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Article: On the prediction of air and pollutant exchange rates in street canyons of different aspect ratios using large-eddy simulation

TitleOn the prediction of air and pollutant exchange rates in street canyons of different aspect ratios using large-eddy simulation
Authors
KeywordsAir exchange rate (ACH)
Large-eddy simulation (LES)
Pollutant exchange rate (PCH)
Street canyon
Vehicular pollution
Issue Date2005
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/atmosenv
Citation
Atmospheric Environment, 2005, v. 39 n. 9, p. 1567-1574 How to Cite?
AbstractThis study employs a large-eddy simulation (LES) technique to predict the air exchange rate (ACH) and pollutant exchange rate (PCH) for street canyons of aspect ratio (h/b, building-height-to-street-width) 0.5, 1.0, and 2.0 at a Reynolds number (Re) of 12,000 and a Schmidt number (Sc) of 0.72. The air ventilation and pollutant dilution of the street canyons are investigated by means of the distribution, average concentration, and retention time of pollutant in the street canyons. The flow in the street canyons at this Re and Sc lies in the wake-interference flow regime, in which the recirculations are isolated from the free-stream flow and the pollutant removal is governed by turbulent transport. Based on the LES database, the ACH and PCH of the street canyons are determined by the roof-level transient turbulence properties. The ACH increases with decreasing h/b, which is in line with the common observation of the better air ventilation in street canyons of smaller h/b. The PCH is found to be equal to the amount of pollutant emitted. Positive PCH shows that the pollutant removal rate is greater than the ground-level pollutant emission rate. As a consequence, some of the pollutant in the free surface layer, which originated from the street canyon, re-enters the canyon, lengthening the pollutant retention time in the street canyon. If pollutants from upstream sources reside in the free stream flow, the pollutant entrainment would contribute to degrading the air quality in the street canyons. © 2004 Elsevier Ltd. All rights reserved.
Persistent Identifierhttp://hdl.handle.net/10722/75818
ISSN
2015 Impact Factor: 3.459
2015 SCImago Journal Rankings: 1.999
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorLiu, CHen_HK
dc.contributor.authorLeung, DYCen_HK
dc.contributor.authorBarth, MCen_HK
dc.date.accessioned2010-09-06T07:14:52Z-
dc.date.available2010-09-06T07:14:52Z-
dc.date.issued2005en_HK
dc.identifier.citationAtmospheric Environment, 2005, v. 39 n. 9, p. 1567-1574en_HK
dc.identifier.issn1352-2310en_HK
dc.identifier.urihttp://hdl.handle.net/10722/75818-
dc.description.abstractThis study employs a large-eddy simulation (LES) technique to predict the air exchange rate (ACH) and pollutant exchange rate (PCH) for street canyons of aspect ratio (h/b, building-height-to-street-width) 0.5, 1.0, and 2.0 at a Reynolds number (Re) of 12,000 and a Schmidt number (Sc) of 0.72. The air ventilation and pollutant dilution of the street canyons are investigated by means of the distribution, average concentration, and retention time of pollutant in the street canyons. The flow in the street canyons at this Re and Sc lies in the wake-interference flow regime, in which the recirculations are isolated from the free-stream flow and the pollutant removal is governed by turbulent transport. Based on the LES database, the ACH and PCH of the street canyons are determined by the roof-level transient turbulence properties. The ACH increases with decreasing h/b, which is in line with the common observation of the better air ventilation in street canyons of smaller h/b. The PCH is found to be equal to the amount of pollutant emitted. Positive PCH shows that the pollutant removal rate is greater than the ground-level pollutant emission rate. As a consequence, some of the pollutant in the free surface layer, which originated from the street canyon, re-enters the canyon, lengthening the pollutant retention time in the street canyon. If pollutants from upstream sources reside in the free stream flow, the pollutant entrainment would contribute to degrading the air quality in the street canyons. © 2004 Elsevier Ltd. All rights reserved.en_HK
dc.languageengen_HK
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/atmosenven_HK
dc.relation.ispartofAtmospheric Environmenten_HK
dc.subjectAir exchange rate (ACH)en_HK
dc.subjectLarge-eddy simulation (LES)en_HK
dc.subjectPollutant exchange rate (PCH)en_HK
dc.subjectStreet canyonen_HK
dc.subjectVehicular pollutionen_HK
dc.titleOn the prediction of air and pollutant exchange rates in street canyons of different aspect ratios using large-eddy simulationen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=1352-2310&volume=39&issue=9&spage=1567&epage=1574&date=2005&atitle=On+the+prediction+of+air+and+pollutant+exchange+rates+in+street+canyons+of+different+aspect+ratios+using+large-eddy+simulationen_HK
dc.identifier.emailLiu, CH:chliu@hkucc.hku.hken_HK
dc.identifier.emailLeung, DYC:ycleung@hku.hken_HK
dc.identifier.authorityLiu, CH=rp00152en_HK
dc.identifier.authorityLeung, DYC=rp00149en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1016/j.atmosenv.2004.08.036en_HK
dc.identifier.scopuseid_2-s2.0-14644387606en_HK
dc.identifier.hkuros98495en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-14644387606&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume39en_HK
dc.identifier.issue9en_HK
dc.identifier.spage1567en_HK
dc.identifier.epage1574en_HK
dc.identifier.isiWOS:000227857600001-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridLiu, CH=36065161300en_HK
dc.identifier.scopusauthoridLeung, DYC=7203002484en_HK
dc.identifier.scopusauthoridBarth, MC=7102913661en_HK
dc.identifier.citeulike2710468-

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