Impacts of shape and height of building roof on airflow and pollutant dispersion inside an isolated street canyon

Two-dimensional numerical simulations were performed using the FLUENT code to investigate the impacts of the shape and height of building roofs on flow and pollutant dispersion inside an isolated street canyon. The numerical model was validated against wind tunnel measured data. Five different roof shapes (vaulted, trapezoidal, slanted, upward wedge-shaped, and downward wedge-shaped roofs) and three different roof heights ( = 1/6, 1/3, and 1/2, where is the roof height and H is the building height) were considered in the simulations. The numerical results revealed that the vortical flow structure and pollutant distribution within an isolated canyon depend significantly on the shape and height of building roofs. A large unique clockwise vortex is established in the canyon, and thus the pollutants accumulate in the leeward side of the canyon for the vaulted and downward wedge-shaped roofs at = 1/6, 1/3, and 1/2, the trapezoidal roof at = 1/6 and 1/3, and the slanted and upward wedge-shaped roofs at ...