File Download

There are no files associated with this item.

  Links for fulltext
     (May Require Subscription)
Supplementary

Article: Passive urban ventilation by combined buoyancy-driven slope flow and wall flow: parametric CFD studies on idealized city models

TitlePassive urban ventilation by combined buoyancy-driven slope flow and wall flow: parametric CFD studies on idealized city models
Authors
KeywordsAge of air
Air change rates
Background winds
Building height
Buoyancy driven flows
Issue Date2011
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/atmosenv
Citation
Atmospheric Environment, 2011, v. 45 n. 32, p. 5946-5956 How to Cite?
Abstract
This paper reports the results of a parametric CFD study on idealized city models to investigate the potential of slope flow in ventilating a city located in a mountainous region when the background synoptic wind is absent. Examples of such a city include Tokyo in Japan, Los Angeles and Phoenix in the US, and Hong Kong. Two types of buoyancy-driven flow are considered, i.e., slope flow from the mountain slope (katabatic wind at night and anabatic wind in the daytime), and wall flow due to heated/cooled urban surfaces. The combined buoyancy-driven flow system can serve the purpose of dispersing the accumulated urban air pollutants when the background wind is weak or absent. The microscopic picture of ventilation performance within the urban structures was evaluated in terms of air change rate (ACH) and age of air. The simulation results reveal that the slope flow plays an important role in ventilating the urban area, especially in calm conditions. Katabatic flow at night is conducive to mitigating the nocturnal urban heat island. In the present parametric study, the mountain slope angle and mountain height are assumed to be constant, and the changing variables are heating/cooling intensity and building height. For a typical mountain of 500 m inclined at an angle of 20° to the horizontal level, the interactive structure is very much dependent on the ratio of heating/cooling intensity as well as building height. When the building is lower than 60 m, the slope wind dominates. When the building is as high as 100 m, the contribution from the urban wall flow cannot be ignored. It is found that katabatic wind can be very beneficial to the thermal environment as well as air quality at the pedestrian level. The air change rate for the pedestrian volume can be as high as 300 ACH. © 2011 Elsevier Ltd.
Persistent Identifierhttp://hdl.handle.net/10722/157155
ISSN
2013 Impact Factor: 3.062
2013 SCImago Journal Rankings: 1.776
ISI Accession Number ID
Funding AgencyGrant Number
Research Grants Council of Hong Kong Special Administrative Region, ChinaHKU 7145/07E
Funding Information:

The work described was supported by the Research Grants Council of Hong Kong Special Administrative Region, China (Project No. HKU 7145/07E). We thank two anonymous reviewers' comments to further improve the paper.

References

 

Author Affiliations
  1. The University of Hong Kong
DC FieldValueLanguage
dc.contributor.authorLuo, Zen_US
dc.contributor.authorLi, Yen_US
dc.date.accessioned2012-08-08T08:45:34Z-
dc.date.available2012-08-08T08:45:34Z-
dc.date.issued2011en_US
dc.identifier.citationAtmospheric Environment, 2011, v. 45 n. 32, p. 5946-5956en_US
dc.identifier.issn1352-2310en_US
dc.identifier.urihttp://hdl.handle.net/10722/157155-
dc.description.abstractThis paper reports the results of a parametric CFD study on idealized city models to investigate the potential of slope flow in ventilating a city located in a mountainous region when the background synoptic wind is absent. Examples of such a city include Tokyo in Japan, Los Angeles and Phoenix in the US, and Hong Kong. Two types of buoyancy-driven flow are considered, i.e., slope flow from the mountain slope (katabatic wind at night and anabatic wind in the daytime), and wall flow due to heated/cooled urban surfaces. The combined buoyancy-driven flow system can serve the purpose of dispersing the accumulated urban air pollutants when the background wind is weak or absent. The microscopic picture of ventilation performance within the urban structures was evaluated in terms of air change rate (ACH) and age of air. The simulation results reveal that the slope flow plays an important role in ventilating the urban area, especially in calm conditions. Katabatic flow at night is conducive to mitigating the nocturnal urban heat island. In the present parametric study, the mountain slope angle and mountain height are assumed to be constant, and the changing variables are heating/cooling intensity and building height. For a typical mountain of 500 m inclined at an angle of 20° to the horizontal level, the interactive structure is very much dependent on the ratio of heating/cooling intensity as well as building height. When the building is lower than 60 m, the slope wind dominates. When the building is as high as 100 m, the contribution from the urban wall flow cannot be ignored. It is found that katabatic wind can be very beneficial to the thermal environment as well as air quality at the pedestrian level. The air change rate for the pedestrian volume can be as high as 300 ACH. © 2011 Elsevier Ltd.en_US
dc.languageengen_US
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/atmosenven_US
dc.relation.ispartofAtmospheric Environmenten_US
dc.subjectAge of airen_US
dc.subjectAir change ratesen_US
dc.subjectBackground windsen_US
dc.subjectBuilding heighten_US
dc.subjectBuoyancy driven flowsen_US
dc.titlePassive urban ventilation by combined buoyancy-driven slope flow and wall flow: parametric CFD studies on idealized city modelsen_US
dc.typeArticleen_US
dc.identifier.emailLuo, Z: vinluo@hku.hken_US
dc.identifier.emailLi, Y: liyg@hku.hk-
dc.identifier.authorityLi, Y=rp00151en_US
dc.description.naturelink_to_subscribed_fulltexten_US
dc.identifier.doi10.1016/j.atmosenv.2011.04.010en_US
dc.identifier.scopuseid_2-s2.0-81155162506en_US
dc.identifier.hkuros209897-
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-81155162506&selection=ref&src=s&origin=recordpageen_US
dc.identifier.volume45en_US
dc.identifier.issue32en_US
dc.identifier.spage5946en_US
dc.identifier.epage5956en_US
dc.identifier.isiWOS:000295607300032-
dc.publisher.placeUnited Kingdomen_US
dc.identifier.scopusauthoridLi, Y=7502094052en_US
dc.identifier.scopusauthoridLuo, Z=35746716000en_US

Export via OAI-PMH Interface in XML Formats


OR


Export to Other Non-XML Formats