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Modeling of the Denebulization of Warm Fogs by Hygroscopic Seeding: Effect of Various Operating Conditions and of the Turbulence Intensity

Reuge, Nicolas and Fede, Pascal and Berthoumieu, Jean-François and Foucoin, Florian and Simonin, Olivier Modeling of the Denebulization of Warm Fogs by Hygroscopic Seeding: Effect of Various Operating Conditions and of the Turbulence Intensity. (2017) Journal of Applied Meteorology and Climatology, 56 (2). 249-261. ISSN 1558-8424

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Official URL: https://doi.org/10.1175/JAMC-D-16-0151.1

Abstract

This study addresses the modeling of the denebulization (i.e., the removal of droplets) of warm fogs (T ≥ 0°C) by hygroscopic salt microparticles from the initial seeding at the top of the fog layer to the fall of the rain droplets on the ground. Two main phenomena can occur: condensation of water vapor on salted droplets and the concomitant evaporation of fog droplets, and coalescence between the salted droplets and the fog droplets. Three salts have been investigated: NaCl, CaCl2, and KCl. Based on the conservation equations, the modeling approach (1D) considers the hygroscopicity of the salts through the water activity in the aqueous solution and the coalescence induced by gravity and turbulence. From this study, NaCl is the most efficient salt in the tested operating conditions. Actually, this result can be explained by the strong hygroscopicity of this salt in very dilute solutions. From the calculations, 15 kg of NaCl particles of 6.7-μm diameter can dissipate a typical fog layer of 40 m in height within less than 17 min over 0.25 km2. According to the calculations, a fog layer of 100 m in height can be denebulized within 45 min. The contribution of the coalescence induced by gravity and by turbulence seems to have a negligible effect on the final horizontal visibility, the condensation/evaporation phenomena being preponderant for these operating conditions.

Item Type:Article
HAL Id:hal-01917922
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Agralis Services (FRANCE)
Other partners > Etienne Lacroix Group (FRANCE)
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Deposited On:09 Nov 2018 16:58

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