Computational modeling of droplet spreading and coalescence on fiber rails

Flow phenomena in porous media are relevant in many technological applications including emulsion filtration, gas diffusion membranes, and biomedical implants. Fiber materials can be used as filtration membranes with tailored permeability range and controllable pore size distribution. In this talk, we will present lattice Boltzmann simulations of droplet spreading on fiber rails. The simulation results reveal the dependence of the droplet morphology on the fluid volume, fiber size, and contact angle. The transition from a barrel shaped drop to a liquid column shows hysteresis depending on the capillary pressure. We further present preliminary results on capillary trapping of droplets on fiber rails and coalescence induced detachment. We will outline how the results can be used to determine the critical capillary number between trapping and squeezing. We will discuss how these insights can be used to design functional materials for coalescence filtration and other applications.