Prediction of acoustic radiation forces in three dimensional flow through resonators

Abstract

In large scale acoustophoretic particle separation systems, the acoustic radiation force exerted on the particles exceeds the combined effect of the fluid drag force and gravitational force on the particle. This results in the trapping of the particles in the acoustic standing wave, followed by aggregation of the particles, and ultimately gravitational settling and separation of the secondary phase. The separation system typically consists of a flow chamber in which a three dimensional acoustic standing wave is generated by piezoelectric transducers. Accurate prediction models of the acoustic radiation force are needed so that they can be used as a tool in the design and development of such separation systems. The prediction model consists of two steps. First, COMSOL Multiphysics ¯ software is used to predict the acoustic field in the separation devices. Next, theoretical models [Gor’kov, Sov. Phys. Dokl. 6, 773–775 (1962) and Ilinskii et al., J. Acoust. Soc. Am. 133, 3237 (2013)] are used to calculate the acoustic radiation force on a suspended particle. Numerical results were verified by comparison with the theoretical results for a rectangular cavity [Barmatz and Collas, J. Acoust. Soc. Am. 77, 928 (1985)]. [Work supported by NSF PFI:BIC 1237723.]