Natural convection flow of a non-Newtonian power-law fluid from a slotted vertical surface with uniform surface heat flux

2008 ◽  
Vol 223 (3) ◽  
pp. 637-642 ◽  
Author(s):  
R S R Gorla ◽  
M A Hossain
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Power Law ◽  
Vertical Surface ◽  
Surface Heat ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Boundary Layer Equations ◽  
Power Law Index ◽  
Type Power

In the present paper, the natural convection flow of an Ostwalde—de Waele type power-law non-Newtonian fluid past a uniformly heated vertical slotted surface has been investigated numerically. The equations governing the flow and heat transfer are reduced to local non-similarity form. The transformed boundary-layer equations are solved numerically using implicit finite-difference method for values of ξ in the interval [0, ∞]. Solutions for heat transfer rate obtained for the rigid surface compared well with those documented in the published literature. From the present analysis, it is observed that an increase in ξ leads to increasing the skin-friction as well as reduction in heat transfer at the surface. As the power-law index n increases, the friction factor as well as the surface heat transfer increases.

Transient Analysis of Heat Transfer by Natural Convection Along a Vertical Wavy Surface

2017 ◽  
Vol 18 (3-4) ◽  
pp. 175-185
Author(s):  
Sadia Siddiqa ◽  
M. Mahfooz ◽  
M. A. Hossain
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Transient Behavior ◽  
Vertical Surface ◽  
Wavy Surface ◽  
Convection Flow ◽  
Physical Parameters ◽  
Surface Boundary ◽  
Surface Boundary Layer ◽  
Boundary Layer Equations

AbstractThe problem considered in this paper deal with the transient behavior of heat transfer by natural convection flow of fluid along an infinite vertical heated wavy surface. The governing equations are transformed into dimensionless form and solutions are obtained for the two dimensional flow for both pure (α=0) and uneven surface (α ≠ 0). For pure vertical surface boundary layer equations are solved in the (i) upstream (small τ) (ii) downstream (large τ) and (iii) entire (0<τ<∞) regimes using analytical and numerical techniques. A very good agreement is found when results of above mentioned regimes are compared. Further, for wavy surface solutions are obtained for the entire time regime and results are discussed in terms of average Nusselt number coefficient and isotherms. Numerical results are served to reveal the influence of the physical parameters such as the Prandtl number, Pr, and wavy geometry, α, for the surface conditions.

scholarly journals Non-Newtonian effect on heat transfer and entropy generation of natural convection nanofluid flow inside a vertical wavy porous cavity

2021 ◽  
Vol 3 (3) ◽  
Author(s):  
Mahbuba Tasmin ◽  
Preetom Nag ◽  
Zarin T. Hoque ◽  
Md. Mamun Molla
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Entropy Generation ◽  
Power Law ◽  
Volume Fraction ◽  
Local Entropy ◽  
Nanofluid Flow ◽  
Porosity Level ◽  
Power Law Index ◽  
Local Entropy Generation

AbstractA numerical study on heat transfer and entropy generation in natural convection of non-Newtonian nanofluid flow has been explored within a differentially heated two-dimensional wavy porous cavity. In the present study, copper (Cu)–water nanofluid is considered for the investigation where the specific behavior of Cu nanoparticles in water is considered to behave as non-Newtonian based on previously established experimental results. The power-law model and the Brinkman-extended Darcy model has been used to characterize the non-Newtonian porous medium. The governing equations of the flow are solved using the finite volume method with the collocated grid arrangement. Numerical results are presented through streamlines, isotherms, local Nusselt number and entropy generation rate to study the effects of a range of Darcy number (Da), volume fractions (ϕ) of nanofluids, Rayleigh numbers (Ra), and the power-law index (n). Results show that the rate of heat transfer from the wavy wall to the medium becomes enhanced by decreasing the power-law index but increasing the volume fraction of nanoparticles. Increase of porosity level and buoyancy forces of the medium augments flow strength and results in a thinner boundary layer within the cavity. At negligible porosity level of the enclosure, effect of volume fraction of nanoparticles over thermal conductivity of the nanofluids is imperceptible. Interestingly, when the Darcy–Rayleigh number $$Ra^*\gg 10$$ R a ∗ ≫ 10 , the power-law effect becomes more significant than the volume fraction effect in the augmentation of the convective heat transfer process. The local entropy generation is highly dominated by heat transfer irreversibility within the porous enclosure for all conditions of the flow medium. The particular wavy shape of the cavity strongly influences the heat transfer flow pattern and local entropy generation. Interestingly, contour graphs of local entropy generation and local Bejan number show a rotationally symmetric pattern of order two about the center of the wavy cavity.

