RANS simulation of near-field dispersion of reactive air pollutants

A.U. Weerasuriya, Xuelin Zhang, K.T. Tse, Chun-Ho Liu, Kenny C. S. Kwok

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

In conventional modeling of air pollution dispersion, pollutants are treated as passive scalars or inert species even though most of them are chemically reactive [1]. Chemical reactions contribute to pollutant dispersion via the generation and depletion of pollutants, in addition to other two mechanisms: advection and turbulent diffusion. This study investigated how chemical reactions affect near-field pollution dispersion by integrating the simple NOx-O3 chemistry into RANS-based computational fluid dynamics (CFD) simulation. CFD simulation was used to model a mixed emission of NO and NO2 from a short stack attached to a building into ambient O3, prompting chemical reactions between the NO, NO2, and O3. Various degrees of chemical reactivity were modeled by varying the Damkhöler number (Da) between 0.073 and 4.363. The results showed significant chemical reactivity for cases where Da [NO] > 1, while cases with Da [NO] < 1 had pollutant dispersion patterns similar to inert species. Noticeable modifications in concentrations were detected at ground level, where the NO concentration was depleted and NO2 concentration increased significantly. A budget analysis revealed major contributions of chemistry and turbulent diffusion to plume dispersion in the surroundings, while advection mainly carried the pollutants downstream from the source.
Original languageEnglish
Article number108553
Number of pages15
JournalBuilding and Environment
Volume207
DOIs
Publication statusPublished - 2022

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