纳米尺度通道内的界面流体粘性研究

含液微纳米孔隙在自然界中普遍存在,在发展 日趋精密化、微型化的工业中也有着广泛的应用,深刻理解流体在微纳米通道内的物性变化对于相关自然现象以及工业应用具有重要的指导意义.本文基于分子动力学方法,建立了由金属铂板构成的二维纳米尺度通道分子模型,分别考察了受限Lennard-Jones流体和水的物性变化.根据密度、剪切应力和粘性在通道高度方向的分布情况,确定了两种流体的边界层厚度约为4.8 ?和4.6 ?.针对边界层内的流体,发现界面流体的粘性相比宏观尺度体态流体粘性明显提高,且随着固-液相互作用强度的增加而增加,但随着通道壁面晶格常数的增加而减少.基于计算结果,给出了由接触角表征的具有一定普适性的流体界面粘性计算公式.研究工作为微纳米尺度通道输运性能及其调控提供了有价值的参考和指导.

The viscosity of interfacial fluid confined in nanoscale channel

Fluid-filled micro- and nano- scale pores are ubiquitous in nature and have wide applications in industry.The trend is towards high precision and miniaturization.Understanding the change in the physical properties of the fluid induced by the small confinement is crucial for the relevant natural phenomena and industrial developments.In this paper,based on molecular dynamics simulations,platinum layers are utilized to construct two-dimensional nanoscale channels to examine the physical properties of the confined Lennard-Jones (LJ) fluid and water.According to the distributions of density,shear stress and viscosity along the channel height,we determine the thicknesses of the boundary layer as 4.8 Å and 4.6 Å for LJ fluid and water,respectively.Based on the interfacial fluid in the mentioned boundary region,it is revealed that the viscosity of interfacial fluid increases relatively to the viscosity of bulk fluid at macroscale.The viscosity of interfacial fluid increases with increasing the solid-fluid interaction but decreases with increasing lattice constant of channel surface.A universal equation for estimating the viscosity of interfacial fluid by contact angle is proposed on the basis of the present computational results.This work provides valuable reference and guidance for the transport performance of nanoscale channels and the relevant tunable strategy through the channel design.