Modeling of street-scale pollutant dispersion by coupled simulation of chemical reaction, aerosol dynamics, and CFD

• Published in: Atmospheric chemistry and physics Vol. 23; no. 2; pp. 1421 - 1436
• Main Authors: Lin, Chao, Wang, Yunyi, Ooka, Ryozo, Flageul, Cédric, Kim, Youngseob, Kikumoto, Hideki, Wang, Zhizhao, Sartelet, Karine
• Format: Journal Article
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 26.01.2023; European Geosciences Union; Copernicus Publications
• Subjects: Aerosol dynamics; Aerosols; Ammonium; Ammonium compounds; Ammonium nitrate; Analysis; Anthropogenic factors; Atmospheric and Oceanic Physics; Black carbon; Boundary conditions; Carbon; Carbon content; Chemical reactions; Chemistry; Computational fluid dynamics; Computer applications; Dispersion; Emissions; Environmental aspects; Exhaust emissions; Fluid dynamics; Gases; Human influences; Hydrodynamics; Mathematical models; Modelling; Navier-Stokes equations; Organic compounds; Particle size; Particulate emissions; Particulate matter; Pedestrians; Physics; Pollutants; Pollution dispersion; Reynolds averaged Navier-Stokes method; Scalars; Secondary aerosols; Simulation; Street canyons; Turbulence models; Urban environments
• ISSN: 1680-7324; 1680-7316; 1680-7324
• DOI: 10.5194/acp-23-1421-2023

In the urban environment, gas and particles impose adverse impacts on the health of pedestrians. The conventional computational fluid dynamics (CFD) methods that regard pollutants as passive scalars cannot reproduce the formation of secondary pollutants and lead to uncertain prediction. In this study, SSH-aerosol, a modular box model that simulates the evolution of gas, primary and secondary aerosols, is coupled with the CFD software, OpenFOAM and Code_Saturne. The transient dispersion of pollutants emitted from traffic in a street canyon is simulated using the unsteady Reynolds-averaged Navier–Stokes equations (RANS) model. The simulated concentrations of NO2, PM10, and black carbon (BC) are compared with field measurements on a street of Greater Paris. The simulated NO2 and PM10 concentrations based on the coupled model achieved better agreement with measurement data than the conventional CFD simulation. Meanwhile, the black carbon concentration is underestimated, probably partly because of the underestimation of non-exhaust emissions (tire and road wear). Aerosol dynamics lead to a large increase of ammonium nitrate and anthropogenic organic compounds from precursor gas emitted in the street canyon.