Heat Transfer in Fully Developed Laminar Flow of Power Law Fluids

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
A. Baptista ◽  
M. A. Alves ◽  
P. M. Coelho
Keyword(s):  
Nusselt Number ◽  
Laminar Flow ◽  
Viscous Dissipation ◽  
Power Law ◽  
Numerical Solutions ◽  
Constant Heat Flux ◽  
Parallel Plates ◽  
Constant Wall Temperature ◽  
Power Law Fluids ◽  
Wide Range

In this work, we present approximate and exact solutions for the temperature profile and Nusselt number under fully developed laminar flow of a power law fluid inside pipes and between parallel plates. Constant wall temperature and negligible axial heat conduction are considered, for both the cases with and without viscous dissipation. For completeness, the corresponding solutions for the related problem of constant heat flux at the wall are also presented. In the absence of viscous dissipation, the solutions obtained are semi-analytic, since they rely upon an iterative procedure. As a benchmark result, to allow comparison with the results obtained with the semi-analytical expressions, we also present highly accurate numerical solutions for the Nusselt number, Nu, based on numerical integration of the energy equation. Also based on these numerical results, simplified correlations for Nu are proposed, valid for a wide range of the power law index.

Effect of Power-Law Fluid Behavior on Nusselt Number of a Circular Disk in the Forced Convection Regime

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
P. Mishra ◽  
S. A. Patel ◽  
M. Trivedi ◽  
R. P. Chhabra
Keyword(s):  
Nusselt Number ◽  
Forced Convection ◽  
Power Law ◽  
Average Nusselt Number ◽  
Creeping Flow ◽  
Constant Wall Temperature ◽  
Fluid Behavior ◽  
Power Law Fluids ◽  
Wide Range ◽  
Power Law Index

Forced convection heat transfer is investigated from a thin disk in power-law fluids over wide range of conditions such as: Reynolds number, 1 ≤ Re ≤ 100, Prandtl number, 1 ≤ Pr ≤ 100, power-law index, 0.4 ≤ n ≤ 1.8, and disk thickness to diameter ratio, t/D = 0.01, 0.025, 0.05, and 0.075. The wide range of values of the power-law index spanned here covers both shear-thinning as well as shear-thickening fluid behavior. These results also elucidate the influence of the type of thermal boundary conditions, i.e., constant wall temperature condition (CWT) and constant heat flux condition (CHF) prescribed on the disk surface. Extensive results are presented in terms of the local and average Nusselt numbers to delineate the effect of each of the influencing parameters, Re, Pr, n, t/D for each thermal boundary condition. Limited results are also included here at vanishingly small values of the Peclet number to understand the behavior in the creeping flow condition. Finally, the present numerical results on the average Nusselt number have been consolidated in the form of a predictive equation to facilitate the interpolation of the present data for intermediate values of the parameters and/or a priori estimation of the average Nusselt number in a new application.

The Nonlinear Increase of Nusselt Number With Friction Factor in Fully Developed Laminar Duct Flow

2004 ◽  
Vol 126 (5) ◽  
pp. 840-842 ◽  
Author(s):  
E. Van den Bulck
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Friction Factor ◽  
Constant Heat Flux ◽  
Duct Flow ◽  
Parallel Plates ◽  
Physical Explanation ◽  
Constant Heat ◽  
Constant Wall Temperature ◽  
Nonlinear Increase

This paper deals with heat transfer in fully developed laminar flow in cylindrical ducts. For this type of flow, the product of friction factor with Reynolds number f Re and the Nusselt number are both constants. It is known that the Nusselt number increases with the shift of boundary condition from constant wall temperature to constant heat flux. Also, the ratio of the Nusselt number to f Re increases when the convexity of the duct is reduced, e.g., a cylinder visavis parallel plates. This paper gives a simple physical explanation for these two phenomenona.

Variation of the Recirculation Length of Newtonian and Non-Newtonian Power-Law Fluids in Laminar Flow Through a Suddenly Expanded Axisymmetric Geometry

2006 ◽  
Vol 129 (2) ◽  
pp. 245-250 ◽  
Author(s):  
Debabrata Nag ◽  
Amitava Datta
Keyword(s):  
Laminar Flow ◽  
Power Law ◽  
Numerical Study ◽  
Shear Thickening ◽  
Expansion Ratio ◽  
Rheological Parameters ◽  
Power Law Fluids ◽  
Wide Range ◽  
Flow Through ◽  
Recirculation Length

A numerical study has been carried out for the laminar flow of Newtonian and non-Newtonian power-law fluids through a suddenly expanded axisymmetric geometry. Mathematical correlations are proposed for the prediction of the length of the recirculating eddy in terms of Reynolds number, expansion ratio and rheological parameters. A wide range of expansion ratios (1.25⩽ER⩽8.0) has been covered for the Newtonian fluid and both the shear-thinning and shear-thickening flow characteristic fluids have been considered for the non-Newtonian fluids.

Forced convection heat transfer study of a blunt-headed cylinder in non-Newtonian power-law fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaspinder Kaur ◽  
Roderick Melnik ◽  
Anurag Kumar Tiwari
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Power Law ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Total Drag ◽  
Shear Thinning Fluids ◽  
Power Law Fluids

Abstract In this present work, forced convection heat transfer from a heated blunt-headed cylinder in power-law fluids has been investigated numerically over the range of parameters, namely, Reynolds number (Re): 1–40, Prandtl number (Pr): 10–100 and power-law index (n): 0.3–1.8. The results are expressed in terms of local parameters, like streamline, isotherm, pressure coefficient, and local Nusselt number and global parameters, like wake length, drag coefficient, and average Nusselt number. The length of the recirculation zone on the rear side of the cylinder increases with the increasing value of Re and n. The effect of the total drag coefficient acting on the cylinder is seen to be higher at the low value of Re and its effect significant in shear-thinning fluids (n < 1). On the heat transfer aspect, the rate of heat transfer in fluids is increased by increasing the value of Re and Pr. The effect of heat transfer is enhanced in shear-thinning fluids up to ∼ 40% and it impedes it’s to ∼20% shear-thickening fluids. In the end, the numerical results of the total drag coefficient and average Nusselt number (in terms of J H −factor) have been correlated by simple expression to estimate the intermediate value for the new application.

Laminar flow of power-law fluids past a rotating cylinder

2010 ◽  
Vol 165 (21-22) ◽  
pp. 1442-1461 ◽  
Author(s):  
Saroj K. Panda ◽  
R.P. Chhabra
Keyword(s):  
Laminar Flow ◽  
Power Law ◽  
Rotating Cylinder ◽  
Power Law Fluids
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