Numerical Simulation of Dense Colloidal Gels

Michael Bybee, University of Illinois at Urbana-Champaign

The dynamics of concentrated suspensions of colloidal particles (1nm to 1µm) in a viscous fluid is a problem of great technical interest and computational challenge. These systems are governed by many-body hydrodynamics, stochastic Brownian motion, and interparticle forces. The introduction of weakly attractive particle-particle interactions can induce a reversible transition from a homogeneous fluid phase to a non-equilibrium gel state. Both the short-range and long-range microstructure of these colloidal gels directly affect their mechanical and rheological properties.

Our goal is to study colloidal gels through numerical simulation which allows access to length-scales and time-scales inaccessible by experiment. More specifically, we seek to study the effect of the range and strength of attraction on the microstructure and on the mechanical and rheological properties of colloidal gels. Owing to the difficulty of accurately computing hydrodynamic interactions, the computational cost of traditional methods scales as O(N³) which has limited simulations to systems of N=25-100 particles. These systems are too small to exhibit the important long-range order of colloidal gels. In our research group, new algorithms have been developed which scale as O(N ln N) allowing dynamic simulations for up to 27,000 particles for Brownian suspensions. This poster presents governing equations, computational algorithms, and preliminary results for simulations of dense colloidal gels.

Abstract Author(s): Michael Bybee