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Conference Paper: Laboratory study of Passive-scalar Plume Dispersion over Hypothetical Urban Roughness

TitleLaboratory study of Passive-scalar Plume Dispersion over Hypothetical Urban Roughness
Authors
Issue Date2017
Citation
American Meteorological Society 97th Annual Meeting (AMS 2017), Seattle, USA, 22-26 January 2017 How to Cite?
AbstractBehaviours of pollutant dispersion in the atmospheric boundary layers (ABLs) are strongly affected by surface roughness of urban areas. A wind tunnel approach was deployed in this study to investigate the characteristic plume dispersion of passive scalar over hypothetical urban roughness elements in the form of ribs (with various separations apart) in cross flows. An array of idealised street canyons was fabricated by identical square aluminum bars with different aspect (building-height-to-street-width) ratios, i.e. h/b = 1/2, 1/4, 1/8, and 1/10. Moisture was released from a ground-level source into the fully-developed turbulent boundary layers (TBLs) to simulate passive-scalar dispersion over rough surfaces. The velocity and humidity were measured simultaneously using hot-wire anemometry (HWA) and humidity sensors, respectively, on the vertical x-z plane. The profiles of wind and moisture content were compared among different surface configurations in attempt to elucidate the turbulent transport processes. Besides, the vertical dispersion coefficient (σz) was examined in details to illustrate the plume behaviours. Previous numerical modelling showed that plume dispersion strongly depended on the aerodynamic resistance. As such, the relationship between σz and friction factor f was tested based on the physical modelling results in order to verify the mathematical hypothesis. This study could advance our understanding of pollutant dispersion mechanism over urban areas in response to different surface roughness.
Description13th Symposium of the Urban Environment - Session 1: Urban Canopy and Roughness Sublayers- Part l: no. 1.2
Persistent Identifierhttp://hdl.handle.net/10722/247849

 

DC FieldValueLanguage
dc.contributor.authorMo, Z-
dc.contributor.authorLiu, CH-
dc.date.accessioned2017-10-18T08:33:38Z-
dc.date.available2017-10-18T08:33:38Z-
dc.date.issued2017-
dc.identifier.citationAmerican Meteorological Society 97th Annual Meeting (AMS 2017), Seattle, USA, 22-26 January 2017-
dc.identifier.urihttp://hdl.handle.net/10722/247849-
dc.description13th Symposium of the Urban Environment - Session 1: Urban Canopy and Roughness Sublayers- Part l: no. 1.2-
dc.description.abstractBehaviours of pollutant dispersion in the atmospheric boundary layers (ABLs) are strongly affected by surface roughness of urban areas. A wind tunnel approach was deployed in this study to investigate the characteristic plume dispersion of passive scalar over hypothetical urban roughness elements in the form of ribs (with various separations apart) in cross flows. An array of idealised street canyons was fabricated by identical square aluminum bars with different aspect (building-height-to-street-width) ratios, i.e. h/b = 1/2, 1/4, 1/8, and 1/10. Moisture was released from a ground-level source into the fully-developed turbulent boundary layers (TBLs) to simulate passive-scalar dispersion over rough surfaces. The velocity and humidity were measured simultaneously using hot-wire anemometry (HWA) and humidity sensors, respectively, on the vertical x-z plane. The profiles of wind and moisture content were compared among different surface configurations in attempt to elucidate the turbulent transport processes. Besides, the vertical dispersion coefficient (σz) was examined in details to illustrate the plume behaviours. Previous numerical modelling showed that plume dispersion strongly depended on the aerodynamic resistance. As such, the relationship between σz and friction factor f was tested based on the physical modelling results in order to verify the mathematical hypothesis. This study could advance our understanding of pollutant dispersion mechanism over urban areas in response to different surface roughness.-
dc.languageeng-
dc.relation.ispartofAmerican Meteorological Society 97th Annual Meeting, 2017-
dc.titleLaboratory study of Passive-scalar Plume Dispersion over Hypothetical Urban Roughness-
dc.typeConference_Paper-
dc.identifier.emailLiu, CH: chliu@hkucc.hku.hk-
dc.identifier.authorityLiu, CH=rp00152-
dc.identifier.hkuros281392-

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