The flow of non-Newtonian fluids in both concentric and eccentric annuli was investigated in this thesis. The model for generalized Bingham (Herschel-Bulkley) fluids was used in the studies, which included fully developed flow, entrance flow, start-up flow and pulsating flow in a concentric annulus and start-up flow in an eccentric annulus. A set of mathematical formulations has been developed for fully developed flow of generalized Bingham fluids in a concentric annulus. Velocity profiles are presented by using a numerical scheme to solve the equations. The position of the unsheared plug in the annulus may be determined by the solutions. The equations of motion for entrance flow and unsteady flow of generalized Bingham fluids in a concentric annulus have been derived with a group of dimensionless variables. A control volume based finite difference technique was used to solve the governing equations. The effects of generalized Bingham number Pl, flow index n and radius ratio s on velocity profiles and pressure drop in the annulus are presented. Velocity profiles of start-up flow of generalized Bingham fluids in an eccentric annulus were obtained from finite difference solutions of the equation of motion after transformation into bipolar coordinates. The effects of eccentricity were also considered.
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