Wind Distribution in Doushi Garden Site

Yi Jiang, Ph.D. Student

Building Technology Program, MIT

In Doushi Garden site, there are over 10 high-rise buildings. The lowest one is 33 meters high, and the highest one 90 meters. Since Beijing is windy in winter and spring, in such a high-rise building area, the investigation studies if the preliminary City Garden design would cause discomfort in the site.

Determination of the Incoming Wind

In a typical year, there are 9 days during which the wind speed is higher than 7.6 m/s (17 mph) in Beijing (1997 ASHRAE Fundamentals Handbook, 26.30). So we set the incoming wind speed to be 7.6 m/s at the height of 10 meters. The incoming wind profile is

            U = c z^1/4

Calculation Results

We plan to calculate four cases, in which the wind is from north, south, east and west directions respectively. Two cases with the wind from the north and the west are reported here.

For the wind from the north:

Fig. 1 (3 Dimensional) and Fig. 2 (2 Dimensional) show the wind velocity distribution at the height of 1.5 meters above the ground to evaluate pedestrian’s comfort.

Fig. 3 shows the wind speed distribution at section 1-1.

Fig. 4 shows the wind speed distribution at section 2-2.

Fig. 5 shows the wind velocity distribution at the height of 30 meters above the ground. Since the heights of all buildings are above 30 meters, we would like to find the wind speed at that height.

Fig. 6 shows the wind velocity distribution at the height of 70 meters above the ground. There are 8 buildings whose heights are above 70 meters.

For the wind from the west:

Fig. 7 (3 Dimensional) and Fig. 8 (2 Dimensional) show the wind velocity distribution at the height of 1.5 meters above the ground to evaluate pedestrian’s comfort.

Preliminary Analysis

Our preliminary calculations found that the current design can cause serious discomfort problems.

(1)   The wind speed at section 1 and 2 may reach 8 ~ 9m/s that is well above the comfort limit (5 m/s)

(2)   Although the wind speed at the community area is not very high for the north wind, the high wind speed will occur when the wind is from the west due to the bell arrangement of the buildings.

(3)   At the height of 30 meters, the wind speeds in the most buildings are 9~10 m/s. At the height of 70 meters, the wind speed above 12 m/s.

Fig. 1 Wind velocity distribution at the height of 1.5 meters (3-D) above the ground.

 Fig. 2 Wind velocity distribution at the height of 1.5 meters (2-D) above the ground.

Fig. 3  The wind speed distribution at section 1-1.

Fig. 4 The wind speed distribution at section 2-2.
 Fig. 5 The wind velocity distribution at the height of 30 meters above the ground.
Fig. 6 The wind velocity distribution at the height of 70 meters above the ground.

Fig. 7 Wind velocity distribution at the height of 1.5 meters (3-D) above the ground.

Fig. 8 Wind velocity distribution at the height of 1.5 meters (2-D) above the ground.

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