# Study of the Interaction between Regular Waves and a Wind-Fish Combined Structure
## 3 Results
### The Influence of the Geometrical Dimensions of the Cage  
The fish yield in the fish cage is affected by the dimensions of the cage. However, the dimensions of the cage are also determined by the power supply of the wind turbine. In addition, the hydrodynamic load on the fish cage can be also transferred to the foundation of the wind turbine. Thus, it is beneficial to understand the influence of the geometrical dimensions of the fish cage on the safety design of the combined structure. The diameter and height of the cage are important factors to be considered when designing cage dimensions. Three different cage heights and six different diameters of the cages are set in this paper, and the specific design parameters are shown in Table 3. The wave height is 0.12 m, the period is 1.4 s, the water depth is 1 m, and the cage is commonly at the liquid level. The forces on the combined structure with different cage sizes are shown in Figures 9 and 10. It can be seen that the increase in cage height does not significantly affect the horizontal wave load on the combined structure. An increase in the diameter \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Case No.** & \begin{tabular}{c} **Wind Turbine** \\ **Foundation Load (N)** \\ \end{tabular} & \begin{tabular}{c} **Cage Load** \\ **(N)** \\ \end{tabular} & \begin{tabular}{c} **Proportion of** \\ **Wind Turbine Load** \\ \end{tabular} \\ \hline \multirow{3}{*}{\begin{tabular}{c} Different wave \\ heights \\ \end{tabular} } & 1 & 20.70 & 1.56 & 94\% \\  & 2 & 24.00 & 2.43 & 91.53\% \\  & 3 & 27.90 & 3.72 & 88.6\% \\ \hline \multirow{3}{*}{\
\begin{tabular}{c} Different periods \\ \end{tabular} } & 4 & 26.91 & 3.42 & 88.72\% \\  & 2 & 24.91 & 2.08 & 92.29\% \\  & 5 & 27.07 & 6.99 & 79.48\% \\ \hline \multirow{3}{*}{
\begin{tabular}{c} Different water \\ depths \\ \end{tabular} } & 2 & 24.91 & 1.86 & 93.05\% \\  & 6 & 26.42 & 1.95 & 93.13\% \\ \cline{1-1}  & 7 & 26.65 & 1.86 & 93.48\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Maximum horizontal load distribution and proportion of combined structure under different wave factors. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Case No. **} & \begin{tabular}{c} **Height of Cage** \\ **(m)** \\ \end{tabular}  & \ \begin{tabular}{c} **Diameter of** \\ **Cage (m)** \\ \end{tabular}  & \begin{tabular}{c} **Density of Cage** \\ **Depth (m)** \\ \end{tabular}  \\ \hline
8 & 0.3 & 2.0 & 0.27 & 0 \\
9 & 0.5 & 2.0 & 0.27 & 0 \\
10 & 0.7 & 2.0 & 0.27 & 0 \\
11 & 0.5 & 1.2 & 0.27 & 0 \\
12 & 0.5 & 1.4 & 0.27 & 0 \\
13 & 0.5 & 1.6 & 0.27 & 0 \\
14 & 0.5 & 1.8 & 0.27 & 0 \\
15 & 0.5 & 2.2 of the cage results in no obvious change in the trend of the horizontal wave load on the composite structure. The inertial force dominates the load on a combined structure, while the drag force is weak. Table 4 and Figure 11 present the maximum horizontal load proportion. The results show that with the increase in cage height, the proportion of the maximum horizontal load of the wind turbine foundation gradually decreases from 93.28% to 91.06%, showing that the wave-making resistance of cage gradually increases, mainly because the increase in cage height increases the effective area of the cage. With the increase in the diameter of the cage, the proportion of the maximum horizontal load of the offshore wind turbine gradually increases from 80.21% to 93.67%, indicating that the influence of the cage's wave resistance on the load on the wind turbine's foundation structure is gradually reduced. The wind turbine foundation bears the primary load on the combined structure.