Viscous mechanism for Leidenfrost propulsion on a ratchet
Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS, ESPCI - 75005 Paris, France, EU
2 Ladhyx, UMR 7646 du CNRS, École Polytechnique - 91128 Palaiseau Cedex, France, EU
3 Center for Smart Interfaces, Technische Universität Darmstadt - Petersenstraße 32, D-64287 Darmstadt, Germany, EU
Accepted: 7 October 2011
An evaporating drop placed on a ratchet self-propels, as discovered by Linke et al. in 2006. Sublimating platelets do the same, and we discuss here a possible viscous mechanism for these motions. We report that the flow of vapor below the levitating material is rectified by the asymmetric teeth of the ratchet, in the direction of descending slopes along each tooth. As a consequence, the resulting viscous stress can entrain the material in the same direction, and we discuss the resulting self-propelling force.
PACS: 83.50.Lh – Slip boundary effects (interfacial and free surface flows)
© EPLA, 2011