Dresden 2014 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 37: Poster Session 2
CPP 37.23: Poster
Wednesday, April 2, 2014, 15:00–19:00, P3
Capillary leveling of stepped perturbations in thin viscous films — •Marco Rivetti1, Thomas Salez2, Stephan Herminghaus1, and Oliver Bäumchen1 — 1Max Planck Institute for Dynamics and Self-Organization (MPIDS), 37077 Göttingen, Germany — 2Laboratoire de Physico-Chimie Théorique, UMR Gulliver 7083 CNRS & ESPCI, Paris, France
Leveling occurs in thin liquid films if the free surface has a non-constant curvature. The consequent flow is driven by local curvature gradients and resisted by viscosity, and it is well described in the lubrication theory through the thin film equation. We here revisit recent developments and present new experiments on the capillary leveling of thin polymer films where the initial non-equilibrium profile is given by a Heaviside function (i.e. a step geometry) [1]. Experimental profiles for several film geometries and molecular weights are measured during relaxation. The leveling is shown to be self-similar, in agreement with theoretical predictions. An analytical solution of the profile has been obtained for small steps, when linearization of the problem is possible [2]. For steps comparable to the thickness of the film we present numerical solutions of the thin film equation which show good agreement with the experiments. We will also discuss the possible transition from leveling to the spreading regime occurring for ultra-thin films. 1mm [1] J.D. McGraw et al., Phys. Rev. Lett. 109, 128303 (2012)
[2] T. Salez et al., Phys. of Fluids 24, 102111 (2012)