基于粘度影响的稀薄效应下壁面速度滑移的数学建模  

Modeling and Simulation of Correlation between Velocity Slip at Wall Boundary and Effective Viscosity of Rarefied Gas

作　　者：宁方伟[1] 龙威[1] 裴浩[1] 杨绍华[1] 

机构地区：[1]昆明理工大学机电工程学院,昆明650500

出　　处：《真空科学与技术学报》2017年第3期302-308,共7页Chinese Journal of Vacuum Science and Technology

基　　金：国家自然科学基金(51305185)资助

摘　　要：以气膜分层理论为基础,根据近壁层、稀薄层、连续流层内分子运动形式,结合层内黏度的变化特征,建立壁面滑移模型,并给出相应的数学表达式。通过LAMMPS和2DMD数值分析的方法,结合实验测试结果发现:在稀薄层内,沿竖直方向的速度呈线性变化,越靠近壁面,速度越小;在近壁层内,由于分子与壁面的摩擦使得近壁层分子速度骤减;在连续流层内,气体分子做全滑移运动;此外,温度越高,黏度越小,速度滑移越大,近壁层与稀薄层速度差值越大。温度一定时,无量纲滑移长度和Kn数成线性关系。Thevelocity slip of the lubricating gas-film wasmathematically modeled in stratification theory,theoretically analyzed in gas kinetics,numerically simulated with software LAMMPS/2DMD,and experimentally evaluated. The influence of the temperature,viscosity and thickness of gas-film on the velocity slip in the near-wall/continuous-flow/rarefied gas layers was investigated. The calculated and simulated results show that depending on the temperature and viscosity,the rarefied gas layer strongly affects the velocity slip. For example,in the rarefied layer,the velocity increases with the increasing distance from the wall; in the near-wall layer,the velocity decreases sharply for interfacial friction; in the continuous flow layer,gas molecule flows in full slip mode. Besides,the velocity and the velocity difference between the rarefied and near-wall layers increase with an increase of temperature and/or a decrease of viscosity; at a fixed temperature,the dimensionless slip length ls linearly depends on Kn number.

关 键 词：稀薄效应 速度滑移 有效黏度 分子碰撞 牛顿摩擦 

分 类 号：TH47[机械工程—机械制造及自动化]