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THERMOCAPILLARY-DRIVEN FLOW IN A FREE LIQUID FILM

Ichiro Ueno
Department of Mechanical Engineering, Faculty Science & Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan

Toshiki Watanabe
Division of Mechanical Engineering, School of Science & Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan

Takeshi Katsuta
Division of Mechanical Engineering, School of Science & Technology Tokyo University of Science 2641 Yamazaki, Noda, Chiba 278-8510, Japan

Аннотация

We focus on flow patterns in a free liquid film induced by thermocapillary effect, transition of the induced flow from a two-dimensional steady state to a chaotic state, and corresponding static/dynamic deformation of the film. The free liquid film is formed in a rectangular hole of O(0.1 mm) in thickness under a designated temperature difference between the end walls. Temperature dependence of the surface tension results in a non-uniform surface tension distribution over the free surfaces, which leads unique flow patterns in the film. We employ a confocal laser displacement meter to detect the local positions in height of the free surfaces, and to detect the film thickness distribution under variable aspect ratio and volume ratio of the liquid film. We will introduce several flow patterns induced in the film and corresponding film profiles as functions of the aspect ratios and volume ratio of the film. Under unity volume ratio to the volume of the hole to suspend the liquid film, we have two major basic flow patterns at small-enough thermocapillary effect; double-layered basic flow and single-layered basic flow. The net flow direction of the fluid in both cases is from hot- to cold-end walls. In the case of volume ratio of the film is larger than unity, it is found that the net flow direction becomes opposite to the normal case. We will discuss the occurring condition of those flow patterns and the effect of the shape of the film against those patterns.