Why we need to compute all the directions of the wind to compute the pedestrian comfort ?

Why we need to compute all the directions of the wind to compute the pedestrian comfort ?

Uncomfortable wind conditions are phenomenon well-known around buildings. We know how complex can be the flow pattern around the vicinity of building.

Lot of hard work has been done understanding aerodynamic around bluff bodies. It’s much trickier when it comes to complex buildings, even more in complex urban areas with high buildings.

My point here is to illustrate how important is to take into account all direction of the climatology to compute the pedestrian comfort in this complex outdoor environment.

I have created a random combination of building from 6 m to 60 m height (Figure 1). The wind rose for this project is located at 100 m height in Galicia, Spain. The predominant winds are from NE and SO (figure 2).

Figure 1 - Random Combination of Buildings

Figure 1 – Random Combination of Buildings

Figure 2 - Wind  Rose

Figure 2 – Wind Rose

 

Compute the pedestrian comfort

We’re going to crosscheck the importance of taking into account the full climatology instead of one direction. After directional computations (mesh is about 16 Millions of cells), the mean speed will be computed from :

  • Complete climatology (figure 3)
  • Wind characteristic from 60 deg (figure 4)
  • Wind characteristic from 240 deg (figure 5).

 

 

We can notice most of the wind pattern from the two predominant winds can be found on the full climatology. But full understanding from one direction apart from other directions makes the analysis difficult to guest the final result, overall its intensity. One could imagine that the wind speed is much harder to predict from few directions when the climatology will not show any predominant wind.

    Author

    Guillaume Caniot
    Master of turbulance. I'm specialized in pedestrian comfort, natural ventilation, small wind energy assessment in urban area.

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