3.5.3 Impact of corner radius

Urban wind energy potential: Impacts of building corner modifications 57

Figure 3.11. Contours of dimensionless power density for case with chamfer length of 0.05B in (a) a vertical plane at y/B = 0 (midplane), (b) a horizontal plane at z/H = 1.03 (just above the roof), (c) and in a vertical plane at y/B = 1.1 (besides the buildings). (d-f) same for case with chamfer length of 0.2B. Note that the high turbulence region (Iref > 0.16) is masked with white, signaling its unsuitability for turbine installation. The black arrow indicates the flow direction.

Table 3.4. Ratio of high-turbulence area (Iref > 0.16, unsuitable for turbine installation) over the total area of the planes shown in Fig. 3.11 for different chamfer lengths.

Case ID Chamfer length, l

Case C1 0.05B Case C2 0.10B Case C3 0.15B Case C4 0.20B Along the passages between the buildings (y/B = 0) 25% 28% 45% 56% Selected area

Above the roofs (z/H=1.03) 24% 9% 0% 0% Beside the buildings (y/B = 1.1) 51% 45% 43% 26%

3.5.3 Impact of corner radius

To assess the impact of the corner radius on the wind power density, four radii are studied: r = 1 m, 2 m, 3m, and 4 m (i.e., 0.05B, 0.10B, 0.15B, and 0.20B). Figure 3.12 shows the contour plots of the predicted PD/PDref, with high turbulence regions with Iref > 0.16 masked with white color, over three possible areas for r = 0.05B, and 0.20B. The URAR values are listed in Table 3.5.

58 Chapter 3

- Along the passages between the buildings at y/B = 0 (Fig. 3.12a-b & Table 3.5): Enlarging corner radius from 0.05B to 0.20B can enhance PD/PDref by 26%. As the corner radius increases from 0.05B to 0.20B, URAR increases with 62%. - Above the roofs at z/H = 1.03 and beside the buildings at y/B = 1.1 (Fig. 3.12c-f & Table 3.5):

By enlarging the corner radius, PD/PDref can increase 23% and 350% above the building roofs and beside the buildings, respectively. Increasing the corner radius can reduce URAR and enhance the power density. URAR is zero above the roof for the corner radius of 0.15B and 0.20B.

Figure 3.12. Contours of dimensionless power density for case with rounded radius of 0.05B (a) a vertical plane at y/B = 0 (midplane), (b) a horizontal plane at z/H = 1.03 (just above the roof), (c) and in a vertical plane at y/B = 1.1 (besides the buildings). (d-f) same for case with rounded radius of 0.2B. Note that the high turbulence region (Iref > 0.16) is masked with white, signaling its unsuitability for turbine installation. The black arrow indicates the flow direction.

Table 3.5. Ratio of high-turbulence region (Iref > 0.16, unsuitable for turbine installation) over the total area of the planes shown in Fig. 3.12 for different corner radius.

Case ID Rounded corner radius, r

Case R1 0.05B Case R2 0.10B Case R3 0.15B Along the passages between the buildings (y/B = 0) 24% 25% 27% Selected area

Above the roofs (z/H=1.03) 28% 13% 0% Beside the buildings (y/B = 1.1) 76% 37% 28%