Flow and dispersion around an isolated building

Experimental investigations have been carried out on flow and dispersion around an isolated building, paying particular attention to the fluctuating components of the dispersion. Results are presented of experiments conducted in neutral or slightly unstable weather conditions in flat terrain using a model building, which represents real structures at a scale of between 1/3 and 1/10. A particular feature of the building is that it is rotatable, enabling it to be positioned at any desired orientation relative to the mean wind direction. A tracer gas was released upwind of the building and concentrations measured using a detector system with a response time of approximately 1 s. Experiments were undertaken for the purpose of comparing the concentration distributions measured at various locations in the field with those measured in earlier experiments conducted in a wind tunnel. Comparisons were made of a range of statistical parameters of the concentration distribution about the building including mean, standard deviation, intermittency and concentration fluctuation intensity. Cumulative distribution functions of concentration were also constructed. It was found that, in general, concentration fluctuation intensities occurring in the field were larger than those measured in the wind tunnel, except in the near-wake region.