Numerical simulation of wind flow structures and pollutant dispersion within street canyon under thermally unstable atmospheric conditions

Numerical studies were conducted to envisage the wind flow structures and pollutant dispersion in street canyon for differential heated wall and Froude numbers. Standard k-ε was used as its shows good accuracy compared to Renormalization Group (RNG) k-ε and Realizable k-ε. The obtained results demonstrate that the differentially heated wall/floor gives significant effects on the wind flow field compared with those under isothermal conditions. At high Froude number, there were no discernible effects on the flow structures and pollutant dispersion. At low Froude number however, vortex intensification was observed for the case of ground or leeward heated wall and results in reduced pollutant in street canyon. Meanwhile, for the case of windward heated wall, the ventilation was much reduced and results in higher pollutant in street canyon.