Abstract: A molecular dynamics simulation of two-dimensional Couette flow has been conducted to investigate the influence of fluid density on velocity slip of fluid flow in nanochannel.The effects of fluid density on microscopic structure，velocity distribution and slip length are analyzed and discussed.The results indicate that oscillation distribution of fluid density occurs near the wall owing to the effect of solid surface potential，and a small oscillation and layering as well as a wide homogenous region are observed with the decreasing ratio of fluid-to-solid density.In addition，decreases in the ratio of fluid-to-solid density induces the hardship of the motion state of solid surface transferred to the fluid and hence lead to large loss of energy transport across the fluid-solid interface，which contribute to large velocity slip at the boundary.Accordingly，the slip length increases as the ratio of fluid-to-solid density decreases.

Key words: velocity slip, molecular dynamics, fluid density, nanochannel

摘要： 基于纳通道内的二维Couette流，采用分子动力学方法研究了流体密度对纳通道内流体流动滑移的影响，分析讨论了流体密度变化对纳通道内流体的微观结构、速度分布以及滑移长度的影响。研究结果表明，由于受到固体表面势作用，流体密度在表面附近呈“振荡”分布，随着流固密度比的减少，密度分布的振荡幅度和分层数也相应减少，各向同质区域范围随之扩大。并且，流固密度比的减小使得固体表面的运动状态难于传递给流体，能量传递穿过流固界面时的损耗增加，导致边界速度滑移程度增加。与之相对应，流体流动的滑移长度将随着流固密度比的减小而增加。

关键词: 速度滑移, 分子动力学, 流体密度, 纳通道