## 3 Results and Discussion  
### Evaluation of the Numerical Model  
The model evaluation was carried out through statistical analysis (mean, standard deviation, and RMSE), between the simulation results and the experimental data of six ammonia points and 13 temperature points (Figure 2). Data were collected during the study period and point averages were estimated, both for the boundary conditions and the points to validate the model.  
\begin{table}
\begin{tabular}{l l l} \hline \hline
**Boundary** & **Type** & **Condition** \\ \hline Entry & Velocity inlet & Temperature: 17 \({}^{\circ}\)C; wind speed: 0.25 m s\({}^{-1}\) \\  & & Wind direction: 161\({}^{\circ}\) components (x = \(-\)0.87, y = 0, z = \(-\)0.48) \\ Exit & Pressure outlet & Pressure: 0 Pa \\ Outside air & interior & Air \\ Outside soil & Wall & Soil \\ Floor & Wall & Concrete; temperature: 19.8 \({}^{\circ}\)C \\ Collector & Wall & Temperature: 34.8 \({}^{\circ}\)C; ammonia: 15.4 ppm = 0.0154 g kg\({}^{-1}\) \\ Indoor air & Interior & Air \\ Ceiling & Wall & Wood; thickness: 0.5 cm; temperature: 23.8 \({}^{\circ}\)C \\ Walls & Wall & Wood; thickness: 1 cm \\ Windows & Porous jump & Mesh; permeability: 3.98 \(\times\) 10\({}^{-9}\) (m\({}^{2}\)); thickness: 0.0032 (m) \\  & & Drag coefficient: 19,185.7 (m\({}^{-1}\)) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Summary of the boundary conditions used during the simulation.  
Figure 2: Comparison between measured and simulated data for ammonia and temperature.  
The results show a mean ammonia concentration in the measured and simulated data of 12.58 \(\pm\) 0.22 ppm and 12.73 \(\pm\) 1.43 ppm, respectively. Regarding the air temperature variable, the obtained mean was 19.37 \(\pm\) 0.39 \({}^{\circ}\)C for the measured data and 19.61 \(\pm\) 0.1 \({}^{\circ}\)C for the simulated data. The calculated percentage error of the six points in ammonia ranged between 0.4 and 18.2%, and the 13 points in temperature ranged between 0.12 and 4.25%.  
The comparison between the measured and simulated data (Figure 2) showed an RMSE of 1.16 and 0.41 for ammonia and temperature, respectively.  
To validate the model, experimentally measured data were used. For the boundary conditions, wind speed and temperature were used. Ammonium concentrations and heat flux were used as initial conditions. The simulation was carried out in a steady state at midday with average values at solar noon. With the experimental and simulated results at the same point, statistical indicators were applied to assess the agreement between this series of values. Figure 2 shows in a discrete way the experimental values and the fit line with the simulated values of temperature and ammonia in the same points of the farm.  
The results of the evaluation between the measured and simulated data graphically show that under the simulated conditions, the data adjust to the measured values, which provides numerical confidence for the use of the model to be able to infer the dynamics of the air inside the farm. Consequently, the model was used to predict the variations of ammonia concentration in the AOR and the vertical variation of ammonia concentration and air temperature within the farm in three cross sections A, B, and C, located at 4, 12, and 20 m respectively, in the direction of the \(z\) axis (Figure 3). Air temperature data of 22 \({}^{\circ}\)C, an outdoor wind speed of 2.5 m s\({}^{-1}\), and three wind incidence directions 0\({}^{\circ}\), 45\({}^{\circ}\), and 90\({}^{\circ}\) with respect to the \(z\) axis were used as boundary conditions.