Berlin 2018 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 17: Focus: Droplets (joint session DY/CPP)

DY 17.11: Vortrag

Montag, 12. März 2018, 18:15–18:30, BH-N 334

Morphological evolution of microscopic dewetting droplets with slip — Tak S. Chan¹, Joshua D. McGraw^1,2, Thomas Salez³, Ralf Seemann¹, and •Martin Brinkmann¹ — ¹Experimental Physics, D-66123 Saarland University — ²Département de Physique, Ecole Normale Supérieure/PSL Research University, CNRS, 24 rue Lhomond, 75005 Paris, France — ³Laboratoire de Physico-Chimie Théorique, UMR CNRS Gulliver 7083, ESPCI Paris, PSL Research University, Paris, France

A liquid drop sitting on a smooth substrate will contract or spread depending on the equilibrium contact angle and the initial shape of the drop. One well known example is that of drops spreading over a completely wetting surface, which follow Tanner’s law. In this study, we numerically compute the dynamics of contracting microscopic droplets where the slip-length b on the substrate is comparable to the intial drop height H. As quantified by the asphericity of the drop shape, we find a cross-over between two different dynamic regimes at slip length b ≪ H and b≫ H. These findings are explained from a competition between viscous dissipation in elongational flows for b ≫ H, friction at the substrate for b ≈ H, and viscous dissipation in shear flows for b ≪ H. Following the changes between the dominant dissipation mechanisms, our study not only indicates two universal rescalings of the evolution of asphericity, but also a cross–over to the quasi-static shape evolution when b is many orders of magnitude smaller than the slip length b_m where the asphericity assume its maximum value.