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Dynamics of microdroplets over the surface of hot water.

Umeki T, Ohata M, Nakanishi H, Ichikawa M - Sci Rep (2015)

Bottom Line: 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.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 10 μm; ii) they levitate above the water surface by 10 ~ 100 μm; 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Kyoto University, Kyoto 606-8502, Japan.

ABSTRACT
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 1 mm 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 10 μm; ii) they levitate above the water surface by 10 ~ 100 μm; 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.

No MeSH data available.


Schematic diagram of the experimental setup.
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f2: Schematic diagram of the experimental setup.

Mentions: After the preliminary observations, we made closer observations of hot tap water with a high-speed video camera using a setup designed for this phenomenon (Fig. 2). The experimental setup had a water container, a liquid light-guide illumination system, and a microscope with a high speed-video camera (KEYENCE VW-9000, Japan). To avoid water condensation on the lens, the water surface was observed from below under bright- or dark-field illuminations from above. The dual wall chamber was used for the water container to reduce external disturbances. The container was filled with hot water of 60 ~ 90°C in the room temperature environment of 20 ~ 25°C; the room temperature and humidity were not controlled during the experiments. The recorded images were analysed using image-processing software, mainly ImageJ.


Dynamics of microdroplets over the surface of hot water.

Umeki T, Ohata M, Nakanishi H, Ichikawa M - Sci Rep (2015)

Schematic diagram of the experimental setup.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306967&req=5

f2: Schematic diagram of the experimental setup.
Mentions: After the preliminary observations, we made closer observations of hot tap water with a high-speed video camera using a setup designed for this phenomenon (Fig. 2). The experimental setup had a water container, a liquid light-guide illumination system, and a microscope with a high speed-video camera (KEYENCE VW-9000, Japan). To avoid water condensation on the lens, the water surface was observed from below under bright- or dark-field illuminations from above. The dual wall chamber was used for the water container to reduce external disturbances. The container was filled with hot water of 60 ~ 90°C in the room temperature environment of 20 ~ 25°C; the room temperature and humidity were not controlled during the experiments. The recorded images were analysed using image-processing software, mainly ImageJ.

Bottom Line: 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.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 10 μm; ii) they levitate above the water surface by 10 ~ 100 μm; 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Kyoto University, Kyoto 606-8502, Japan.

ABSTRACT
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 1 mm 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 10 μm; ii) they levitate above the water surface by 10 ~ 100 μm; 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.

No MeSH data available.