Field and wind-tunnel study of pollutant dispersion in a built-up area under various meteorological conditions

Pollutant dispersion over a built-up area was investigated experimentally in the field and wind-tunnel experiments under different conditions of thermal stability for various wind directions using a tracer gas technique from a point source without buoyancy. Tracer gas concentration data were collected from 17 sites, including parking places, streets, open areas, and high-rise buildings, in a dense urban environment in the Hamamatsu-cho Minato-ku area, Tokyo, Japan. Concentration data were also examined in a boundary layer wind tunnel using a building-block model at a scale of 1:600. Eighty-three points were selected for measuring concentration in the wind-tunnel experiments. The concentration data measured in the wind-tunnel experiments was compared with the results of the field experiments in order to evaluate the prediction accuracy of the wind-tunnel experiments. The results of the wind-tunnel experiments showed good agreement with the results of the field experiments. The obtained results indicate that the wind direction is one of the important parameters in studying atmospheric diffusion. Moreover, these results are used to validate the corresponding computational fluid dynamics (CFD) prediction.