Scattering of water waves by a wave energy device consisting of a pair of co-axial cylinders in a uniform water having finite channel width

• A coaxial floating hollow and solid cylinder are considered in channel having finite width. • Exciting forces due to both the cylinders are evaluated. • Effect of width of the channel walls on the exciting forces are evaluated. • Effect of other various parameters (radii, drafts, gap, etc.) on the exciting forces are evaluated. We consider a device which consists of a floating structure over a cylindrical plate placed at a finite height from the impermeable ocean floor. This paper developes the interaction of linear water waves with such a device. The whole fluid domain is divided into a number of sub-domains and boundary value problems are formulated for each identified sub-domain. The channel multipoles, separation of variables and matched eigenfunction expansion methods allow us to solve boundary value problems for the diffracted velocity potentials in each sub-domain. We investigate the wave forces exerted on the proposed device. Consequently, the effects of the various parameters, e.g., drafts, radii, the gap between the cylinders and mainly channel width of the device on the wave forces exerted by the cylinders are presented graphically. We observe a small oscillation nature near the peak value of the exciting force for the particular value of channel width w = 2.4 m . The peak value of the exciting forces occurs near the wavenumber k r 1 = 1.0 for different width of the channel walls. The obtained results are compared with some available results, and it shows a good agreement between the obtained and available results.