演講公告
新聞標題： ( 2016-10-05 )
演講主題：Resonance of Sessile Drops
主講人：張鈞棣教授 (國立台灣大學機械系)
演講日期：2016年10月11日(星期二) 下午14:00 - 15:00
演講地點：(光復校區) 科學一館223室
茶會時間：當天下午1:30 (科學一館205室)
摘要內容：
This study experimentally examines the resonance of mechanically vibrated sessile drops. Shape, frequency and amplitude responses of the drops are investigated for individual modes. The observations are characterized by relating to Rayleigh-Lamb (RL), Bostwick-Steen invisid (BS inviscid) and Bostwick-Steen viscous potential flow (VPF) theories. Observed mode shapes are compared to predictions from RL and BS inviscid theories via ray-tracing simulation. The comparison of frequency response suggests that VPF theory most adequately predicts resonance frequency of observed modes. The adequacy implies the necessity of considering both substrate constraint and viscosity, and hence distinguishes viscous sessile drops from and inviscid free spherical drops. The amplitude responses of modes are explored from the growth and decay of the lowest axisymmetric mode. Evident nonlinearity is observed. The amplitude study thus exposes the surprising extent to which our nonlinear observations can be understood in the context of linear theories. Further exploration reveals the interactions of modes such as spectral crossing and mode mixing. For subhemispherical drops, typical observations are mixtures of a half-frequency subharmonic non-zonal mixing a harmonic zonal mode. For superhemispherical drops, more diverse mixing phenomena are discovered. From the scientific perspective, the study reveals a rich collection of resonance modes catagorized according to shapes and harmonic types for future investigation. From engineers, the study provides guidelines for applications relevant to pattern selection of surface waves, such as ordered self-assembly of particles, droplet transport, drop atomization, enhanced mixing, and suspension collection.相關檔案：Talk_20161011.pdf
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