ENTRANCE LAMINAR FLOWS OF VISCOPLASTIC FLUIDS IN CONCENTRIC ANNULI

Developing flows of generalized Bingham (Herschel-Bulkley) fluids in c oncentric annuli were studied numerically. A control volume approach b ased upon an upwinding finite difference technique was used to solve t he equation of motion. The results in terms of velocity and pressure d rop profiles are shown graphically. Radius ratios of 0.02, 0.2, 0.4 an d 0.6; power-law indices (n) of 0.7, 1.0 and 1.2; generalized Bingham numbers of 5, 10 and 15 were investigated. At present, there are no ex perimental results with which to make comparisons. However, there are results for fully developed flows and comparison has been made with th ese. In all cases the agreement was good.