scholarly journals Joule heating effect on magnetohydrodynamic natural convection flow along a vertical wavy surface

2012 ◽  
Vol 9 (1) ◽  
pp. 11-24 ◽  
Author(s):  
Nazma Parveen ◽  
M A Alim
Keyword(s):  
Natural Convection ◽  
Joule Heating ◽  
Skin Friction Coefficient ◽  
Wavy Surface ◽  
Convection Flow ◽  
Surface Shear Stress ◽  
Natural Convection Flow ◽  
Surface Shear ◽  
Boundary Layer Equations ◽  
Marine Engineering

In this paper, the effect of Joule heating on magnetohydrodynamic natural convection flow of viscous incompressible fluid along a uniformly heated vertical wavy surface has been investigated. The governing boundary layer equations with associated boundary conditions for this phenomenon are converted to nondimensional form using a suitable transformation. The equations are mapped into the domain of a vertical flat plate and then solved numerically employing the implicit finite difference method, known as the Keller-box scheme. Effects of pertinent parameters, such as the Joule heating parameter (J), Prandtl number (Pr), magnetic parameter (M) and the amplitude of the wavy surface ? on the surface shear stress in terms of the skin friction coefficient (Cfx), the rate of heat transfer in terms of local Nusselt number (Nux), the streamlines and the isotherms are discussed. A comparison with previously published work is performed and the results show excellent agreement. DOI: http://dx.doi.org/10.3329/jname.v9i1.5954 Journal of Naval Architecture and Marine Engineering 9(2012) 11-24

Transient Natural Convection Between Two Zones in an Insulated Enclosure

1988 ◽  
Vol 110 (1) ◽  
pp. 116-125 ◽  
Author(s):  
P. A. Litsek ◽  
A. Bejan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Experiments ◽  
Thermal Stratification ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Flow And Heat Transfer ◽  
Vertical Opening ◽  
The Right ◽  
Rayleigh Numbers

The natural convection flow and heat transfer between two enclosures that communicate through a vertical opening is studied by considering the evolution of an enclosed fluid in which the left half is originally at a different temperature than the right half. Numerical experiments show that at sufficiently high Rayleigh numbers the ensuing flow is oscillatory. This and other features are anticipated on the basis of scale analysis. The time scales of the oscillation, the establishment of thermal stratification, and eventual thermal equilibrium are determined and tested numerically. At sufficiently high Rayleigh numbers the heat transfer between the communicating zones is by convection, in accordance with the constant-Stanton-number trend pointed out by Jones and Otis (1986). The range covered by the numerical experiments is 102 < Ra < 107, 0.71 < Pr < 100, and 0.25 < H/L < 1.

Conjugate natural convection flow over a vertical surface with radiation

2015 ◽  
Vol 52 (6) ◽  
pp. 1193-1202 ◽  
Author(s):  
Sadia Siddiqa ◽  
Md. Anwar Hossain ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Natural Convection ◽  
Vertical Surface ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Conjugate Natural Convection

Numerical Simulation of Natural Convection Flow in a Cube With a Horizontal Heated Strip

2008 ◽  
Author(s):  
Esam M. Alawadhi
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Nusselt Number ◽  
High Temperature ◽  
Natural Convection ◽  
Vertical Wall ◽  
Convection Flow ◽  
Front Wall ◽  
Natural Convection Flow ◽  
Rayleigh Numbers

Natural convection flow in a cube with a heated strip is solved numerically. The heated strip is attached horizontally to the front wall and maintained at high temperature, while the entire opposite wall is maintained at low temperature. The heated strip simulates an array of electronic chips The Rayleigh numbers of 104, 105, and 106 are considered in the analysis and the heated strip is horizontally attached to the wall. The results indicate that the heat transfer strongly depends on the position of the heated strip. The maximum Nusselt number can be achieved if the heater is placed at the lower half of the vertical wall. Increasing the Rayleigh number significantly promotes heat transfer in the enclosure. Flow streamlines and temperature contours are presented, and the results are validated against published works.

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