Acoustic radiation torque on a particle in a fluid: An angular spectrum based compact expression.

In this work, a set of compact analytical formulas is derived expressing the three-dimensional acoustic radiation torque (ART) exerted on a particle of arbitrary shape embedded in a fluid and insonified by an arbitrary acoustic field. This formulation enables direct computation of the ART from the angular spectrum based beam shape coefficients introduced by Sapozhnikov and Bailey [J. Acoust. Soc. Am. 133, 661-676 (2013)] and the partial wave coefficients. It is particularly well suited to determine the ART exerted on a particle when the acoustic field is known in a source plane.