Title: Influence of turbulence closure on the simulation of flow and dispersion in complex terrain

Authors: Stefano Alessandrini, Enrico Ferrero, Silvia Trini Castelli, Domenico Anfossi

Addresses: CESI S.p.a. via Rubattino 54, 20100 Milano, Italy. ' Dipartimento di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale, 'A. Avogadro' Via Bellini, 25/G, 15100 Alessandria, Italy. ' ISAC-CNR, C. Fiume, 4, 10133 Torino, Italy. ' ISAC-CNR, C. Fiume, 4, 10133 Torino, Italy

Abstract: A dispersion simulation test for the RAMS-MIRS-SPRAY (RMS) modelling system in real complex terrain is presented. As a test case, the TRACT campaign was chosen because this data set allows the comparison of both the meteorological variables and the tracer concentrations. Particular attention was focused on testing alternative turbulence closures and assessing their influence on modelling both the meteorology and the dispersion. Firstly, the different turbulence closures introduced in the meteorological model are compared. Secondly, the dispersion simulations are performed using the turbulence provided by the different models. It is demonstrated that using different closure models for turbulence modifies also the mean flow. Concerning the tracer dispersion, the new closures utilising a fully 3D equation for the turbulent kinetic energy seem to give promising results.

Keywords: turbulence closures; atmospheric dispersion modelling; meteorological variables; tracer concentrations; air pollution modelling; experimental campaign; simulation; meteorological model; mean flow; kinetic energy; pollutant concentration; air quality.

DOI: 10.1504/IJEP.2005.007391

International Journal of Environment and Pollution, 2005 Vol.24 No.1/2/3/4, pp.154 - 170

Published online: 15 Jul 2005 *

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