Researchers found that the movement of Leidenfrost drops were due to unbalanced flow inside the liquid.
A team of researchers at Physique et Mecanique des Milieux Heterogenes in France studied over the Leidenfrost effect drops and concluded that the drops were capable to move around on a hot pan as they could be self-propelled. The research work with detailed study of Leidenfrost effect drops was published in the journal Nature Physics on September 2018.
Existing research on Leidenfrost effect drops relied on the slipperiness of the drops due to a thin layer of vapor, which is developed between the drop and the surface that causes the drop to jump. However, the reason behind the apparent alleviation was not explained by the researchers.
To analyze the mechanism behind the drops, the team injected tiny glass spheres into a small sample of water, which was used for generating droplets. A high-speed camera was attached to track the movement of the drops. The experiment was viewed by magnifying the size on computer screen, they observed that the glass spheres flowed in a smooth manner and the drops on the hot plate hardly moved. However, the larger drops were capable of moving as it was previously believed, while the smaller drops decreased its size owing to evaporation. The flow of the liquid inside the drops became unbalanced, due to which the drop was capable of moving forward.
Moreover, the researchers observed that the small drops tilted downwards in the identical path as the drop was moving due to the unbalance inside the drop, akin to a miniature tidal wave. They believe that the new mechanism could be used in understanding and designing a new type of self-propelled devices.