Computer Simulation of Evaporation Process into the Vacuum

One of the important problems of a gas dynamics is a question of interaction of gas molecules with the surface of a condensed phasel. Near the surface of a gas phase the molecules also collide with the molecules reflected from the surface. Near the surface there is a Knudsen’s layer, in which practically there are no collisions of the molecules with each other 2,3. The value of this layer is equal to the length of a free molecule run of the gas phase. Thus, there are two independent flows of molecules in the Knudsen’s layer: one flow consists of molecules flying to the surface from the gas phase and the other consisting of molecules flying from the surface into the gas phase. The difficulty for obtaining a distribution function of molecule speeds in the Knudsen’s layer is that the process of molecule interaction with the surface is non-equilibrium and the function of the distribution of such molecules differs from that of equilibrium.