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Advances in Atmospheric Sciences

, Volume 29, Issue 6, pp 1227–1237 | Cite as

Numerical study on the impact of ground heating and ambient wind speed on flow fields in street canyons

  • Lei Li (李 磊)Email author
  • Lin Yang (杨 琳)
  • Li-Jie Zhang (张立杰)
  • Yin Jiang (江 崟)
Article

Abstract

The impact of ground heating on flow fields in street canyons under different ambient wind speed conditions was studied based on numerical methods. A series of numerical tests were performed, and three factors including height-to-width (H/W) ratio, ambient wind speed and ground heating intensity were taken into account. Three types of street canyon with H/W ratios of 0.5, 1.0 and 2.0, respectively, were used in the simulation and seven speed values ranging from 0.0 to 3.0 m s−1 were set for the ambient wind speed. The ground heating intensity, which was defined as the difference between the ground temperature and air temperature, ranged from 10 to 40 K with an increase of 10 K in the tests. The results showed that under calm conditions, ground heating could induce circulation with a wind speed of around 1.0 m s−1, which is enough to disperse pollutants in a street canyon. It was also found that an ambient wind speed threshold may exist for street canyons with a fixed H/W ratio. When ambient wind speed was lower than the threshold identified in this study, the impact of the thermal effect on the flow field was obvious, and there existed a multi-vortex flow pattern in the street canyon. When the ambient wind speed was higher than the threshold, the circulation pattern was basically determined by dynamic effects. The tests on the impact of heating intensity showed that a higher ground heating intensity could strengthen the vortical flow within the street canyon, which would help improve pollutant diffusion capability in street canyons.

Key words

street canyon thermal effect ambient wind ground heating intensity computational fluid dynamics (CFD) 

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Copyright information

© Chinese National Committee for International Association of Meteorology and Atmospheric Sciences, Institute of Atmospheric Physics, Science Press and Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Lei Li (李 磊)
    • 1
    Email author
  • Lin Yang (杨 琳)
    • 2
  • Li-Jie Zhang (张立杰)
    • 1
  • Yin Jiang (江 崟)
    • 1
  1. 1.Shenzhen National Climate ObservatoryMeteorological Bureau of Shenzhen MunicipalityShenzhenChina
  2. 2.Shenzhen Meteorological Service CenterMeteorological Bureau of Shenzhen MunicipalityShenzhenChina

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