纳米限域Couette流边界气泡减阻机理  

Mechanism of boundary bubble drag reduction of Couette flow in nano-confined domain

作　　者：张鹏 张彦如 张福建 刘珍[2] 张忠强[1,3] Zhang Peng;Zhang Yan-Ru;Zhang Fu-Jian;Liu Zhen;Zhang Zhong-Qiang(School of Mechanical Engineering,Jiangsu University,Zhenjiang 212013,China;School of Ship and Ocean Engineering,Jiangsu University of Science and Technology,Zhenjiang 212003,China;State Key Laboratory of Structural Analysis of Industrial Equipment,Dalian University of Technology,Dalian 116024,China)

机构地区：[1]江苏大学机械工程学院,镇江212013 [2]江苏科技大学船舶与海洋工程学院,镇江212003 [3]大连理工大学,工业装备结构分析国家重点实验室,大连116024

出　　处：《物理学报》2024年第15期123-132,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12272151,52005222,92248301)资助的课题.

摘　　要：气泡减阻技术对于提高水下航行器推进效率,降低航行过程中的综合能耗具有重要意义.本文采用分子动力学方法研究了气-液两相Couette流在平行壁板纳米通道内的流动特性和气泡边界减阻特性,分析了表面润湿性、壁面粗糙度和气体浓度对边界滑移速度和减阻效果的影响规律.研究结果表明:气泡减阻效果随边界滑移速度的增大而增强;在气-液两相流动区域,随着剪切速度的增大,边界吸附气泡的横向变形和边界滑移速度增大,边界气泡减阻效果增强.固-气相互作用强度和气体浓度增大均导致气体原子在近壁面的富集现象增强,提高了壁面上气泡的铺展特性,从而增大了固-液界面滑移速度.壁面粗糙度会改变气泡的铺展特性,影响边界滑移速度,进而改变流固界面减阻效果;随着肋高的增大,气体原子在肋条间凹槽中聚集,肋条上表面气体原子吸附量减少,导致固-液界面边界滑移速度减小,并最终降低了减阻效果.研究结果将对大型舰船和水下航行器边界减阻技术提供重要理论指导.Bubble drag reduction technology is of great significance in improving the propulsion efficiency of underwater vehicle and reducing the comprehensive energy consumption during navigation.Bubble drag reduction is a highly effective method of reducing the frictional resistance encountered by large ships and underwater vehicles during navigation.It exhibits excellent stability in drag reduction,and has advantages such as environmental friendliness,adaptability to various flow environments,and suitability for all underwater components of ships.Therefore,it is greatly significant to conduct in-depth research on bubble drag reduction and its underlying mechanism.In this work,the flow characteristics and the boundary bubble drag reduction mechanism of gas-liquid Couette flow in parallel wall nanochannels are studied by molecular dynamics method,and the influences of surface wettability,wall roughness,and gas concentration on boundary slip velocity and bubble drag reduction effect are analyzed.The results indicate that the bubble drag reduction effect is enhanced with the increase of boundary slip velocity.In the gas-liquid two-phase flow region,with the increase of shear velocity,the lateral deformation of boundary adsorbed bubble and boundary slip velocity increase,thus enhancing the bubble drag reduction effect.The increase of solid-gas interaction strength and gas concentration can lead to the enrichment of gas atoms near the wall,improve the bubble spreading characteristics on the wall,and thus increase the slip velocity of the solid-liquid interface.The wall roughness can change the spreading characteristics of bubble,affect the boundary slip velocity,and then change the drag reduction effect of the fluid-solid interface.As the rib height increases,gas atoms accumulate in the grooves between ribs and the adsorption quantity of gas atoms on the upper surface of the rib decreases,which leads to the decrease of the boundary slip velocity of the solid-liquid interface and ultimately reduces the drag reduction effect.Th

关 键 词：气泡减阻 边界滑移 COUETTE流 分子动力学 

分 类 号：U674.941[交通运输工程—船舶及航道工程]