液体壁面滑移的分子动力学研究

Study on the liquid wall slippage by molecular dynamics simulation

以平行板间液氩的Poiseuille流为例,用分子动力学模拟的方法,对壁面润湿性、外部驱动力以及通道宽度影响液体壁面滑移现象进行了研究。结果表明:在疏水性微通道中,液体的流动存在边界正滑移;在亲水性微通道中,在外力较小时,液体的流动存在边界负滑移,即有类似宏观的边界粘滞层存在,而当外力逐渐增大时,边界滑移从负滑移变为正的滑移。液体在不同宽度的微通道中流动时,绝对滑移长度均随外力的增大而变小,并趋向于定值。研究还发现在不同空间大小的通道中,壁面滑移速度随外力的增大而增大的变化存在拐点,在拐点两侧,界面作用的影响不同。

In this paper,the liquid Argon poiseuille flow between two parallel planes was taken as the physical model and the influences of wettability,the driving force and the dimension of micro-channels on the wall slippage were investigated by Non-Equilibrium Molecular Dynamics（NEMD） simulation.The results show that there exists the positive slippage on hydrophobic channels and the negative slippage on the hydrophilic boundary,when the driving force is weak.The negative slip length is similar with the adhesive boundary layer in macro-scale.The negative slippage changes to positive with the increment of the external force.The absolute slip length decreases with the external force increasing and tends to a constant.In different dimensions of channels,the boundary slip velocity inflection point is found with driving force increasing,and the boundary effect is different when driving force is smaller or bigger than the value of this inflection point.