Boundary-Layer Meteorology

, Volume 137, Issue 2, pp 187–204 | Cite as

Large-Eddy Simulation of Flow and Pollutant Transport in Urban Street Canyons with Ground Heating

  • Xian-Xiang LiEmail author
  • Rex E. Britter
  • Tieh Yong Koh
  • Leslie K. Norford
  • Chun-Ho Liu
  • Dara Entekhabi
  • Dennis Y. C. Leung
Open Access


Our study employed large-eddy simulation (LES) based on a one-equation subgrid-scale model to investigate the flow field and pollutant dispersion characteristics inside urban street canyons. Unstable thermal stratification was produced by heating the ground of the street canyon. Using the Boussinesq approximation, thermal buoyancy forces were taken into account in both the Navier–Stokes equations and the transport equation for subgrid-scale turbulent kinetic energy (TKE). The LESs were validated against experimental data obtained in wind-tunnel studies before the model was applied to study the detailed turbulence, temperature, and pollutant dispersion characteristics in the street canyon of aspect ratio 1. The effects of different Richardson numbers (Ri) were investigated. The ground heating significantly enhanced mean flow, turbulence, and pollutant flux inside the street canyon, but weakened the shear at the roof level. The mean flow was observed to be no longer isolated from the free stream and fresh air could be entrained into the street canyon at the roof-level leeward corner. Weighed against higher temperature, the ground heating facilitated pollutant removal from the street canyon.


Ground heating Large-eddy simulation Pollutant dispersion Unstable stratification Urban street canyon 



This project was funded by Singapore National Research Foundation (NRF) through the Singapore-MIT Alliance for Research and Technology (SMART) Center for Environmental Sensing and Modeling (CENSAM).

Open Access

This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.


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Copyright information

© The Author(s) 2010

Open AccessThis is an open access article distributed under the terms of the Creative Commons Attribution Noncommercial License (, which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.

Authors and Affiliations

  • Xian-Xiang Li
    • 1
    Email author
  • Rex E. Britter
    • 2
  • Tieh Yong Koh
    • 3
  • Leslie K. Norford
    • 4
  • Chun-Ho Liu
    • 5
  • Dara Entekhabi
    • 6
  • Dennis Y. C. Leung
    • 5
  1. 1.CENSAMSingapore-MIT Alliance for Research and TechnologySingaporeSingapore
  2. 2.Department of Urban Studies and PlanningMassachusetts Institute of TechnologyCambridgeUSA
  3. 3.School of Physical and Mathematical SciencesNanyang Technological UniversitySingaporeSingapore
  4. 4.Department of ArchitectureMassachusetts Institute of TechnologyCambridgeUSA
  5. 5.Department of Mechanical EngineeringThe University of Hong KongHong KongChina
  6. 6.Department of Civil and Environmental EngineeringMassachusetts Institute of TechnologyCambridgeUSA

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