Mixed Thermal Convection of Power-Law Fluids Past Bodies With Uniform Fluid Injection or Suction

1990 ◽  
Vol 112 (1) ◽  
pp. 151-156 ◽  
Author(s):  
T.-Y. Wang ◽  
C. Kleinstreuer
Keyword(s):  
Heat Transfer ◽  
Skin Friction ◽  
Power Law ◽  
Viscosity Index ◽  
Fluid Injection ◽  
Local Skin ◽  
Power Law Fluids ◽  
Local Skin Friction ◽  
Transfer Group ◽  
Cylinders And Spheres

Steady laminar flow of power-law fluids past heated two-dimensional or axisym-metric bodies is strongly influenced by the rate of fluid mass transfer at the wall, the buoyancy force, and the characteristics of the power-law fluid. The effects of these parameters on the local skin friction group and heat transfer group are analyzed for wedges of different angles, horizontal cylinders, and spheres. The local heat transfer group, HTG~Nux, for wedge flows is greatly affected by the power-law viscosity index n, and by fluid withdrawal especially when the generalized Prandtl number is relatively high. Fluid suction at larger Prandtl numbers also generates high HTG values for cylinders and spheres. However, the local skin friction group, SFG~Cf, for cylinders or spheres increases with fluid injection and decreases with suction largely because of buoyancy effects.

Convection Heat Transfer of Power-Law Fluids Along the Inclined Nonuniformly Heated Plate With Suction or Injection

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Jize Sui ◽  
Liancun Zheng ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Prandtl Number ◽  
Skin Friction ◽  
Power Law ◽  
Inclination Angle ◽  
Convection Heat Transfer ◽  
Heated Plate ◽  
Convection Heat ◽  
Power Law Fluids ◽  
Suction Or Injection

A comprehensive analysis to convection heat transfer of power-law fluids along the inclined nonuniformly heated plate with suction or injection is presented. The effects of power-law viscosity on temperature field are taken into account in highly coupled velocity and temperature fields. Analytical solutions are established by homotopy analysis method (HAM), and the effects of pertinent parameters (velocity power-law exponent, temperature power index, suction/injection parameter, and inclination angle) are analyzed. Some new interesting phenomena are found, for example, unlike classical boundary layer problem in which the skin friction monotonically increases (decreases) with suction increases (injection increases), but there exists a special region where the skin friction is not monotonic, which is strongly bound up with Prandtl number, which have never been reported before. The nonmonotony occurs in suction region for Prandtl number Npr < 1 and injection region for Npr > 1. Results also illustrate that the velocity profile decreases but the heat convection is enhanced obviously with increasing in temperature power exponent m (generalized Prandtl number Npr has similar effects), the decreases in inclination angle lead to the reduction in convection and heat transfer efficiency.

Coupling Effects of Viscous Sheet and Ambient Fluid on Boundary Layer Flow and Heat Transfer in Power-Law Fluids

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Xiaochuan Liu ◽  
Liancun Zheng ◽  
Goong Chen ◽  
Lianxi Ma
Keyword(s):  
Heat Transfer ◽  
Power Law ◽  
Numerical Solutions ◽  
Skin Friction Coefficient ◽  
Similarity Solutions ◽  
Temperature Fields ◽  
Ambient Fluid ◽  
Local Skin ◽  
Flow And Heat Transfer ◽  
Power Law Fluids

This paper investigates the flow and heat transfer of power-law fluids over a stretching sheet where the coupling dynamics influence of viscous sheet and ambient fluid is taken into account via the stress balance. A modified Fourier's law is introduced in which the effects of viscous dissipation are taken into account by assuming that the thermal conductivity is to be shear-dependent on the velocity gradient. The conditions for both velocity and thermal boundary layers admitting similarity solutions are found, and numerical solutions are computed by a Bvp4c program. The results show that the viscous sheet and rheological properties of ambient fluids have significantly influences on both velocity and temperature fields characteristics. The formation of sheet varies with the viscosity of fluid and draw ratio, which then strongly affects the relations of the local skin friction coefficient, the local Nusselt number, and the generalized Reynolds number. Moreover, for specified parameters, the flow and heat transfer behaviors are discussed in detail.

