Modeling sound propagation in range-dependent waveguides has received considerable attention in the ocean acoustics community. A variety of approaches have been developed for solving this problem, for example, the parabolic equation method, the normal mode method, the wave-number spectrum method, the finite element method and so on. However, each method has its limitations.

So LUO Wenyu, YANG Chunmei and ZHANG Renhe from State Key Laboratory of Acoustics of Institute of Acoustics, Chinese Academy of Sciences carried out a series of studies and suggested an accurate and numerically stable method based on the coupled-mode theory. They apply the direct global matrix approach to obtain the modal expansion coefficients and this method is numerically stable. In addition, they put forward appropriately normalized range solutions, which resolve the overflow problem entirely. Furthermore, they put forward source conditions appropriate for the line-source problem in plane geometry. As a result, this method is capable of dealing with the scenario where a line source is located inside the region of a deformation. Closed-form expressions for coupling matrices are provided for ideal waveguides. Numerical results indicate that the present method is accurate and numerically stable. Consequently, this model can serve as a benchmark in range-dependent propagation modeling.

This research result was published on the recently issued CHIN. PHYS. LETT. (2012, Vol. 29, No. 1)