Author(s)

M.F. Yassin, S. Kato, R. Ooka, T. Takahashi & R. Kouno

Abstract

Study on effects of fluctuations in the wind direction on pollutant diffusion in urban areas M.F. Yassin, S. Kato, R. Ooka, T. Takahashi & R. Kouno Institute of Industrial Science, University of Tokyo, Japan Abstract The effect of varying wind directions on pollutant diffision from a point source in an urban area have been studied in a wind tunnel experiment, using tracer gas techniques. Most experiments were conducted under neutral conditions of the atmospheric boundary layer. Some cases were investigated in stable and unstable conditions. Diffusion fields on a city model of Hamamatsucho in Tokyo, Japan were simulated in a turbulent boundary layer wind tunnel. The scale of the model was taken as 1:600. Ethylene, C2H,, was used as the tracer gas. A total of nineteen wind directions from west-northwest 292.5' to north- northwest 337.5' were investigated at eighty-three sampling point? located on the model during the diffusion experiments. Flow characteristics were studied by local changes in the

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