title: Numerical investigation of dynamic effects for sliding drops on wetting defects.
abstract: The ability to trap or deflect sliding drops is of great interest in microfluidics, as it has several technological applications, ranging from self-cleaning and fog harvesting surfaces to laboratory-on-a-chip devices. We present a three-dimensional numerical model that describes sliding droplets interacting with wetting defects of variable strength and size. This approach provides relevant insight if compared to simplified analytic models, as it allows us to assess the relevance of the internal degrees of freedom of the droplet. We observe that the deformation of the drop enhances the effective strength and range of the defect, and we quantify this effect by comparison to a point-mass model. We also analyze the role of the steepness and strength of the defect on the drop motion, observing that small, strong defects are more effective at trapping than large, shallow traps of same excess surface energy. Finally, our results show quantitative agreement with previously reported electrowetting experiments, suggesting a universal behavior in droplet trapping that does not depend strongly on the nature of the defect.
authors.affiliation: Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands.
authors.forename: Andrea
authors.initials: A
authors.lastname: Cavalli
authors.affiliation: Product and Process Engineering, TNW-PPE/TP, Delft University of Technology, 2628 CN Delft, The Netherlands.
authors.forename: Michiel
authors.initials: M
authors.lastname: Musterd
authors.affiliation: Physics of Complex Fluids and MESA+ Institute for Nanotechnology, University of Twente, 7522 NB Enschede, The Netherlands.
authors.forename: Frieder
authors.initials: F
authors.lastname: Mugele