Using Phase Field Models to Simulate Colloidal Chemohydrodynamics in 3D in both Chemically Homogeneous and Chemically Heterogeneous Environments

Colloidal particles can migrate in a solution in response to a solute concentration field, a phenomenon known as diffusiophoresis. A chemically active colloid can modify the concentration field of its surrounding, thus harvesting energy from the environment to self-propel or to change the trajectory of neighboring colloids. To date, the most efficient methods to simulate these active systems rely on Green's functions of the Laplace and Stokes operators that are only valid in the steady and dilute limits. However, many active systems of interest display interesting feedback behavior in dense and unsteady systems. We have recently developed a method using phase field models that performs full chemohydrodynamics simulations of such dense and unsteady systems and incorporates colloidal particles as highly viscous fluid phases. We demonstrate the feasibility of this by simulating particles in 3D in chemically homogeneous and chemically heterogeneous environments and compare to known theoretical results. We also verify that both near- and far-field hydrodynamic interactions are reproduced by this method and quantify the error of the viscous fluid approximation for these particles. Lastly, we demonstrate the ability of the method to simulate self-diffusiophoresis by adding asymmetric chemical reactions to colloidal systems.