## 3 Results
### Deck-roof Building  
#### 3.2.1 Wind Velocity  
The following subsection presents the results of the velocity measurements above the deck-roof building, obtained for wind angles of 0\({}^{\circ}\) and 45\({}^{\circ}\). The mean velocity and turbulence intensity have been measured above two points on the roof top, i.e., points 50 and 58, marked in red in Figure 4b. The velocity has been measured at ten heights above the roof centre point (point 58 in Figure 4b) and five heights above point 50 at 0\({}^{\circ}\), and four heights above both points at 45\({}^{\circ}\). The normalised velocity profiles, based on the stream-wise and vertical velocity components above these points, are shown in Figure 10, together with the longitudinal (\(I_{U}\)) and vertical (\(I_{W}\)) turbulence intensities calculated using Equation (1). Figure 10 also shows the percentage increase in the mean value of the stream-wise velocity component as in the previous section. In order to compare the behaviour of the deck-roof to  
Figure 9: Mean distributions of the surface pressure coefficient (\(C_{p,mam}\)) along alignment \(x\)/\(D\) = 0.5 for different building configurations, a half cube \(H\)/\(D\) = 1:2 and a cube \(H\)/\(D\) = 1:1 from the Architectural Institute of Japan (AIJ) database and high-rise \(H\)/\(D\) = 3:1 from the present experiment for two wind angles: (**a**) 0\({}^{\circ}\) and (**b**) 45\({}^{\circ}\). that of the flat-roof building, Figure 10 also shows the wind profiles above \(x/D=0.5\) (points 20 and 36) for the same wind angles. Figure 10: Velocity vectors profiles, based on the stream-wise and vertical velocity components, showing the stream-wise turbulence intensity \(I_{U}\), the vertical turbulence intensity \(I_{W}\) and the percentage increase in the stream-wise wind speed. Each numerical value reported at every measurement point in the figure shows the following statistics: \(I_{U}\)**[%]** above on the left; \(I_{W}\)**[%]** below on the left; (**U-\(U_{ref}\)**)/\(U_{ref}\)**[%]** below on the right. Profiles over the deck-roof high-rise building are measured above points 18 and 50 (alignment \(x/D=0.2\), left-hand-side), for wind directions of: (**a**) 0\({}^{\circ}\) and (**c**) 45\({}^{\circ}\); and over the flat-roof high-rise building above the points 20 and 36 (\(x/D=0.5\)), for wind directions of: (**b**) 0\({}^{\circ}\) and (**d**) 45\({}^{\circ}\). The arrows indicate the velocity magnitude normalised with reference velocity (\(U_{ref}\)), as referred to the unity vector represented in the legend. At 0\({}^{\circ}\), results in Figure 10a show that velocity vectors above point 50 point upwards, which suggests that the flow separates at the windward edge of the deck-roof building. However, the velocity vectors above point 58 are almost parallel to the roof, indicating that the size of the separation bubble is much smaller than that above the flat-roof building presented in Figure 10b. It is interesting to note that turbulence intensities are lower close to the top of the deck-roof building, in contrast to high-turbulence intensity zones detected in the same zone in Figure 10b. This may be explained by the effect of the shape of the deck roof. As the incoming air overcomes the obstacle provided by the high-rise building, lifting over the roof of the building, the streamlines of the velocity vectors follow the shape of the roof, thus preventing the development of the large separation bubble at the upstream edge. This fact is supported by the flow acceleration noticeable in the vicinity of the roof. At 45\({}^{\circ}\), a similar flow pattern can be observed above the central points (point 58 in Figure 10c and point 36 in Figure 10d) for both roof shapes. The lack of a vertical velocity component at the lowest measurement positions as well as low turbulence levels indicate that the flow is attached to the roof. The difference is noticeable in the flow above point 50 for the deck-roof building case and point 20 for the flat roof case.