A finite element model for acoustic scattering from objects near a fluid–fluid interface

We present a finite element model for acoustic scattering from an elastic object situated near (or intersecting) the surface separating two fluid domains, each of semi-infinite extent. The fluid domains are truncated using a perfectly matched layer (PML) formulated as an intrinsic part of the mathematical model. This approach provides a great deal of flexibility in dealing with the geometry of the scatterer and the fluid–fluid interface. The high level of accuracy achievable with the PML is established with standard validation problems for scattering in a homogeneous fluid. The model is also applied to the problem of acoustic scattering from objects situated near the ocean floor, where the ocean bottom is modeled acoustically as a fluid. Numerical results show very close agreement with a published T-matrix solution for the same problem.