Boundary element method for target scattering in shallow water waveguide

The boundary element method is coupled with normal modes model for the acoustic scattering from three dimensional objects in range independent shallow water ocean environment with arbitrary sound-speed profile. Theory and numerical example show that the waveguide Green function can be approximated by free space Green function when target is not too close to the waveguide boundary and multi-scattering effects can be ignore. The image method and addition theorems for the spherical wave functions are used to deduce exact analytic solution for sphere scattering in ideal waveguide. This solution can be used as a benchmark solution to validate the present numerical method. Scattering field from submerged vehicles in shallow water waveguide is calculated. Numerical results show that the effects of boundary reflection and sound-speed profile to target scattering in shallow water waveguide are obvious.