Análise numérica do desenvolvimento de estruturas turbulentas em leitos de partículas e sua relação com eventos de emissão atmosférica
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Data
2025-05-06
Autores
Espírito Santo, Geisiely do
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Universidade Federal do Espírito Santo
Resumo
Industrial activities, although essential for human life, contribute significantly to air pollution. Among these activities, steelworks stand out, as they have large open areas where stockpiles of granular materials such as iron ore and coal are exposed to wind action. This scenario favors wind erosion, a natural phenomenon that promotes the emission of particulate matter, compromising air quality and posing risks to human health, including respiratory and cardiovascular diseases. To estimate this type of emission, the model developed by the United States Environmental Protection Agency (USEPA) is widely used. However, this model does not consider the proportion of non-erodible particles in the composition of granular materials, a factor that plays a fundamental role in flow turbulence and in the estimation of particle emissions. In view of this limitation, this study numerically investigated the development of turbulent structures in the presence of roughness elements, using Computational Fluid Dynamics and Large Eddy Simulations (LES). Three infinite beds containing different amounts of non-erodible particles, represented by cylindrical elements, were analyzed. The analysis focused on descriptive statistics, application of probability distributions, quadrant analysis, and observation of flow images and vorticity vectors. To ensure the reliability of the results, validation of the numerical simulations for the smooth bed was performed based on experimental references available in the literature. The results showed that the friction velocity (𝑢∗) behaved differently at each analyzed point and for each bed. In locations where the flow was obstructed by rough elements, 𝑢∗ values were reduced, which was confirmed by the analysis of vorticity vectors, indicating zones of low shear and recirculation. On the other hand, higher values of 𝑢∗ were found in the frontal regions of the roughness elements and in the flow channeling areas. The comparison among different coverage rates showed that beds with a greater amount of non-erodible particles presented lower friction velocities, reducing wind erosion. Regarding the Probability Density Function analyses, the distribution that best fitted the friction velocity fluctuations was the Gamma distribution, with an average shape parameter of 2.14 and an average scale parameter of 0.068. These results can serve as a reference for the parameterization of emission models, contributing to the development of more effective strategies for controlling and mitigating atmospheric pollution
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Dinâmica dos fluidos computacional , Erosão eólica , Simulações numéricas , Partículas não-erodíveis , Taxa de cobertura , Velocidade de fricção , Wind erosion , Numerical simulations , Non-erodible particles , Coverage rate , Friction velocity