The motion of elastic filaments in a viscous fluid under small deformation is governed by a force balance equation where viscous force opposes linear bending force. But under large deformation, geometric constraints arising out of material behaviour, such as conservation of length, make the filament dynamics non-linear. How does this non-linearity affect the filament dynamics? We probe this question using experiments and numerical simulation.
Droplets transported through microfluidic devices are prone to interacting with boundary walls and the contents being polluted. A safe transport mechanism predicates a solid covering for such small droplets. One way to achieve this is by covering the droplet using thin plastic sheets. What is the phase space of different shapes a sheet can take when in contact with a liquid droplet? We understand this morphological phase space of the droplet-sheet system using experiments and asymptotic calculations.
Wetting of an elastic sheet subject to external tension. Gregory Kozyref, Benny Davidovitch, Ganga Prasath, S., Guillaume Palumbo, and Fabian Brau. [arXiv]
When a stress-free filament is floated on a thin flat film, it takes the shape of a staight line as this configuration has minimum energy. On the other hand confining it to non-planar surfaces with finite Gaussian curvature forces it to take bent shapes. Are these shapes special in any manner? We explore this question through experiments on soap films and develop a simplified theory that accounts for the effects of geometric confinement.