## 6 Results and Discussion  
The current investigation's main purpose is to maximize the available hydropneumatic power of the OWC device, which depends directly on the pressure and mass flow rate changes due to the proposed geometric variations of the hydropneumatic chamber. The RMS (root mean square) was used to calculate the average values of the performance indicator. The monitoring of the water-free surface elevation takes place through the following integral:  
\[\int\alpha_{water}dA=\sum_{t=1}^{n}\alpha_{t}|A_{t}| \tag{16}\]  
where \(\alpha_{water}\) is the amount of water in each volume and \(A_{t}\) is the area of each volume (m\({}^{2}\)). The following integral is used to monitor the mass flow rate in the center of each turbine duct:  
\[\int\rho_{air}\overset{\rightarrow}{v}_{air}\cdot d\overset{\rightarrow}{A} =\sum_{t=1}^{n}\left(\rho_{air}^{t}\right)\overset{\rightarrow}{v}_{air}^{t} \overset{\rightarrow}{(A_{t})} \tag{17}\]  
where \(\overset{\rightarrow}{v}_{air}\) represents the air velocity in the z-direction (m/s), and \(\rho_{air}\) is the density of the air (kg/m\({}^{3}\)). The mean values were calculated using the arithmetic mean for transient RMS problems:  
Figure 9: Comparison among the results obtained in the present study and those presented by [PERSON] et al. [11] for different wave periods. \[X=\sqrt{\frac{1}{T}\sum_{n=1}^{T}\left(n\right)^{2}} \tag{18}\]  
where \(n\) represents the quantity to be calculated on the average RMS. For further details, it is recommended to consult [PERSON] et al. [54]. The available hydropneumatic power is calculated according to [55]:  
\[P_{hyd}=\left(p_{e,air}+\frac{\rho_{air}\overset{\rightarrow}{\
u}_{air}^{2}}{2 }\right)\frac{\dot{m}_{air}}{\rho_{air}} \tag{19}\]  
where \(p_{e,air}\) is the static pressure in the turbine duct of the OWC device (Pa), \(\dot{m}_{air}\) is the air mass flow rate through the turbine duct (kg/s), and \(v_{air}\) is the velocity of the air in the turbine duct (m/s); the other parameters can be found in [PERSON] [37] and [PERSON] [56]. Altogether, seventy-six different geometric configurations proposed by the Constructal Design application are analyzed in relation to the height and length of the devices, keeping the input volume constant. The choice of values is made considering the height of the wave tank so that the height of the devices does not reach the bottom of the tank, making the passage of water impossible and its length not being so small as to make the energy conversion unviable. The cases of geometric variation in the thickness and height of the wall dividing the devices can be found in [PERSON] et al. [20]. The numerical simulation process starts with an OWC device with only a single hydropneumatic chamber and analyzes pressure, mass flow, and hydropneumatic power as the degrees of freedom vary. This process is repeated with the increase in coupled chambers up to a total of five. The analysis of the results takes place by exploring each chamber individually and, thus, defining the highest values for the performance indicators. The result obtained in each chamber is added to the others in the coupled cases. The maximum performance of the device is defined as the sum of the individual performance indicators of each one. Figure 10 shows the RMS pressure values for the cases varying the number of coupled chambers (CC), where each line represents each of the studied cases. The increase in pressure occurs for two reasons. The first is that with the increase in the CC height, there is a greater pressure concentration in each chamber, even with the increase in CC. The second reason refers to the geometry of the chambers. It appears that the chambers with three coupled devices present a higher pressure than chambers with four devices in some configurations.