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Conference Paper: Large-eddy simulation of turbulent transports in urban street canyons in different thermal stabilities

TitleLarge-eddy simulation of turbulent transports in urban street canyons in different thermal stabilities
Authors
Issue Date2010
Citation
The 5th International Symposium on Computational Wind Engineering (CWE2010), Chapel Hill, N.C., 23-27 May 2010. How to Cite?
AbstractThree scenarios of large-eddy simulation (LES) were performed to examine the characteristic flow and pollutant dispersion in urban street canyons under neutral, unstable and stable thermal stratifications. Street canyons of unity aspect ratio with ground-heating or –cooling are considered. In the LESs of the thermal stabilities tested, a large primary recirculation is developed in the center core and the turbulence production is dominated at the roof level of the street canyon. The current LES results demonstrate that unstable stratification enhances the mean wind, turbulence and pollutant removal of street canyons. On the other hand, in stable stratification, which has been less investigated in the past, the ground-level mean wind and turbulence are substantially suppressed by the large temperature inversion. Whereas, the weakened recirculating wind in the street canyon results in a larger velocity gradient that increases the turbulence production at the roof level. It also slows down the turbulence being carried from the roof down to the lower street canyon. Therefore, a higher level of turbulent kinetic energy (TKE) is retained at the mid-level of the windward side in the stably stratified street canyon.
Persistent Identifierhttp://hdl.handle.net/10722/126329

 

DC FieldValueLanguage
dc.contributor.authorCheng, WCen_HK
dc.contributor.authorLiu, CHen_HK
dc.contributor.authorLeung, DYCen_HK
dc.date.accessioned2010-10-31T12:22:25Z-
dc.date.available2010-10-31T12:22:25Z-
dc.date.issued2010en_HK
dc.identifier.citationThe 5th International Symposium on Computational Wind Engineering (CWE2010), Chapel Hill, N.C., 23-27 May 2010.en_HK
dc.identifier.urihttp://hdl.handle.net/10722/126329-
dc.description.abstractThree scenarios of large-eddy simulation (LES) were performed to examine the characteristic flow and pollutant dispersion in urban street canyons under neutral, unstable and stable thermal stratifications. Street canyons of unity aspect ratio with ground-heating or –cooling are considered. In the LESs of the thermal stabilities tested, a large primary recirculation is developed in the center core and the turbulence production is dominated at the roof level of the street canyon. The current LES results demonstrate that unstable stratification enhances the mean wind, turbulence and pollutant removal of street canyons. On the other hand, in stable stratification, which has been less investigated in the past, the ground-level mean wind and turbulence are substantially suppressed by the large temperature inversion. Whereas, the weakened recirculating wind in the street canyon results in a larger velocity gradient that increases the turbulence production at the roof level. It also slows down the turbulence being carried from the roof down to the lower street canyon. Therefore, a higher level of turbulent kinetic energy (TKE) is retained at the mid-level of the windward side in the stably stratified street canyon.-
dc.languageengen_HK
dc.relation.ispartofInternational Symposium on Computational Wind Engineering-
dc.rightsCreative Commons: Attribution 3.0 Hong Kong License-
dc.titleLarge-eddy simulation of turbulent transports in urban street canyons in different thermal stabilitiesen_HK
dc.typeConference_Paperen_HK
dc.identifier.emailCheng, WC: wccheng2007@yahoo.com.hken_HK
dc.identifier.emailLiu, CH: chliu@hkucc.hku.hk, liuchunho@graduate.hku.hken_HK
dc.identifier.emailLeung, DYC: ycleung@hku.hk-
dc.description.naturepostprint-
dc.identifier.hkuros179364en_HK
dc.description.otherThe 5th International Symposium on Computational Wind Engineering (CWE2010), Chapel Hill, N.C., 23-27 May 2010.-

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