Numerical simulation of pollutant dispersion on built-up environmental under changes of atmospheric stability

The main objective of this study is to numerically investigate the dispersion of pollutants of stack emissions on the building roof with various atmospheric stabilities, (stable, neutral and unstable). The three-dimensional flow and dispersal of gaseous pollutants were modelled using a computational fluid dynamics model. Computational simulations were conducted using an isolated cubical building model. The diffusion flow fields in the building-up environment were examined with three atmospheric stabilities: (1) stable condition, (2) neutral condition, and (3) stable condition. Atmospheric dispersion was examined at different distances downwind of the leeward side of the cubical building. The numerical data was validated against wind-tunnel data to optimize the turbulence model. The numerical results agreed reasonably with the wind tunnel results. The results indicate that there is an increase in concentrations with stable conditions, and a decrease in concentrations with unstable conditions in the wake region.