TY - JOUR
T1 - High-speed imaging of ultrasonic emulsification using a water-gallium system
AU - Yamamoto, Takuya
AU - Matsutaka, Ryo
AU - Komarov, Sergey V.
N1 - Funding Information:
The present research is supported partly by Nippon Steel corporation and Photron Limited, and partly by JSPS KAKENHI Grant Number JP17K18969, and JP20K15079.
Publisher Copyright:
© 2020 The Author(s)
PY - 2021/3
Y1 - 2021/3
N2 - Aiming at elucidating ultrasonic emulsification mechanisms, the interaction between a single or multiple acoustic cavitation bubbles and gallium droplet interface was investigated using an high-speed imaging technique. To our best knowledge, the moment of emulsification and formation of fine droplets during ultrasound irradiation were observed for the first time. It was found that the detachment of fine gallium droplets occurs from the water-gallium interface during collapse of big cavitation bubbles. The results suggest that the maximum size of cavitation bubble before collapsing is of prime importance for emulsification phenomena. Previous numerical simulation revealed that the collapse of big cavitation bubble is followed by generation of high-velocity liquid jet directed toward the water-gallium interface. Such a jet is assumed to be the prime cause of liquid emulsification. The distance between cavitation bubbles and water-gallium interface was found to slightly affect the emulsification onset. The droplet fragmentation conditions are also discussed in terms of the balance between (1) interfacial and kinetic energies and (2) dynamic and Laplace pressure during droplet formation.
AB - Aiming at elucidating ultrasonic emulsification mechanisms, the interaction between a single or multiple acoustic cavitation bubbles and gallium droplet interface was investigated using an high-speed imaging technique. To our best knowledge, the moment of emulsification and formation of fine droplets during ultrasound irradiation were observed for the first time. It was found that the detachment of fine gallium droplets occurs from the water-gallium interface during collapse of big cavitation bubbles. The results suggest that the maximum size of cavitation bubble before collapsing is of prime importance for emulsification phenomena. Previous numerical simulation revealed that the collapse of big cavitation bubble is followed by generation of high-velocity liquid jet directed toward the water-gallium interface. Such a jet is assumed to be the prime cause of liquid emulsification. The distance between cavitation bubbles and water-gallium interface was found to slightly affect the emulsification onset. The droplet fragmentation conditions are also discussed in terms of the balance between (1) interfacial and kinetic energies and (2) dynamic and Laplace pressure during droplet formation.
KW - Acoustic cavitation
KW - Droplet and bubble behavior
KW - High-speed imaging
KW - High-speed liquid jet
KW - Ultrasonic emulsification
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U2 - 10.1016/j.ultsonch.2020.105387
DO - 10.1016/j.ultsonch.2020.105387
M3 - Article
C2 - 33246315
AN - SCOPUS:85096703958
SN - 1350-4177
VL - 71
JO - Ultrasonics Sonochemistry
JF - Ultrasonics Sonochemistry
M1 - 105387
ER -