Abstract
In previous studies of pollutant dispersion around street canyons, researchers have found that pollutants do not dissipate easily under stable conditions, but they have tended to study only under weak stability conditions and relatively little research has been done on strong stability conditions. In this study, we mainly used 3-D computational fluid dynamics (CFD) technology to investigate the influence of various Richardson numbers (Rib) on the flow field structure and pollutant dispersion around an ideal street canyon under stable stratification. The results show that under stable stratification, different Rib values have significant effects on the flow field, turbulent field, and concentration field around the street canyon. The main effects are that as Rib increases, the vortices inside the street canyon gradually become larger and move downward, the length of the attachment point behind the buildings first increases and then gradually decreases, and the normalized turbulent kinetic energy (TKE/uH2) gradually decreases. The vertical diffusion range of the plume decreases, the horizontal transport distance increases, and the maximum concentration value at the center of the plume gradually increases. This research result may provide new scientific basis for the prediction and control of urban air pollution.
Published Version
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