Modeling three-dimensional acoustic scattering from targets near an elastic bottom using an interior-transmission formulation

For targets near the sediment–fluid interface, the scattering response is fundamentally influenced by the characterization of the sediment in the model. We show that if the model consists of a three-dimensional elastic sediment with acoustic fluid on top, then the use of perfectly matched-layer (PML) approximation for the truncation of the infinite exterior domain for scattering applications has fundamental problems and gives erroneous results. We present a novel formulation using the an interior-transmission representation of the scattering problem where the exterior truncation with PML does not induce errors in the result. Numerical examples will be presented to verify the application of this formulation to scattering from elastic targets near a fluid–sediment interface.