Coal dust leakage from coal stacks leads to intensive contamination of the working areas. Therefore, determining level of air pollution near the coal piles for various meteorological situations, when new coal piles are arranged, is an important applied problem. For practice, it is necessary to have quick-calculating mathematical models whiсh take into account the most significant physical processes impacting on formation of contamination zones near the coal piles. Today, to predict the level of air pollution at dust leaking from the coal stacks, the normative technique OND-86 or the Gauss model is used. These forecasting methods make it possible to quickly calculate the contamination zones, but they do not take into account geometric shape of the coal stack and unevenness of the velocity field near it. The subject of this research was creation of a mathematical model for predicting the level of air pollution near coal piles with taking into account the aerodynamics of air flows around them. The purpose of the work was to develop a set of numerical models for quick calculation of the level of air pollution at coal dust leaking from the coal piles with taking into account the uneven emission of dust from different areas of the stack surface. The modelling equations are the three-dimensional mass transfer equation (Marchuk's model) and the three-dimensional equation for the velocity potential. The Marchuk's model allows taking into account rate of the coal dust particles settling, parameters of turbulent diffusion and uneven air flow rate near the coal pile. The Dirac delta function is used for modelling coal dust leaking from various sections of the coal pile. For the numerical solution of the mass transfer equation, a difference splitting scheme is used. On the basis of the three-dimensional equation for the velocity potential, an uneven velocity field near the coal pile is determined. The Richardson method is used for numerical solution of the three-dimensional equation for the velocity potential. An algorithm for solving the problem of calculating a level of contamination of working areas near a coal pile is considered. The description of the structure of the created complex of computer programs is given.
Breakaway properties of film formed on copper and copper alloys in erosion–corrosion by mass transfer equation
