微重力环境下蒸发液层热毛细对流的数值模拟

提出了一种新模型来研究由单一物质构成的液层在其纯蒸气中的蒸发.液层置于微重力环境中并且受到水平方向温度梯度的作用,液层的热毛细对流和蒸发耦合在一起,使得气液界面的传热传质规律更加复杂.用理论分析的方法求解了不考虑热毛细效应的纯蒸发模型,得出温度场分布和界面质量流量的解析表达式.对于热毛细对流和蒸发耦合情况,采用有限差分的投影算法同时求解Navier-Stokes方程和能量方程,得到了不同蒸发Biot数和Marangoni数下流场和温度场的稳态数值解.论述了蒸发Biot数和Marangoni数对界面传热传质的影响,提出并解释了蒸发和热毛细对流耦合的三种模式.

Numerical Simulation of Thermocapillary Convection in an Evaporating Liquid Layer Under Microgravity Condition

A new model of the evaporation of a pure liquid layer underlying its own vapor is proposed and analyzed.The liquid layer is subjected to horizontal temperature gradient under microgravity condition.The thermocapillary convection is coupled with the evaporation,adding complication in the interfacial mass and heat transfer.An analytical expression for temperature distribution is given in pure evaporation case without considering thermocapillarity.For the case of both evaporation and thermocapillary convection,a finite difference algorithm is developed to solve simultaneously the thermal and flow fields in the liquid layer at various evaporation Biot number and Marangoni number until the steady state solution is achieved.The influence of evaporation Biot number and Marangoni number on the interfacial mass and heat transfer has been discussed.Three regimes of the coupling between evaporation and thermocapillary convection are found and explained from our numerical results.