hig.sePublications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
City breathability in medium density urban-like geometries evaluated through the pollutant transport rate and the net escape velocity
Department of Atmospheric Sciences, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, China.
Department of Atmospheric Sciences, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, China .
Department of Atmospheric Sciences, School of Environmental Science and Engineering, Sun Yat-Sen University, Guangzhou, China .
University of Gävle, Faculty of Engineering and Sustainable Development, Department of Building, Energy and Environmental Engineering.
Show others and affiliations
2015 (English)In: Building and Environment, ISSN 0360-1323, E-ISSN 1873-684X, Vol. 94, no P1, 166-182 p., 4213Article in journal (Refereed) Published
Abstract [en]

This paper investigates pollutant removal at pedestrian level in urban canopy layer (UCL) models of medium packing density (λ<inf>p</inf> = λ<inf>f</inf> = 0.25) using computational fluid dynamics (CFD) simulations. Urban size, building height variations, wind direction and uniform wall heating are investigated. The standard and RNG k-ε turbulence models, validated against wind tunnel data, are used. The contribution of mean flows and turbulent diffusion in removing pollutants at pedestrian level is quantified by three indicators: the net escape velocity (NEV), the pollutant transport rate (PTR) across UCL boundaries and their contribution ratios (CR).Results show that under parallel approaching wind, after a wind-adjustment region, a fully-developed region develops. Longer urban models attain smaller NEV due to pollutant accumulation. Specifically, for street-scale models (~100 m), most pollutants are removed out across leeward street openings and the dilution by horizontal mean flows contributes mostly to NEV. For neighbourhood-scale models (~1 km), both horizontal mean flows and turbulent diffusion contribute more to NEV than vertical mean flows which instead produce significant pollutant re-entry across street roofs. In contrast to uniform height, building height variations increase the contribution of vertical mean flows, but only slightly influence NEV. Finally, flow conditions with parallel wind and uniform wall heating attain larger NEV than oblique wind and isothermal condition.The paper proves that by analysing the values of the three indicators it is possible to form maps of urban breathability according to prevailing wind conditions and known urban morphology that can be of easy use for planning purposes. 

Place, publisher, year, edition, pages
2015. Vol. 94, no P1, 166-182 p., 4213
Keyword [en]
Computational fluid dynamics, Contribution ratio, Net escape velocity, Pollutant transport rate, Urban canopy layer, Atmospheric turbulence, Diffusion, Diffusion in liquids, Fluid dynamics, Pollution, Transport properties, Turbulence models, Walls (structural partitions), Wind tunnels, Building height variations, Computational fluid dynamics simulations, Contribution ratios, Escape velocities, Pollutant transport, Street scale models, Turbulent diffusion, Urban canopy layers, Urban transportation, canopy, turbulence, urban area, urban morphology
National Category
Fluid Mechanics and Acoustics Civil Engineering
Identifiers
URN: urn:nbn:se:hig:diva-20221DOI: 10.1016/j.buildenv.2015.08.002ISI: 000367759300015ScopusID: 2-s2.0-84983727401OAI: oai:DiVA.org:hig-20221DiVA: diva2:852388
Note

Forskningsfinansiärer/Funding Agency:

National Natural Science Foundation of China  Grant no: 51108102, 51478486 

Key Laboratory of Eco Planning & Green Building, Ministry of Education (Tsinghua University), China  Grant no: 2013U-5 

Available from: 2015-09-09 Created: 2015-09-09 Last updated: 2016-12-07Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Sandberg, Mats
By organisation
Department of Building, Energy and Environmental Engineering
In the same journal
Building and Environment
Fluid Mechanics and AcousticsCivil Engineering

Search outside of DiVA

GoogleGoogle Scholar

Altmetric score

Total: 407 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf