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Contact line modeling under evaporation and partial wetting

30 mai 2013

Contact line modeling under evaporation and partial wetting

Vladislav Janecek, FAST
Mercredi 12 juin à 10h30
Amphithéâtre Nougaro

Résumé :
A liquid wedge-shaped layer confined between the heated substrate and the gas-liquid interface appears at small scales near the liquid-gas-solid contact line (CL) in all main evaporation geometries such as a bubble attached to a solid substrate (at nucleate boiling), a liquid meniscus in a capillary, or a sessile drop deposited on a substrate. The case in which the gas is a pure vapor corresponding to liquid is considered ; the evaporation dynamics is then controlled by the heat supply from the heater.

This liquid wedge-shaped region (microregion) is crucially important for two reasons. First, a significant part of the evaporative heat flux that is spent to compensate the latent heat occurs there. Second, a strong meniscus curvature that occurs in this region leads to the apparent contact angle larger than its actual microscopic value. Processes taking place within the microregion may thus impact the global dynamics of the macroscopic evaporation case. Microregion model describing the coupled thermal and hydrodynamic parts of the problem is presented. Multiscale nature of the phenomenon and simplified single vapor bubble growth numerical simulation using the previously established microregion model are discussed.

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