https://www.youtube.com/watch?v=iiBpUISTTe0
Slow motion video of boiling ice, a research project of the Laboratory of Nature-Inspired Fluids and Interfaces at Virginia Tech.
Sprinkle a few drops of water on top of the very hot pot and the water will rise into the air and flow wildly around the pot. Physicists at Virginia Tech have found that this can be achieved by placing thin and flat ice on a heated aluminum surface. New paper The Physical Review was published in the journal Fluids. Problem: There is a very high critical temperature before the ice plate rises.
Like us I mentioned earlierSaid in 1756 by a German scientist Johann Gottlob Leidenfrost The Notice that For unusual phenomena. He commented that water usually splashes into a very hot pot and evaporates very quickly. But if the temperature of the pan is above the boiling point of the water, “bright mercury-like droplets” will form and fly over the surface. On the phone “Leidenfrost effect To honor him.
Over the next 250 years, physicists found a reasonable explanation for why this happened. If the surface is at least 400 degrees Fahrenheit (well above the boiling point of the water), a cushion of moisture or vapor will form beneath it, keeping it at a height. The lidon frost effect works with other liquids, including oils and alcohol, but the temperature at which they occur varies.
Phenomenon Still amazing Physicist. For example, in 2018, Discovered by a French physicist Steam drops do not flow over the cushion; As long as it is not too big, it pushes itself. This is due to the imbalance of fluid flow in the lidon frost droplets. Behave like Small internal drive. Larger droplets show an equilibrium flow, but as the droplets evaporate they become smaller (approximately half a millimeter in diameter) and in a more circular shape, an imbalance of forces occurs. This causes the drop to rotate like a wheel, tilting downward in the same direction as the liquid flowing in the droplet, helping to create a kind of “ratchet” effect. French physicists called their discovery the “Leidenfrost Wheel”.
In 2019, an international team of scientists Finally I determined the source From the crack sound reported by Leidenfrost. Scientists Find it It depends on the size of the drop. Small droplets will slip off the surface and evaporate, while larger droplets will explode with this apparent fracture. The culprit is particle contaminants found in almost all liquids. Larger droplets start with a higher concentration of contaminant, and this concentration increases as the droplets shrink. They end up at a high density where the particles slowly form a crust around the droplet. These projectile tiles interfere with the vapor cushion that retains the high droplet and explodes when it hits the surface.
Last year, MIT scientists determined why droplets flow on the surface of hot oil 100 times faster than open metal. Under the right conditions, a thin layer like a coat forms on the outside of each drop. As the droplets heat up, small bubbles of moisture begin to form between the droplets and the oil, and then move on. Subsequent bubbles usually form near the same point, forming a vapor path that leads the droplet in the desired direction.
But can you achieve the lidon frost effect with snow? That’s what the Virginia tech team wanted to find. “There’s a lot of paper around the liquid lift, and we’d like to ask a question about the ice lift.” Co-author Jonathan Boreko said:. “It simply came to our notice then. Our research was inspired by the question of whether the three-phase lidon frost effect can be achieved with solids, liquids, and vapors.
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