Microclimate and urban planning

Large complex urban area

How to break the computational matters for large complex urban area?

In this example, a mixed development zone is designed near the seashore on the North West of France. Urban planners want to know if the pedestrian wind comfort is achieved in any part of the original design of the district.

The size of the district is large about 250 m x 650 m (about 0.125 km² or 12.5 ha or 30 acres).



In the wind rose of a local mast (see picture on the right), even if the prevailing wind direction represent about half of the total, all wind directions need to be computed, at least 18.

It could be a major failure to look only the prevailing wind direction to assess the wind pedestrian comfort with precision. In that context for large urban area, the computation time become a severe issue when designer does not have large IT resources. UrbaWind 3 offers new performances to exceed this situation.


In this case, because of the narrowness of the street, fine resolution needs to capture small aerodynamic effect. With a resolution of 1 m near wall and 0.2 m near the ground, the total amount of cells is about 2.5 Million of cells. For such large domain UrbaWind 2 needs 41 hours to compute all the directions.

The average mean speed map at the pedestrian elevation is represented below :




Numerical parameters can be tuned in UrbaWind 3 for complex case in order to achieve convergence faster. As you can notice, on this example, one can expect more than 60% acceleration time! Only 15 hours is needed to obtain the same wind mapping.

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UW 2

UW 3

Amount of Computational time (s) for 18 directions on 1 core



% / UW 2


- 62.3 %


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