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.

Mixed Convection Heat Transfer of Shear-Thinning Fluids around Confined Square Cylinder at Low Reynolds Number

2018 ◽  
Vol 384 ◽  
pp. 12-20
Author(s):  
Houssem Laidoudi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Power Law ◽  
Convection Heat Transfer ◽  
Shear Thinning ◽  
Square Cylinder ◽  
Thermal Buoyancy ◽  
Shear Thinning Fluids ◽  
Power Law Index

This work deals with the effect of thermal buoyancy on momentum and heat transfer characteristics of confined square cylinder submerged in Non Newtonian shear-thinning fluids. In two-dimension, the governing equations are solved by using the commercial code ANSYS-CFX. The effects of thermal buoyancy and power-law index, n, on the non-dimensional Drag coefficient and Nusselt number are studied for the conditions: Ri = 0 to 1, n = 0.3 to 0.9, Re = 40, Pr = 1 and blockage ratio β = 1/4. The detailed flow and temperature field are presented in terms of streamlines and isotherm contours. It is found that for all values of Richardson number increase in the power-law index increases the total drag coefficient and decreases the non-dimensional Nusselt number.

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.

scholarly journals Prediction of Natural Convection Heat Transfer Phenomena of Nanofluids in Corrugated Annulus

2020 ◽  
Author(s):  
Sattar Aljobair ◽  
Akeel Abdullah Mohammed ◽  
Israa Alesbe
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Outer Cylinder ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat

Abstract The natural convection heat transfer and fluid flow characteristic of water based Al2O3 nano-fluids in a symmetrical and unsymmetrical corrugated annulus enclosure has been studied numerically using CFD. The inner cylinder is heated isothermally while the outer cylinder is kept constant cold temperature. The study includes eight models of corrugated annulus enclosure with constant aspect ratio of 1.5. The governing equations of fluid motion and heat transfer are solved using stream-vorticity formulation in curvilinear coordinates. The range of solid volume fractions of nanoparticles extends from PHI=0 to 0.25, and Rayleigh number varies from 104 to 107. Streamlines, isotherms, local and average Nusselt number of inner and outer cylinder has been investigated in this study. Sixty-four correlations have been deduced for the average Nusselt number for the inner and outer cylinders as a function of Rayleigh number have been deduced for eight models and five values of volume fraction of nano particles with an accuracy range 6-12 %. The results show that, the average heat transfer rate increases significantly as particle volume fraction and Rayleigh number increase. Also, increase the number of undulations in unsymmetrical annuli reduces the heat transfer rates which remain higher than that in symmetrical annuli. There is no remarkable change in isotherms contour with increase of volume fraction of nanofluid.

Unsteady Forced Convection Heat Transfer for Power Law Fluids in a Pipe

2010 ◽  
Author(s):  
Botong Li ◽  
Liancun Zheng ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Power Law ◽  
Control Volume ◽  
Convection Heat Transfer ◽  
Inlet Temperature ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Power Law Fluids ◽  
Power Law Index

This paper studied the problem of forced convection heat transfer for power law fluids in a pipe which was affected by the varying inlet temperature. The fluid flow was hydrodynamically fully-developed and laminar while the effects of viscous dissipation and the power law kinematic viscosity on heat transfer were considered. A control volume technique based on the finite difference model coupled with the LU decomposition method was adopted and the least squares polynomial was introduced to approximate the non-linear items. The results show that the heat transfer behaviors are strongly depending on the value of the power law index. It is found that the thermal wave of the inlet temperature has less penetration with the increasing axial coordinate, and the effect of heat transfer is dominant away from the wall. The temperature profile is flatter as the power law index increases, which is implies that the shear-thickening non-Newtonian flows are affected easier by the inlet temperature than the shear-thinning fluids.

An Experimental Study on the Effect of Partition Angle on Free Convection Heat Transfer in a Partition Cavity by Laser Interferometry Method

2010 ◽  
Author(s):  
Tooraj Yousefi ◽  
Sajjad Mahmoodi Nezhad ◽  
Masood Bigharaz ◽  
Saeed Ebrahimi
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Free Convection ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Laser Interferometry ◽  
Heated Wall ◽  
Convection Heat ◽  
Free Convection Heat

Steady state two-dimensional free convection heat transfer in a partitioned cavity with adiabatic horizontal and isothermally vertical walls and an adiabatic partition has been investigated experimentally. The experiments have been carried out using a Mach-Zehnder interferometer. The effects of the angel of the adiabatic partition and Rayleigh number on the heat transfer from the heated wall are investigated. Experiments are performed for the values of Rayleigh number based on the cavity side length in the range between 1.5×105 to 4.5×105 and various angle of the partition with respect to horizon from 0° to 90°. The results indicate that at each angle of the adiabatic partition, by increasing the Rayleigh number, the average Nusselt number and heat transfer increase and at each Rayleigh number, the maximum and the minimum heat transfer occur at θ=45° and θ=90°, respectively. A correlation based on the experimental data for the average Nusselt number of the heated wall as a function of Rayleigh number and the angel of the adiabatic partition is presented in the aforementioned ranges.

Magnetohydrodynamics Thermocapillary Marangoni Convection Heat Transfer of Power-Law Fluids Driven by Temperature Gradient

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
Yanhai Lin ◽  
Liancun Zheng ◽  
Xinxin Zhang
Keyword(s):  
Heat Transfer ◽  
Temperature Gradient ◽  
Differential Equations ◽  
Power Law ◽  
Numerical Solutions ◽  
Marangoni Convection ◽  
Convection Heat Transfer ◽  
Temperature Fields ◽  
Convection Heat ◽  
Power Law Fluids

This paper presents an investigation for magnetohydrodynamics (MHD) thermocapillary Marangoni convection heat transfer of an electrically conducting power-law fluid driven by temperature gradient. The surface tension is assumed to vary linearly with temperature and the effects of power-law viscosity on temperature fields are taken into account by modified Fourier law for power-law fluids (proposed by Pop). The governing partial differential equations are converted into ordinary differential equations and numerical solutions are presented. The effects of the Hartmann number, the power-law index and the Marangoni number on the velocity and temperature fields are discussed and analyzed in detail.

scholarly journals Mixed convection heat transfer from a heated circular cylinder

2019 ◽  
Vol 54 (1) ◽  
pp. 83-88
Author(s):  
H Laidoudi ◽  
M Bouzit
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Circular Cylinders ◽  
Governing Equations ◽  
Thermal Buoyancy ◽  
Flow And Heat Transfer ◽  
Mixed Convection Heat Transfer

This paper performs the effects of thermal buoyancy and the triangular arrangement of circular cylinders on fluid flow and heat transfer within a horizontal channel, the governing equations involving continuity; momentum and energy are solved in two-dimensional, laminar and steady flow regime. The average Nusselt number and drag coefficient are computed for the range of these conditions: Ri = 0 to 2 at fixed value of Pr = 1, Reynolds number Re = 30 and geometrical configurations (blockage ratio of β = 0.1). In order to observe the flow structure and temperature field under the gradual effect of thermal buoyancy, the streamlines and isotherm contours are illustrated. It is found that, a gradual increase in the value of buoyancy strength creates an asymmetrical flow around the cylinders. Interesting variations of drag coefficient and average Nusselt number are plotted with respect to Richardson number for each cylinder. Bangladesh J. Sci. Ind. Res.54(1), 83-88, 2019

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