Sound Scattered by Deforming Bodies Through Boundary Integral Formulations

This paper presents a novel methodology for the prediction of sound scattered by deforming bodies of arbitrary shape. It is based on a deformable-boundary integral formulation, which solves an arbitrarily forced acoustic wave equation governing the propagation of perturbations in a fluid medium. Neglecting nonlinear terms, the acoustic field is represented either by acoustic pressure or velocity potential, and determined through time-domain and frequency-domain boundary element method approaches. In particular, a novel frequency-domain solution algorithm is proposed, which is capable of providing accurate predictions of the multiharmonic scattered field occurring in the presence of deforming scatterers. It is suitable for the analysis of problems involving high-frequency signals for which time-domain solvers may suffer from numerical inaccuracies that make their predictions unreliable. For low-frequency incident waves, the time-domain and frequency-domain solution approaches are successfully correlated. Furthermore, the proposed solution method is validated through comparison against analytical results concerning both rigid and pulsating spherical scatterers. Finally, the multiharmonic frequency-domain solver is applied to examine the effect of body deformation on the directivity pattern of the multiple-tone, scattered noise.