Wind-tunnel experiment and numerical analysis on flow and dispersion in street canyons

Street canyons are typical urban building structures. Recently, many studies have concerned on the flow and pollution dispersion characteristics around these urban structures. The similarity criteria of flow and dispersion in wind-tunnel experiments were investigated by CFD technology. The results show that the velocity distribution would be independent of Reynolds number for the structure studied if the building Reynolds number (Re_H) is over the critical value ReH,crit = 3×10⁴. Furthermore, if the density Froude number (Fr_ρ) of the model is equal to that of the prototype, the similarity criteria of flow and dispersion would be mostly satisfied. Based on the Re independence and Fr_ρ equality, a good agreement was achieved between numerical simulation and wind-tunnel experiments.