Poloidal Flow and Toroidal Particle Ring Formation in a Sessile Drop Driven by Megahertz Order Vibration

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• 作者：Amgad R. Rezk ; Leslie Y. Yeo ; James R. Friend
• 刊名：Langmuir
• 出版年：2014
• 出版时间：September 23, 2014
• 年：2014
• 卷：30
• 期：37
• 页码：11243-11247
• 全文大小：333K
• ISSN：1520-5827

文摘

Poloidal flow is curiously formed in a microliter sessile water drop over 157鈥?25 MHz because of acoustic streaming from three-dimensional standing Lamb waves in a lithium niobate substrate. The flow possesses radial symmetry with downwelling at the center and upwelling around the periphery of the drop. Outside this frequency range, the attenuation occurs over a length scale incompatible with the drop size and the poloidal flow vanishes. Remarkably, shear-induced migration was found to drive toroidal particle ring formation with diameters inversely proportional to the frequency of the acoustic irradiation.