title: Effect of Marangoni Flows on the Shape of Thin Sessile Droplets Evaporating into Air.
abstract: Freely receding evaporating sessile droplets of perfectly wetting liquids, for which the observed finite contact angles are attributed to evaporation, are studied with a Mach-Zehnder interferometer. The experimentally obtained droplet shapes are found to depart, under some conditions, from the classical macroscopic static profile of a sessile droplet. The observed deviations (or the absence thereof) are explained in terms of a Marangoni flow due to evaporation-induced thermal gradients along the liquid-air interface. When such a Marangoni effect is strong, the experimental profiles exhibit a maximum of the slope at a certain distance from the contact line. In this case, the axisymmetric flow is directed from the contact line to the apex (along the liquid-air interface), hence delivering more liquid to the center of the droplet and making it appear inflated. These findings are quantitatively confirmed by predictions of a lubrication model accounting for the impact of the Marangoni effect on the droplet shape.
authors.affiliation: Université Libre de Bruxelles , TIPs (Transfers, Interfaces and Processes), CP 165/67, Av. F. D. Roosevelt 50, B-1050 Brussels, Belgium.
authors.forename: Yannis
authors.initials: Y
authors.lastname: Tsoumpas
authors.affiliation: Université Libre de Bruxelles , TIPs (Transfers, Interfaces and Processes), CP 165/67, Av. F. D. Roosevelt 50, B-1050 Brussels, Belgium.
authors.forename: Sam
authors.initials: S
authors.lastname: Dehaeck
authors.affiliation: Université Libre de Bruxelles , TIPs (Transfers, Interfaces and Processes), CP 165/67, Av. F. D. Roosevelt 50, B-1050 Brussels, Belgium.
authors.forename: Alexey
authors.initials: A
authors.lastname: Rednikov
authors.affiliation: Université Libre de Bruxelles , TIPs (Transfers, Interfaces and Processes), CP 165/67, Av. F. D. Roosevelt 50, B-1050 Brussels, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Colinet