著者

郡司 博史 酒井 敏

出版者

日本流体力学会

雑誌

日本流体力学会年会講演論文集

巻号頁・発行日

vol.2002, pp.92-93, 2002

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A milk crown is a very attractive phenomenon. However, it is very difficult to catch a continuous picture. Therefore, there is almost no systematic research. Then, with the digital Video Camera, we took the continuous image and analyzed them. The parameters of the experiment are the velocity of the waterdrops which collides with a thin liquid layer, the depth of a liquid layer, and the viscosity of fluid of the experiment. Surprisingly, we found that crown-like structure at about 10ms to 30ms after the collision of waterdrop expand at the same speed unrelated to the parameters.

著者

郡司 博史 石井 秀樹 斉藤 亜矢 酒井 敏

出版者

社団法人 日本流体力学会

雑誌

日本流体力学会誌「ながれ」 (ISSN:02863154)

巻号頁・発行日

vol.22, no.6, pp.499-500, 2003

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If liquid drop collides with a thin fluid layer, crown-like structure (milk crown) will be formed. In such phenomenon, surface tension is dominant, and a time scale is very short. To catch a continuous image of such phenomena, expensive equipment, such as a high-speed camera, would be required. Therefore, systematic researches which change parameters, such as collision speed of liquid, were not done. Then, we considered how to record with a cheap commercial digital video camera, conducted the systematic experiment by this method, and analyzed the obtained picture. Consequently, we found that the diameter of a crown was proportional to the 1/4th power of the lapsed time after liquid drop collides. That of the trace after a crown disappears was proportional to the 1/2nd power of the lapsed time. The domain where the diameter of a crown is proportional to the 1/2nd power of lapsed time has only been found in the trace after a crown disappeared. We think that the crown turns into the capillary wave during its collapse. We found that the time that the crown grows up is longer than the crown falls down. Considering a simplified model concerning of mass change and surface tension of the crown upper part, we could reproduce the asymmetry.