Abstract: We study multiple acoustic scattering of three dimensional multiple obstacles in shallow water waveguides. A method coupling finite-element and natural boundary-element is developed to solve acoustic scattering based on Galerkin variational principle and DtN mapping. The method avoids adoption of absorbing boundary used in conventional finite element method. It is validate by numerical study of 3D multiple obstacles with various shapes.

Key words: oceanic waveguide, multiple scattering objects, finit element method, natural boundary element