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| Titel |
Aerosol–computational fluid dynamics modeling of ultrafine and black carbon particle emission, dilution, and growth near roadways |
| VerfasserIn |
L. Huang, S. L. Gong, M. Gordon, J. Liggio, R. Staebler, C. A. Stroud, G. Lu, C. Mihele, J. R. Brook, C. Q. Jia |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 23 ; Nr. 14, no. 23 (2014-12-02), S.12631-12648 |
| Datensatznummer |
250119200
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| Publikation (Nr.) |
 copernicus.org/acp-14-12631-2014.pdf |
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| Zusammenfassung |
| Many studies have shown that on-road vehicle emissions are the dominant
source of ultrafine particles (UFPs; diameter < 100 nm) in urban
areas and near-roadway environments. In order to advance our knowledge on
the complex interactions and competition among atmospheric dilution,
dispersion, and dynamics of UFPs, an aerosol dynamics–computational fluid dynamics (CFD) coupled model is
developed and validated against field measurements. A unique approach of
applying periodic boundary conditions is proposed to model pollutant
dispersion and dynamics in one unified domain from the tailpipe level to the
ambient near-road environment. This approach significantly reduces the size
of the computational domain, and therefore allows fast simulation of
multiple scenarios. The model is validated against measured turbulent
kinetic energy (TKE) and horizontal gradient of pollution concentrations
perpendicular to a major highway. Through a model sensitivity analysis, the
relative importance of individual aerosol dynamical processes on the total
particle number concentration (N) and particle number–size distribution (PSD)
near a highway is investigated. The results demonstrate that (1) coagulation
has a negligible effect on N and particle growth, (2) binary homogeneous
nucleation (BHN) of H2SO4–H2O is likely responsible for
elevated N closest to the road, and (3) N and particle growth are very sensitive
to the condensation of semi-volatile organics (SVOCs), particle dry
deposition, and the interaction between these processes. The results also
indicate that, without the proper treatment of the atmospheric boundary layer
(i.e., its wind profile and turbulence quantities), the nucleation rate would
be underestimated by a factor of 5 in the vehicle wake region due to
overestimated dilution. Therefore, introducing atmospheric boundary layer (ABL) conditions to
activity-based emission models may potentially improve their performance in
estimating UFP traffic emissions. |
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