SOUND SCATTERING BY LOCALIZED OCEAN FLOW INHOMOGENEITY

摘要

The paper considers the propagation of sound in the vicinity of a rather general class of localised flows induced by the motion of spherically symmetric structures of the type of solid spheres and droplets or vortices in the liquid, say, ocean environment. Acoustic scattering from such inhomogeneities, situated inside various flows is analysed with aid of M.J.Lighthill equation boundary value problem solution both in the presence of vorticity and without it. The role of a moving body generating inhomogeneity as well as a role of surface at which the tangential component of flow velocity could suffer a discontinuity are demonstrated in most general form. Comparison of body and flow contribution to observed scattered field is presented. Physical condition of flow presumable yield in forward scattering direction -situation of the type encountered in conventional ocean tomography system, comprising source - detector line, are proposed. The angular structure of the scattering amplitude and the frequency dependence of the scattered sound are evaluated.