Measurements and modeling of three-dimensional acoustic propagation in a scale-model canyon

Abstract

Scale-model acoustic propagation experiments were conducted in a laboratory tank to investigate three-dimensional (3D) propagation effects induced by range-dependent bathymetry. The model bathymetry, patterned after measured bathymetric data, represents a portion of the Hudson Canyon at 1:7500 scale and was fabricated from closed-cell polyurethane foam using a computer-numerically controlled (CNC) milling machine. In the measurement apparatus, a computer-controlled positioning system precisely locates the receiving hydrophone which permits the creation of synthetic horizontal line arrays. Results are shown for propagation paths along and across the axis of the canyon. The measurements are explained using both a hybrid method known as vertical modes/horizontal parabolic equation and a 3D ray model known as Bellhop3D. For propagation along the canyon axis, horizontal focusing is observed and discussed in the context of normal modes. For the across canyon propagation, the reflective foam walls of the canyon ...