The Leidenfrost point (~220 °C for water) is when the
surface is so hot that a thin vapour film forms instantly beneath a
droplet, insulating it from the pan.
Below this point, droplets spread and evaporate violently (nucleate boiling). Above it, they levitate and can last 10× longer,
gliding freely across the surface.
Click on the pan to add droplets · Temperature controls evaporation
rate and regime
About the Leidenfrost Effect
This simulation shows water droplets meeting a heated pan and how their behaviour changes with surface temperature. As you raise the pan from below 100 °C up to 450 °C, the droplets pass through four regimes: below boiling, nucleate boiling, transition boiling, and the Leidenfrost regime. The model uses fixed thresholds (100, 160 and 220 °C) and a regime-dependent evaporation rate to govern how quickly each droplet shrinks and how it moves.
The single temperature slider (80–450 °C) sets the regime, while preset buttons jump to characteristic points and the add button or a click on the pan spawns droplets. Above the Leidenfrost point a thin vapour film insulates the droplet, so it levitates, glides and evaporates surprisingly slowly. This effect explains why a drop dances on a very hot pan, and underlies phenomena from spheroidal cooling in metallurgy to the brief safety of a wet finger touching molten metal.
Frequently Asked Questions
What is the Leidenfrost effect?
It is the phenomenon where a liquid droplet placed on a surface far hotter than its boiling point produces an insulating layer of its own vapour. This vapour cushion lifts the droplet clear of the surface, dramatically slowing heat transfer so the droplet survives much longer and skates around almost frictionlessly.
What temperature triggers it for water?
In this simulation the Leidenfrost point for water is set at 220 °C, which matches the commonly quoted value of roughly 200–220 °C for a clean pan. Below that, droplets sit on the metal and boil; above it, a stable vapour film forms instantly and the droplet levitates.
What do the four regimes mean?
Below 100 °C the pan is under the boiling point, so droplets just spread and evaporate slowly. From 100 to 160 °C is nucleate boiling, with vigorous bubbling. From 160 to 220 °C is transition boiling, an unstable mix. At 220 °C and above is the Leidenfrost regime, where the droplet floats on vapour.
What do the controls do?
The temperature slider sets the pan from 80 to 450 °C, which selects the regime and the evaporation rate. The six preset buttons jump to warm, nucleate, transition, Leidenfrost, superheated and maximum-heat settings. The add button drops a new droplet, and you can also click anywhere on the pan to place one, up to a limit of twenty droplets.
Why do droplets last longer when the pan is hotter?
This is the counter-intuitive heart of the effect. In nucleate and transition boiling the droplet touches the hot metal directly, so heat floods in and it evaporates fast. Once the vapour film forms above the Leidenfrost point, that gas layer is a poor conductor, throttling the heat flow so a hotter pan actually keeps the droplet alive longer.
How does the simulation model evaporation?
Each droplet has a radius that shrinks at a rate that depends on the regime. Nucleate and transition boiling give the fastest shrink rates, rising with temperature, while the cold and Leidenfrost regimes shrink slowly. When a droplet's radius falls below one pixel it is removed, which is why levitating droplets persist far longer on screen.
Why does the levitating droplet bounce and drift?
In the Leidenfrost regime the model applies gravity and a springy repulsion from the vapour cushion near the pan, so droplets gently bounce. Small random jitter is added to the horizontal velocity to mimic pressure fluctuations in the vapour film, producing the wandering, gliding motion seen with real Leidenfrost droplets.
How accurate is this simulation?
It is a qualitative, illustrative model rather than a quantitative fluid solver. The regime thresholds and the slower-evaporation-when-hotter behaviour reflect real physics, but droplet motion, the vapour cushion thickness and the shrink rates are simplified parameters tuned for clarity, not exact numbers from heat-transfer theory.
Does the same effect happen with other liquids?
Yes. Any liquid shows a Leidenfrost effect, but the point depends on the liquid's boiling point and properties. Liquid nitrogen, with a boiling point near -196 °C, becomes Leidenfrost at room temperature, which is why spilled nitrogen beads and rolls across the floor instead of instantly boiling away.
Where does the effect matter in the real world?
It limits how fast hot metal can be quenched, because a vapour blanket slows cooling in metallurgy and nuclear reactor safety. It explains the old trick of flicking water onto a pan to test if it is hot enough for searing, and it is being explored for self-propelling droplets and frictionless transport on textured heated surfaces.