ASA 124th Meeting New Orleans 1992 October

4aPA2. Modifications to a parabolic equation algorithm for the prediction of atmospheric sound fields which extend its range and improve its accuracy.

M. West

R. A. Sack

Dept. of Appl. Acoust., Univ. of Salford, Salford M5 4WT, UK

A two-dimensional algorithm based on Gilbert and White's method [West et al., Appl. Acoust. 36, 1--19 (1992)] coded for a 486 PC, has served as a test bed for the following modifications: (i) a new second-order ground boundary condition, (ii) a ``tuned'' upper absorbing layer, (iii) a novel upper boundary condition, which replaces the absorbing layer, and (iv) a new procedure for calculation of the starter field. The algorithm with the above modifications has also been adapted to operate with range-dependent sound-speed profiles obtained from an isoturbulent atmospheric model. [Work supported by MOD and DRA.]