CFD for airflow around buildings

Here is a picture produced by Paraview and showing streamlines, from a CFD simulation made with OpenFoam (RANS modeling).

Paraview website 

OpenFoam website 

CFD makes it possible to carefully study interaction between wind and buildings. It is very useful to evaluate thermal comfort for pedestrian and wind pressure over buildings faces.

It is very valuable because wind over building facades can have significant effect on ventilation inside (HVAC and smoke management systems).

CFD simulation at urban scale is continuously developping to get realistic prediction of buildings aeraulics.