Field experiments of dispersion through regular arrays of cubic structures

To investigate the effect of plan area density on the near-field dispersion of pollutant plumes in built-up areas, scaled field measurements have been made of the dispersion of a plume released upwind of regular arrays of cubes of varying plan area density.It was found that the lateral concentration profiles were Gaussian in all cases. Close to the source, the lateral dispersion parameter σy was increased, relative to that of a plume in open terrain and was highest for the most dense array. Despite the increased plume dimensions in the array, the reduction in advection velocity resulted in ground-level concentrations that were in general not too different from those of a plume in open terrain. This behaviour can be modelled by a Gaussian-plume-type expression for time-averaged concentration.