ASA 126th Meeting Denver 1993 October 4-8

5aUW7. A fast one-way normal mode propagation method.

E. White M. F. Werby

NRL, Theoretical Acoustics, Code 7181, Stennis Space Center, MS 39529

The development of a new fast normal mode method produces vertical wave functions that are in closed form. One-way coupled mode methods can be based on projection matrices that are generated by integral overlaps between vertical wave function of adjacent domains. For methods that require numerical solutions of the vertical wave functions the computation of the matrix elements is very time consuming and can even lead to inaccuracies at higher frequencies. However the closed form solutions allow one to code matrix elements in relatively simple closed form based on simple arithmetic sums. This leads to a rapid method for generating the projection matrices and therefore connects the stepwise domains in a rapid fashion. The method is tested and compared with other available coupled mode programs. Ultimately the method will be used for the object in a waveguide program for which this method was originally designed. [Work supported by Naval Research Laboratory 6.1 program (element 601153N) with technical management provided by NRL-SSC.]