Temperature Dependence of the Lifetime of a Droplet on a Liquid Surface
Tonau Nakai, Takahiro Ueno, Kenji Kanzawa,
and Tomonobu Goto
Department of Mechanical and Aerospace Engineering, Graduate School of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan
When a liquid is dropped onto a surface of the same liquid, the droplet often remains floating on the surface for a while because of the thin air film between the droplet and the surface. We find that the time during which this phenomenon is sustained depends on the temperature of the droplet and surface. In our experiment using silicone oil at a temperature range of 20-150°C, the lifetime of a droplet was found to be longer when the temperature difference between the droplet and surface was larger at the moment of the droplet’s landing. The lifetime was longer for a cold droplet on a hot surface than the opposite case, with the same temperature difference. Time-series measurements of the temperature of the floating droplet revealed that it coalesces with the liquid surface at a certain threshold temperature difference. These results indicate that the lifetime of a droplet is determined by the time it takes the temperature difference to decrease to the threshold.
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