Mesoscale hydrodynamics simulations of attractive rod-like colloids in shear flow

Suspensions of rod-like colloids show in equilibrium an isotropic-nematic coexistence region, which depends on the strength of an attractive interaction between the rods. We study the behavior of this system in shear flow for various interaction strengths. A hybrid simulation approach is employed, which consists of a mesoscale particle-based hydrodynamics technique (multi-particle collision dynamics) for the solvent and molecular dynamics simulations for the colloidal rods. The shear flow induces alignment in the initially isotropic phase, which generated an additional free volume around each rod and causes the densification of the isotropic phase at the expense of an erosion of the initially nematic phase. Furthermore, the nematic phase exhibits a collective rotational motion. The associated rotational time decreases linearly in 1/γ-dot with increasing shear rate γ-dot, and increases with increasing attraction strength between the rods. The density difference between these two regions at different shear rates allows us to determine the binodal line of the phase diagram. For large applied shear rates, the difference between the phases disappears in favor of a homogeneous flow-aligned state