The effect of the flow-to-wall temperature ratio on strong condensation of gas

The method of direct statistical simulation is used to investigate the effect of the flow-to-wall temperature ratio $T$ on the strong subsonic condensation of monatomic gas. It is demonstrated that the dependence of relative pressure at the boundary of the Knudsen layer on relative temperature at a fixed value of the Mach number $M$ has a minimum. In so doing, the marked supercooling of condensing gas ($T < 1$) causes an abrupt increase in relative pressure. At the same time, for a «moderately cold» wall ($1.5 < T < 10$), the dependence of relative pressure on relative temperature at a fixed value of $M$ is very weak. It is demonstrated that, in the case of supersonic condensation, the dependence of minimal possible relative pressure on $T$ at a fixed value of $M$ likewise has a minimum. The calculation results agree well with the results of calculations by the method of moments using the suggested approximation of the molecule distribution function.