Viscous mechanism for Leidenfrost propulsion on a ratchet G. Dupeux, M. Le Merrer, G. Lagubeau, C. Clanet, S. Hardt and D. Quéré EPL, 96 5 (2011) 58001 Published online: 22 November 2011 DOI: 10.1209/0295-5075/96/58001