A Spectral Coupled-Mode Formulation for Sound Propagation around Axisymmetric Seamounts

A spectral coupled-mode solution of the three-dimensional (3D) acoustic field generated by a point source in the presence of an axisymmetric seamount is developed. Based on the same theoretical foundation as the formulation presented by Taroudakis J. Comput. Acoust. 4 (1996) 101, the present approach combines a spectral decomposition in azimuth with a coupled-mode theory for two-way range-dependent propagation. However, the earlier formulations are severely limited in terms of frequency, size and geometry of the seamount, the seabed composition, and the distance between the source and the seamount, and are therefore severely limited in regard to realistic seamount problems. Without changing the fundamental theoretical foundation, the present approach applies a number of modifications to the formulation, leading to orders of magnitude improvement in numerical efficiency for realistic problems. Therefore, realistic propagation and scattering scenarios can be modeled, including effects of seamount roughness and realistic sedimentary structure.