EXPERIMENTAL MEASUREMENTS OF 3-DIMENSIONAL PROPAGATION IN A WEDGE-SHAPED OCEAN WITH PRESSURE-RELEASE BOUNDARY-CONDITIONS

The theoretical solution for three-dimensional acoustic propagation in a wedge-shaped ocean with ideal pressure-release boundaries predicts a well-defined beam in the down-slope direction that diverges as the energy propagates out towards deep water. Outside of the beam, shadow zones are formed, and its spatial extent is determined by the lowest mode of propagation. The purpose of the experimental results presented here is to check the theoretical analyses, as part of an ongoing investigation into three-dimensional propagation in the ocean environment. The wedge model in this experiment has a pressure-release bottom and a slope that is around 20 deg. For convenience of analysis, only the lowest mode is excited by locating a source near the cutoff range. It has been found that for down-slope propagation, the spatial characteristics of the field in a direction parallel to the shore line are in good agreement with the theoretical solution, and the azimuthal extent of the beam depends on the wedge angle. In addition to the evaluation of the exact theory, measurements have been made of acoustic pulse propagation and distortion in the wedge. © 1990, Acoustical Society of America. All rights reserved.