Heat Transfer by Natural Convection Between a Vertical Surface and a Stably Stratified Fluid

1978 ◽  
Vol 100 (2) ◽  
pp. 378-381 ◽  
Author(s):  
G. D. Raithby ◽  
K. G. T. Hollands
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Stratified Fluid ◽  
Vertical Surface

Natural Convection From a Vertical Surface to a Thermally Stratified Fluid

1976 ◽  
Vol 98 (3) ◽  
pp. 446-451 ◽  
Author(s):  
C. C. Chen ◽  
R. Eichhorn
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Stratified Fluid ◽  
Vertical Surface ◽  
Temperature Profiles ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Experimental Configuration ◽  
Copper Cylinder ◽  
Rigid Walls

Results are presented of a study of natural convection from an isothermal finite plate immersed in a stable thermally stratified fluid. An analytical solution to the problem is obtained by using the local nonsimilarity method. Theoretical local and overall heat transfer coefficients are given for Pr = 0.7 and 6.0. Velocity and temperature profiles are given for Pr = 6.0. The actual experimental configuration was a vertical copper cylinder enclosed in a cube with rigid walls. Heat transfer data are correlated with the measured ambient thermal gradient. Visual studies of the flow field are also discussed. Excellent agreement is achieved between analysis and experiment.

Natural Convection Heat Transfer From an Isothermal Vertical Surface to a Stable Thermally Stratified Fluid

1992 ◽  
Vol 114 (4) ◽  
pp. 917-923 ◽  
Author(s):  
D. Angirasa ◽  
J. Srinivasan
Keyword(s):  
Natural Convection ◽  
Thermal Stratification ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Stratified Fluid ◽  
Vertical Surface ◽  
Natural Convection Heat Transfer ◽  
Plate Temperature ◽  
Transient Nature ◽  
Wide Range

Natural convection from an isothermal vertical surface to a thermally stratified fluid is studied numerically. A wide range of stratification levels is considered. It is shown that at high levels of ambient thermal stratification, a portion at the top of the plate absorbs heat, while a horizontal plume forms around a location where the plate temperature equals the ambient temperature. The plume is shown to be inherently unsteady, and its transient nature is investigated in detail. The effect of the temperature defect in striating the plume is discussed. Average Nusselt number data are presented for Pr=6.0 and 0.7.

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.

Impact of Thermal Stratification on Unsteady Natural Convection Couette Flow Formation in a Vertical Channel Filled with Anisotropic Porous Material

2021 ◽  
Vol 408 ◽  
pp. 67-82
Author(s):  
Basant Kumar Jha ◽  
Muhammad Kabir Musa ◽  
Abiodun O. Ajibade
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Differential Equations ◽  
Porous Material ◽  
Couette Flow ◽  
Fluid Velocity ◽  
Vertical Channel ◽  
Stratified Fluid ◽  
Fluid Temperature ◽  
Riemann Sum

Recently, heat transfer problems where anisotropic porous medium or stably stratified fluid are taken into account have been separately studied. Developing a mathematical model that combines these physical quantities naturally results to complex coupled differential equations. In this paper, a fully developed time dependent natural convection Couette flow of stably stratified fluid between vertical parallel channels filled with anisotropic porous material is investigated. The governing partial differential equations are transformed into ordinary differential equations using Laplace transform techniques and then decoupled using D’Alembert method. Exact solutions in Laplace domain for the velocity and temperature equations are then obtained. A numerical method: Riemann-sum approximation is then used to invert the expressions for the velocity and temperature profiles, as well as the resulting skin friction, rate of heat transfer and volumetric mass flow rate into their corresponding time domain. The research establishes that both the anisotropic and the stratification parameters aid in regulating the fluid temperature and velocity. The research further reveals that the fluid velocity attains its maximum (or minimum) velocity when θ = 900 (or θ = 00) for k*<1 and when k*>1, the fluid velocity is least (or maximum) when θ = 900 (or θ = 00).

Laminar Natural Convection From Isothermal Vertical Cylinders: Revisting a Classical Subject

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Jerod C. Day ◽  
Matthew K. Zemler ◽  
Matthew J. Traum ◽  
Sandra K. S. Boetcher
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Vertical Cylinder ◽  
Vertical Surface ◽  
Nusselt Numbers ◽  
Recent Interest ◽  
Laminar Natural Convection ◽  
Vertical Cylinders ◽  
Classical Subject

Although an extensively studied classical subject, laminar natural convection heat transfer from the vertical surface of a cylinder has generated some recent interest in the literature. In this investigation, numerical experiments are performed to determine average Nusselt numbers for isothermal vertical cylinders (102<RaL<109,0.1<L/D<10, and Pr = 0.7) situated on an adiabatic surface in a quiescent ambient environment. Average Nusselt numbers for various cases will be presented and compared with commonly used correlations. Using Nusselt numbers for isothermal tops to approximate Nusselt numbers for heated tops will also be examined. Furthermore, the limit for which the heat transfer results for a vertical flat plate may be used as an approximation for the heat transfer from a vertical cylinder will be investigated.

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