Study of atmospheric dispersion under low wind conditions in an urban environment, first results

Hanane Bounouas (1, 2) , Pierre Roupsard (1) , Eric Dupont (2) , Yelva Roustan (2) , Johann Chardeur (1) , Olivier Connan (1) , Didier Hebert (1) , Philippe Laguionie (1) , Denis Maro (1) , Hugo Renard (1) , Marianne Rozet (1) , Thaddé Regi (2) , Bertrand Carissimo (2, 3) , Aurélien Faucheux (2) , Yannick Lefranc (2)

1 IRSN/PSE-ENV/SRTE/LRC - Laboratoire de Radioécologie de Cherbourg-Octeville
2 CEREA - Centre d'Enseignement et de Recherche en Environnement Atmosphérique
3 EDF R&D - EDF R&D

All atmospheric conditions must be considered in the impact calculation of industrial facilities. In low wind conditions (wind speed below 2m.s-1), the meandering (low frequency horizontal wind oscillation) becomes one of the predominant physical processes which drive atmospheric dispersion of pollutants. Experimentally, it can be identified by analyzing the autocorrection function of the horizontal wind speed components. However, modeling these situations is more complicated, and most models are unable to correctly reproduce the turbulent flow structure and the resulting plume dispersion. The CFD models could overcome these limits by adapting the existing modeling approaches to low wind speed situations. In this study, we present the first analyses of datasets from an experimental campaign that has been performed at SIRTA in the south of Paris in 2020 as well as first simulation results obtained with a CFD model using two different modelling approaches: stationary and pseudo stationary conditions. The analysis of wind data acquired during one selected time period of the campaign allowed to identify the presence of meandering and to estimate its period. Compared to concentration measurements, the first modelling approach seems to lower lateral dispersion while the second approach seems to give closer results.

Mots clés: Low wind speed built-environment meandering atmospheric dispersion CFD; Low wind speed; built-environment; meandering; atmospheric dispersion; CFD

Domaines: Sciences de l'environnement

Hanane Bounouas, Pierre Roupsard, Eric Dupont, Yelva Roustan, Johann Chardeur, et al.. Study of atmospheric dispersion under low wind conditions in an urban environment, first results. 21st International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes, University of Aveiro, Sep 2022, Aveiro, Portugal. ⟨irsn-03994349⟩