## 3 Simulation Results and Analysis  
### External Simulation Results for Winter  
The main assessment criteria for the outdoor wind conditions in winter are the wind speed at the location and the surface wind pressure difference on the exterior walls of buildings. Figure 6 illustrates the horizontal wind speed at a height of 1.5 m outdoors for four different scenarios during winter. A red dot indicates the peak outdoor wind speed, while the black figures denote the wind speed at a height of 1.5 m. The Figure shows that the highest outdoor wind speed in the four scenarios varies from 1.5 m/s to 1.57 m/s, all falling below the 5 m/s limit set in the \"Green Building Evaluation Standard\" (GB/T50378-2019) [37]. The main reason for this is the obstruction and slowing down caused by the crowded buildings in the city center. Row-by-row floor planning and modest building spacing in Scenario 1 generate a \"canyon effect\" between buildings, resulting in higher wind speeds. The wind speed, while comfortable, helps to remove unclean air from the area and improve the rate of outdoor air renewal. Scenarios 2, 3, and 4 have buildings that hinder outside wind flow, leading to decreased wind speed. The wind speed is comfortable overall but not suitable for outdoor air circulation. Figure 7 depicts the contour map of wind speed amplification factor distribution at a height of 1.5 m outdoors for four scenarios in winter. The maximum outdoor wind speed amplification factor is marked with a white dot. It can be observed that, in winter, the outdoor maximum wind speed amplification factors of the four scenarios are similar, ranging from 1.02 to 1.07, and all meet the requirement of the \"Green Building Evaluation Standard\" (GB/T50378-2019) [37], which stipulates that the wind speed amplification factor should be less than 2. Among the four scenarios, as Scenarios 2, 3, and 4 form enclosed or semi-enclosed areas, the wind speed amplification factor in the regions close to the buildings in these three scenarios is relatively small at approximately 0.2. This is consistent with the wind speed performance. The wind speed amplification factor in other regions close to the buildings does not show significant differences, with most values ranging from 0.4 to 0.5. Therefore, from the perspective of outdoor wind speed and wind speed \begin{table}
\begin{tabular}{c c c} \hline \hline
**Type of Grids** & \multicolumn{2}{c}{**Size of Meshes**} \\ \hline \multirow{4}{*}{Regular grids} & Arc Precision (m) & 0.24 \\ \cline{2-3}  & Initial grid (m) & 8.0 \\ \cline{2-3}  & The smallest subdivision level & 1 \\ \cline{2-3}  & The largest subdivision level & 2 \\ \hline \multirow{3}{*}{Ground grids} & The subdivision levels in the far field & 1 \\ \cline{2-3}  & The subdivision levels in the near field & 2 \\ \hline \multirow{4}{*}{Boundary layer grids} & The number of boundary layers that are close to \\  & the ground surfaces & 2 \\ \cline{2-3}  & The number of boundary layers that are close to \\ \cline{2-3}  & the surfaces of buildings & 0 \\ \hline \multicolumn{3}{c}{Number of cells: 2,377,463} \\ \end{tabular}
\end{table} 
Table 5: Mesh used for simulations. amplification factor performance, Scenario 1, which employs row-by-row floor planning, can achieve better outdoor wind environment performance in winter. Figure 8 shows the wind pressure distribution on the windward and leeward sides of the buildings in the four scenarios in winter. The windward side has higher positive wind pressure compared to the leeward side. Scenario 1 has the lowest maximum positive wind  
Figure 6: Wind Speed Contour Map at 1.5 m Height Outdoors in Winter. Figure 7: Wind Speed Amplification Factor Contour Map at 1.5 m Height in Winter. pressure of 2.39 Pa, while Scenario 4 has the highest maximum positive wind pressure at 2.64 Pa. Scenario 2 and Scenario 3 both show maximum positive wind pressures of 2.51 Pa and 2.49 Pa, respectively.