Numerical simulation of toxic chemical dispersion after accident at railway

TLDR: In this article, the authors developed an applied numerical model to calculate the dynamics of atmospheric pollution in the emission of dangerous chemical substances in the event of transportation by railway, taking into account the effect of wind, atmospheric diffusion, the power of emission source, and the movement of the source of emission (depressurized tank) on the process of pollutant dispersion.

Abstract: Purpose. This research focuses on the development of an applied numerical model to calculate the dynamics of atmospheric pollution in the emission of dangerous chemical substances in the event of transportation by railway. Methodology. For the numerical simulation of transport process of the dangerous chemical substance in the atmosphere the equation of convection-diffusion pollutant transport is used. This equation takes into account the effect of wind, atmospheric diffusion, the power of emission source, as well as the movement of the source of emission (depressurized tank) on the process of pollutant dispersion. When carrying out computing experiment one also takes into account the profile of the speed of the wind flow. For the numerical integration of pollutant transport in the atmosphere implicit finite-difference splitting scheme is used. The numerical calculation is divided into four steps of splitting and at each step of splitting the unknown value of the concentration of hazardous substance is determined by the explicit running account scheme. On the basis of the numerical model it was created the code using the algorithmic language FORTRAN. One conducted the computational experiments to assess the level of air pollution near the railway station «Illarionovo» in the event of a possible accident during transportation of ammonia. Findings. The proposed model allows you to quickly calculate the air pollution after the emission of chemically hazardous substance, taking into account the motion of the emission source. The model makes it possible to determine the size of the land surface pollution zones and the amount of pollutants deposited on a specific area. Using the developed numerical model it was estimated the environmental damage near the railway station «Illarionovo». Originality. One can use the numerical model to calculate the size and intensity of the chemical contamination zones after accidents on transport. Practical value. The numerical model, developed by authors, can be used to estimate the size and intensity of the chemical contamination zones during emergency on transport. The developed numerical model solves the problem of assessing the impact of emergency emission of ammonia near the railway station «Illarionovo».