A CFD modelling study of reactive pollutant dispersion in an urban street canyon

This study numerically explores the diffusion rules of pollutants in an idealized urban street canyon where photochemical reactions are present in the neighbourhood. The airborne pollutants dispersion and reaction in street canyons are further investigated in this study. There is a relatively tense traffic pollutants release in urban neighborhoods, including nitrogen oxides and hydrocarbons. Photochemical reaction occurs at strong solar radiation, forming photochemical smog and other environment issues. We selected typical O₃ + NO→O₂ + NO₂ reactions. Effects of the pollutant source location on pollutant dispersion and reaction are also investigated. Numerical simulations were conducted on chemically activity reactive air nitrogen oxides in urban street canyons with W (street canyon wide)/H (building height) = 1. Provided three different locations from the line source street canyon bottom exhaust nitric oxide diffusion and react with ozone in the free stream. The chemical reaction has a significant impact on the concentration of pollutants in the valley volume.