Three-dimensional acoustic scattering in highly geometrically constrained environments

Abstract

For active sonar systems, transmission Loss (TL) and reverberation level (RL) are key parameters derived from the acoustic fields predicted by models and used to assess sonar performance. The existing propagation and scattering models may be appropriate for applications in the deep ocean or open littorals, but sonar operators are increasingly being asked to perform tasks including navigation or detection in significantly more confined waterways such as rivers or ports. Physics-based models are generally not available for predicting the acoustic field in such highly geometrically constrained and dynamic 3D environments often characterized by highly variable azimuthal boundaries such as irregularly shaped port geometries, piers, and breakwaters that may also have high large tidally driven depth variations over short time periods. They also may be populated with large scattering objects such as deep draft vessels and mooring dolphins. A virtual source research model capable of predicting the three-dimensional field, including propagation, scattering, and reverberation in such complex underwater environments is presented here. A complex, variable geometry, harbor scenario containing a large scattering object such as a vessel hull has been modeled in order represent the resultant acoustic field and to investigate scattering mechanisms present. [Work supported by ONR.]