title: Inverted Leidenfrost-like Effect during Condensation.
abstract: Water droplets condensing on solidified phase change materials such as benzene and cyclohexane near their melting point show in-plane jumping and continuous "crawling" motion. The jumping drop motion has been tentatively explained as an outcome of melting and refreezing of the materials surface beneath the droplets and can be thus considered as an inverted Leidenfrost-like effect (in the classical case vapor is generated from a droplet on a hot substrate). We present here a detailed investigation of jumping movements using high-speed imaging and static cross-sectional cryogenic focused ion beam scanning electron microscope imaging. Our results show that drop motion is induced by a thermocapillary (Marangoni) effect. The in-plane jumping motion can be delineated to occur in two stages. The first stage occurs on a millisecond time scale and comprises melting the substrate due to drop condensation. This results in droplet depinning, partial spreading, and thermocapillary movement until freezing of the cyclohexane film. The second stage occurs on a second time scale and comprises relaxation motion of the drop contact line (change in drop contact radius and contact angle) after substrate freezing. When the cyclohexane film cannot freeze, the droplet continuously glides on the surface, resulting in the crawling motion.
authors: †Physique et Mécanique des Milieux Hétérogènes, Unité Mixte de Recherches (UMR) 7636, École Supérieure de Physique et Chimie Industrielles ParisTech, Université Pierre et Marie Curie, Université Paris-Diderot, Centre National de la Recherche Scientifique (CNRS), 10 rue Vauquelin, 75231 Paris, France.|‡Department of Physics and Applied Mathematics, University of Navarra, 31008 Pamplona, Spain.
authors: Ramchandra
authors: R
authors: Narhe
authors: §Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Sushant
authors: S
authors: Anand
authors: ∥School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85281, United States.
authors: Konrad
authors: K
authors: Rykaczewski
authors: †Physique et Mécanique des Milieux Hétérogènes, Unité Mixte de Recherches (UMR) 7636, École Supérieure de Physique et Chimie Industrielles ParisTech, Université Pierre et Marie Curie, Université Paris-Diderot, Centre National de la Recherche Scientifique (CNRS), 10 rue Vauquelin, 75231 Paris, France.|⊥Université Nice Sophia Antipolis, CNRS, Laboratoire de Physique de la Mateière Condensée-UMR 7336, Parc Valrose, 06100 Nice, France.
authors: Marie-Gabrielle
authors: MG
authors: Medici
authors: ‡Department of Physics and Applied Mathematics, University of Navarra, 31008 Pamplona, Spain.
authors: Wenceslao
authors: W
authors: González-Viñas
authors: §Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
authors: Kripa K
authors: KK
authors: Varanasi
authors: †Physique et Mécanique des Milieux Hétérogènes, Unité Mixte de Recherches (UMR) 7636, École Supérieure de Physique et Chimie Industrielles ParisTech, Université Pierre et Marie Curie, Université Paris-Diderot, Centre National de la Recherche Scientifique (CNRS), 10 rue Vauquelin, 75231 Paris, France.|#Service des Basses Températures, CEA-Grenoble and Université Joseph Fourier, 38041 Grenoble, France.
authors: Daniel
authors: D
authors: Beysens