Article
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Preserved in Portico This version is not peer-reviewed
Coalescence Dynamics of Acoustically Levitated Droplets
Version 1
: Received: 27 February 2020 / Approved: 28 February 2020 / Online: 28 February 2020 (13:02:22 CET)
A peer-reviewed article of this Preprint also exists.
Hasegawa, K.; Watanabe, A.; Kaneko, A.; Abe, Y. Coalescence Dynamics of Acoustically Levitated Droplets. Micromachines 2020, 11, 343. Hasegawa, K.; Watanabe, A.; Kaneko, A.; Abe, Y. Coalescence Dynamics of Acoustically Levitated Droplets. Micromachines 2020, 11, 343.
Abstract
The contactless coalescence of a droplet is of paramount importance for physical and industrial applications. This paper describes a coalescence method in mid-air via acoustic levitation using an ultrasonic phased array system. Acoustic levitation using ultrasonic phased arrays provides promising lab-on-a-drop applications, such as transportation, coalescence, mixing, separation, evaporation, and extraction in a continuous operation. The mechanism of droplet coalescence in mid-air may be better understood by experimentally and numerically exploring the droplet dynamics immediately before the coalescence. In this study, water droplets were experimentally levitated, transported, and coalesced by controlling acoustic fields. We observed that the edge of droplets deformed and attracted each other immediately before the coalescence. Through image processing, the radii of curvature of the droplets were quantified and the pressure difference between the inside and outside the droplet was simulated to obtain the pressure and velocity information on the droplet surface. The results revealed that the sound pressure acting on the droplet clearly decreased before the impact of the droplets. This pressure on the droplets was quantitatively analyzed from the experimental data. Our experimental and numerical results provide deeper physical insights into contactless droplet manipulation for futuristic lab-on-a-drop applications.
Keywords
acoustic levitation; ultrasonic phased array; droplet; coalescence; lab-on-a-drop
Subject
Engineering, Mechanical Engineering
Copyright: This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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