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Ultrasound resonance in coflowing immiscible liquids in a microchannel
S.Z. Hoque,
Published in American Physical Society
2023
PMID: 37073059
Volume: 107
   
Issue: 3
Abstract
We study ultrasonic resonance in a coflow system comprising a pair of immiscible liquids in a microchannel exposed to bulk acoustic waves. We show using an analytical model that there are two resonating frequencies corresponding to each of the coflowing liquids, which depend on the speed of sound and stream width of the liquid. We perform a frequency domain analysis using numerical simulations to reveal that resonance can be achieved by actuating both liquids at a single resonating frequency that depends on the speeds of sound, densities, and widths of the liquids. In a coflow system with equal speeds of sound and densities of the pair of fluids, the resonating frequency is found to be independent of the relative width of the two streams. In coflow systems with unequal speeds of sound or densities, even with matching characteristic acoustic impedances, the resonating frequency depends on the stream width ratio, and the value increases with an increase in the stream width of the liquid with a higher speed of sound. We show that a pressure nodal plane can be realized at the channel center by operating at a half-wave resonating frequency when the speeds of sound and densities are equal. However, the pressure nodal plane is found to shift away from the center of the microchannel when the speeds of sound and densities of the two liquids are unequal. The results of the model and simulations are verified experimentally via acoustic focusing of microparticles suggesting the formation of a pressure nodal plane and hence a resonance condition. Our study will find relevance in acoustomicrofluidics involving immiscible coflow systems. © 2023 American Physical Society.
About the journal
JournalPhysical Review E
PublisherAmerican Physical Society
ISSN24700045