## 5 Conclusions and Recommendations  
### Conclusions  
Simulations in a numerical wave tank (NWT), performed with the computational fluid dynamics (CFD) model Open FOAM, were performed to analyze the behavior of a wave energy converter (WEC) that included a cylinder buoy with a pivot point as the axis of rotation. The device was tested with different buoy radii to analyze the effect on power absorption when subjected to regular waves (1 st-order Stokes theory) with a uniform wave height (\(H=1.0\) m) and periods of 4 and 8 s.  
A considerable amount of literature has been published regarding the use of OpenFOAM to model floating objects interacting with fluids; however, little discussion has been found about the \(AR\), \(AD\), \(ID\), and \(OD\) coefficients that are related to body motion parameters. Care must be taken when changing these coefficients, since high values can induce instability due to mesh distortion. The sensibility tests performed with a 0.25 m buoy radius exhibited the greatest variation in the values of torque, which can lead to an overestimation of the output power. Nevertheless, the highest percentage of error (\(SI\) value) achieved in this study was relatively low (1.25%) and linked to changes in OD. On the other hand, the values of the angular velocity presented very low errors, compensating for the overestimation tendency of the torque when calculating the power. The values adopted for the analysis coincided with those where the power estimates were lower to avoid overestimation (tests P1 and P7).  
The most important result, relative to power absorption by the buoy, is that more power is absorbed by buoys with a greater radius, and that, for a given radius, higher-frequency waves (4 s in this case) absorb several times more power than lower frequency waves (8 s). The power absorbed increases exponentially with the buoy's radius. The type of WEC device analyzed here performed much better for steep high-frequency waves. The results also show that, for a fixed capture efficiency, shorter-frequency waves need much smaller buoy radii than longer-frequency waves, making the manufacturing process more economically competitive at sites where shorter-frequency waves predominate. The technological development of point-absorber wave energy devices is increasingly close to being economically viable [55]. The results obtained by [51] are similar to those reported here.  
This type of device could also serve as an aid to coastal protection if the WEC arrays are properly designed. Not only is energy absorption/dissipation achieved by the obstacle, as observed by the low-transmission coefficients, but also due to the transformations that the buoy induces on the nonlinear properties of the wave field, such as wave skewness and asymmetry. Skewness values increased considerably at the position of the buoy and further onshore, suggesting that the devices could induce onshore sediment transport.  
As it was not possible to evaluate all cases with complex geometries at a high resolution in this research, the NWT was set up with a coarse mesh. However, instead of changing the mesh density, the most critical scenario was evaluated after numerical sensitive tests, in order not to overestimate the result.