Davidson M. Moreira

Comparison between analytical models to simulate pollutant dispersion in the atmosphere

We present a numerical and statistical comparison between ADMM and GILTT approaches to simulate pollutant dispersion in the Planetary Boundary Layer (PBL). The numerical and statistical comparison of the ADMM and GILTT results confirms the equivalence of these methods. However, the ADMM approach is more efficient under computational point of view regarding the issue of computational time and, therefore, is more appropriate to be used as an operational air pollution model.

Meteorologia e poluição atmosférica

Neste trabalho apresentam-se os principais aspectos relacionados a meteorologia ligada ao processo de dispersao turbulenta de poluentes atmosfericos. Ressalta-se que a meteorologia desempenha um papel fundamental para o controle da qualidade do ar, pois os eventos meteorologicos guiam a dispersao de poluentes e sua deposicao no solo. Discutem-se os recentes melhoramentos da descricao e previsao dos fenomenos que envolvem a poluicao atmosferica considerando a melhoria da qualidade de vida da populacao.

Tritium dispersion simulation in the atmosphere from ANGRA I Nuclear Power Plant

In this work, we check the ability of an air pollution model to simulate the concentration of radioactive material emitted from the Nuclear Power Plant of Angra dos Reis, Brazil. To achieve this goal, we solve the time-dependent two-dimensional equation by the Generalised Integral Laplace Transform Technique (GILTT) method. The wind field was reconstructed by the MM5 mesoscale model and the analysis of the results shows a good agreement between the values computed by the model against the experimental ones.

Tritium dispersion simulation in the atmosphere by the integral transform technique using micrometeorological parameters generated by large eddy simulation

In this work, we report a numerical and statistical comparison between Advection-Diffusion Multilayer Method (ADMM) and Generalised Integral Laplace Transform Technique (GILTT) approaches to simulate a radioactive pollutant dispersion in the Atmospheric Boundary Layer (ABL) using micrometeorological parameters generated by Large Eddy Simulation (LES). To better describe the wind profile of the irregular ground level terrain, we considered the wind profile as a solution of the MesoNH model. We performed numerical simulations and comparisons against the data of Angra dos Reis-Brazil field experiments.

An Analytical Air Pollution Model: Eddy Diffusivities Depending on the Source Distance

This paper describes the development and testing of an analytical model that simulates the dispersion of contaminants into a convective boundary layer. The model is based on the advection-diffusion equation which is solved by the Laplace transform technique. This model assumes vertical eddy diffusivities varying with the distance from the source and related with the turbulence properties (inhomogeneous turbulence). The inclusion of eddy diffusivities as function of downwind distance has been often cited as something to be included in analytical dispersion models in order to take into consideration the different physics aspects of near-source and far-source dispersion. To investigate the turbulence memory effect for low and tall stacks a numerical comparison, using the well-known Copenhagen and Prairie Grass datasets, is also performed with results derived from a simulation using a vertical eddy diffusivity valid for large diffusion time and that is only dependent on the turbulence properties. It is also important to emphasize that the concentrations simulated by the eddy diffusivities depending on the source distance are better than the ones simulated by the asymptotic eddy diffusivity valid only for the far field of a continuos point source.

On the new parameterisation of the eddy diffusivity for radioactive pollutant dispersion

In the present work, starting from the evolution equation for the turbulent energy density spectrum, we develop a new model for the growth of the turbulence in convective boundary layer. We apply dimensional analysis to parameterise the unknown inertial transport and convective source term in the dynamic equation for the three-dimensional spectrum. The non-linear integrodifferential equation is solved by Adomian decomposition method. Using the micrometeorological parameters generated by large eddy simulation, for the first time, we employ the vertical component of the energy spectrum to calculate the eddy diffusivity (required in dispersion models). This new eddy diffusivity is used in the GILTT approach to simulate ground-level concentrations considering experimental data of Angra I Nuclear Power Plant.