Discussion on the Gaseous Slip Model Based on Langmuir Adsorption Isotherm

Different from the Maxwell slip model, the gaseous slip model based on the Langmuir adsorption isotherm, i.e. the Langmuir slip model, takes into account the interfacial interaction between the gas molecules and the wall surface. For pressure-driven micro-channel gas flow, both slip models are adopted and the velocity formulae of gas flow are derived analytically. The result indicates that the velocity formulae for the gas flow are the same except that one parameter which could be inferred from experiment data or theoretical prediction. In Maxwell slip model, the parameter is related with the surface accommodation coefficient; On the other hand, the parameter is related with the gas particle interaction potential and the heat of adsorption in Langmuir slip model. Therefore, the Langmuir slip model still has the same difficulty in determining the value of the parameter as the Maxwell slip model.