纳米通道内液体流动的滑移现象

采用分子动力学模拟方法研究了液态氩在铂纳米通道内的流动，通过改变流体和壁面之间的势能作用获得了流体和通道表面之间浸润性质不同时的滑移现象. 研究发现：液体分子在亲水性通道表面附近呈类固体性质，数密度和有序性较大，而在疏水性表面附近的平均数密度降低，形成一个低密度层；液体流动在固体表面的速度滑移随着液体与表面势能作用的增强而减小，当液体和表面的浸润性不同时可以发生滑移、表观无滑移和负滑移现象；液体在固体表面的表观滑移是液体在固体表面的速度滑移、粘附和流体内部滑移的综合作用的结果. 关键词： 纳米尺度流动 速度滑移 浸润性 分子动力学模拟

Velocity slip of liquid flow in nanochannels

Molecular dynamics simulations are carried out to investigate the velocity slip phenomenom of liquid flow in nanochannels. The liquid is argon, and the wall is taken to be platinum or its model solids. The effect of the surface wettability on the velocity slip is obtained through varying the potential interaction strength between the liquid and the wall. The simulation results show that the liquid adjacent to a hydrophilic surface is solid-like and has high density and orderliness. However, the liquid near a hydrophobic surface forms a gap of low density. The velocity slip of the liquid flow over solids decreases with the increasing interaction strength between the liquid and the channel surface. The slip, the no-slip and the negative slip are all possible to take place for different liquid-surface wettabilities. We find that the apparent slip of the liquid flow over solids is affected by the integrated factors of boundary slip, liquid sticking and liquid-internal slip.