Complex ray solutions to the 3-D wedge ASA benchmark problems

Abstract

In support of the ASA’s effort to benchmark shallow-water, range-dependent acoustic propagation models, a complex ray approach is applied to the three-dimensional wedge problems. The ray model [Westwood, J. Acoust. Soc. Am. 92, 2212–2222 (1992)] is designed specifically for the case of a point source in a 3-D wedge, where the receiver may lie cross slope, as well as downslope or upslope, from the source, and where the wedge of water and the bottom are isovelocity. The total field in the 3-D wedge is expressed as a sum of ray fields, each of which corresponds to a saddle point of a double integral over plane waves. The broadband case of the benchmarking problem is solved by finding frequency-dependent eigenrays at coarsely spaced frequencies and interpolating the eigenray characteristics. Eigenray diagrams provide an intuitive picture of the horizontal refraction effects associated with three-dimensional underwater acoustic propagation. [Work supported by ONR.]