Acoustic scattering by two spheres: Multiple scattering and symmetry considerations

Acoustic scattering by two identical spheres is theoretically, numerically and experimentally studied by highlighting the role of the symmetries of th e scatterer. Incident and scattered fields are expanded over the different irreducible representations of D-infinityh, the continuous symmetry group o f the scatterer. Then, from the boundary conditions, one obtains for each i rreducible representation an infinite system of linear complex algebraic eq uations where the unknown scattering coefficients are uncoupled. This featu re greatly simplifies the treatment of the problem and speeds up calculatio ns. Farfield form functions are computed in the cases of Neumann boundary c onditions (rigid spheres) and elastic boundary conditions (elastic spheres immersed in water). A series of experiments based on ultrasonic spectroscop y is performed in the case of two stainless-steel spheres immersed in water . The comparison between the theoretical and the experimental results provi des quite a good agreement. (C) 2001 Academic Press.