A NUMERICAL STUDY OF THE RHEOLOGICAL PROPERTIES OF SUSPENSIONS OF RIGID, NON-BROWNIAN FIBERS

Using techniques developed in our previous publication (Mackaplow et a l. 1994), we complete a comprehensive set of numerical simulations of the volume-averaged stress tensor in a suspension of rigid, non-Browni an slender fibres at zero Reynolds number. In our problem formulation, we use slender-body theory to develop a set of integral equations to describe the interfibre hydrodynamic interactions at all orders. These integral equations are solved for a large number of interacting fibre s in a periodically extended box. The simulations thus developed are a n accurate representation of the suspensions at concentrations up to a nd including the semidilute regime. Thus, large changes in the suspens ions properties can be obtained. The rheological properties of suspens ions with concentrations ranging from the dilute regime, through the d ilute/semi-dilute transition, and into the semi-dilute regime, are sur prisingly well predicted by a dilute theory that takes into account tw o-body interactions. The accuracy of our simulations is verified by th eir ability to reproduce published suspension extensional and shear vi scosity data for a variety of fibre aspect ratios and orientation dist ributions, as well as a wide range of suspension concentrations.