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Indexed by:期刊论文

Date of Publication:2018-12-25

Journal:SURFACE & COATINGS TECHNOLOGY

Included Journals:SCIE、Scopus

Volume:356

Page Number:132-137

ISSN No.:0257-8972

Key Words:Gradient grooves; Contact boiling; Leidenfrost; Directional movement

Abstract:Droplet impact dynamics on gradient textures at room temperature have been intensively studied in the past decade. The wetting gradient surfaces are reported to direct the droplet motion. In this work, we show an undirectional rebound behavior of impacting droplets on gradient grooved surfaces at high temperature. The impinging droplet rebounds towards the denser microstructure region at contact boiling state, but towards to the sparser region when at Leidenfrost film boiling state. Our analysis indicates that the non-directional rebounding direction is attributed to the unbalanced Young's forces or vapor pressure difference between the droplet and the substrate. In contact boiling regime, the droplet rebounds towards the denser region due to the unbalanced Young's force. However, in the Leidenfrost film boiling region, adequate vapor generated underneath the droplet impedes the direct contact and larger vapor pressure in the denser region causes the droplet to rebound oppositely. This study is envisioned to promote the understanding of droplet dynamics at high temperature and provide promising applications in various systems where regulating droplet motion is needed.