Abstract
Part 1 of this study investigated the flow and diffusion around a cube in a wind tunnel. The flow around a cube was measured with a split-fiber probe designed for measuring flow velocity in those regions of highly turbulent and reversing flows. The rooftop and wake region concentrations of tracer gas released from two different sources (one at the center and one at the downwind corner of the rooftop) were measured.
In the wake region, the flow reattachment behind the building occurred at 1.6 times the building height from the model center. A high turbulent flow region was observed at roof level and behind the cube in the planes of its sides. The data of the standard deviation of u-component velocity showed that the high, turbulence region persisted throughout the downwind region. The high turbulent regions υ-and ω-components increased in area and heared the ground with respected to the down-wind distance.
In the case of the corner emission source on the rooftop, the peak concentration just behind the building occurred at rooftop level. As the source was on the corner of the roof and not in the center, the position of the peak concentration was to the one side of the building, but moved closer to the center as it moved farther downwind. In the case of the center emission, the degree of concentration near the building was less than that of the corner emission as a result of the initial difference in diffusion.
