Enhanced interfacial deformation in a Marangoni flow: A measure of the dynamical surface tension
Résumé
We investigate the flows and deformations resulting from the deposition of awater solublesurfactant at a bare oil-water interface. Once the surfactant is deposited, we show thatthe oil-water interface is deformed with a water bump rising upward into the oil. For agiven oil, the maximal deformation—located at the surfactant deposition point—decreaseswith the oil-layer thickness. We also observe a critical oil-layer thickness below whichthe deformation becomes as large as the oil layer, leading to the rupture of this layer andan oil-water dewetting. Experimentally, it is found that this critical thickness depends onthe oil density and viscosity. We then provide an analytical modelization that explainsquantitatively all these experimental features. In particular, our analysis allows us to derivean analytical relationship between the vertical profile of the oil-water interface and thein-plane surface tension profile. Therefore, we propose that the monitoring of the interfacevertical shape can be used as a new spatially resolved tensiometry technique.
Domaines
Matière Molle [cond-mat.soft]Origine | Fichiers produits par l'(les) auteur(s) |
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