A CFD Study of Pollution Dispersion in a Historic Ventilation Corridor with an Evolving Urban Complex

Ventilation corridors can play an important role in removing harmful air pollution in cities; however, there are social pressures to use this corridor land for new buildings. The presented study employs RANS fluid flow simulations with the k-ϵ turbulence model to investigate how the addition of buildings in the historical ventilation corridor impedes CO traced pollution removal. The urban complex situated near Raclawicka Street in Warsaw is selected as a case study for which two urban layouts dating from 2006 and 2017 are compared. The investigation includes varying ambient wind speeds and direction, with a prescribed CO-air mixture source representing a supply of road pollution. The results provide aerodynamic and dispersion characteristics and identify several generic trends indicating that the orthogonal urban layouts help to remove the pollution faster, especially when compared to courtyard building configurations, and that the introduction of occasional wide gaps between buildings can also speed up the pollution removal in the direction perpendicular to the gaps. Furthermore, for this urban complex the addition of new buildings had predominantly a local impact. The results showed that for light and mild winds, ambient speeds have little impact on dispersion patterns, but the effects of a dynamic ambient wind reversal are pronounced.