ASA 124th Meeting New Orleans 1992 October

5aUW8. Development of a three-dimensional marching technique for backscattering.

D. Lee

G. Botseas

Naval Underwater Weapons Ctr., New London, CT 06320

M. H. Schultz

Yale Univ., New Haven, CT 06520

W. L. Siegmann

Rensselaer Polytechnic Inst., Troy, NY 12180

A marching method for numerical computation of weak backscattering has been constructed recently. A two-dimensional implementation of this method has been tested for accuracy with exact and benchmark solutions. The procedure has now been extended for application to three-dimensional problems with weak backscattering and full azimuthal coupling. The new numerical implementation will be described. Computational experience with the algorithm will be reported, including indications of convergence and attainable accuracy. Since fully coupled three-dimensional propagation can be produced by density variations, these must be incorporated accurately into the method. The numerical modifications to accommodate density variations will be described, and experience with the extended algorithm will be illustrated. The current objective of our development is the capability to calculate three-dimensional propagation features in the presence of weak backscattering, with future extensions to strong backscattering. [Work supported by ONR and NUWC.]