Non-contact rheology of finite-size air-water interfaces

Vincent Bertin (1) , Zaicheng Zhang (1) , Rodolphe Boisgard (1) , Christine Grauby-Heywang (1) , Elie Raphael (2) , Thomas Salez (1) , Abdelhamid Maali (1)

1 LOMA - Laboratoire Ondes et Matière d'Aquitaine
2 Gulliver (UMR 7083)

We present non-contact atomic-force-microscopy measurements of the hydrodynamic interactions between a rigid sphere and an air bubble in water at the microscale. The size of the bubble is found to have a significant effect on the mechanical response due to the long-range capillary deformation of the air-water interface. We develop a viscocapillary lubrication model accounting for the finite-size effect that allows to rationalize the experimental data. This comparison allows us to measure the air-water surface tension, without contact and thus wetting, paving the way towards robust non-contact tensiometry of polluted air-water interfaces.

Domaines: Matière Molle [cond-mat.soft]; Dynamique des Fluides [physics.flu-dyn]; Mécanique des fluides [physics.class-ph]

Vincent Bertin, Zaicheng Zhang, Rodolphe Boisgard, Christine Grauby-Heywang, Elie Raphael, et al.. Non-contact rheology of finite-size air-water interfaces. 2020. ⟨hal-02952832v1⟩