ASA 127th Meeting M.I.T. 1994 June 6-10

3aUW17. Solutions of coupled-mode equations with a large dimension in underwater acoustics.

S. A. Stotts

D. P. Knobles

S. J. Levinson

S. K. Mitchell

Appl. Res. Lab., Univ. of Texas at Austin, P.O. Box 8029, Austin, TX 787123

A new fast and efficient acoustic propagation model is introduced which solves the coupled-mode differential equations in underwater acoustics for range-dependent, fluid-layered, ocean environments. The coupled range equations are first modified and then solved using the Lanczos method, an approach recently introduced in nuclear theory. This method has been successfully applied to the description of the nuclear response of heavy atomic nuclei in the giant resonance region of the energy excitation spectrum [T. Udagawa and B. T. Kim, Phys. Rev. C 40, 2271--2275 (1989)], as well as, other physical processes in low to medium energy in nuclear theory. The efficiency of this method permits the solution of coupled mode equations with large dimensions. The eigenvalues and depth-dependent mode functions are quickly obtained using an Airy function approach, which allows the range-dependent mode-coupling matrices to be evaluated analytically. The validity of the model is demonstrated, and example calculations are presented. [This work is supported by the Office of Naval Research (ONR 4530) Project RO35K01.]