Gas dispersion near a cubical model building. Part II. Concentration fluctuation measurements

A wind-tunnel study has been performed of concentration fluctuations in the near-wake region (1.0 ? x/H ? 5.0) of a cubical model building in a simulated, neutrally stratified shear layer. Contaminants were released at a central roof vent for buildings with 0° and 45° orientations, and at a downwind roof vent for a building with 0° orientation.The log-normal concentration probability model was found appropriate for measurements in the building wake, and concentration fluctuation intensity was found to be reduced by the presence of the model building in an obstructed flow. A simple algorithm, based on the relation of the peak-to-mean concentration ratio to the local intensity, suggests an upper limit to the peak-to-mean concentration ratio near the ground centerline.