On the Oscillation affecting filtered partial differential formulations handled with the generalized integral transform technique - GITT

• Autor(a) principal: Almeida, Gevaldo L.
• Data de Publicação: 2003
• Outros Autores: Pimentel, Luis Claudio G., Cotta, Renato M., Instituto de Engenharia Nuclear
• Tipo de documento: Relatório
• Idioma: eng
• Título da fonte: Repositório Institucional do IEN
• Texto Completo: http://carpedien.ien.gov.br:8080/handle/ien/2224
• topic: Atmospheric pollutant; Integral transforms; Gibbs Phenomenon; Partial differential equation filtering; Boundary condition homogeneization

Anomalous oscillations have been detected in the solution of filtered partial differential formulations using the Generalized Integral Transform Technique – GITT. These oscillations, affecting the vertical concentration profile at the emission height, even at relatively fast distances from the source, and the longitudinal one, at beginning of the downwind domain and its neighborhood, have been studied in order to determine their origin and to seek after a proper approach to overcome them. The study involved two filters, a constant and a steady-state diffusive one, both applied to the process, aiming at the homogenization of a boundary condition at x=0. As a result, a method has been developed to forecast the truncation orders which coincide with the knots of the oscillations, assuring thus a final solution free of them. Attempts to achieve convergence on the usual way, would lead to a waste of processing time and poorer results.