A MATHEMATICAL-MODEL FOR THE DISPERSION OF AIR-POLLUTANTS IN LOW WINDCONDITIONS

For the atmospheric dispersion of pollutants in low wind conditions, a steady-state mathematical model has been formulated which takes into account the diffusion in all the coordinate directions and the advecti on due to mean wind. The analytical solution has been obtained by assu ming constant eddy diffusivity coefficients in the advection-diffusion equation. The solution reduces to a familiar form which yields the st andard Gaussian plume solution when slender or thin plume approximatio n is invoked. The analytical solution obtained matches with the Gaussi an plume solution for ground-level concentration at the plume centreli ne. The model has been evaluated with data collected from the experime nts conducted at the sports ground of the Indian Institute of Technolo gy, Delhi (India). The results are reasonably good keeping in view the limitations of the data and the model. The model performs well as ind icated by the agreement between the observed concentrations and those calculated using 30 min and 3 min averaging.