Abstract:

Acoustic reverberation in the ocean is due to collective scattering from a large number and diverse range of distributed objects. In this work, a model for predicting the sonar target strengths of an important class of clutter objects, i.e., rocks and sea shells lying on the ocean floor, is presented. The model incorporates a simplified approach, in which rocks are represented by either rigid movable spheres or elastic spheres, a technique which has been previously used to model aqueous suspensions of sand over the frequency range of interest. Sea shells are represented by water-filled spherical shells. The model predicts scattering strength values for areas of the ocean floor covered by randomized arrangements of rocks and shells, using sizes, numbers, geologic type, and material compositions typically found on the bottom. The scattering as a function of azimuth is determined by coherent addition, and allows both monostatic and bistatic geometries to be investigated. [Work supported by ONR/NRL]