Motion of a rigid prolate spheroid in a sound wave field

Abstract

The motions of a rigid and unconstrained prolate spheroid subjected to plane sound waves are computed using preliminary analytic derivation and numerical approach. The acoustically induced motions are found comprising torsional motion as well as translational motion in the case of acoustic oblique incidence and present great relevance to the sound wavelength, body geometry, and density. The relationship between the motions and acoustic particle velocity is obtained through finite element simulation in terms of sound wavelengths much longer than the overall size of the prolate spheroid. The results are relevant to the design of inertial acoustic particle velocity sensors based on prolate spheroids.

Long waves induced motions to rigid spheroids

“…(5). Then (9) and similarly (10) where K i = M ii /m 0 denotes a dimensionless coefficient of added mass. It is evident that the acoustically induced translational motion is only dominated by densities and added mass coefficients.…”

“…However, as for rigid spheroidal bodies, the researches on the acoustical responses are considerably limited and more compendious [6], while the fluid flow driven motions have been perfectly investigated in the domain of hydrodynamics [7,8]. Some preliminary works have been completed by us through numerical simulation [9], and this paper, on the basis of sound radiation from spheroids [10,11], is devoted to providing a theoretical analysis of prolate and oblate spheroids motions due to the low frequency underwater acoustic field, which is extremely significant for designing acoustic vector receivers of spheroidal shape.…”