par Colinet, Pierre ;Rednikov, Alexei
Editeur scientifique Brutin, David
Référence Droplet Wetting and Evaporation, From Pure to Complex Fluids, Academic Press - Elsevier, Ed. 1
Publication Publié, 2015
Partie d'ouvrage collectif
Résumé : This chapter focuses on the small-scale structure of a contact line formed by a pure liquid, a gas (in particular, the vapor of the liquid considered), and a smooth and chemically homogeneous solid substrate. On the basis of the lubrication approximation (small slopes of the liquid/gas interface), various situations are considered, including volatile or nonvolatile liquid, partial or complete wetting, and advancing or receding contact lines. Two types of microfilms ahead of the contact line are considered: extended (i.e., covering the substrate everywhere) and truncated (i.e., formally ending at some “dry” spot). On the macroscopic side, results useful for the study of many configurations, such as droplet evaporation and boiling, are provided in terms of the Cox Voinov relationship, relating the scale-dependent apparent contact angle to the velocity of the contact line. Parameters entering this relationship—namely, the apparent contact angle of the steady microstructure and the microlength below which singularities of the contact line are regularized—are calculated in various cases. Particular attention is devoted to discussing the pertinence of disjoining pressure and the Kelvin effect (curvature dependence of saturation conditions) at small scales in relation with the resolution of contact line singularities. The selection between microstructures with extended and truncated films is also discussed.