Applications of physical modeling to the investigations of air pollution problems in urban areas

Abstract

Wind tunnel modeling of atmospheric flow and diffusion in the boundary layer over an urban area are discussed. Measurements were made over a model of an urban area composed of a network of uniform city blocks and streets. Two line sources emitting a radioactive tracer gas represented automobile emissions in a one-block length of a city street. Pollutant concentrations were calculated from samples of the tracer gas collected on building faces, in street canyons, and in the flow field above the model. Non dimensionalized concentration patterns were constructed from the analysis of the samples. Three wind directions were considered. The effects of a simple modification of the uniform model were evaluated.