Integral transform solutions for atmospheric pollutant dispersion |
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Authors: | Gevaldo L de Almeida Luiz C G Pimentel Renato M Cotta |
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Institution: | 1. Instituto de Engenharia Nuclear, IEN, Comiss?o Nacional de Energia Nuclear, CNEN, Rio de Janeiro, RJ,, Brazil 2. LAMMA/Departamento de Meteorologia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil 3. Center for Analysis and Simulations in Environmental Engineering (CASEE), Universidade Federal do Rio de Janeiro, LTTC – PEM/COPPE/UFRJ, Caixa Postal 68503 Cidade Universitaria, Rio de Janeiro, RJ, CEP 21945-970, Brazil
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Abstract: | A transient two-dimensional advection–diffusion model describing the turbulent dispersion of pollutants in the atmosphere
has been solved via the Generalized Integral Transform Technique (GITT), by two different schemes. The first approach performs
numerical integration of the transformed system using available routines for initial value problems with automatic error control.
In spite of the time-consuming character of such a scheme, its flexibility allows the handling of problems involving time-dependent
meteorological parameters such as wind speed and eddy diffusivities. The second approach works fully analytically being thus
intrinsically more robust and economic, although not directly applicable in dealing with time-dependent parameters. For the
test problem used in this work, both methods agree very well with each other, as well as with a known analytical solution
for a simpler formulation used as benchmark. The impact of the longitudinal diffusivity on the stiffness of the ordinary differential
equation (ODE) system arising from the integral transformation has been assessed through the processing time demanded to solve
it when the numerical approach is used. The observed CPU times show that the analytical approach is clearly preferable unless
the problem involves time-dependent parameters. |
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Keywords: | integral transforms dispersion hybrid methods advection-diffusion atmospheric pollution |
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