Elasto-capillary fluid-solid interaction with compound droplets

Compound droplets are of pivotal importance in pharmaceutical, biological and food industrial applications. The interaction of deformable solids with compound droplets in some of these applications remains unexplored. This fluid-solid interaction problem at micro- and nano-scales is governed by elasto-capillarity, a phenomenon where a solid is deformed by the capillary forces at fluid-fluid interfaces. We develop a high-fidelity computational model for simulating elasto-capillary problems involving compound droplets. We study the static wetting of a compound droplet on a soft solid and capillary origamis of compound droplets. Our numerical results show that the dynamics of the droplet-solid interaction can be controlled by varying the surface wettability of the solid, fluid-fluid surface tensions and droplet volumes. Our results suggest better ways to self-assemble micro- and nano-structures in additive manufacturing.