Theoretical and physical insights of acoustic radiation forces beyond Gor’kov potential

Abstract

Acoustic radiation forces exerted on small objects by standing waves can be simply described by the Gor’kov potential that provides a basis for designs of acoustofluidic devices for trapping and separation of particles. However, when considering forces exerted on large objects by general sound beams, theoretical and physical insights into the forces must rely on momentum conservation. Nevertheless, the relative complexity of analysis of the force starting from stress tensor or spatial integral of acoustic radiation pressure creates a barrier on the insights in the frame of momentum conservation. Despite the early availability of momentum conservation frame for acoustic radiation pressure on interface between two media, the insights into acoustic radiation forces on large objects beyond Gor’kov potential are still limited. These insights are now enhanced by our recent theory of momentum conservation frame for three-dimensional acoustic radiations forces. The theory has simplified analytical results for acoustic radiation forces into compact and physically meaningful formulas. These formulas provide an understanding for forces and torques exerted by sound beams on both large objects and interface between two media in various scenarios, which will be summarized and reviewed.