Influence in Building Width and Orientation on Plume Dispersion in the Wake of a Building

摘要

In a wind-tunnel study, the influence of building width and orientation into the wind was examined through concentration profiles in the near wake of the building. The model building was placed in a simulated atmospheric boundary layer. The effects of building width were examined for buildings having width-to-height ratios ranging from 2 to 22. The effects of oblique orientation were examined for angles ranging from -30 to +50 degrees. For most cases, the source was placed midway along the lee side of the building. The stack height was either at ground level of 1.5 times the height of the building. The lateral plume spread from a point source placed near the building was observed to be largest for a width/height ratio of 10. The influence of the end flow around the sides of the building had less effect for wider buildings. For the ground-level source, an oblique angle resulted in a maximum ground level concentration increase by a factor of 2-3 at three building heights downstream. Concentrations were increased by less than a factor of 1.5 at ten building heights downstream. For an elevated source, the building influence on ground-level concentrations was quite similar but with an even larger increase.