RELATION BETWEEN CONVECTIVE THERMAL PATTERNS AND HEAT FLUX THROUGH AN EVAPORATING SURFACE VIA TWO-DIMENSIONAL AND THREE-DIMENSIONAL NUMERICAL SIMULATIONS

It is the purpose of this paper to investigate the temporal behavior of convection flow, pattern formation, and heat flux through a liquid-gas interface for a pure liquid (HFE-7100) evaporating into a nitrogen gas flow. Two- and three-dimensional numerical fluid-dynamics simulations are performed using the software ComSol (finite elements method). This study is related to an experimental setup to be flown onboard the International Space Station (ESA "Evaporation Patterns" project). The two-dimensional results show that, due to the surface-tension variation with cooling, small rolls are formed near the liquid-gas interface, followed by the rolls growing into the bulk liquid, due to buoyancy. The three-dimensional results show that regular patterns are formed in the beginning accompanied by small fluctuations of the heat flux. Afterward, these patterns transform into chaotic flow and the fluctuations of the heat flux attenuate. Nonetheless, the heat flux fluctuations deviate only slightly from the mean value.