Collaborative Research: Interfacial Instability, Convective Motion and Heat Transfer in Evaporating Films

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Collaborative Research: Interfacial Instability, Convective Motionand Heat Transfer in Evaporating FilmsUniversity of Washington and Michigan Technological University This program will study the behavior of thin, evaporating films. Of specific interest are the disturbances at the fluid surface and the fluid motion within the film caused by evaporation, and how these disturbances impact the film structure and the heat transfer. Key considerations in these films include buoyancy, differences in surface tension, and mass loss due to evaporation. The action of these mechanisms will be systematically studied by varying the conditions of the experiment, including the fashion in which the heat is supplied to the evaporating film. Experiments will be conducted using pure test fluids in a pressure-regulated test cell. Films with different thermal conditions will be studied by varying both the magnitude of the temperature difference across the film, as well as changing the direction of this temperature difference. Each thermal boundary condition will yield different temperature profiles within the film, with different impacts on the fluid motion within the film. The evaporating films will be studied by high-speed imaging, measurement of the temperature within the films and the heat transfer at the wall, and ultrasonic measurements of the film thickness. The behavior of evaporating films will also be examined using linear stability theory. This research is expected to lead to an improved understanding of fundamental evaporation processes. Two very important practical applications of this research are the growth of crystals in semiconductor materials and the texturing of surfaces in magnetic storage devices. The proposed research will also impact the education, recruiting, and outreach programs at the University of Washington (UW) and Michigan Technological University (MTU). For example, the ultrasound and diagnostic technique will be introduced into existing primary experimental methods courses in Aeronautics and Astronautics at the UW.