Simulação tridimensional da dispersão de poluentes considerando o fechamento não local da turbulência

Abstract

The gradient transport hypothesis is one of the most used ways to solve the advectiondiffusion equation closure problem, which assumes that the concentration turbulent flow is proportional to the mean concentration gradient magnitude. However, the gradient transport hypothesis is not valid in the top of the convective boundary layer, because in this region there is the presence of a countergradient flow. Considering the non-local turbulence closure, can be taken into account the asymmetry in the pollutants dispersion process in the atmosphere. Thus, a generic equation for turbulent diffusion can be used, considering that the flux plus its derivative are proportional to the average gradient, causing an additional term to appear in the equation that is associated with the countergradient term. The aim of this work is to evaluate the pollutants dispersion in the atmosphere, considering the transient threedimensional advection-diffusion equation, the longitudinal diffusion and non-local turbulence closure term. The proposed problem solution is found using integral transform techniques. To obtain the results and evaluate the model, data from IIT-Delhi and Copenhagen diffusion experiments were used. The model satisfactorily simulated the pollutants concentration when compared to experimental data and literature results.