Watch droplets bounce off one another as they levitate on a scorching plate

A twist on the basic Leidenfrost impact sees orbs of various liquids repel one another as they float on a scorching plate

By Leah Crane

Making droplets levitate may also make them delinquent. When two totally different liquids are positioned on a scorching sufficient floor, they may levitate and bounce off each other, even after they would sometimes combine collectively simply, in what researchers have named the triple Leidenfrost impact.

The Leidenfrost effect happens when droplets of a liquid skitter throughout a scorching floor on cushions of steam as an alternative of merely flowing collectively and remaining in a single place. René Ledesma-Alonso on the Universidad de las Américas Puebla in Mexico and his colleagues discovered that these vapour cushions, referred to as Leidenfrost layers, may also type between totally different liquids on scorching surfaces.

“It was, like many new findings, a mistake in the lab,” says Ledesma-Alonso. “Felipe [Pacheco-Vásquez, one of the researchers] was working with some students in the lab, and one of the students poured some ethanol in the same plate as the other student was pouring water.”

The common Leidenfrost impact occurs because of the temperature of the floor being far hotter than the boiling temperature of the liquid, so the perimeters of the liquid boil and create Leidenfrost layers. When two liquid droplets on the identical floor have totally different boiling factors, the warmer liquid may also warmth up the sting of the cooler liquid, creating an extra Leidenfrost layer that makes the droplets bounce off each other.

The researchers examined this with 11 totally different liquids, which they positioned on a heated aluminium floor and filmed with a excessive velocity digital camera. They discovered that the when the liquids had different boiling points, they bounced off each other till the cooler droplet grew to become too small to create a cushion of vapour. Then they merged.

The bouncing lasted anyplace from a number of seconds to some minutes, relying on the velocity of evaporation of the cooler droplets. “There is a size limit, but not a time limit,” says Ledesma-Alonso. “It’s going to be difficult because the droplets will be bouncing the whole time, but if you can keep replenishing the droplets they could bounce forever.”

Journal reference: Physical Review Letters, DOI: 10.1103/PhysRevLett.127.204501