Direct numerical simulation of a flexible fiber interacting with a fluidic interface

The dynamics of fibers at a fluidic interface is of significant importance in various processes, among which stand out textile flotation, stabilization of emulsions, micro-folding of elastic structures, and clogging of feather fibers by oil droplets. A consistent formulation for the direct numerical simulation of a flexible fiber interacting with a fluidic interface is presently suggested. The fiber is geometrically decomposed into a chain of spherical beads, which undergo stretching, bending, and twisting interactions. The capillary force, acting at the three-phase contact line, is calculated using a ternary diffuse-interface model. Each ingredient of the model was validated against theoretical solutions. Partial and complete wrapping of an immersed three-dimensional drop is successfully simulated. The results show that the fiber curvature increases linearly with the square of the elasto-capillary length, for both low and large structural deformation, in-line with previously experimental observations