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Hybrid Methods in Engineering

Modeling, Programming, Analysis, Animation

ISSN for PRINT: 1099-2391

Institutional price:	$396.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2002, Volume4

126 pages

Issue price - $250.00

DISPERSION PARAMETERIZATION APPLIED TO STRONG CONVECTION: LOW SOURCES CASE

Davidson M. Moreira
Departamento de Engenharia Mecânica, Universidade Federal do Rio Grande do Sul

J. C. Carvalho
Institute Nacional de Pesquisas Espaciais (INPE), Caixa Postal 515, 12201-970 São José dos Campos - SP, Brazil

Gervasio Annes Degrazia
Departamento de Fisica, Universidade Federal de Santa Maria, Santa Maria; Consiglio Nazionale delle Ricerche, lstituto di Cosmo-Geofisica, Torino, Italy; and Universidade de Sao Paulo, Institute Astrondmico e Geofisico, Sao Paulo, Brazil

Marco T. Vilhena
Instituto de Matematica Aplicada, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil

Marcelo Romero De Moraes
Centro de Informaçoes de Recursos Ambientais de Santa Catarina, Florianpólis, Brasil

ABSTRACT

Accounting for the current knowledge of the convective boundary layer (CBL) structure and characteristics, a simple semi-empirical formulation for the eddy diffusivity and dispersion parameter to be used in atmospheric dispersion models has been derived. That is, an expression for the dispersion parameter and eddy diffusivity depending on source distance for inhomogeneous turbulence in strongly unstable conditions is proposed. Yaglom's similarity theory is used to estimate these quantities. In addition, this vertical eddy diffusivity expression was introduced into an air pollution model, validated using data from the Prairie Grass experiments, and then compared with a Gaussian model. The results of this parameterization are shown to agree with the measurements of Prairie Grass and also with those of the Gaussian model. Furthermore, the present study suggests that the inclusion of the memory effect in Yaglom's similarity theory, which is important in near regions from a low continuous point source under strongly unstable conditions, improves the description of the turbulent transport process of atmospheric contaminants.