scholarly journals Free Convection Phenomena in a Ribbed Wall

1990 ◽  
Author(s):  
N. S. Maravegias ◽  
D. P. Georgiou ◽  
D. D. Papailiou
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Thermal Field ◽  
Experimental Information ◽  
Convection Flow ◽  
Heated Plate ◽  
Transfer Enhancement ◽  
Free Convection Flow ◽  
Distance Ratio ◽  
Transfer Rates

The present study reports on experimental information regarding the turbulent free convection flow and thermal field structure, along an isothermally heated vertical flat plate with ribs. The hight to distance ratio of the ribs was equal to 0.1. The obtained experimental data consist of visualization of the flow, as well as detailed mean temperature and turbulent intensity distribution measurements covering the ribbed part of the heated plate. Heat transfer rates and their enhancement, due to the presence of the ribs, have been estimated from the obtained temperature profiles and by using Newton’s cooling law. Comparisons with corresponding measurements in forced convection reported in the literature, are also made. The described experiments constitute a first approach towards a more detailed investigation regarding the significant free convection currents existing under certain conditions in cooled channels. However, they also reveal some physical aspects of the heat transfer enhancement processes in ribbed surfaces which are believed to be applicable in more general situations and could lead to establishing some design criteria for ribbed surfaces.

scholarly journals EFFECT OF NON-UNIFORM HEAT SOURCE AND RADIATION ON UNSTEADY MHD FREE CONVECTION FLOW PAST AN INFINITE HEATED VERTICAL PLATE IN POROUS MEDIUM

2020 ◽  
Vol 9 (4) ◽  
pp. 219
Author(s):  
PRATIBHA MISHRA ◽  
SWETA TRIPATHI
Keyword(s):  
Heat Transfer ◽  
Porous Medium ◽  
Heat Source ◽  
Free Convection ◽  
Skin Friction ◽  
Time Dependent ◽  
Convection Flow ◽  
Heated Plate ◽  
Free Convection Flow ◽  
Uniform Heat

Influence of radiation and non-uniform heat source on unsteady, magneto-hydrodynamic free convection flow of viscous incompressible fluid past an infinite vertical heated plate embedded in porous medium of an optically thin environment with time dependent suction and viscous dissipation is investigated in this paper. Analytical solutions of the coupled non-linear equations are obtained for the velocity field and temperature distribution using oscillating time-dependent perturbation technique. Expressions for skin-friction and heat transfer rate are also derived. The effects of the material parameters on velocity, temperature, skin-friction, and rate of heat transfer are discussed quantitatively.

An Experimental Investigation of Heat Transfer and Buoyancy Induced Transition from Laminar Forced Convection to Turbulent Free Convection over a Horizontal Isothermally Heated Plate

1978 ◽  
Vol 100 (3) ◽  
pp. 429-434 ◽  
Author(s):  
H. Imura ◽  
R. R. Gilpin ◽  
K. C. Cheng
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Forced Convection ◽  
Leading Edge ◽  
Finite Amplitude ◽  
Heated Plate ◽  
Transfer Rates ◽  
Longitudinal Vortices ◽  
Turbulent Flow Regime ◽  
Laminar Forced Convection

The flow over a horizontal isothermally heated plate at Reynolds numbers below that at which hydrodynamic instabilities exist, is characterized by a region of laminar forced convection near the leading edge, followed by the onset of longitudinal vortices and their growth to a finite amplitude and finally a transition to a turbulent flow regime. Results are presented for the temperature profiles, the thermal boundary layer thickness, and the local Nusselt number. They are used to identify the various flow regimes. It was found that the transition from laminar forced convection to turbulent convection was characterized by the parameter Grx/Rex1.5 falling in the range 100 to 300. For values of this parameter greater than 300 the heat transfer rates were independent of Reynolds number and typical of those for turbulent free convection from a horizontal surface.

scholarly journals Free convection flow of power law fluid in a vertical cylinder of finite height

1995 ◽  
Vol 17 (2) ◽  
pp. 34-39
Author(s):  
Nguyen Van Que
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Power Law ◽  
Average Velocity ◽  
Vertical Cylinder ◽  
Convection Flow ◽  
Power Law Fluid ◽  
Free Convection Flow ◽  
Finite Height ◽  
Good Agreement

A numerical solution has been presented for free convection flow of power law fluid in a vertical cylinder of finite height. The average velocity along the channel and the heat transfer have been calculated. Graphs of velocities and temperature are shown. The results show good agreement with analytic one in the asymptotic case.

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