Leidenfrost effect

The Leidenfrost effect occurs when a liquid droplet on a surface far hotter than its boiling point forms an insulating vapor layer that supports the droplet and slows its evaporation.

Nucleate boiling: A boiling regime in which vapor bubbles form at discrete sites on a heated surface. Below the Leidenfrost point, direct contact and bubble formation replace the stable vapor cushion.
Boiling: The rapid vaporization of a liquid when vapor bubbles form within it. The effect changes how boiling proceeds at a sufficiently hot surface.
Johann Gottlob Leidenfrost: A German physician who described the levitation of water droplets on very hot surfaces in 1756. His account gave the effect its name.
Leidenfrost droplet propulsion: The directed motion of a Leidenfrost droplet caused by asymmetry in its vapor flow or supporting surface. Patterned surfaces can steer droplets by controlling the vapor escaping beneath them.
Minimum film-boiling temperature: The lowest surface temperature at which a continuous vapor film can persist during film boiling. Its relation to the Leidenfrost point helps determine when levitation begins.
Film boiling: A boiling regime in which a continuous vapor film separates liquid from a heated surface. The effect is a droplet-scale instance of this vapor-film boiling regime.
Evaporation: The transition of molecules from a liquid into a gas at its surface. The vapor layer slows the droplet’s loss of liquid.
De Aquae Communis Nonnullis Qualitatibus Tractatus: Johann Gottlob Leidenfrost’s 1756 treatise on unusual properties of ordinary water. It contains the classic description of droplets moving over glowing iron.
Leidenfrost maze: A patterned hot surface that guides Leidenfrost droplets through channels using vapor-flow asymmetry. It demonstrates how the effect can power passive droplet transport.
Dynamic Leidenfrost effect: Leidenfrost behavior under rapidly changing conditions such as impact, motion, or transient heating. Static thresholds do not fully predict vapor-film formation during fast encounters.

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