Host: Science Council of Japan
Co-host: Architectural Institute of Japan, Japan Association for Wind Engineering, The Institute of Electrical Engineering of Japan, Japan Society of Steel Construction, Japan Society of Civil Engineering, Meteorological Society of Japan
Pages 12
Flow and pollutant diffusion in an urban environment have been studied in a wind tunnel under three atmospheric conditions: stable, neutral and unstable by using Laser Doppler Velocimetry (LDV), thermocouples and a hydrocarbon analyzer detector (FID). The flow and diffusion fields in the boundary layer in an urban environment were investigated in three flow obstacle cases: i) without flow obstacles, ii) after 2-D fence, and iii) after 3-D cubic building model. Ethylene, C2H4, is used as tracer gas. Gaseous pollutant is discharged in the simulated boundary layer over the flat area. The effluent velocity of the pollutant is set to be negligible. The results obtained are as the following: a) the inner boundary layer produced by flow obstacles is very thick around the wake region due to the turbulence mixing, b) All turbulent velocities is reduced by the stable stratification, c) the maximums concentration appears around the wake region of the obstacles. The concentration spreads measured in the experiment may be used for the evaluation of numerical models and expert estimating of air quality in the urban environment
