Numerical Simulation of Flow with Phase Change Using Phase Boundary Conditions Based on the Kinetic Theory of Gases

Abstract

A numerical method for liquid-vapor two-phase flows accompanied by condensation/ evaporation is proposed. The phase change model at the vapor-liquid interface, which had been theoretically derived by Sone and Onishi, is coupled with an interface capturing scheme. The model gives the condensation/evaporation rate as boundary conditions. The interface is captured by the volume-of-fluid method associated by the reconstruction scheme, and the scheme to obtain the pressure with consideration for thermodynamics in the vicinity of the interface is employed. These methods are coupled and arranged on the cylindrical coordinate system to appropriately deal with the liquid film flow around a cool cylinder in a natural convection of vapor. The development of a liquid film due to the condensation, the flow in a thin layer and a drop of the distilled liquid are successfully reproduced in our result. The influence of the volumetric conservation is confirmed by comparing the results of condensation case and a non-condensation case. Besides the Nusselt number is in good agreement with a theoretically estimated value.

Computations of flows with phase change by implicit coupling of vof method and boundary conditions based on kinetic theory

“…In our previous study (Ohshima and Kajishima, 2012), we used the boundary condition (Sone and Onishi, 1978) based on the kinetic theory (Sone, 2002) to simulate condensation around a horizontal cylinder. In the method, the phase change rate was given by the difference between the vapor pressure and saturated pressure at the interface.…”