物理学报2024，Vol.73Issue(1)：197-204,8.DOI:10.7498/aps.73.20231296
前进接触线薄液膜结构与运移机制
Structure and migration mechanism of thin liquid film in vicinity of advancing contact line
摘要
Abstract
Thin liquid film near the gas-liquid-solid three phase contact line is the core area of oil and gas production,phase-change heat transfer,and material synthesis systems.Although there are many experimental studies on fluid dynamics in the contact line region,the prediction of contact angle is still difficult,and the bottleneck lies in the special structure of thin liquid film in the contact line region.Because the microstructure of thin liquid film is not well understood,the prediction of dynamic contact angle is always controversial.At present,the main controversial points focus on whether the microscopic contact angle changes with speed,and whether the microscopic contact angle is the same as the macroscopic contact angle.Therefore,it is crucial to monitor the dynamic process of the microscopic contact angle in the thin liquid film region of the contact line.In this work,the wetting system of 50 nm liquid droplets on different solid surfaces is constructed by molecular dynamics simulation,and the structure and migration mechanism of thin liquid film are studied.The structure of the precursor liquid film in the completely wetting droplet advancing contact line region and the nanoscale convex structure in the partially wetting droplet advancing contact line region are obtained.The precursor liquid film is 2-3 molecular layers in thickness,leading the droplet to move forward.However,there is no precursor liquid film in a partially wetting system,and the convex nano-bending larger than 10 nm is formed in the wetting process,resulting in the microscopic contact angle.By comparing the difference between the absolute smooth surface dynamic wetting process and the actual solid surface dynamic wetting process,the dynamic evolution law of the micro contact angle and the macro contact angle with time are obtained for the first time in the simulation.The liquid molecules in the contact line region are tracked and statistically analyzed by means of particle tracer.It is revealed that the liquid molecules in thin liquid film change from sliding mode to rolling mode with speed increasing under the action of solid surface friction,and then the air entrainment at the bottom of the contact line leads to slip and sputtering.The research results are expected to provide theoretical guidance for the following three directions:1)improving heat transfer efficiency of micro and nano device based on wettability control;2)improving the imbibition displacement efficiency of shale oil micro-nano matrix based on wettability regulation;3)constructing universal contact angle prediction model.关键词
接触线/薄液膜/润湿/界面/分子模拟Key words
contact line/thin liquid film/wetting/interface/molecular simulation引用本文复制引用
刘乔,黄家宸,王昊,邓亚骏..前进接触线薄液膜结构与运移机制[J].物理学报,2024,73(1):197-204,8.基金项目
中石化科技部项目(批准号:P23196)、国家重点研发计划(批准号:2019YFA0705502-4)和中石化石油勘探开发研究院优青项目(批准号:YK-2023-28-2)资助的课题.Project supported by the Sinopec Science and Technology Department Project,China(Grant No.P23196),the National Key R&D Program of China(Grant No.2019YFA0705502-4),and the Sinopec Petroleum Exploration and Development Research Institute Outstanding Youth Project,China(Grant No.YK-2023-28-2). （批准号:P23196）
