Transition between evaporation and condensation caused by the reflection of sound at a vapor-liquid interface

We study the transition processes from evaporation to condensation and vice versa by solving the Boltzmann-Krook-Welander equation numerically. The steady evaporation state and condensation state have already been well-analyzed based on the kinetic theory of gases (see, for example, book by Sone, 2007). However, unsteady evaporation and condensation phenomena, especially transition between them, still include unresolved problems. In the present study, we address the transition processes caused by the reflection of sound at a vapor-liquid interface. As a result of careful numerical analysis, we find the wave reflection law which determines the velocity and pressure in the sound wave reflected at the interface.