Physical Modeling of Flow Field inside Urban Street Canyons

• Published in: Journal of applied meteorology and climatology Vol. 47; no. 7; pp. 2058 - 2067
• Main Authors: Li, Xian-Xiang, Leung, Dennis Y. C., Liu, Chun-Ho, Lam, K. M.
• Format: Journal Article
• Language: English
• Published: Boston, MA American Meteorological Society 01.07.2008
• Subjects: Air pollutants; Aspect ratio; Atmospheric boundary layer; Canyons; Channels; Computational fluid dynamics; Convection, turbulence, diffusion. Boundary layer structure and dynamics; Doppler sonar; Earth, ocean, space; Exact sciences and technology; Experiments; External geophysics; Flow characteristics; Flow distribution; Flow pattern; Flow velocity; Laboratories; Lasers; Mathematical models; Meteorology; Modelling; Numerical analysis; Numerical models; Outdoor air quality; Phase Doppler Anemometer; Pollutants; Pollution transport; Ratios; Reynolds number; Street canyons; Streets; Studies; Turbulence; Urban areas; Velocity; Velocity distribution; Water channels; Water flow; Water pollution; Wind tunnels; Velocity distribution; urban areas; Aspect ratio; Wake; Street canyon; Air flow; Flow regime; Physical simulation; Complex terrain; Atmospheric boundary layer; Doppler laser anemometer; Laser Doppler anemometry; flow field; Boundary layer turbulence
• DOI: 10.1175/2007JAMC1815.1
• ISSN: 1558-8424

The flow characteristics inside urban street canyons were studied in a laboratory water channel. The approaching flow direction was horizontal and perpendicular to the street axis. The street width was adjusted to form street canyons of aspect ratios 0.5, 1.0, and 2.0. The velocity field and turbulent intensity were measured with a laser Doppler anemometer at various locations within the street canyons, which were used to elucidate the flow pattern inside the street canyons. It was found that the previous numerical modeling results are in good agreement with the current experimental results at most locations. For the street canyon of aspect ratio 0.5, which belongs to the wake interference flow regime, the mean and fluctuating velocity components were more difficult to measure as compared with the other two cases because of its more complicated flow pattern. Some guidelines for numerical modeling were developed based on the measurement results. The data presented in this paper can also be used as a comprehensive database for the validation of numerical models.