Tak Shing Chan: Directional spreading of a viscous droplet on a conical fiber
Abstract: If a droplet smaller than the capillary length is placed on a substrate with a conical shape, it spreads by itself in the direction of growing fibre radius. We describe this capillary spreading dynamics by developing a lubrication flow approximation on a cone and by using the perturbation method of matched asymptotic expansions. The droplet velocity is found to increase with the cone angle but decrease with the cone radius. We show that a film is formed at the receding part of the droplet, much like the classical Landau–Levich–Derjaguin film. By using the approach of matching asymptotic profiles in the film region and the quasi-static droplet, we obtain the same film thickness as the results from the lubrication approach. Our results show that manipulating the droplet size, the cone angle and the slip length provides different schemes for guiding droplet motion and coating the substrate with a film.
This talk is part of the Mechanics Lunch Seminar series. That means 20min talks plus discussion in an informal setting.
Zoom: To obtain the Zoom meeting details please contact Timo Koch (timokoch at math.uio.no).