Abbasi Hossein Reza, Karimian S M Hossein
Department of Aerospace Engineering, Amirkabir University of Technology (Tehran Polytechnic), Tehran, Iran.
J Mol Model. 2016 Sep;22(9):198. doi: 10.1007/s00894-016-3071-4. Epub 2016 Aug 3.
The role of electrical charge in controlling the velocity of water molecules in a finite single-walled carbon nanotube (CNT) was studied in detail using molecular dynamics simulation. Different test cases were examined to determine the parameters affecting the control of water-flow velocity in CNT upon electrically charging the surface of a CNT. The results showed that charge magnitude and volume, as well as the charging scenario, are the parameters having greatest effect. The implementation of electric charge on the surface of a CNT was demonstrated to decrease the resistance of CNT to incoming water flow at the entrance, but to increase friction-type resistance to flow along the CNT. Therefore, through controlling the magnitude of electric charge, water flow through the CNT may be accelerated, or decelerated. The results show that the velocity of molecular flow in the CNT increases to a maximum value, and then decreases with electric charge regardless of its sign. In the case studied here, this maximum velocity occurs at electric charging of ±0.25e/atom. It was also shown that, to reach similar flow velocities in a CNT, it is not sufficient to merely implement equal volumes of electric charge, where the volume of electric charging is defined as charge magnitude × charging time. In fact , both magnitude of charging and volume of electric charging must be equal to each other. These findings, together with options to implement scenarios with alternative charging, provide the means to effectively adjust desired velocities in a CNT.
利用分子动力学模拟详细研究了电荷在控制有限单壁碳纳米管（CNT）中水分子速度方面的作用。研究了不同的测试案例，以确定在对碳纳米管表面进行充电时影响碳纳米管内水流速度控制的参数。结果表明，电荷量、电荷体积以及充电方式是影响最大的参数。已证明在碳纳米管表面施加电荷会降低碳纳米管入口处对流入水流的阻力，但会增加沿碳纳米管流动的摩擦型阻力。因此，通过控制电荷量，可以加速或减缓通过碳纳米管的水流。结果表明，无论电荷符号如何，碳纳米管内分子流的速度都会随着电荷增加先增加到最大值，然后下降。在本文研究的案例中，这个最大速度出现在±0.25e/原子的充电量时。还表明，要在碳纳米管中达到相似的流速，仅仅施加等量电荷体积是不够的，这里电荷体积定义为电荷量×充电时间。实际上，充电量和电荷体积都必须彼此相等。这些发现，连同实现不同充电方式的选项，提供了有效调节碳纳米管中所需流速的方法。
