Acoustic Propagation Modeling in Shallow Water Using Ray Theory
Abstract
A ray method is developed for modeling acoustic propagation in low- frequency, shallow water ocean environments. Each field is expressed as a plane wave integral. The approach for solving the integral is based on the classical method of steepest descent, but the plane wave reflection and transmission coefficients are allowed to influence the location of the saddle points and their steepest descent paths. As a consequence, saddle points are, in general, complex, and complicated processes such as the reflected lateral wave field and the transmitted evanescent field are incorporated in the saddle point formulation. The saddle point criterion may be expressed in terms of eigenrays and their characteristics, which provides physical insight into the paths and mechanisms of propagation. The method is applied to two simple models for shallow water ocean environments: the flat, isovelocity waveguide (the Pekeris model) and the sloping-bottom, isovelocity waveguide (the penetrable wedge). For the flat waveguide, near perfect agreement is found between the ray model and a model whose algorithm solves the wave equation numerically (the SAFARI fast field model). The ray method proves to be accurate even when the water depth is only half of the acoustic wavelength. For the sloping-bottom waveguide, ray model solutions to benchmark problems are compared to solutions from a model based on two-way coupled mode theory. For cases of upslope propagation in shallow-water penetrable wedges, agreement between the two independent models is excellent, both in water and in the bottom. The ray method is applied to the three-dimensional wedge problem, where the source and receiver may lie across the slope from each other.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 21, 1989
- Accession Number
- ADA206282
Entities
People
- Evan K. Westwood
Organizations
- University of Texas at Austin