A New Technique for Treatment of Surface Boundary Conditions Arising from Particulate Plume Dispersion

Abstract

The Gaussian plume dispersion model has gained wide acceptance for use as a predictor of average ambient air quality over a given airshed. An explicit assumption of this model is that the dispersing substance under investigation has neutral buoyancy with respect to the atmosphere. Since the modeler is often interested in the dispersion of particulate matter which has a nonzero sink rate, this assumption must be violated. Such a violation leads to mathematical difficulty when treating the surface boundary condition. In this paper, a new formulation has been developed which deals with surface deposition and reflection in a proper way. It is shown that several widely used gaseous models are subsets of this more general formulation, and that the new model reduces to these models for special cases of interest. A few numerical calculations are given to verify the development, and to compare results for existing models and the new technique.