title: Dynamic Leidenfrost Effect: Relevant Time and Length Scales.
abstract: When a liquid droplet impacts a hot solid surface, enough vapor may be generated under it to prevent its contact with the solid. The minimum solid temperature for this so-called Leidenfrost effect to occur is termed the Leidenfrost temperature, or the dynamic Leidenfrost temperature when the droplet velocity is non-negligible. We observe the wetting or drying and the levitation dynamics of the droplet impacting on an (isothermal) smooth sapphire surface using high-speed total internal reflection imaging, which enables us to observe the droplet base up to about 100 nm above the substrate surface. By this method we are able to reveal the processes responsible for the transitional regime between the fully wetting and the fully levitated droplet as the solid temperature increases, thus shedding light on the characteristic time and length scales setting the dynamic Leidenfrost temperature for droplet impact on an isothermal substrate.
authors.affiliation: Physics of Fluids Group, Mesa+ Institute, University of Twente, 7500 AE Enschede, Netherlands.
authors.forename: Minori
authors.initials: M
authors.lastname: Shirota
authors.affiliation: Physics of Fluids Group, Mesa+ Institute, University of Twente, 7500 AE Enschede, Netherlands.
authors.forename: Michiel A J
authors.initials: MA
authors.lastname: van Limbeek
authors.affiliation: Physics of Fluids Group, Mesa+ Institute, University of Twente, 7500 AE Enschede, Netherlands.|Center for Combustion Energy and Department of Thermal Engineering, Tsinghua University, 100084 Beijing, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.affiliation: Physics of Fluids Group, Mesa+ Institute, University of Twente, 7500 AE Enschede, Netherlands.|Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland 21218, USA.
authors.forename: Andrea
authors.initials: A
authors.lastname: Prosperetti
authors.affiliation: Physics of Fluids Group, Mesa+ Institute, University of Twente, 7500 AE Enschede, Netherlands.|Max Planck Institute for Dynamics and Self-Organization, 37077 Göttingen, Germany.
authors.forename: Detlef
authors.initials: D
authors.lastname: Lohse