Impacts of high-rise building on urban airflows and pollutant dispersion under different temperature stratifications: Numerical investigations

Abstract

In this study, the effects of high-rise building on the flow and pollutant dispersion under different temperature stratification conditions were simulated using the Reynolds Averaged Navier Stokes (RANS) method and standard k-ε turbulence model. The results showed the following: Both the height of central building and temperature stratification significantly affect the airflow around building arrays. When the height of the central building is 0H (H is the height of surrounding buildings), the flow structure under the different temperature stratification conditions are invariably wake interference flows in morphology but are markedly different in terms of the vortex morphology and quantity. When the height of the central building is 2H, the central building has marked blocking effect, increasing the complexity of the flow fields in the surrounding blocks, the length of the recirculation zones of downstream buildings, and the range of pollutant dispersion, particularly under stable conditions. Increasing the central building height to 2H markedly decreases the turbulent kinetic energy in downstream street canyons due to the effect of the recirculation zones of the central building. Under non-neutral conditions, increasing the central building height to 2H intensifies the mechanical turbulence, resulting in nonsignificant temperature stratification variations in the building arrays.