Model of Boundary Conditions on Metal Surfaces for Rarefied Gas

Abstract

Currently, the classical theory discusses issues related to the sliding of liquid and gas along a wall at low external flow velocities. These questions become especially relevant when the surface size is reduced to the nanoscale. The article discusses the formation of sliding conditions and an adsorption layer for an ideal crystalline surface. For gas, the Knudsen layer is proposed to be divided into two parts: an adjacent layer with a thickness of several molecular interaction radii, in which molecules do not collide with each other, and a layer in which the Chapman-Enskog method is defined. The solution for this layer can be found by the small parameter method. For water, there is no Knudsen layer, but adhesion and the formation of a thin stationary layer are possible. Various possible causes of slipping are discussed. The formation of a dislocation from a point defect near the surface, which is a vacancy, is considered. An analysis of the causes of pore clogging during water movement near the surface was carried out. The emphasis is on the change in stress in the metal, taking into account the influence of the moment that occurs when the position of the molecules changes.