Leidenfrost droplets on microstructured surfaces

Gail Duursma, Ross Kennedy, Khellil Sefiane, Yu Yong

Research output: Contribution to journalArticlepeer-review

Abstract

The lifetime of a droplet deposited on a hot plate decreases when the temperature of the plate increases, but above the critical Leidenfrost temperature, the lifetime suddenly increases. This is due to the formation of a thin layer of vapor between the droplet and the substrate, which plays a double role: First, it thermally insulates the droplet from the plate, and second, it allows the droplet to “levitate.” The Leidenfrost point is affected by the roughness or microstructure of the surface. In this work, a silicon surface with different microstructured regions of square pillars was prepared such that there is a sharp transition (boundary) between areas of different pillar spacing. The Leidenfrost point was identified in experiments using water droplets ranging in size from 8 to 24 μl and the behavior of the droplets was recorded using high-speed digital photography. The Leidenfrost point was found to vary by up to 120°C for pillar spacings from 10 to 100 μm. If the droplet is placed on the boundary between structured sections, the droplet becomes asymmetric and may move or spin. An axisymmetric computational fluid dynamics (CFD) model is also presented that shows qualitative agreement with experimental observations.
Original languageEnglish
Pages (from-to)1190-1200
JournalHeat Transfer Engineering
Volume37
Issue number13-14
Early online date24 Mar 2016
DOIs
Publication statusPublished - 2016
Event4th Micro and Nano Flows Conference - University College London, London, United Kingdom
Duration: 7 Sep 201410 Sep 2014

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