Final fate of a Leidenfrost droplet: Explosion or takeoff

ORAL

Abstract

When a liquid droplet is placed on a very hot solid, it levitates on its own vapor layer, a phenomenon called the Leidenfrost effect. Although the mechanisms governing the droplet's levitation have been explored, not much is known about the fate of the Leidenfrost droplet. Here we report on the final stages of evaporation of Leidenfrost droplets. While initially small droplets tend to take off, unexpectedly, the initially large ones explode with a crack sound. We interpret these in the context of unavoidable droplet contaminants, which accumulate at the droplet-air interface, resulting in reduced evaporation rate, and contact with the substrate. We validate this hypothesis by introducing controlled amounts of microparticles and reveal a universal 1/3-scaling law for the dimensionless explosion radius versus contaminant fraction. Our findings open up new opportunities for controlling the duration and rate of Leidenfrost heat transfer and propulsion by tuning the droplet's size and contamination.

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Authors

  • Sijia Lyu

    Tsinghua University

  • Varghese Mathai

    Brown University, School of Engineering, Brown University

  • Yujie Wang

    Tsinghua University

  • Benjamin Sobac

    Université libre de Bruxelles

  • Pierre Colinet

    Université libre de Bruxelles, Université Libre de Bruxelles

  • Detlef Lohse

    Physics of Fluids Group and Max Planck Center Twente, MESA+ Institute and J. M. Burgers Centre for Fluid Dynamics, University of Twente, P.O. Box 217,, Physics of Fluids group, University of Twente, Physics of Fluids Group, University of Twente, Univ of Twente, PoF - University of Twente, The Netherlands, Twente University, Physics of Fluids Group, University of Twente; Max Planck Institute for Dynamics and Self-Organization, University of Twente

  • Chao Sun

    Tsinghua University, Tsinghua University, 100084 Beijing, China