E Stat Nonlin Soft Matter Phys. 2005 Jul;72(1 Pt 2):016705. doi: 10.1103/PhysRevE.72.016705. Epub 2005 Jul 12.
We combine molecular dynamics (MD) and Monte Carlo (MC) simulations to study the properties of gas molecules confined between two hard walls of a microchannel or nanochannel. The coupling between MD and MC simulations is introduced by performing MD near the boundaries for accuracy and MC in the bulk because of the low computational cost. We characterize the influence of different densities and molecule sizes on the equilibrium properties of the gas in the microchannel. The effect of the particle size on the simulation results is very small in the case of a dilute gas and increases with the density. The hybrid MD-MC simulation method is validated by comparing the results for density and temperature profiles with those of pure MD and pure MC simulations. These results compare well for pure MD and pure MC, as well as hybrid MD-MC, both in the bulk and near the boundaries, when hard-sphere interactions are used. When Lennard-Jones potentials are used to accurately model the interactions between the gas and wall molecules instead, the results of pure MD simulations differ significantly from the pure MC simulations near the boundaries, but the results of the hybrid method compare well with the pure MD results near the wall, and with the pure MC and pure MD results in the middle of the channel. The hybrid method also very accurately simulates the interface between the MD and MC simulation domains. Comparisons between MD, MC, and hybrid MD-MC computational costs are outlined. The speedup when using 50% of the domain for MD simulations and 50% for MC simulations is very small compared to pure MD simulations times, but this speedup increases drastically for more realistic situations where the region near the wall is small compared to the bulk region.
我们结合分子动力学（MD）和蒙特卡罗（MC）模拟来研究限制在微通道或纳米通道两个硬壁之间的气体分子的性质。MD和MC模拟之间的耦合是通过在边界附近进行MD模拟以确保准确性，并在主体区域进行MC模拟以降低计算成本来实现的。我们表征了不同密度和分子大小对微通道中气体平衡性质的影响。在稀薄气体情况下，粒径对模拟结果的影响非常小，并且随着密度的增加而增大。通过将密度和温度分布的结果与纯MD和纯MC模拟的结果进行比较，验证了混合MD-MC模拟方法。当使用硬球相互作用时，无论是在主体区域还是在边界附近，纯MD、纯MC以及混合MD-MC的这些结果都比较吻合。相反，当使用 Lennard-Jones 势来精确模拟气体与壁分子之间的相互作用时，纯MD模拟的结果在边界附近与纯MC模拟的结果有显著差异，但混合方法的结果在壁附近与纯MD结果比较吻合，在通道中部与纯MC和纯MD结果比较吻合。混合方法还非常准确地模拟了MD和MC模拟域之间的界面。概述了MD、MC和混合MD-MC计算成本之间的比较。与纯MD模拟相比，当使用50%的区域进行MD模拟和50%的区域进行MC模拟时，加速比非常小，但在更实际的情况下，即与主体区域相比壁附近区域较小的情况下，这种加速比会急剧增加。
