双尺度疏油结构纳米通道滑移效应的研究

针对双尺度结构表面疏油特性的优异性,采用分子动力学的方法建立油液流体正十六烷烃分子模型,研究双尺度结构壁面润湿性影响下的纳米通道内流体的流动特性,通过对通道壁面亲疏油性下的双尺度结构的构建,与光滑壁面和单尺度壁面进行比较来探究双尺度纳米通道表面结构影响下油液流体在纳米通道内密度分布、速度分布、速度滑移和滑移长度的影响.模拟结果表明:对于亲油通道壁面,双尺度结构壁面亲油性明显加强,主流区域流体密度、流体速度和速度滑移都减小,甚至出现负滑移;而对于疏油通道壁面,双尺度分层结构能加强壁面的疏油性,通道内壁面形成稳定的气层使流体主流区域的密度增大,并且通道内流体的速度、速度滑移和滑移长度明显大于光滑和单尺度结构壁面.因此,纳米通道内双尺度结构能改变通道壁面的润湿性,并且能够加强流体在纳米疏油通道内的滑移减阻效应,为纳米通道内油液运输以及润滑薄膜减阻提供了设计基础.

Research on Slip Effect of Nano-channel with Dual-scale Oleophobic Structure

Aiming at the excellent oleophobic properties of the dual-scale structure, molecular dynamics methods are used to establish the oil fluid n-hexadecane molecular model to study the flow characteristics of the fluid in the nanochannel under the influence of the wall wettability of the dual-scale structure. By constructing a dual-scale structure under the oleophobicity of the channel wall and comparing it with a smooth wall and a single-scale wall, we explore the influence of the dual-scale nanochannel surface structure on the density distribution, velocity distribution, velocity slip and slip length of liquid fluid in nanochannels. The simulation results show that for the wall of the oleophilic channel, the lipophilicity of the wall of the dual-scale structure is significantly enhanced, and the fluid density, fluid velocity and velocity slip in the mainstream area are reduced, and even negative slip occurs; for the wall of the oleophobic channel, the dual-scale hierarchical structure can enhance the oleophobicity of the wall surface, the inner wall of the channel forms a stable gas layer to increase the density of the fluid mainstream area, and the velocity, speed slip and slip length of the fluid in the channel are significantly larger than those in the smooth and single-scale structure wall. Therefore, the dual-scale structure in the nanochannel can change the wettability of the channel wall, and can enhance the sliding drag reduction effect of the fluid in the nano oleophobic channel, providing a design basis for the oil transportation in the nanochannel and the lubricating film drag reduction.