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论文类型：期刊论文

第一作者：Liu, Yahua

通讯作者：Wang, ZK (reprint author), City Univ Hong Kong, Dept Mech & Biomed Engn, Hong Kong, Hong Kong, Peoples R China.

合写作者：Whyman, Gene,Bormashenko, Edward,Hao, Chonglei,Wang, Zuankai

发表时间：2015-08-03

发表刊物：APPLIED PHYSICS LETTERS

收录刊物：SCIE、EI、Scopus

卷号：107

期号：5

ISSN号：0003-6951

摘要：Drop hitting on superhydrophobic surfaces usually undergoes spreading and retraction stages before its complete rebound and there exists a minimum amount of time for the spreading and retraction processes. Impressively, it was recently shown that the so-called contact time can be significantly reduced by engineering surfaces with millimeter-scale tapered post arrays that allow the impinging drop to leave the surfaces in a pancake shape at the end of lateral spreading (pancake bouncing). Despite exciting progress, it remains elusive to rationally control the contact time and quantitatively predict the critical Weber number for the occurrence of pancake bouncing. Here, we experimentally demonstrated that the drop bouncing is intricately modulated by the surface morphology. Under the same centre-to-centre post spacing, surfaces with a larger apex angle could give rise to more robust pancake bouncing, which is characterized by significant contact time reduction, smaller critical Weber number, and wider Weber number range. We also developed simple harmonic spring models and theoretically revealed the dependence of timescales associated with the impinging drop and the critical Weber number for pancake bouncing on the surface morphology. The insights learned from this work will allow us to rationally design various surfaces for many practical applications. (C) 2015 AIP Publishing LLC.