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Numerical investiga...
Numerical investigations of Re-independence and influence of wall heating on flow characteristics and ventilation in full-scale 2D street canyons
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- Yang, H. (author)
- Sun Yat-sen University, China
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- Lam, C. K. C. (author)
- Sun Yat-sen University, Guangzhou, China; Ministry of Education, Zhuhai, China
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- Lin, Yuanyuan (author)
- Högskolan i Gävle,Energisystem och byggnadsteknik,Sun Yat-sen University, China
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- Chen, L. (author)
- Sun Yat-sen University, China; The Hong Kong Polytechnic University, Hong Kong
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- Mattsson, Magnus, 1964- (author)
- Högskolan i Gävle,Energisystem och byggnadsteknik
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- Sandberg, Mats, 1945- (author)
- Högskolan i Gävle,Energisystem och byggnadsteknik
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- Hayati, Abolfazl (author)
- Högskolan i Gävle,Energisystem och byggnadsteknik
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Claesson, Leif (author)
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- Hang, J. (author)
- Sun Yat-sen University, Guangzhou, China; Ministry of Education, Zhuhai, China
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(creator_code:org_t)
- IEEE, 2021
- 2021
- English.
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In: Building and Environment. - : IEEE. - 0360-1323 .- 1873-684X. ; 189
- Related links:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Subject headings
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- Validated by wind tunnel data, this study numerically investigates the integrated impacts of wind and thermal buoyancy on urban turbulence, ventilation and pollutant dispersion in full-scale 2D deep street canyons (aspect ratio AR = H/W = 3 and 5, W = 24 m). Isothermal urban airflows for such deep street canyons can be Reynolds-number-independent when reference Reynolds number (Re) exceeds the critical Re (Rec~106,107 when AR = 3, 5), i.e. AR = 5 experiences two main vortices and one-order smaller NEV* (~10−3, the normalized net escape velocity) than AR = 3 with a single main vortex (NEV*~10−2). With sufficiently large Re (Re > Rec) and the same air-wall temperature difference (Ri = 2.62, 4.36 when AR = 3, 5), four uniform wall heating patterns were considered, including leeward-wall heating (L-H), windward-wall heating (W–H), ground heating (G-H), and all-wall heating (A-H). Various indicators were adopted to evaluate street ventilation and pollutant dilution capacity (e.g. age of air (τ,s), NEV*, pollutant transport rates (PTR)). Full-scale wall heating produces a strong upward near-wall buoyancy force, which significantly influences flow patterns and improves street ventilation for most cases. When AR = 3, L-H strengthens the single-vortex airflow. When AR = 5, L-H converts the isothermal double vortices into a single-clockwise vortex. For both ARs, W–H reverses the main clockwise vortex to an enhanced counterclockwise one, moreover G-H and A-H cause a more complicated multi-vortex pattern than isothermal cases. Overall, when AR = 3, L-H and W–H increase NEV* by 68% and 40% than the isothermal case. When AR = 5, four wall heating patterns all raise NEV* considerably (by 150%–556%). For both ARs, the L-H, W–H and A-H amplify the contribution of mean flows on removing pollutants but reduce that by turbulent diffusion compared with isothermal cases.
Subject headings
- TEKNIK OCH TEKNOLOGIER -- Maskinteknik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Mechanical Engineering (hsv//eng)
- TEKNIK OCH TEKNOLOGIER -- Samhällsbyggnadsteknik (hsv//swe)
- ENGINEERING AND TECHNOLOGY -- Civil Engineering (hsv//eng)
- NATURVETENSKAP -- Fysik (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences (hsv//eng)
Keyword
- 2D deep street canyon
- Buoyancy effect
- Computational fluid dynamics (CFD)
- Net escape velocity
- Reynolds number-independence
- Street ventilation
- Hållbar stadsutveckling
- Sustainable Urban Development
Publication and Content Type
- ref (subject category)
- art (subject category)
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- By the author/editor
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Yang, H.
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Lam, C. K. C.
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Lin, Yuanyuan
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Chen, L.
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Mattsson, Magnus ...
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Sandberg, Mats, ...
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show more...
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Hayati, Abolfazl
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Claesson, Leif
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Hang, J.
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show less...
- About the subject
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- ENGINEERING AND TECHNOLOGY
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ENGINEERING AND ...
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and Mechanical Engin ...
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- ENGINEERING AND TECHNOLOGY
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ENGINEERING AND ...
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and Civil Engineerin ...
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- NATURAL SCIENCES
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NATURAL SCIENCES
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and Physical Science ...
- Articles in the publication
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Building and Env ...
- By the university
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University of Gävle