## 3 Results
### Impact of Opening Positions
#### 3.2.3 Results for Building Models with a Fixed 60 mm Inlet Position and Varying Outlet Positions  
The velocity contours, pressure contours, and streamline distributions obtained from numerical analysis for the Upper-Lower, Upper-Middle, and Upper-Upper configurations, where the center of the inlet window opening in an isolated building with a single inlet and outlet is fixed at 60 mm from the ground and the outlet window opening varies at 20 mm, 40 mm, and 60 mm, are shown in Figure 25, Figure 26, and Figure 27, respectively. When examining the results, it is observed that, in all configurations, the air impacting the lower part of the building gains an upward motion after contacting the building wall, causing the inlet flow to be directed upward. Similarly, the outgoing airflow exhibits an upward movement, particularly in the Upper-Upper configuration where the inlet and outlet openings are aligned; this configuration displays the most stable velocity contours, and the highest velocity contour compared to the other two cases. Notably, the distribution of pressure on the windward facade is similar across all situations, indicating that different outlet opening ratios do not have a significant impact in this area. Examining the streamline distribution reveals that in cases where the windward opening is positioned higher than the leeward opening (Upper-Lower and Upper-Middle), the flow enters the building with an upward inclination, while the outflow from the leeward opening exhibits a downward pattern. This outcome highlights how the airflow path within the building and the exit direction are influenced by the positioning of the window openings. It can be stated that these scenarios, where the windward opening is positioned higher, have a significant impact on the direction and velocity distribution of indoor ventilation. Figure 23: Pressure coefficient distributions for a fixed 40 mm inlet opening with a variable outlet opening. (**a**) Middle-Lower, (**b**) Middle-Middle, (**c**) Middle-Upper. Figure 24: Streamline distributions for a fixed 40 mm inlet opening with a variable outlet opening. (**a**) Middle-Lower, (**b**) Middle-Middle, (**c**) Middle-Upper. The incoming jet adheres to the ceiling surface and is directed upwards due to the Coanda effect, as emphasized by [PERSON] and [PERSON] [28]. Unlike other configurations, setting the windward opening to the highest position creates counterclockwise vortices in the roof section. Figure 28 illustrates the change in \(\mathrm{U/U_{ref}}\) along the window openings for various configurations. Among the symmetric opening configurations, the highest non-dimensional velocity ratio was obtained in Upper-Upper, followed by Middle-Middle and Lower-Lower, respectively. This finding obtained in this study exhibits similar results to those reported in the PIV experiments conducted by [PERSON] [9] and CFD study by [PERSON] et al. [56]. Figure 27: Streamline distributions for a fixed 60 mm inlet opening with a variable outlet opening. (**a**) Upper-Lower, (**b**) Upper-Middle, (**c**) Upper-Upper. Figure 25: Dimensionless velocity distributions for a fixed 60 mm inlet opening with a variable outlet opening. (**a**) Upper-Lower, (**b**) Upper-Middle, (**c**) Upper-Upper. When examining the Upper-Lower and Lower-Upper configurations, the U/U\({}_{\text{ref}}\) is higher in the Upper-Lower configuration in both the windward and leeward openings. This indicates that the airflow speed in the upper part is better than the air intake in the lower part. This result is similar to the findings of [PERSON] et al. [56]. Except for the Upper-Lower and Upper-Middle configurations, which had the highest speed ratio values of 0.656700 and 0.621798, respectively, an increase in speed ratios occurred at the x/D = 0 point for all configurations. Although there were significant decreases in the velocity ratio values of the air entering the building at the x/D = 0.5 point for all conditions, the decrease in velocity was slow in the Middle-Lower configuration, amounting to only a 3% decrease.