Constructal Design of an Overtopping Wave Energy Converter Incorporated in a Breakwater

Abstract

A numerical study was performed in the present work about an Overtopping Device Wave Energy Converter (OTD-WEC) with one and two ramps incorporated in a real breakwater. The Constructal Design method was applied to evaluate the effects on the average dimensionless overtopping flow of the degrees of freedom of the device with one and two ramps. In addition, a comparison was carried out among the different geometry configurations of the OTD-WEC to determine which one presents the best hydrodynamic performance. The work used the JONSWAP spectrum and the multiphase Volume of Fluid model. It also solved the conservation equations for mass, momentum, and an equation for the transport of the volume fraction using the Finite Volume Method. Results showed that a device with a two-ramps configuration presented an average dimensionless overtopping flow 6.48% higher than those obtained for the one ramp. Present results obtained using Constructal Design theoretical recommendations about the influence of a complex configuration with four degrees of freedom over the performance of an OTD-WEC integrated into the east breakwater of the city of São José do Norte, State of Rio Grande do Sul (RS), Brazil.

Numerical Analysis of an Overtopping Wave Energy Converter Subjected to the Incidence of Irregular and Regular Waves from Realistic Sea States

“…Therefore, a twodimensional computational model was developed to simulate the operational principle of the device. It is worth mentioning that the 2-D numerical approach has been widely used for the investigation of WECs [18,21,22,38,43,44], including overtopping devices [6][7][8][9][10]13,15]. This simplification is reasonable especially for the overtopping WEC, since the physical phenomenon that occurred due to the incidence of waves can be adequately approximated as an in-plane problem.…”

“…Additionally, Di Lauro et al [12] performed numerical simulations based on the VARANS equations, aiming to investigate the hydraulic performance and structural stability of the innovative OBREC-V, and concluded that the proposed non-conventional geometry can promote significant improvements in wave energy extraction, reduction of the wave reflection, and hydraulic stability when compared with the traditional OBREC design. More recently, Martins et al [13], also applying the JONSWAP spectrum, developed a numerical study on an overtopping device with one and two ramps incorporated into a real breakwater, performing a geometric evaluation through the Constructal Design method. It should be highlighted that one can find several other studies addressing the overtopping devices and OBRECs with different approaches and goals, such as the studies by Liu et al [14], Barbosa et al [15], Contestabile et al [16], and Mariani et al [17].…”

Numerical Analysis of the Available Power in an Overtopping Wave Energy Converter Subjected to a Sea State of the Coastal Region of Tramandaí, Brazil

“…The volume of fluid (VOF) method [34] is used to solve multiphase flow systems considering immiscible fluids and its main contribution was the introduction of the volumetric fraction in momentum equations. Subsequently, the method was improved and has been adopted for numerous wave energy investigations, not only for overtopping devices, but also for other types such as oscillating water column (OWC) and submerged plate [11,17,20,26,27,35].…”

“…The solutions obtained in this study were considered converged when the residuals of continuity and momentum equations in the x and z directions were lower than 10 −3 . A verification of the numerical methods employed in this study was previously performed by Martins et al [27], who compared results with the solution of the empirical model proposed by EurOtop [41].…”

“…As for numerical studies of overtopping WECs subjected to irregular waves, the incidence of a monochromatic wave and a wave spectrum for an overtopping device were compared [24]; the power produced by a Wave Dragon-type overtopping device subjected to irregular waves was evaluated [25]; the fluid dynamic behavior of an overtopping device subjected to regular and irregular waves was compared, finding results that indicate a larger amount of accumulated water inside the reservoir for irregular waves [26]; and the geometry of an overtopping WEC, containing either one or two ramps, was evaluated by means of Constructal Design [27]. Finally, regarding the study of the generation of irregular numerical waves, the use of OpenFoam software for fluid dynamics simulation of irregular waves was studied [28,29] and several parameters of the propagation of irregular waves in wave channels was simulated [30].…”