Leidenfrost wheels
Leidenfrost drops – which skitter almost frictionlessly across extremely hot surfaces on a thin layer of their own vapor – are notoriously mobile. We’ve all seen numerous methods of controlling their propulsion, often using specially-shaped surfaces. But it turns out that some Leidenfrost drops can self-propel even on a smooth, flat surface.
Internally, large Leidenfrost drops have complicated, but symmetric flows that are driven by temperature and surface tension variations across the drop. But as the drop evaporates, that symmetry eventually gets broken, leaving behind a single large circulating flow.
Beneath the drop, that internal circulation affects the vapor layer. It causes the layer to take on an overall tilt, and the rotation, along with that slight angle in the vapor layer, causes the Leidenfrost drop to roll away like a wheel.
Image and research credit: A. Bouillant et al.; via NYTimes
Journal article
https://www.nature.com/articles/s41567-018-0275-9
Source:
https://www.nytimes.com/2018/09/14/science/leidenfrost-effect.html
#physics #leidenfrosdroplets #science
yes, a kitchen technique of reduction on large hot plate parallels. How interesting, Merci Beaucoup.
ReplyDeleteI never knew this phenomenon had a name. Sometimes when drops of water fall onto a larger mass of water they bounce and skitter on a cushion of air. It's a similar phenomenon, but assuming it has a name it's presumably a different one.
ReplyDeleteI can imagine this droplet jumping to a beat. What is interesting is that it applies to other (any?) liquid on a surface hotter that the liquids boiling point. A wet finger can be put into molten lead, not sure I want to try that though
ReplyDeleteExplanation: the liquid flows through a circular section whose area is different from 0. This means that the velocity along the circular section is not identical in all its points, and this creates a rotary motion. In addition, the plane must also be considered, since it can have an inclination other than 0. The vertical oscillation is due to the potential energy jump.
ReplyDeleteSam Collett
ReplyDelete😳🤔the motion is uniformly accelerated so the forward t time is (2h / g) ^ (1/2), h, is the height from the plane of the center of mass of the drop, g, is the acceleration of gravity. To know the rhythm multiplies by 2 this time. The other answers find me unprepared. But we can see that you have a fixation for Physics, always answer xxx 😀😂🤣🤣😅🤠👋😇
There is an idea that a matter-antimatter encounter might behave similarly to a Leidenfrost barrier
ReplyDelete