2016 Fiscal Year Final Research Report
Micro-droplets levitated over hot water: Physics of coffee steam
| Project/Area Number |
25610124
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| Research Category |
Grant-in-Aid for Challenging Exploratory Research
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| Allocation Type | Multi-year Fund |
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| Research Field |
Biological physics/Chemical physics/Soft matter physics
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| Research Institution | Kyushu University |
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Principal Investigator |
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| Co-Investigator(Renkei-kenkyūsha) |
SAKAUE Takahiro 九州大学, 理学研究院, 助教 (30512959)
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| Project Period (FY) |
2013-04-01 – 2017-03-31
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| Keywords | 微小水滴 / 凝集 |
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| Outline of Final Research Achievements |
When drinking a cup of coffee under the morning sunshine, you may notice white membranes of steam floating on the surface of the hot water. They stay notably close to the surface and appear to almost stick to it. Although the membranes whiffle because of the air flow of rising steam, peculiarly fast splitting events occasionally occur. They resemble cracking to open slits approximately 1mm wide in the membranes, and leave curious patterns. We studied this phenomenon using a microscope with a high-speed video camera and found intriguing details: i) the white membranes consist of fairly monodispersed small droplets of the order of 10μm; ii) they levitate above the water surface by 10-100μm; iii) the splitting events are a collective disappearance of the droplets, which propagates as a wave front of the surface wave with a speed of 1-2 m/s; and iv) these events are triggered by a surface disturbance, which results from the disappearance of a single droplet.
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| Free Research Field |
統計物理学
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