Hybrid molecular-continuum simulations of water flow through carbon nanotube membranes of realistic thickness
Hybrid molecular-continuum simulations of water flow through carbon nanotube membranes of realistic thickness
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DOI：
10.1007/s10404-015-1617-x
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发表时间：
2015-07
影响因子：
2.8
通讯作者：
Konstantinos Ritos;M. Borg;D. Lockerby;D. Emerson;J. Reese
中科院分区：
文献类型：
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作者：
Konstantinos Ritos;M. Borg;D. Lockerby;D. Emerson;J. Reese
我们提出了新的混合分子连续模拟水流过过滤膜。膜由高纵横比的对齐的碳纳米管（CNT）组成，其中管直径为约1- 2nm，并且管长度（即膜厚度）比其大2-6个数量级。碳纳米管中的流动是亚连续的，这意味着标准连续流体方程不能充分模拟流动;此外，全分子动力学（MD）模拟对于模拟这些膜厚度来说计算成本太高。然而，在这个问题中，在时间和空间上的尺度分离的不同程度可以利用多尺度方法：我们使用串联网络内部流多尺度方法（SeN-IMM）。我们的结果从这种混合方法比较非常好的全MD模拟的流动情况下，膜厚度为150 nm，超过任何完整的MD模拟是计算上棘手的。我们继续使用SeN-IMM来预测厚度为150 nm-2 μm的膜中的流动，并将这些结果与修改后的Hagen-Poiagille流动方程和相同膜配置的实验结果进行比较。我们还发现实验和我们的数值计算结果之间的一致性良好的直径约1.1 nm的碳纳米管制成的1毫米厚的膜。在这种情况下，混合模拟比完全MD模拟快几个数量级。
We present new hybrid molecular-continuum simulations of water flow through filtration membranes. The membranes consist of aligned carbon nanotubes (CNTs) of high aspect ratio, where the tube diameters are ~1–2 nm and the tube lengths (i.e. the membrane thicknesses) are 2–6 orders of magnitude larger than this. The flow in the CNTs is subcontinuum, meaning standard continuum fluid equations cannot adequately model the flow; also, full molecular dynamics (MD) simulations are too computationally expensive for modelling these membrane thicknesses. However, various degrees of scale separation in both time and space in this problem can be exploited by a multiscale method: we use the serial-network internal-flow multiscale method (SeN-IMM). Our results from this hybrid method compare very well with full MD simulations of flow cases up to a membrane thickness of 150 nm, beyond which any full MD simulation is computationally intractable. We proceed to use the SeN-IMM to predict the flow in membranes of thicknesses 150 nm–2 μm, and compare these results with both a modified Hagen–Poiseuille flow equation and experimental results for the same membrane configuration. We also find good agreement between experimental and our numerical results for a 1-mm-thick membrane made of CNTs with diameters around 1.1 nm. In this case, the hybrid simulation is orders of magnitude quicker than a full MD simulation would be.