Computer simulation studies of dense suspension rheology
Rheological properties of idealised models which exhibit all the non-Newtonian flow phenomenology commonly seen in dense suspensions are investigated by particulate-dynamics computer-simulations. The objectives of these investigations are: (i) to establish the origins of various aspects of dense suspension rheology such as shear-thinning, shear thickening and dilatancy; (ii) To elucidate the different regions of a typical dense suspension rheogram by examining underlying structures and shear induced anisotropies in kinetic energy, diffusivity and pressure;(iii) to investigate the scaling of the simplest idealised model suspension; i.e. the hard-sphere model in Newtonian media and its relationship to the isokinetic flow curves obtained through non-equilibrium molecular dynamics (NEMD) simulations; (iv) to preliminarily determine the effects of perturbations present in all real colloidal suspensions, namely particle size polydispersity and a slight `softness' of the inter-particle potential. Non-equilibrium isokinetic simulations have been performed upon systems of particles interacting through the classical hard-sphere potential and a perturbation thereof, in which the hard-core is surrounded by a `slightly soft' repulsive skin. The decision to base the present work upon isokinetic studies was made in order to obtain a better understanding of suspension rheology by making a direct connection with previous NEMD studies of thermal systems(93). These studies have shown that the non-linear behaviour exhibited by these systems under shear is attributable to a linear-induced perturbation of the equilibrium phase behaviour. The present study shows this behaviour to correspond to the high shear region of the generalised suspension flow curve.
"Computer simulation studies of dense suspension rheology"
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