6.1
Wind fields and turbulence statistics in an urban street canyon
Ingegard Eliasson, Göteborg University, Göteborg, Sweden; and B. D. Offerle, C. S. B. Grimmond, and S. Lindqvist
In 2003 a field study of the wind, temperature, radiation and energy fields within an urban street canyon (H/W=2.1) was initiated in Göteborg Sweden. This study involves instrumentation deployed for more than a year. The long term measurements are used to explore within canyon wind fields and turbulence statistics based on above canopy flow characteristics for a range of stability and synoptic conditions. Such relationships can greatly enhance and simplify modelling of street level dispersion and energy exchange. The experimental setup and the mean and turbulent statistics with respect to above canyon flow using data collected under predominantly clear-sky conditions are described. Preliminary results from the ongoing project show that under most circumstances of clear sky conditions cross-canyon (within 60° of orthogonal) flow a single helical vortex exists. The single vortex is in apparent contrast to numerical experiments that suggest two vortices may develop for canyons of this aspect ratio. The deep penetration of the primary flow into the canyon at this site under clear sky conditions may be aided by roof shape and/or local topography. Mean and turbulence statistics within the canyon seem to be in agreement with previous studies. Turbulent kinetic energy (TKE), for example, increases with height at the canyon centre and nearer the downstream or windward wall while the TKE profile at the leeward wall is nearly vertical. The project is funded by the Wallenberg foundation (Knut och Alice Wallenbergs Stiftelse) and the Swedish Research Council for Environment, Agricultural Sciences (Formas).
Session 6, turbulent transport and dispersion processes (in urban areas and around buildings) (parallel with session 5)
Tuesday, 24 August 2004, 8:30 AM-11:45 AM
Next paper