Anomalous predictions of pressure drop and heat transfer in ducts of arbitrary cross-section with modified power law fluids

2001 ◽  
Vol 38 (1-2) ◽  
pp. 141-149 ◽  
Author(s):  
S. Park ◽  
D.-R. Lee
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Cross Section ◽  
Power Law ◽  
Arbitrary Cross Section ◽  
Power Law Fluids ◽  
Modified Power Law

Numerical Simulation of Laminar Flow of Yield-Power-Law Fluids in Conduits of Arbitrary Cross-Section

1993 ◽  
Vol 115 (4) ◽  
pp. 710-716 ◽  
Author(s):  
Idir Azouz ◽  
Siamack A. Shirazi ◽  
Ali Pilehvari ◽  
J. J. Azar
Keyword(s):  
Laminar Flow ◽  
Cross Section ◽  
Power Law ◽  
Annular Flow ◽  
Flow Behavior ◽  
Arbitrary Cross Section ◽  
Curvilinear Coordinates ◽  
Eccentric Annulus ◽  
Power Law Fluids ◽  
Eccentric Annuli

A numerical model has been developed to simulate laminar flow of Power-law and Yield-Power law fluids in conduits of arbitrary cross-section. The model is based on general, nonorthogonal, boundary-fitted, curvilinear coordinates, and represents a new approach to the solution of annular flow problems. The use of an effective viscosity in the governing equation of the flow allows the study of the flow behavior of any fluid for which the shear stress is a function of shear rate only. The model has been developed primarily to simulate annular flow of fluids used in drilling and completion operations of oil or gas wells. Predicted flow rates versus pressure gradient for laminar flow of Newtonian fluids in concentric and eccentric annuli, and Power-law fluids in concentric annuli compare very well with results derived from analytical expressions. Moreover, the predictions for laminar flow of Power-law and Yield-Power-law fluids in eccentric annuli are in excellent agreement with numerical and experimental data published in the literature. The model was also successfully applied to the case of laminar flow of Power-law fluids in an eccentric annulus containing a stationary bed of drilled cuttings and the results are presented herein.

Mixed Convection Heat Transfer to Power Law Fluids in Arbitrary Cross-Sectional Ducts

1989 ◽  
Vol 111 (2) ◽  
pp. 399-406 ◽  
Author(s):  
A. Lawal
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Mixed Convection ◽  
Power Law ◽  
Convection Heat Transfer ◽  
Local Heat Transfer ◽  
Convection Flow ◽  
Transfer Coefficients ◽  
Cross Sectional ◽  
Power Law Fluids

An analytical investigation of three-dimensional mixed convection flow and heat transfer to power-law fluids in horizontal arbitrary cross-sectional ducts is undertaken. The continuity equation and parabolic forms of the energy and momentum equations in rectangular coordinates are transformed into new orthogonal coordinates with the boundaries of the duct coinciding with the coordinate surfaces. The transformed equations are solved by the finite difference technique. The fluid enters the duct with constant velocity and temperature profiles with the wall of the duct subjected to constant temperature. Local heat transfer coefficients and pressure drop for several values of Gr/Re and power-law index n are computed for the triangular, square, trapezoidal, pentagonal, and circular ducts. The buoyancy force is found to increase both the Nusselt number and the pressure drop.

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