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Boundary-Layer Meteorology

, Volume 138, Issue 2, pp 195–213 | Cite as

Large-Eddy Simulation for the Mechanism of Pollutant Removal from a Two-Dimensional Street Canyon

  • Takenobu Michioka
  • Ayumu Sato
  • Hiroshi Takimoto
  • Manabu Kanda
Article

Abstract

Large-eddy simulation (LES) is conducted to investigate the mechanism of pollutant removal from a two-dimensional street canyon with a building-height to street-width (aspect) ratio of 1. A pollutant is released as a ground-level line source at the centre of the canyon floor. The mean velocities, turbulent fluctuations, and mean pollutant concentration estimated by LES are in good agreement with those obtained by wind-tunnel experiments. Pollutant removal from the canyon is mainly determined by turbulent motions, except in the adjacent area to the windward wall. The turbulent motions are composed of small vortices and small-scale coherent structures of low-momentum fluid generated close to the plane of the roof. Although both small vortices and small-scale coherent structures affect pollutant removal, the pollutant is largely emitted from the canyon by ejection of low-momentum fluid when the small-scale coherent structures appear just above the canyon where the pollutant is retained. Large-scale coherent structures also develop above the canyon, but they do not always affect pollutant removal.

Keywords

Gas exchange Large-eddy simulation Urban canyon Wind-tunnel experiment 

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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  • Takenobu Michioka
    • 1
  • Ayumu Sato
    • 1
  • Hiroshi Takimoto
    • 2
  • Manabu Kanda
    • 2
  1. 1.Environmental Science Research LaboratoryCentral Research Institute of Electric Power IndustryChiba-kenJapan
  2. 2.Department of International Development EngineeringTokyo Institute of TechnologyTokyoJapan

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