分子动力学模拟剪切速度对纳米间隙中角鲨烷界面滑移的影响.pdfVIP

第 67 卷 第 4 期 化 工 学 报 Vol.67 No.4 2016 年 4 月 CIESC Journal April 2016 分子动力学模拟剪切速度对纳米间隙中角鲨烷界面滑移的影响 潘伶，高诚辉 （福州大学机械工程及自动化学院，福建 福州 350108） 摘要：采用聚合物一致性力场（PCFF），分别在 7 种剪切速度 V 和 3 种油膜厚度 h 下对纳米间隙中润滑剂角鲨烷 进行分子动力学模拟，分析固液界面的密度、分子和流速的分布，探究纳米薄膜润滑的润滑机理和剪切速度对界 面滑移的影响。结果表明，纳米间隙中润滑剂存在分层现象，各层间距相近，并非越远离固体壁面层间距越大， 层间距约为角鲨烷分子单个 C C 键距离的 3～4 倍；随着油膜厚度的减小，纳米间隙中润滑剂层状分布越明显， 固化层密度越大；当油膜厚度为 3.44 nm 时，固液界面滑移现象明显，滑移长度 b 值随着 V 先增大后减小，当 V 为 22.8 m·s?1 时，b 达到最大值 4.35 nm；根据模拟和计算结果，给出滑移长度与剪切速度的关系公式。 关键词：分子模拟；纳米结构；聚合物；界面滑移；薄膜润滑；角鲨烷 DOI：10.11949/j.issn.0438-1157 中图分类号：TH 117.2 文献标志码：A 文章编号：0438—1157（2016）04—1440—08 Molecular dynamics simulation of boundary slip in nanogap: effect of shear velocity PAN Ling, GAO Chenghui (School of Mechanical Engineering and Automation, Fuzhou University, Fuzhou 350108, Fujian, China) Abstract: Molecular dynamics (MD) simulations using the polymer consistent force field (PCFF) were adopted to investigate the density, molecular and velocity distributions of lubricant squalane in nanogap at 293 K, three different film thicknesses and a wide range of shear velocities. The lubrication mechanism and boundary slip were analyzed. The results showed that the lubricant atoms tended to form layers parallel to the confining wall. The distances between the layers of lubricant atoms were irregular rather than broadening far away from the walls and were about three to four times the length of C C bond in the squalane. The tendency of lubricant atoms to form layers and the density of solid-like layer increased with decreas