A STUDY OF THE DISPERSION OF AIR POLLUTANTS WITH THE K-E TURBULENCE MODEL

Abstract

In order to establish a practical air pollution dispersion model to predict pollutant transport and diffusion in a turbulent wind field, H2S plumes from a continuous point source discharging at different heights into a fully-developed wind field in a wind tunnel was studied experimentally and numerically. In the numerical study, the governing equations involved the three dimensional Navier-Stokes equations, the concentration diffusion equation and the k-? turbulence model and these were discretized into finite difference form with a power law scheme over a non-uniform staggered grid system. The computational procedure followed the SIMPLE algorithm. In the experimental study, the wind velocity profiles were measured and the distributions of the H2S concentration at selected cross sections were monitored. The results indicate that discharging pollutants at a higher elevation is conductive to lessening the air pollution at ground level near the source. The H2S concentration profiles showed good agreement between the measurements and the predicted values. Comparisons between the standard deviations of the lateral profiles and those of the vertical profiles suggested that the transverse diffusivities are much larger than the vertical diffusivities. The study demonstrated that the k-? numerical model may be used successfully to monitor the dispersion plume of a gas release in a boundary layer flow.