Numerical Simulation of Pollutant Distribution in Urban Environment
The complex environmental situation in industrial regions requires the development of applied methods to assess the impact of industrial emissions on the environment. Purpose: Development of numerical simulation methods of pollutant distribution in urban environment. Methodology: Steady-state numerical simulation is performed in Ansys Fluent using the Species Transport model, which simulates mixing and transport of chemical substances by solving equations of concentration transport under the gradient diffusion hypothesis. The model is validated against classic 2D and 3D cases of substances mixing in a pipe. Research findings: Numerical simulation methods for the pollutant distribution in urban environment is developed and applied to nitrogen dioxide (NO 2 ) and sulphur dioxide (SO 2 ) emissions from chimneys of a cement plant in five wind directions. Practical capabilities of the developed methods are demonstrated, including clear visualization of the nature of the pollutant distribution from the point of emission, the concentration level of each substance in a selected area, and areas with exceeded maximum permissible concentrations. In this study, the distribution of substances resembles bands, which widen with increasing distance from emission sources. For the given mass fractions and emission volumes, maximum permissible concentrations for NO 2 and SO 2 exceed 7.9 and 8.9 times, respectively. Conclusions: The developed numerical simulation method of the pollutant distribution used in Ansys Fluent, are effective and informative for analysing the environmental situation in urban environment. However, for greater reliability, accurate, officially verified data on the qualitative and quantitative composition of emissions from industrial facilities is required, as well as the consideration of a greater number of factors influencing the concentration of harmful substances in the atmosphere.