ASA 126th Meeting Denver 1993 October 4-8

5aUW9. Three-dimensional modeling of acoustic pulse propagation through shallow water.

Robert T. Chapman Donald J. McDowell, Jr.

Naval Undersea Warfare Ctr., Div. Newport, Detachment New London, Code 423, New London, CT 06320

A three-dimensional model capable of simulating the propagation, scattering, and reverberation of acoustic waveforms with an arbitrary time dependence is presented. The finite element method is used to model the spatial characteristics of the shallow water domain. An explicit integration scheme is used to obtain the time-dependent pressure field solution, for the entire computational space, due to a prescribed source function. Multiple independent sources, depth- and range-dependent bathymetry, volumetric scattering, fluid sediments, and scattering from irregular bottom topography may be considered with this modeling technique. As implemented, the computational scheme utilizes enhanced supercomputer vector processing, and an element-by-element storage strategy to enhance the computational efficiency and feasibility for the three-dimensional, time-dependent problems of interest. Computational results will be presented for the propagation of a finite duration pulse from a point source in deep water, up a sloping bottom, into shallow water. [Work supported by the NUWC IR and IED programs.]