Wave energy extraction by an OWC device in the presence of a porous bottom

Abstract

The present study explores the effects of a porous bed on an oscillating water column (OWC) device under the assumptions of the linearized water wave theory and small-amplitude of the surface waves. The velocity potentials in each region have been determined by using the far-field and boundary conditions. To tackle the physical problem, two different mathematical techniques have been employed: the boundary element method (BEM) and the matched eigenfunction expansion method (EEM). The findings of the study are validated by the existing literature. The outcomes of the numerical results and analytical results are in good agreement. It is noted that as the width of the chamber increases, there is an increase in radiation conductance and a decrease in radiation susceptance. The zero efficiencies are observed multiple times as the width of the OWC device increases with respect to the dimensionless wavenumber. Moreover, the study reveals that full efficiency can be obtained by an OWC device over a porous bed for certain wave and structural parameters as obtained in the presence of an impermeable bottom. The proposed model can help to design and develop a successful OWC device. © 2024