Water-wave scattering and energy dissipation by a floating porous elastic plate in three dimensions

•Eigenfunction matching method developed for wave scattering by circular porous plate.•Coupled boundary-finite element method developed for plate of arbitrary shape.•Porosity shown to damp incident-wave transmission and increase scattering.•Finite value of porosity parameter shown to produce maximum wave-energy dissipation.

An eigenfunction-matching method is developed for the problem of linear water-wave scattering by a circular floating porous elastic plate, and a coupled boundary-element and finite-element method is developed for the problem in which the plate is of arbitrary shape. The methods are shown to produce the same solutions for a circular plate, and their convergence properties are established. The impact of porosity on the far field (the wave field away from the plate) is investigated using integral representations for the Bessel and Hankel functions. It is shown that wave-energy dissipation due to porosity initially increases as the plate becomes more porous, but reaches a maximum and then slowly decreases as the porosity increases further.