Modeling of Acoustic Scattering by Spherical Targets Above a Planar Seafloor

A model of acoustic scattering from spherical targets above a planar seafloor is established on a condition of irradiation by a point source, with both of T matrix method and complex images method. Compared to the other model of Fawcett and Lim, this model can be used to calculate the scattering field from targets above a planar interface in three-dimensional space. Comparison of some coefficients by the complex images method with that by analytical formula or numerical quadrature, the computation method of the model is examined to be efficient and accurate. In addition, numerical examples of a rigid sphere and an elastic spherical shell are presented for the scattering field from the target on a fluid seabed, and the scattering field dependent angle is investigated from the different grazing angles of incident wave. In order to verify the model, an experiment is carried out to measure the scattered field received by a vertical array in laboratory. Data are analyzed and compared with calculated results.