Acoustic radiation force exerted on an object of arbitrary shape and composition by an arbitrary incident sound beam can be calculated using spherical harmonic expansions of the pressure field. The coefficients in the expansions of the incident and scattered fields, when substituted into existing models, determine the radiation force on the object. Analytical expressions for the coefficients of both the incident and scattered fields are available for very few cases, such as a plane wave incident on a rigid sphere. In the present work, finite element modeling is used to calculate the coefficients, and resulting radiation force, for a variety of incident fields and object geometries. Different compositions of the objects are also considered. Validation of the approach is demonstrated by comparison with semi-analytical results available for the radiation force exerted by progressive and standing plane waves scattered by compressible spheroids in different orientations with respect to the incident field. Motivation for this approach is development of a model that can be used to compare with direct measurements of radiation force on irregularly shaped objects of different compositions. [BES is supported by the ARL:UT Chester M. McKinney Graduate Fellowship in Acoustics.]
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