## 3 Results
### Impact of Opening Positions  
#### 3.2.1 Results for Building Models with a Fixed 20 mm Inlet Position and Varying Outlet Positions  
Figures 19 and 20 present the velocity and pressure contours for three different cases in an isolated gable roof building with a fixed inlet opening height of 20 mm and variable outlet openings (20 mm, 40 mm, and 60 mm). Figure 20 shows the streamlines for these configurations. Due to the no-slip condition on the ground and the fixed inlet opening height of 20 mm in all building models, the inflow directed downward inside the building exhibits a similar flow pattern across all cases. In buildings with outlet openings at 40 mm (Lower-Middle) and 60 mm (Lower-Upper), the flow is observed to be directed upward within the building, and these configurations display a notably similar behavior. When examining all cases, it is observed that the highest inlet velocity occurs when the inlet  
Figure 18: Comparison between the streamwise U/U\({}_{\text{ref}}\) along the centerline of the building models for varying outlet openings.  
and outlet openings are aligned (Lower-Lower). As the outlet opening height increases, there is a decrease in inlet velocity and internal velocity values, resulting in an increase in internal pressure within the building. These findings align with [PERSON]'s principle, which explains the inverse relationship between velocity and pressure. Additionally, the pressure distribution on the windward facade appears similar across all cases.  
The streamline distributions in Figure 21 reveal that in the Lower-Lower, Lower-Middle, and Lower-Upper configurations, the flow distinctly enters the building with a downward inclination, then exits with an upward inclination. Notably, in the Lower-Middle and Lower-Upper cases, where the windward opening is positioned lower than the leeward opening, the outflow from the leeward opening shows an upward tendency. This upward tendency may enhance ventilation efficiency by creating a compatible air circulation with the airflow movement and wind effect within the building.  
The horseshoe vortex in the front of the building generates a standing vortex, a phenomenon that has been reported in previously conducted studies ([PERSON] et al. [9],  
Figure 19: Dimensionless velocity distributions for a fixed 20 mm inlet opening with a variable outlet opening. (**a**) Lower-Lower, (**b**) Lower-Middle, (**c**) Lower-Upper.  
Figure 20: Pressure coefficient distributions for a fixed 20 mm inlet opening with a variable outlet opening. (**a**) Lower-Lower, (**b**) Lower-Middle, (**c**) Lower-Upper.  
Figure 17: Streamline distributions for a fixed 20 mm inlet opening with a variable outlet opening. (**a**) Lower-Lower, (**b**) Lower-Middle, (**c**) Lower-Upper.  
[PERSON] and [PERSON] [22]. The trajectory of the jet is evidently directed downwards, towards the floor of the building, as a consequence of the standing vortex upstream of the inlet opening, which functions as a downward direction for the incoming jet, as demonstrated in the findings of [PERSON] et al. [9] and [PERSON] and [PERSON] [22; 55]. In all three cases (Lower-Lower, Lower-Middle, Lower-Upper), a vortex has formed in the upper part of the incoming jet, rotating in the opposite direction to the clock in the middle of the central building and covering almost the entire internal volume. The jet moving towards the outlet has left the building at a steeper angle due to the upward shift of the outlet opening.