## 4 Results and Discussion
### Potential Effects of the WEC on Sediment Transport and Coastal Protection  
Another implication of the results presented in Table 6 concerns the floating buoy acting similar to breakwater by reducing the height of the waves reaching the shore. This would only result in a significant energy reduction if the distance to the coast and number of WECs were arranged appropriately. The values of \(K_{t}^{2}\) observed after the waves passed through the WEC were considerably reduced close to the buoy. As would be expected from the arguments presented in the previous section, the protective effect of the WEC would be greater for \(T=4\) s waves than \(T=8\) s waves, since the power absorbed from shorter-period waves is greater. That is, longer waves would have less attenuation when interacting with the WEC floating body, as observed with many floating breakwaters [52]. It is also important to analyze the behavior of the surface elevation in different parts of the NWT, since a wave's shape is a good indicator of non-linear transfers of energy, which could have significant effects on sediment transport close to the shore. Surface elevation time series at different positions of the NWT are presented in Figures 9 and 10. The wave  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Buoy** & \multicolumn{2}{c}{\(T=4\) s} & \multicolumn{2}{c}{\(T=8\) s} \\ \hline  & \(K_{t}^{2}\) & \(K_{t}^{2}\) & \(K_{d}^{2}\) & \(K_{t}^{2}\) & \(K_{t}^{2}\) & \(K_{t}^{2}\) \\ \hline \(R_{1}\) & 0.298 & 0.005 & 0.698 & 0.477 & 0.006 & 0.517 \\ \(R_{2}\) & 0.300 & 0.004 & 0.695 & 0.489 & 0.006 & 0.506 \\ \(R_{3}\) & 0.298 & 0.005 & 0 gauge positions, \(G_{i}[x]\), where \(x\) is in the direction of the wave propagation, were established every meter from \(-10\) to \(10\) m in the \(x\) direction, e.g., the third gauge (from left to right); \(G_{3}\) or \(G_{3}[-8]\) is in position \(x=-8\) m. The position of the WEC was at \(x=0\), with negative values to the left and positive to the right. All gauges were placed at the still water level. The free surface records for \(R=0.25\) m and \(T=4\) s are presented in Figure 9. The gauges in the figure were symetrically selected before (\(x=-8\), \(-4\), \(-2\)) and after (\(x=2\), \(4\), \(8\)) the buoy's position. The free surface deformation in gauges \(G_{9}[-2]\) and \(G_{13}[2]\) was due to the interaction of the waves with the buoy. Figure 10 shows the same, but for \(T=8\) s. Several studies have investigated free surface elevation with OpenFOAM, e.g., [PERSON] et al. compared the maximum crest elevation to both the first- and second-order Stokes theories, showing that the wave elevation predicted by the OpenFOAM simulation and the theory agree well [53]. Figure 9: Surface elevation records for the test with \(H=1.0\) m, \(T=4\) s, and \(R=0.25\) m for virtual gauges at symmetrical distances from the buoy: (**a**) 2, (**b**) 4, and (**c**) 8 m to each side. Negative values to the left of the buoy and positive to the right. Figure 9a shows a fairly symmetrical wave record for the waves at the offshore-end of the buoy, which become increasingly skewed (horizontal asymmetry) with the waves at \(x=2\) m, the ones having the greatest deformation. The waves on the right-hand side of the NWT gradually recovered their sinusoidal shape, but with less height. For \(T=8\) s waves (Figure 10), the surface elevation profile starts by presenting less horizontal asymmetry, and the deformations observed closer to the buoy are less pronounced than those observed for \(T=4\) s. On the right-hand side of the NWT, the waves develop a vertical asymmetry of an inverse saw-tooth shape, which is clearer in the waves farthest from the buoy, at \(x=8\) m.  
A more quantitative assessment of the waves' shape can be performed by calculating the skewness and asymmetry of the waves. As these are associated with processes of sediment transport, the variable used for their evaluation was the near-bottom orbital velocity, rather than surface elevation.