scholarly journals A computational analysis of natural convection in a vertical channel with a modified power law non-Newtonian fluid

1998 ◽  
Author(s):  
S.R. Lee ◽  
T.F. Jr. Irvine ◽  
G.A. Greene
Keyword(s):  
Natural Convection ◽  
Newtonian Fluid ◽  
Power Law ◽  
Computational Analysis ◽  
Vertical Channel ◽  
Modified Power Law

Non-Newtonian Natural Convection Along a Vertical Heated Wavy Surface Using a Modified Power-Law Viscosity Model

2008 ◽  
Vol 131 (1) ◽  
Author(s):  
M. M. Molla ◽  
L. S. Yao
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Shear Rate ◽  
Power Law ◽  
Leading Edge ◽  
Numerical Results ◽  
Wavy Surface ◽  
Viscosity Model ◽  
Length Scale ◽  
Modified Power Law

Natural convection of non-Newtonian fluids along a vertical wavy surface with uniform surface temperature has been investigated using a modified power-law viscosity model. An important parameter of the problem is the ratio of the length scale introduced by the power-law and the wavelength of the wavy surface. In this model there are no physically unrealistic limits in the boundary-layer formulation for power-law, non-Newtonian fluids. The governing equations are transformed into parabolic coordinates and the singularity of the leading edge removed; hence, the boundary-layer equations can be solved straightforwardly by marching downstream from the leading edge. Numerical results are presented for the case of shear-thinning as well as shear-thickening fluid in terms of the viscosity, velocity, and temperature distribution, and for important physical properties, namely, the wall shear stress and heat transfer rates in terms of the local skin-friction coefficient and the local Nusselt number, respectively. Also results are presented for the variation in surface amplitude and the ratio of length scale to surface wavelength. The numerical results demonstrate that a Newtonian-like solution for natural convection exists near the leading edge where the shear-rate is not large enough to trigger non-Newtonian effects. After the shear-rate increases beyond a threshold value, non-Newtonian effects start to develop.

Non-Newtonian Natural Convection Along a Vertical Flat Plate With Uniform Surface Temperature

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
S. Ghosh Moulic ◽  
L. S. Yao
Keyword(s):  
Boundary Layer ◽  
Natural Convection ◽  
Shear Rate ◽  
Newtonian Fluid ◽  
Power Law ◽  
Similarity Solution ◽  
Leading Edge ◽  
Boundary Layer Equations ◽  
Shear Thinning Fluid ◽  
Vertical Flat Plate

Natural-convection boundary-layer flow of a non-Newtonian fluid along a heated semi-infinite vertical flat plate with uniform surface temperature has been investigated using a four-parameter modified power-law viscosity model. In this model, there are no physically unrealistic limits of zero or infinite viscosity that are encountered in the boundary-layer formulation for two-parameter Ostwald–de Waele power-law fluids. The leading-edge singularity is removed using a coordinate transformation. The boundary-layer equations are solved by an implicit finite-difference marching technique. Numerical results are presented for the case of a shear-thinning fluid. The results indicate that a similarity solution exists locally in a region near the leading edge of the plate, where the shear rate is not large enough to induce non-Newtonian effects; this similarity solution is identical to the similarity solution for a Newtonian fluid. The size of this region depends on the Prandtl number. Downstream of this region, the solution of the boundary-layer equations is nonsimilar. As the shear rate increases beyond a threshold value, the viscosity of the shear-thinning fluid is reduced. This leads to a decrease in the wall shear stress compared with that for a Newtonian fluid. The reduction in the viscosity accelerates the fluid in the region close to the wall, resulting in an increase in the local heat transfer rate compared with the case of a Newtonian fluid.

scholarly journals Viscosity and dispersion effects on natural convection from a vertical cone in a nonnewtonian fluid saturated porous medium

2011 ◽  
Vol 15 (suppl. 2) ◽  
pp. 307-316 ◽  
Author(s):  
Rishi Kairi
Keyword(s):  
Mass Transfer ◽  
Porous Medium ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Newtonian Fluid ◽  
Power Law ◽  
Ambient Medium ◽  
Concentration Field ◽  
Physical Parameters ◽  
Vertical Cone

This paper investigates the influence of double dispersion and viscosity on natural convection heat and mass transfer from vertical cone in a non-Darcy porous medium saturated with non- Newtonian fluid. The surface of the cone and the ambient medium are maintained at constant but different levels of temperature and concentration. The Ostwald-de Waele power law model is used to characterize the non-Newtonian fluid behavior. A similarity solution for the transformed governing equations is obtained. The numerical computation is carried out for various values of the non-dimensional physical parameters. The effect of non-Darcy parameter, viscosity parameter, thermal and solutal dispersion, buoyancy ratio, Lewis number and power-law index parameter on the temperature and concentration field as well as on the heat and mass transfer coefficients is analyzed.

scholarly journals Influence of heat sources to finite channel conjugate natural convection of a power fluid

1995 ◽  
Vol 17 (4) ◽  
pp. 29-35
Author(s):  
Vu Duy Quang ◽  
Dang Huu Chung
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Natural Convection ◽  
Heat Source ◽  
Power Law ◽  
Vertical Channel ◽  
Test Cases ◽  
Heat Sources ◽  
Power Law Fluid ◽  
Conjugate Natural Convection

The paper extended the studies of Thomas F. Irvine et al. [1] and V. D. Quang and D. H. Chung [2] by considering the influence of heat transfer into the wall of vertical channel with natural convection motion of a power law fluid as well as the -influence of heat sources. The results obtained in s9me test cases showed that the influence of wall will be clear and impossible to neglect when thermal conductivity of wall is small enough, so the effect of heat source distributed in the fluid is more considerable than in the wall and the heat source from 50kW / m3 will make an effect more considerably.

An Optimal Homotopy Asymptotic Method Solution of Injection of a Newtonian Fluid Through One Side of a Long Vertical Channel

2011 ◽  
Vol 42 (3) ◽  
pp. 267-283
Author(s):  
Rehan Ali Shah ◽  
Saeed Islam ◽  
A. M. Siddiqui ◽  
Ishtiaq Ali ◽  
Manzoor Ellahi
Keyword(s):  
Newtonian Fluid ◽  
Asymptotic Method ◽  
Vertical Channel ◽  
Optimal Homotopy Asymptotic Method
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