Couette-Poiseuille Flow of Non-Newtonian Fluids in Concentric Annuli

摘要

Two types of laminar flows of non-Newtonian fluids in annuli with stationary outer cylinder are analysed from the viewpoint of existence of an exact analytical or almost exact analytical (quasisimilarity) solution relating volumetric flow rate and axial pressure gradient. The exact analytical solution is derived for the Vocadlo (Robertson-Stiff) fluids when flow is caused simultaneously by the inner cylinder moving along its axis and by the pressure gradient imposed in the axial direction. Both cases - either pressure gradient assists to the moving cylinder or opposes - are considered. The quasisimilarity solution is derived for the power-law fluids when the inner cylinder rotates under a constant torque and pressure force is imposed in the axial direction as in the preceding case.