A steady-state 3-D finite-element tool called FESTA (Finite-Element STructural Acoustics), is being developed at the NATO Undersea Research Centre. The code is geared towards a variety of applications in underwater acoustics, such as multistatic scattering from localized inhomogeneities, scattering across interfaces between fluids and/or solids, and multistatic scattering from single and multiple fluid-loaded elastic targets. The hp-adaptive finite-element technology used to develop FESTA allows the user to optimize the convergence as well as the demand on computing resources by selectively changing the element size (h-refinement) and/or by increasing the order of the polynomial finite-element shape functions (p-enrichment). An efficient hybrid tool for the computation of multistatic scattering from targets buried, partially buried or proud inside shallow water waveguides is being developed in conjunction with MIT. In this hybrid tool FESTA is used to perform target computations in the near field of the scatterer, while the waveguide propagation model OASES computes the far field propagation of the incident and scattered acoustic fields. The presentation focuses on the most relevant details of the formulations implemented in FESTA, as well as on application examples for frequencies ranging from 1 kHz to a few tens of kHz.
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