# Wind Loads on Overhead Sign Structures: A Comparative Study
## 4 Results  
### Pressure Contours  
Figure 5 shows the contours of pressure coefficients on the standard panel. The positive pressure on the windward face decreases as it nears the edges. The negative pressure on the leeward is more homogenous.  
Figure 6 shows the contour of pressure coefficients on the windward side of panels with porosity and curvature. The windward face of the panels exhibits the maximum positive pressure coefficient, which decreases towards the edges. Given that the airflow is normal to the panels in all cases, the stagnation points are present with a maximum pressure coefficient value of one, resulting in a relatively high average pressure on the windward face. All cases show common pressure contour characteristics. A dark red region is at the center of every surface, indicating high pressure in this region and a reducing pressure as it nears the edges. The curved panel has a smaller high-pressure region as the airflow has less resistance and gradually decreases in pressure as it nears the edges. The side edges of the curved panel display similar characteristics to the other cases; however, the top and bottom edges have a larger low-pressure region, as these have an active curvature.  
The leeward face has the minimum negative pressure coefficients (Figure 7). The panel with 28 large holes and the curved one ultimately have a uniform pressure region, indicating a recirculating airflow far away from the leeward face for the sign panel with large holes and very little for the curved panel. Dark blue regions indicate the areas with the highest negative pressure. The dark regions occur in the sign panel with 200 uniform holes and the slotted one. These configurations have the smallest area, allowing airflow to pass through and result in an increased velocity through these holes or slots, thus further reducing the pressure on the leeward surface. The panel with 200 uniform holes has the lowest pressure region centrally located in the area surrounding the holes, and the pressure begins to rise near the exterior edges. For the panel with 10 slots, higher pressure can be seen at a section between the slots near the midpoint, indicating a split in airflow where it attaches to either the top and bottom airflow streams produced from the nearest slot and continue downwind. Table 1 lists the corresponding values of the pressure coefficients for each panel on the windward and leeward faces, respectively.  
Figure 5: Pressure coefficients contour on the standard panel: (**a**) windward face, (**b**) side view, (**c**) leeward face, and (**d**) top view.  
Figure 6: Contours of pressure coefficients on the windward face for (**a**) 28 staggered holes, (**b**) 200 uniform square holes, (**c**) 10 rectangular slots, and (**d**) curved.  
Figure 7: Contours of pressure coefficients on the leeward face for (**a**) 28 staggered holes, (**b**) 200 uniform square holes, (**c**) 10 rectangular slots, and (**d**) curved.  
Table 1 shows that, for each case, the windward pressure coefficient regions are relatively the same but with a decreasing value for the curved panel. However, the leeward side has sharp spikes and varies for each case. In porous panels, the increased velocity of the air flowing through these holes and slots does reduce the size of the pressure coefficient region but raises the negative pressure just behind the panel. The smaller the hole diameter, the larger the magnitude of the pressure coefficient.