The present study aims to evaluate the difference in the fluid-dynamic behavior of an overtopping wave energy converter under the incidence of irregular waves based on a realistic sea state when compared to the incidence of regular waves, representative of this sea state. Thus, the sea data of three regions from the Rio Grande do Sul coast, Brazil, were considered. Fluent software was employed for the computational modeling, which is based on the finite volume method (FVM). The numerical generation of waves occurred through the imposition of the velocity boundary conditions using transient discrete values through the WaveMIMO methodology. The volume of fluid (VOF) multiphase model was applied to treat the water–air interaction. The results for the water amount accumulated in the device reservoir showed that the fluid-dynamic behavior of the overtopping converter has significant differences when comparing the two proposed approaches. Differences up to 240% were found for the water mass accumulated in the overtopping device reservoir, showing evidence that the results can be overestimated when the overtopping device is analyzed under the incidence of the representative regular waves. Furthermore, for all studied cases, it was possible to approximate the water volume accumulated over time in the overtopping reservoir through a first-degree polynomial function.

Studies regarding renewable energy sources have gained attention over recent years. One example is wave energy converters, which harvest energy from sea waves using different operational principles such as oscillating water columns, oscillating bodies, and overtopping devices. In the present paper, a numerical study is carried out, and a geometrical investigation of a full-scale overtopping device with a coupled structure mounted on the seabed is performed using the Constructal Design method. The main purpose is to investigate the influence of the design over the available power of the device. The areas of the overtopping ramp (A_r) and the trapezoidal seabed structure (A_t) are the problem constraints. Two degrees of freedom are studied, the ratio between the height and length of the ramp (H₃/L₃) and the ratio between the upper and lower basis of the trapezoidal obstacle (L₁/L₂). The device submersion is kept constant (H₁ = 3.5 m). The equations of continuity, momentum, and the transport of volume fraction are solved with the Finite Volume Method, while the water–air mixture is treated with the multiphase model Volume of Fluid. Results showed that the ratio H₃/L₃ presented a higher sensibility than the ratio L₁/L₂ over the accumulated water in the reservoir. Despite that, the association of a structure coupled to the ramp of an overtopping device improved the performance of the converter by 30% compared to a conventional condition without the structure.

Aiming to contribute to studies related to the generation of electrical energy from renewable sources, this study carried out a geometric investigation of an oscillating water column (OWC) wave energy converter (WEC) device. The structure of this device consists of a hydropneumatic chamber and an air duct, where a turbine is coupled to an electrical energy generator. When waves hit the device, the air inside it is pressurized and depressurized, causing the air to flow through the duct, activating the turbine. In this sense, the present study used the constructal design method to evaluate the influence of the ratio between the height and length of the hydropneumatic chamber ($H_1/L$) on the mean available hydropneumatic power ($P_{H\left(\mathrm{R}\mathrm{M}\mathrm{S}\right)}$). Fluent software was used to perform numerical simulations of representative regular waves from the sea state in the municipality of Tramandaí, southern Brazil, impacting the OWC. Thus, it was possible to identify the geometry that maximized the performance of the OWC WEC, with ${(H_1/L)}_O=0.3430$, yielding $P_{H\left(\mathrm{R}\mathrm{M}\mathrm{S}\right)}=56.66$ W. In contrast, the worst geometry was obtained with $H_1/L=0.1985$, where $P_{H\left(\mathrm{R}\mathrm{M}\mathrm{S}\right)}=28.19$ W. Therefore, the best case is 101% more efficient than the worst one.

Among the various potential renewable energy sources, sea waves offer significant potential, which can be harnessed using wave energy converter (WEC) devices such as overtopping converters. These devices operate by directing incident waves up a ramp into a reservoir. The water then passes through a turbine coupled with an electrical generator before returning to the ocean. Thus, the present study deals with the geometrical evaluation of an overtopping WEC, where the influence of the ratio between the height and length of the device ramp ($H_1/L_1$) on the amount of water mass (M) that enters the reservoir was investigated. Numerical simulations were performed using ANSYS-Fluent software, 22 R1 version, to generate and propagate realistic irregular (RI) waves and representative regular (RR) waves found in the coastal region of the municipality of Rio Grande, in the state of Rio Grande do Sul, southern Brazil. Consequently, through constructal design, the optimal WEC geometry for both wave approaches were identified as the same, where (${H_1/L_1)}_o=0.30$. Thus, considering the RI waves, $M=$ 200,820.77 kg was obtained, while, considering the RR waves, $M=$ 144,054.72 kg was obtained.

The present study aims to analyze the state of the art of scientific studies about the Overtopping device used to convert sea wave energy into electrical energy, by means the Bibliometric methodology. The development of this study took place through the selection of articles from conference proceedings, as well as national and international journals. The Bibliometric methodology consists of a statistical tool that allows quantifying the measurement of production indexes. Using selected keywords, it was conducted a survey of studies in the online databases of Science Direct, SciELO and Google Scholar. The works found then went through a filtering process, in order to limit the Bibliometric study only to studies about Overtopping devices as sea Wave Energy Converter (WEC). Finally, the investigation of these selected articles was carried out under the optics of production and authorship study, content study and study of bibliographic references. Where it was identified growth in publications related to the topic, methodologies used and, among other indicators, the authors most cited in the analyzed articles. The predominant keywords used were “Wave Energy Converter” and “Overtopping”. It was noted that Brazilian universities are leaders in the productivity, presenting more than 36% of the scientific production regarding Overtopping WECs.

Irregular wave generation in numerical simulations is critical for accurately modeling realistic sea conditions, which is essential in coastal and offshore engineering applications, such as for wave energy conversion. Therefore, this study presents theoretical recommendations for generating realistic irregular waves using the WaveMIMO methodology and validates its accuracy against experimental data. For the parameters investigation, spectral data are processed to obtain orbital velocity profiles of wave propagation, which are imposed as boundary conditions (BCs) in a numerical wave channel. The simulations were conducted using the ANSYS-Fluent 2024 R2 software, which employs the multiphase volume of fluid (VOF) model to treat the interface between phases. Seeking theoretical recommendations for the application of this methodology, the present study investigated the discretization of the region where the prescribed velocity BC is imposed, the mesh sensitivity in the free surface region, the time step used, and the location of the velocity vector in each segment of the prescribed velocity BC imposition region. The results obtained were compared with realistic sea state data obtained from the TOMAWAC spectral model, referring to the municipalities of Rio Grande and Tramandaí, in the state of Rio Grande do Sul, Brazil. The results indicated that, compared to recommendations from the previous literature, the recommended configuration improved wave generation accuracy by 7–8% for Rio Grande and 2–3% for Tramandaí. Finally, the WaveMIMO methodology and its theorical recommendations were validated against experimental data found in the literature, reaching an excellent agreement.