(155e) Interactions of Compound Droplets with Microstructured Substrates: Spreading, Breakup, and Rebound

This research numerically examines the behaviors of micron-scale compound droplets impacting superhydrophobic surfaces with micropillar arrays using a 3D free-energy-based lattice Boltzmann method. The study investigates how physical and geometric parameters influence the spreading, breakup, and rebound behaviors of compound droplets. Three distinct flow regimes are identified, with unique ways the core and shell interact and break up. The transition between these regimes and maximum spreading factor can be altered by changing the core-shell size ratio, pillar density, and Weber number. The pillar structures' non-wetting behavior eventually forms a new suspended droplet, either pure or compound, characteristics of which depend on the same parameters. This research provides valuable insights that have far-reaching implications in the design and control of microfluidic devices for applications, including the delivery and release of drugs carried by the core droplets toward targeted diseased sites and production of personal care items.