Dresden 2020 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 41: Droplets and Wetting (joint session DY/CPP)
DY 41.6: Talk
Wednesday, March 18, 2020, 16:15–16:30, ZEU 147
Breakup Dynamics of Capillary Bridges on Hydrophobic Stripes — Maximilian Hartmann1, •Mathis Fricke2, Lukas Weimar1, Dirk Gründing2, Tomislav Maric2, Dieter Bothe2, and Steffen Hardt1 — 1Nano- and Microfluidics Group, TU Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt, Germany — 2Mathematical Modeling and Analysis Group, TU Darmstadt, Alarich-Weiss-Straße 10, 64287 Darmstadt, Germany
The breakup dynamics of a capillary bridge on a hydrophobic stripe between two hydrophilic stripes is studied both experimentally and numerically. The capillary bridge is formed from an evaporating water droplet wetting three neighboring stripes of a chemically patterned surface. The simulations are based on the Volume-of-Fluid (VOF) method implemented in Free Surface 3D (FS3D). By considering the breakup process in phase space, the breakup dynamics can be evaluated without the uncertainty in determining the precise breakup time. It is found that within an intermediate inviscid regime, the breakup dynamics follows a t2/3-scaling, indicating that the breakup process is dominated by the balance of inertial and capillary forces. For smaller bridge widths, the breakup velocity reaches a plateau, which is due to viscous forces becoming more important. In the final stage of breakup, the capillary bridge forms a liquid thread that breaks up consistent with the Rayleigh-Plateau instability. The existence of satellite droplets in a regular pattern indicates that the primary breakup process is followed by self-similar secondary breakups.