Molecular simulation of pressure-driven fluid flow in nanoporous membranes
Molecular simulation of pressure-driven fluid flow in nanoporous membranes
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DOI：
10.1063/1.2749236
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发表时间：
2007-08-07
影响因子：
4.4
通讯作者：
Nakao, Shin-Ichi
中科院分区：
文献类型：
--
作者：
Takaba, Hiromitsu;Onumata, Yasushi;Nakao, Shin-Ichi
发展了一种扩展的非平衡态分子动力学方法来研究纳米多孔薄膜中压力驱动流体流动的输运性质。我们的模拟技术允许模拟的压力驱动的渗透液体通过膜，同时保持恒定的驱动压力，使用波动的墙壁。在施加2.4 × 10（6）Pa的外部压力差通过狭缝状和圆柱形孔时，模拟液态氩气的流动。在膜孔的体积通量和速度分布进行了检查作为孔径的函数，沿着与孔壁的相互作用，这些进行了比较，使用哈根-Poietille流估计的值。当孔径约< 20 σ时，计算的速度强烈地依赖于流体与壁中原子之间的相互作用的强度。计算出的体积通量也显示出对流体和壁中原子之间的相互作用的依赖性。Hagen-Poiffuille定律高估或低估了通量，这取决于相互作用。通过对计算结果的分析，发现膜孔中流体密度与Hagen-Poietille流估算的通量偏差之间存在良好的线性相关性，这表明可以根据孔中流体密度预测纳米孔中Hagen-Poietille流的通量偏差。
An extended nonequilibrium molecular dynamics technique has been developed to investigate the transport properties of pressure-driven fluid flow in thin nanoporous membranes. Our simulation technique allows the simulation of the pressure-driven permeation of liquids through membranes while keeping a constant driving pressure using fluctuating walls. The flow of argon in the liquid state was simulated on applying an external pressure difference of 2.4x10(6) Pa through the slitlike and cylindrical pores. The volume flux and velocity distribution in the membrane pores were examined as a function of pore size, along with the interaction with the pore walls, and these were compared with values estimated using the Hagen-Poiseuille flow. The calculated velocity strongly depends on the strength of the interaction between the fluid and the atoms in the wall when the pore size is approximately < 20 sigma. The calculated volume flux also shows a dependence on the interaction between the fluid and the atoms in the wall. The Hagen-Poiseuille law overestimates or underestimates the flux depending on the interaction. From the analysis of calculated results, a good linear correlation between the density of the fluid in the membrane pores and the deviation of the flux estimated from the Hagen-Poiseuille flow was found. This suggests that the flux deviation in nanopore from the Hagen-Poiseuille flow can be predicted based on the fluid density in the pores.