Two dimensional Leidenfrost Droplets in a Hele Shaw Cell

Franck Celestini (1) , Thomas Frisch (2) , A. Cohen (1) , Christophe Raufaste (3) , Laurent Duchemin (4) , Yves Pomeau (5)

1 LPMC - Laboratoire de physique de la matière condensée
2 INLN - Institut Non Linéaire de Nice Sophia-Antipolis
3 LPMC - Laboratoire de physique de la matière condensée
4 IRPHE - Institut de Recherche sur les Phénomènes Hors Equilibre
5 Department of Mathematics [University of Arizona]

We experimentally and theoretically investigate the behavior of Leidenfrost droplets inserted in a Hele-Shaw cell. As a result of the confinement from the two surfaces, the droplet has the shape of a flattened disc and is thermally isolated from the surface by the two evaporating vapor layers. An analysis of the evaporation rate using simple scaling arguments is in agreement with the experimental results. Using the lubrication approximation we numerically determine the shape of the droplets as a function of its radius. We furthermore find that the droplet width tends to zero at its center when the radius reaches a critical value. This prediction is corroborated experimentally by the direct observation of the sudden transition from a flattened disc into an expending torus. Below this critical size, the droplets are also displaying capillary azimuthal oscillating modes reminiscent of a hydrodynamic instability.

Domaines: Dynamique des Fluides [physics.flu-dyn]

Franck Celestini, Thomas Frisch, A. Cohen, Christophe Raufaste, Laurent Duchemin, et al.. Two dimensional Leidenfrost Droplets in a Hele Shaw Cell. Physics of Fluids, 2014, 26, pp.032103. ⟨hal-00905179⟩