纳米流道内液体特性的分子动力学研究

以非平衡分子动力学方法研究了纳米流道内液体的流动特性,重点探讨上壁面以不同剪切速度运动,下壁面保持静止且在其附近的温度保持相对稳定时,两壁面间液体分子的运动特性及作用机理.模拟获得了不同剪切速度下流体的速度分布、密度分布及温度分布,并分析了速度滑移率、密度分布和最高温度与剪切速度之间的关系.研究结果表明,随着剪切速度的增加,两固体壁面间液体靠近运动平板处的温度呈线性增加,在距离运动壁面0.8倍分子直径范围之内存在着明显的滑移现象,而在这个区域之外,液体分子的速度基本呈线性变化,纳米流道内液体分子密度的非均匀分布和有序化排列结构不受剪切速度的影响,平均剪切应力随着剪切速度的增加而不断增加.

Molecular Dynamics of the Flow Properties of Liquids in Nanochannel

The non-equilibrium molecular dynamics simulation is carried out to investigate the flow properties of liquids confined in nanoehannel, especially the flow behaviours and the interaction mechanism of fluid molecules confined between two solid walls as the upper wall moving at different shear velocities, and the temperature of liquids near the stationary lower wall keeping constant. The distributions of velocities, densities and temperatures are obtained for a variety of shear veloeity; the relationships of the slip of velocity, the density and the temperature profiles with the shear velocity are analyzed. The simulated results show that with the unceasing increase of the shear velocity, the temperature of liquids near the moving wall increases continuously. The slip is easily observed if the distance from the moving wall is less than 0.8 molecular diameter, and beyond this range the velocity profiles appear quite linear. The different shear velocities do not affect the distribution of densities and the order structures of liquids in nanochannel. The average shear stress is enhanced with the increasing shear velocity.