Water droplets making their own way through a metal maze
September 13, 2013
The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass significantly hotter than the liquid’s boiling point, produces an insulating vapor layer which keeps that liquid from boiling rapidly. This is most commonly seen when cooking; one sprinkles drops of water in a pan to gauge its temperature—if the pan’s temperature is at or above the Leidenfrost point, the water skitters across the metal and takes longer to evaporate than it would in a pan that is above boiling temperature, but below the temperature of the Leidenfrost point. The effect is also responsible for the ability of liquid nitrogen to skitter across floors. It has also been used in some potentially dangerous demonstrations, such as dipping a wet finger in molten lead or blowing out a mouthful of liquid nitrogen, both enacted without injury to the demonstrator. The latter is potentially lethal, particularly should one accidentally swallow the liquid nitrogen.
The film features a maze built out of aluminium blocks, designed by the students to demonstrate how water droplets can be made to move in different directions when they come into contact with a heated metal surface:
The Leidenfrost Maze was designed and built by University of Bath undergraduate students Carmen Cheng and Matthew Guy to demonstrate the self-propulsion of Leidenfrost droplets at public outreach events and schools. The video was created by Carmen Cheng as part of her undergraduate project.