LAMINAR NON-NEWTONIAN FLOWS IN ECCENTRIC ANNULI WITH INNER CYLINDER ROTATION
The hydrodynamic characteristics of fully developed axial laminar flow of non-Newtonian fluids in eccentric annuli with a rotating inner cylinder are investigated. The non-Newtonian, shear-thinning fluid is modeled by the Power-law or Ostwald-de Waele constitutive relationship. Using finite-difference method to solve the governing flow equations in bipolar coordinates, computational results for a wide range of annulus geometry (0.2 ? r* ? 0.8, 0 ? eccentricity ? 0.8), rotational Reynolds number (0 ? Re r ? 150) and flow behavior index(0.4 ? n ? 1) are presented. The rotational speeds considered in this study are restricted to the sub-critical Taylor number regime. The results delineate the effects of annuli r* and eccentricity, and inner cylinder rotation speed on the flow structure and frictional losses. Velocity distributions in the flow cross-section and the variation in friction factors (f Re) for fully developed flows in different eccentric annuli flow index are presented. Here, the non-linear shear behavior of the fluid is found to further aggravate the flow maldistribution, and once again the eccentricity is seen to exhibit a very strong influence on the friction behavior. These results are of significant importance to the design and operation of oil and gas drilling wells.
School:University of Cincinnati
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:eccentric ducts non newtonian flows power law
Date of Publication:01/01/2001