Shaat Mohamed, Zheng Yongmei
Department of Mechanical Engineering, Zagazig University, Zagazig, 44511, Egypt.
Mechanical Engineering Department, Abu Dhabi University, Al Ain, P.O.BOX 1790, United Arab Emirates.
Sci Rep. 2019 Apr 5;9(1):5689. doi: 10.1038/s41598-019-42101-4.
We put water flow under scrutiny to report radial distributions of water viscosity within hydrophobic and hydrophilic nanotubes as functions of the water-nanotube interactions ([Formula: see text]), surface wettability (θ), and nanotube size (R) using a proposed hybrid continuum-molecular mechanics. Based on the computed viscosity data, [Formula: see text] phase diagram of the phase transitions of confined water in nanotubes is developed. It is revealed that water exhibits different multiphase structures, and the formation of one of these structures depends on [Formula: see text] R parameters. A drag of water flow at the first water layer is revealed, which is conjugate to sharp increase in the viscosity and formation of an ice phase under severe confinement (R ≤ 3.5 nm) and strong water-nanotube interaction conditions. A vapor/vapor-liquid phase is observed at hydrophobic and hydrophilic interfaces. A state of confinement is revealed at which water exhibits different multiphase structures under the same flow rate. The derived viscosity functions are used to accurately determine factors of flow enhancement/inhibition of confined water.
我们对水流进行了详细研究，采用一种新提出的混合连续介质-分子力学方法，来报告疏水性和亲水性纳米管内水的粘度径向分布，这些分布是水与纳米管相互作用（[公式：见原文]）、表面润湿性（θ）和纳米管尺寸（R）的函数。基于计算得到的粘度数据，绘制了纳米管内受限水相变的[公式：见原文]相图。结果表明，水呈现出不同的多相结构，且其中一种结构的形成取决于[公式：见原文]R参数。揭示了在第一层水处水流存在阻力，这与在强受限（R≤3.5nm）和强水-纳米管相互作用条件下粘度的急剧增加以及冰相的形成相关。在疏水和亲水界面观察到汽相/汽-液相。揭示了一种受限状态，即在相同流速下，水呈现出不同的多相结构。所推导的粘度函数用于准确确定受限水流动增强/抑制的因素。
