Analytical study of transonic flows of a gas condensing onto its plane condensed phase on the basis of kinetic theory

A uniform flow of a gas condensing onto its plane condensed phase (commonly known as the halt-space problem of condensation) is considered. The problem is studied analytically on the basis of the Boltzmann equation when the flow is in a transonic region. The paper clarifies the analytical structure of the solution, especially the mechanism by which the range of the parameters (the flow speed, pressure, and temperature of the uniform flow blowing from infinity) where a steady solution exists changes abruptly (from a surface to a domain in the parameter space) when the flow speed passes the sonic speed, the correspondence of a family of supersonic solutions to a subsonic solution, etc. The solutions constructed analytically are compared with new numerical solutions near the sonic point.