PHYSICAL-PROPERTIES OF MODEL COLLOIDAL LIQUIDS USING BROWNIAN DYNAMICS SIMULATION

Some aspects of the equilibrium and non-Newtonian behaviour of a free draining (Rouse level) Brownian Dynamics, BD, model colloidal liquids have been computed. Simulations have been carried out of spherical par ticles using the r(-n) inverse power repulsive and hard-sphere interac tion. The self-diffusion coefficients, linear dynamic viscosities, non -Newtonian viscosity behaviour and associated restructuring of the ass embly have been computed. Despite the very simple nature of the model, many of the computed properties follow closely the experimental data, giving at worst qualitative agreement. The model also obeys the Cox-M erz rule on rescaling either the frequency or shear rate. Where the mo del does show significant differences from the experimental data, we c an attribute this to the absence of many-body hydrodynamics in the mod el. For example, the long-time self-diffusion coefficient decreases wi th increasing volume fraction, but to a smaller extent than for the ex perimental systems. The magnitude of the viscosity and also the extent of liquid restructuring at high shear rates are other aspects of the model which probably suffer from the absence of many-body hydrodynamic s.