Numerical Simulation of Interfacial Flows of a Hydrogel

Hydrogels are crosslinked polymer networks swollen with an aqueous solvent, and play central roles in biomicrofluidic devices. In such applications, the gel is often in contact with a flowing fluid, thus setting up a fluid-hydrogel two-phase system. Using a recently proposed model (Y.-N. Young et al, Phys. Rev. Fluids 4, 063601, 2019), we treat the hydrogel as a poroelastic material consisting of a neo-Hookean polymer network and a Newtonian viscous solvent, and numerically study the motion and deformation of gel drops suspended in viscous flows. The gel-fluid interface is tracked by using the Arbitrary Lagrangian-Eulerian method that maps the interface to a reference configuration. The interfacial deformation is coupled with the fluid and elasticity governing equations into a monolithic solution algorithm using the finite-element library deal.II. Our numerical simulation of a hydrogel drop in sedimentation and shear flow shows that it deforms in ways that differ from that of a viscous drop or elastic particle, and the solvent perfusion can have a significant effect on the hydrogel dynamics.