Liquid jet directionality and droplet behavior during emulsification of two liquids due to acoustic cavitation

Takuya Yamamoto; Sergey V Komarov

doi:10.1016/j.ultsonch.2019.104874

Liquid jet directionality and droplet behavior during emulsification of two liquids due to acoustic cavitation

Ultrason Sonochem. 2020 Apr:62:104874. doi: 10.1016/j.ultsonch.2019.104874. Epub 2019 Nov 14.

Authors

Takuya Yamamoto¹, Sergey V Komarov²

Affiliations

¹ Graduate School of Environmental Studies, Tohoku University, Miyagi 980-8579, Japan. Electronic address: t-yamamoto@tohoku.ac.jp.
² Graduate School of Environmental Studies, Tohoku University, Miyagi 980-8579, Japan.

PMID: 31810876
DOI: 10.1016/j.ultsonch.2019.104874

Abstract

The present study numerically investigates liquid-jet characteristics of acoustic cavitation during emulsification in water/gallium/air and water/silicone oil/air systems. It is found that a high-speed liquid jet is generated when acoustic cavitation occurs near a minute droplet of one liquid in another. The velocity of liquid jet significantly depends on the ultrasonic pressure monotonically increasing as the pressure amplitude increases. Also, the initial distance between cavitation bubble and liquid droplet affects the jet velocity significantly. The results revealed that the velocity takes maximum values when the initial distance between the droplet and cavitation bubble is moderate. Surprisingly, the liquid jet direction was found to depend on the droplet properties. Specifically, the direction of liquid jet is toward the droplet in the case of water/gallium/air system, and vice versa the jet is directed from the droplet in the case of water/silicone oil/air system. The jet directionality can be explained by location of the high-pressure spot generated during the bubble contraction.

Keywords: Acoustic cavitation; Emulsification; Non-linear oscillation; OpenFOAM; Three-Phases Volume of Fluid (TP-VOF) method.