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Conference Paper: Pollutant dispersion over two-dimensional idealized street canyons: a large-eddy simulation approach

TitlePollutant dispersion over two-dimensional idealized street canyons: a large-eddy simulation approach
Authors
KeywordsLES
Urban roughness
Urban street canyon
Issue Date2011
Citation
The 14th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes (HARMO14), Kos, Greece, 2-6 October 2011. In Conference Proceedings, 2011, p. 524-528 How to Cite?
AbstractA series of two-dimensional (2D) street canyon models with a wide range of building-height-to-street-width (aspect) ratios are employed in this study to elucidate the pollutant transport over idealized urban areas. The large-eddy simulation (LES) is used to resolve the turbulent flows and pollutant transport in the urban boundary layer (UBL) over the street canyons. An area source of uniform pollutant concentration is applied on the ground of the first street canyon to examine the pollutant plume dispersion behaviors over the downstream building roughness elements. The LES results show that, for the street canyon with the pollutant source, the pollutant removal is governed by atmospheric turbulence in both skimming flow and wake-interference regimes. Statistical analysis reveals that the turbulent kinetic energy (TKE) is peaked near the top of the building roughness elements that contributes most to turbulent pollutant removal. The roof-level TKE distribution also demonstrates that the turbulence production is not governed by local wind shear. Instead, the descending TKE from the UBL plays a more important role. In the UBL, the vertical pollutant profiles illustrate self-similarity behaviours in the downstream region. The pollutant disperses rapidly over the buildings, exhibiting a Gaussian-plume shape. Maximum vertical pollutant dispersion coefficient is observed at aspect ratio equal to 1/10. A strong correlation between friction factor and dispersion coefficient is found, implying that the downstream air quality could be improved by increasing the roughness of urban area.
DescriptionSession: H14-117
Persistent Identifierhttp://hdl.handle.net/10722/165402

 

DC FieldValueLanguage
dc.contributor.authorWong, CCCen_US
dc.contributor.authorLiu, CHen_US
dc.date.accessioned2012-09-20T08:17:54Z-
dc.date.available2012-09-20T08:17:54Z-
dc.date.issued2011en_US
dc.identifier.citationThe 14th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes (HARMO14), Kos, Greece, 2-6 October 2011. In Conference Proceedings, 2011, p. 524-528en_US
dc.identifier.urihttp://hdl.handle.net/10722/165402-
dc.descriptionSession: H14-117-
dc.description.abstractA series of two-dimensional (2D) street canyon models with a wide range of building-height-to-street-width (aspect) ratios are employed in this study to elucidate the pollutant transport over idealized urban areas. The large-eddy simulation (LES) is used to resolve the turbulent flows and pollutant transport in the urban boundary layer (UBL) over the street canyons. An area source of uniform pollutant concentration is applied on the ground of the first street canyon to examine the pollutant plume dispersion behaviors over the downstream building roughness elements. The LES results show that, for the street canyon with the pollutant source, the pollutant removal is governed by atmospheric turbulence in both skimming flow and wake-interference regimes. Statistical analysis reveals that the turbulent kinetic energy (TKE) is peaked near the top of the building roughness elements that contributes most to turbulent pollutant removal. The roof-level TKE distribution also demonstrates that the turbulence production is not governed by local wind shear. Instead, the descending TKE from the UBL plays a more important role. In the UBL, the vertical pollutant profiles illustrate self-similarity behaviours in the downstream region. The pollutant disperses rapidly over the buildings, exhibiting a Gaussian-plume shape. Maximum vertical pollutant dispersion coefficient is observed at aspect ratio equal to 1/10. A strong correlation between friction factor and dispersion coefficient is found, implying that the downstream air quality could be improved by increasing the roughness of urban area.-
dc.languageengen_US
dc.relation.ispartof14th HARMO International Conference Proceedingsen_US
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.subjectLES-
dc.subjectUrban roughness-
dc.subjectUrban street canyon-
dc.titlePollutant dispersion over two-dimensional idealized street canyons: a large-eddy simulation approachen_US
dc.typeConference_Paperen_US
dc.identifier.emailWong, CCC: ching167kee@hotmail.comen_US
dc.identifier.emailLiu, CH: chliu@hkucc.hku.hk-
dc.identifier.authorityLiu, CH=rp00152en_US
dc.description.naturepostprint-
dc.identifier.hkuros208121en_US
dc.identifier.spage524-
dc.identifier.epage528-

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