Dewetting of Low-Viscosity Films at Solid/Liquid Interfaces
2012
Péron, Nicolas | Brochard-Wyart, Françoise | Duval, Hervé
We report new experimental results on the dewetting of a mercury film (A) intercalated between a glass slab and an external nonmiscible liquid phase (B) under conditions of a large equilibrium contact angle. The viscosity of the external phase, ηB, was varied over 7 orders of magnitude. We observe a transition between two regimes of dewetting at a threshold viscosity of ηB* ≈ (ρAe|S̃|)¹/², where ρA is the mercury density, e is the film thickness, and |S̃| is the effective spreading coefficient. For ηB < ηB*, the regime is inertial. The velocity of dewetting is constant and ruled by Culick’s law, V ≈ (|S̃|/(ρAe))¹/². Capillary waves were observed at high dewetting velocities: they are a signature of hydraulic shock. For ηB > ηB*, the regime is viscous. The dewetting velocity is constant and scales as V ≈ |S̃|/ηB in the limit of large ηB. We interpret this regime by a balance between the surface energy released during dewetting and the viscous dissipation in the surrounding liquid.
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