J054011 温度差により保持された液滴-液面系の流動速度([J05401]マイクロ・ナノスケールの熱流体現象(1))

概要

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A droplet is kept on a surface of a liquid pool for a certain time without merging separated by a thin air film if the temperatures of the droplet and the pool are sufficiently different. The surfaces of the droplet and the pool are locally heated or cooled each other. The nonuniformity introduces convections on the surfaces, and they induce a flow in the ambient air. The flow sustains the pressure of the thin air film that prevents the coalescence. In this study, the temperature of a droplet kept on a pool and the flow velocity at a point in the droplet were simultaneously measured. A heated silicon oil droplet with a diameter of about 4 mm was dropped on a silicon oil pool at room temperature. The droplet was kept for a few seconds on the pool, and then it coalesced. Temperature change of the droplet was measured by a thermographic camera. Microparticles had been put in the droplet as tracers to estimate the flow velocity in tangential direction near the bottom of the droplet. The temperature of the droplet increased for less than a second just after it was dropped, and it gradually decreased to a value slightly higher than the value of pool temperature, and then the droplet merged. While the droplet was cooled, the flow velocity was decreasing.
一般社団法人日本機械学会の論文
2011-09-11