Simulations of transient flows due to phase change processes

点击翻译按钮获取中文摘要

Transient motions of a vapor and the associated wave propagations due to phase change processes are investigated in such flows as in rectangular regions bounded by solid walls in which two condensed phases are embedded. Shock waves and contact regions (sometimes expansion waves involved), which are produced associated with the phase change processes at the condensed phases, propagate within the regions, bringing the flow fields to their final states. The problems of this kind should be based, of course, on the kinetic equations because of the nonequilibrium regions involved in the flow fields. The present analysis, however, is based not only on the kinetic equations but also on the fluid dynamic formulation which consists of the Navier-Stokes equations subject to the appropriate boundary conditions at the condensed phases derived from the kinetic theory analysis. The latter governing system, which is equivalent to the kinetic system for small Knudsen numbers, enables us to treat problems involving evaporation and condensation processes of arbitrary strength at ordinary fluid dynamic level. Physically important phenomena, such as the hump or pit structure in velocity within the contact region and the breathing behavior in temperature and density fields in an unbounded region are found, the existence of which seems to have not so far been known.