Lipwall Effects on a Shore-Front Oscillating Water Column Based on DBEM and Computational Fluid Dynamic Approaches

The oscillating water column (OWC) is an economical and feasible type of wave energy converter with minimal maintenance costs which have been widely investigated. In this study, the effect of lipwalls for a shore-front OWC is investigated using dual boundary equation method (DBEM) and computational fluid dynamics (CFD) approaches. The boundary value problem is solved using the DBEM method within the framework of linear water wave theory. Whilst in the CFD approach, the volume-of-fluid (VOF) approach is used for simulating the numerical wave tank, with appropriate boundary conditions and regular wave inlet. The DBEM approach is beneficial to understand the complex phenomena inside the chamber, viz., radiation conductance and susceptance. It is inferred that case-B (vertical + shoreward-slant lipwall) is found to exhibit better performance for a wider range of non-dimensional wave frequencies due to its wave trapping configuration where the position of the lower lipwall is orthogonal. The CFD studies provide interesting insights into the optimal damping ratio concerning wave amplification factor at higher relative water depths, power output, and correlation of phase difference. Besides, the study reveals that the pressure and wave elevation inside the chamber are associated with the inhalation and exhalation process of air is attributed to the lower half of the lipwall.