GEOMETRIC EVALUATION USING CONSTRUCTAL DESIGN OF A COASTAL OVERTOPPING DEVICE WITH DOUBLE RAMP CONSIDERING A REGULAR WAVE AND TIDAL VARIATION

Abstract

Concern for the environment and new ways of electricity generation, have led to studies of renewable energy sources, among these the Wave Energy Converters (WECs) are an option, however there are still many challenges to define how best to realize the conversion of the energy of the waves into electricity. In this work, a numerical study was carried out with the purpose of maximizing the available power (P_d) of a two-ramp overtopping device, considering the area fraction of ramps (ϕ₁ and ϕ₂) equal to 0.0006 and the ratio between height and length of the ramps (H₁/L₁ = H₂/L₂) equal to 0.3. The distance between the ramps (L_g) was varied in three values: 1.0; 1.5 and 2.0 m, besides three values for the free surface of water (h): 9.8; 10.0 and 10.2 m; simulating a tidal effect. The Constructal Design and Exhaustive Search methods were used, respectively, in the geometric evaluation (determination of a search field) and optimization. For the wave generation, the Second Order Stokes Theory was used, with wave period (T) of 7.5 s and wave height (H) 1.0 m. The results showed that there was no accumulation of water in the upper ramp of the device, in addition, with the increase of L_g there was an increase of P_d in h = 10.0 and 10.2 m, and P_d kept practically constant in h = 9, 8 m. And, as expected, with increasing of h, there was an increase in P_d.