Analysis of velocity slipping at wall boundary under rarefied gas condition based on the effect of viscosity

Abstract

Purpose

Velocity slipping model, based on the stratification theory (the film in inflatable support area of aerostatic guide way was divided into near wall layer, thin layer and continuous flow layer in the direction of height), was established, and the model was combined with viscosity changes in each layer.

Design/methodology/approach

Simulated and analyzed by LAMMPS and two-dimensional molecular dynamics method, some relevant conclusions were drawn.

Findings

At a high temperature, viscosity is low, velocity slipping is large and velocity gaps in near-wall layer and thin layer are large. When the temperature is constant, the dimensionless slipping length and Kn number are linear.

Research limitations/implications

The effect of the equivalent viscosity on gas slipping model is proposed. viscosity is smaller, gas velocity slipping is greater, temperature is higher, gas velocity slipping is greater, velocity gap of near wall layer and thin layer is larger. When the temperature is constant, the dimensionless slipping length ls and Kn number are linear.

Originality/value

The global model of lubricating film velocity slipping between plates was established, and mathematical expression of slipping model in each layer, based on the stratification theory, was presented.

Citation

Yang, S., Long, W. and Ning, F. (2018), "Analysis of velocity slipping at wall boundary under rarefied gas condition based on the effect of viscosity", Industrial Lubrication and Tribology, Vol. 70 No. 8, pp. 1509-1515. https://doi.org/10.1108/ILT-03-2017-0080