Numerically Investigated the Performance of Parabolic Bottom Profile Land-Fixed OWC by Changing the Orifice Ratio and Relative Opening

The oscillating water column (OWC) device is one of those technologies that the ocean's wave energy converts into mechanical energy. In the present work, a numerical model is used to analyze the influence of orifice ratio and relative opening on the hydrodynamic efficiency of a bottom parabolic profile design with the constant water depth ( d = 0.6). Using the computational fluid dynamics code included in the ANSYS FLUENT software, the numerical simulation is carried out in a 3D numerical wave tank to achieve this goal. The numerical results are compared with published experimental data to verify the accuracy of the current model (Çelik and Altunkaynak in Energy 188:116071, 2019). Specifically, the Reynolds-average Navier–Stokes equations have been solved using the finite volume method. Five distinct wave steepness ( H / L ), three relative openings ( α ) for each wave steepness ( H / L ), and five different orifice ratios ( τ ) are used in this analysis. It has shown that the optimal efficiency ( η ) is achieved at τ = 1.03% and H / L = 0.02 for all values of relative opening ( α ). The optimal efficiency of about 74.78% is obtained at a higher relative opening α = 75% and H / L = 0.02. At a single wave steepness of 0.02, the hydrodynamic efficiency of the parabolic bottom profile configurations of OWC is greater than that of the rectangular bottom profile configurations. The results reveal that increasing the relative opening improves hydrodynamic efficiency regarding the orifice diameter or wave steepness. The hydrodynamic behavior changed as the orifice diameter increased, depending on the wave steepness.