RELATIONSHIP OF ANNULAR AND PARALLEL-PLATE POISEUILLE FLOWS FOR POWER-LAW FLUIDS

This paper deals with both the axial and the tangential annular flows of power-law fluids in concentric annuli, and it specifically focuses on the relation volumetric flow rate Q against pressure drop P. Initially the mutual compatibility of the hitherto obtained results is analyzed, and from this, new results concerning behavior of a parameter lambda [a location of maximum axial (tangential) velocity component] are derived. Then, approximative expressions for relations Q against P (independent of lambda) are proposed in a sufficiently large region (kappa,n) where kappa represents annular aspect ratio and n the flow behavior index n. The deviations of these simple relations from the exact ones are negligible.