Flow visualization and tracer dispersion experiments at street canyon intersections

This paper summarizes results from a series of wind-tunnel experiments on the flow and dispersion behaviour at an idealized intersection of four long street canyons, formed by a group of four rectangular buildings. Flow visualization was used to explore the range of possible flow and dispersion patterns associated with various plan arrangements of the four buildings, and tracer dispersion experiments were then conducted for selected cases to measure dispersion quantitatively. It was found that flow and dispersion patterns can be very sensitive to small changes in the arrangement of the buildings and the incident wind direction, theta. They are also strongly influenced by differences in the heights of individual buildings and the presence of other nearby intersections. The complete set of experimental data is available on request.