The study of the influence of protective screen on reducing the level of air pollution

Abstract

The task of assessing the areas of chemical pollution near the highway, where the protective screen is located, is considered. The protective screen locally changes the aerodynamics of the air flow near the highway, which contributes to the minimization of air pollution in the working zones near the highway. Recently, interest has increased in studying the effectiveness of the use of protective screens of complex shape, which are located near highways. The purpose of the work is to develop a numerical model for calculating pollution zones formed near the protective screen, as well as conducting a laboratory experiment to analyze the patterns of formation of pollution zones near the T-shaped screen. For mathematical modeling of the process of formation of pollution zones near the protective screen, the equation of convective-diffusion transfer of impurities is used. This equation takes into account atmospheric diffusion, wind speed, emission intensity of a chemically hazardous substance, the location of the emission source, and the shape of the protective screen. Two models of aerodynamics are used to calculate the air flow velocity field when flowing around a protective screen. The first model is the Navier-Stokes equations. These equations are written in the variables "eddy current function". The second model is a two-dimensional equation for the velocity potential. For the numerical integration of the vortex transport equation, the splitting method is used, followed by the explicit finite-difference method. For the numerical integration of the Poisson equation for the stream function, the Liebman method is used. To numerically integrate the equation for the velocity potential and the equation for the convective-diffusion transfer of impurities, a locally one-dimensional difference scheme is used. The calculation of unknown parameters is implemented by an explicit formula. A package of application programs was created on the basis of the developed numerical model. The constructed numerical model and software package allow to study the process of the formation of pollution areas near the highway almost in real time. The results of the computational experiment are presented. The results of a laboratory experiment on the study of the structure of the contamination zone near the protective screen are presented.