General Analysis of Steady Laminar Mixed Convection Heat Transfer on Vertical Slender Cylinders

1989 ◽  
Vol 111 (2) ◽  
pp. 393-398 ◽  
Author(s):  
T.-Y. Wang ◽  
C. Kleinstreuer
Keyword(s):  
Heat Transfer ◽  
Mixed Convection ◽  
Skin Friction ◽  
Cooling Mode ◽  
Local Skin ◽  
Friction Parameter ◽  
Laminar Mixed Convection ◽  
Local Skin Friction ◽  
Convection Parameter ◽  
Heat Transfer Parameter

A general analysis has been developed to study fluid flow and heat transfer characteristics for steady laminar mixed convection on vertical slender cylinders covering the entire range from pure forced to pure natural convection. Two uniquely transformed sets of axisymmetric boundary-layer equations for the constant wall heat flux case and the isothermal surface case are solved using a two-point finite difference method with Newton linearization. Of interest are the effects of the new mixed convection parameter, the cylinder heating/cooling mode, the transverse curvature parameter, and the Prandtl number on the velocity/temperature profiles and on the local skin friction parameter and the heat transfer parameter. The results of the validated computer simulation model are as follows. Depending upon the magnitude and direction of the buoyancy force, i.e., the value of the mixed convection parameter and the heating or cooling mode applied, natural convection can have a significant effect on the thermal flow field around vertical cylinders. Specifically, strong variations of the local skin friction parameter and reversing trends in the heat transfer parameter are produced as the buoyancy force becomes stronger in aiding flow. The skin friction parameter increases with higher curvature parameters and Prandtl numbers. Similarly, the modified Nusselt number is larger for higher transverse curvature parameters; however, this parameter may reverse the impact of the Prandtl number on the Nusselt number for predominantly forced convection.

A Note on the Similar and Non-Similar Solutions of Powell-Eyring Fluid Flow Model and Heat Transfer over a Horizontal Stretchable Surface

2020 ◽  
Vol 401 ◽  
pp. 25-35
Author(s):  
Razi Khan ◽  
M. Zaydan ◽  
Abderrahim Wakif ◽  
B. Ahmed ◽  
R.L. Monaledi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Skin Friction ◽  
Power Law ◽  
Nonlinear Partial Differential Equations ◽  
Skin Friction Coefficient ◽  
Point Of View ◽  
Local Skin ◽  
Similarity Transformations ◽  
Similar Solutions

Deliberation on the dynamics of non-Newtonian fluids, most especially Powell-Eyring fluid flow can be described as an open question. In this investigation, the flow and heat transfer characteristics are examined numerically by means of similarity analysis for a Powell-Eyring fluid moving over an isothermal stretched surface along the horizontal direction, whose velocity varies nonlinearly as a function of and follows a specified power-law degree formula. In order to solve the problem under consideration, the resulting system of coupled nonlinear partial differential equations with their corresponding boundary conditions is transformed into a correct similar form by utilizing appropriate similarity transformations, which are exceptionally acceptable for a particular form of the power-law stretching velocity, whose exponent is equal to . From the mathematical point of view, the similar equations of the studied flow cannot be obtained for any form of the power-law surface stretching velocity. As a result, it was found that the use of a general power-law stretching velocity results in non-similar equations. Also, appropriate numerical methods for similar and non-similar equations are used to discuss the results of engineering significance. Furthermore, correlation expressions for the skin friction and Nusselt number have been derived by applying the linear regression on the data outputted from the used computational methods.On the contrary to the heat transfer rate, it was found that the local skin friction coefficient is a decreasing property of power-law stretching.

scholarly journals Magnetohydrodynamic free convection of non-Newtonian power-law fluids over a uniformly heated horizontal plate

2020 ◽  
Vol 24 (2 Part B) ◽  
pp. 1323-1334 ◽  
Author(s):  
Alireza Bahmani ◽  
Hadi Kargarsharifabad
Keyword(s):  
Boundary Layer ◽  
Nusselt Number ◽  
Prandtl Number ◽  
Skin Friction ◽  
Power Law ◽  
Thermal Boundary Layer ◽  
Hartmann Number ◽  
Viscosity Index ◽  
Thermal Boundary Layer Thickness ◽  
Power Law Fluids

The MHD free convection flow of non-Newtonian power-law fluids over a horizontal plate subjected to a constant heat flux is studied. The results are presented for various values of the three influential parameters, i. e. the generalized Hart?mann number, the generalized Prandtl number, and the non-Newtonian power-law viscosity index. Increasing the Hartmann number increases the thermal boundary-layer thickness and the surface temperature and consequently decreases the wall skin friction and Nusselt number. A lower generalized Prandtl number results in a larger skin friction coefficient and higher wall temperature as well as thicker thermal boundary-layer. The viscosity index is predicted to influence the flow conditions depending on the value of generalized Hartmann number. At high generalized Prandtl number numbers, by decreasing non-Newtonian power-law index, the wall skin friction, temperature scale, and thermal boundary-layer thickness are increased and the Nusselt number is decreased, while the opposite trend is observed for low generalized Prandtl number. A general correlation for the Nusselt number is derived using the numerical results

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.

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