Self-propelling uneven Leidenfrost solids

Placed on a hot surface, a solid that sublimates at atmospheric pressure can levitate on a cushion of its own vapor. Discovered by Leidenfrost, this effect has mostly been studied with liquids. Whereas the shape of a droplet is determined by a competition between gravity, surface tension, and stress in the vapor layer, a solid does not deform. In this paper, we show experimentally and theoretically that asymmetric mass distributions in a Leidenfrost solid can lead to a non homogenous vapor layer in which the lubrication flow generates a lateral force able to propel the body.