Wind Assessment in Urban Area with CFD Tools – Application to Natural Ventilation Potential And Outdoor Pedestrian Comfort

The paper presents a numerical methodology to assess wind pedestrian comfort and natural ventilation in urban areas. UrbaWind, an automatic computational fluid dynamics code, is improved to model the wind in dense urban environments. The turbulence modelling, that is to say the dependence of turbulence length on the distance from wall, and the model constants are calibrated in order to reproduce precisely flow separation around buildings walls. Numerical results match well with the experiments: separation patterns, pressure field on walls, and wind speed in dense urban area. Two examples are presented at the end of the paper in order to demonstrate the advantages of the methodology for urban designers.