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Abstract:
Air flow and reactive pollutant dispersion characteristics in a real urban area are studied based on an engineering computational fluid dynamics (CFD) model. The CFD model consists of the large-eddy simulation (LES) transport equations for nitrogen oxides (NOx) and ozone (O3) with photochemistry and artificial ground-level emission of nitric oxide (NO). Kowloon Peninsula, where is the core of downtown Hong Kong, is taken as the case study whose buildings are explicitly resolved for LES modeling. The results show that the inhomogeneous concentration distribution of tracer and chemical species is attributed to the buildings and the complicated turbulence structure. Apparently, vortices behind buildings enhance the mixing processes that in turn promote the reaction rates in turbulent flows. Most primary pollutant NO is consumed by O3, resulting in a substantial nitrogen dioxide NO2 (secondary pollutant) production at street-level around the buildings. Thus, NOx concentrations and O3 consumption are high near the street level and decreases with height. © 2019 Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, HARMO. All rights reserved.
