Particle trajectory simulation of dispersion around a building

Lagrangian stochastic (LS) models have shown to be a powerful technique to calculate pollutant dispersion in complex Bows. In this work, a three-dimensional LS model of dispersion has been tested by means of a comparison with EPA wind-tunnel observations of a buoyant plume in the vicinity of a building (Snyder, 1992, FMF Internal Report, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina). The model is based on the well-mixed criterion (Thomson, 1987, Journal of Fluid Mechanics 180, 529-556) and is able to evaluate dispersion in inhomogeneous, skew turbulence. The input flow field around the building has been carried out by handling EPA data (Snyder and Lawson, 1993, FMF Internal Report, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina). The concentration field predicted by the present model and Thomson's (1987) model have been compared with EPA observations in the same configuration. The dispersion of a tracer emitted from a line source, located at ground level upwind and downwind of the building, has also been investigated, showing the effects of the vortex structure on the mean concentration field. (C) 1997 Elsevier Science Ltd.