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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: 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.

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.


Size distribution (a) and average size of the droplets (b) at various temperatures.The error bars for the average radii represent the standard deviation of the distributions. The data set for each temperature contains several hundreds of data points of droplet radii.
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f4: Size distribution (a) and average size of the droplets (b) at various temperatures.The error bars for the average radii represent the standard deviation of the distributions. The data set for each temperature contains several hundreds of data points of droplet radii.

Mentions: Figure 4 shows the size distributions and average sizes of the droplets at several temperatures. The radius distributions show narrow dispersion, whose standard deviations are typically less than half of their average value. The average radius of the droplet gradually decreases when the temperature decreases. The data at T < 60°C may contain systematic error because the average radius becomes comparable to the resolution limit of the images, i.e., 4.74 μm for 1 pixel.


Dynamics of microdroplets over the surface of hot water.

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

Size distribution (a) and average size of the droplets (b) at various temperatures.The error bars for the average radii represent the standard deviation of the distributions. The data set for each temperature contains several hundreds of data points of droplet radii.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Size distribution (a) and average size of the droplets (b) at various temperatures.The error bars for the average radii represent the standard deviation of the distributions. The data set for each temperature contains several hundreds of data points of droplet radii.
Mentions: Figure 4 shows the size distributions and average sizes of the droplets at several temperatures. The radius distributions show narrow dispersion, whose standard deviations are typically less than half of their average value. The average radius of the droplet gradually decreases when the temperature decreases. The data at T < 60°C may contain systematic error because the average radius becomes comparable to the resolution limit of the images, i.e., 4.74 μm for 1 pixel.

Bottom Line: 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.

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.