An Advection-Diffusion Model for Pollutant Dispersion Near Roadways

Abstract

An advection-diffusion model is constructed, using an eddy-diffusivity tensor derived from the turbulence data obtained during the General Motors Sulfate Dispersion Experiment. The derivation was based on dynamic considerations, with the aid of a second-order closure model. The influence of traffic was approximated by an additive component in the eddy-diffusivity tensor. An ?upwinding? finite element scheme was used for the numerical integration. The concentration predictions agree reasonably well with observations. This is also true when the off-diagonal elements of the diffusivity tensor are neglected. Finally, it is argued that the traffic component of the diffusivity may scale with the resultant of the wind and negative vehicle velocity. A simplified version of the eddy diffusivity is also suggested.