Natural convection from a vertical cylinder in a thermally stratified porous medium |
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Authors: | C-H Chen J-H Horng |
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Institution: | (1) Department of Mechanical Design Engineering National Huwei Institute of Technology, Huwei, Yunlin Taiwan 632, Republic of China, TW;(2) Department of Mechanical and Marine Engineering National Taiwan Ocean University, Keelung Taiwan 20224, Republic of China, TW |
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Abstract: | The problem of non-Darcy natural convection adjacent to a vertical cylinder embedded in a thermally stratified porous medium
has been analyzed. Nonsimilarity solutions are obtained for the case that the ambient temperature increases linearly with
height of the cylinder. A generalized flow model was used in the present study to include the effects of the macroscopic viscous
term and the microscopic inertial force. Also, the thermal dispersion effect is considered in the energy equation. Thus, the
main aim of this work is to examine the effects of thermal stratification and non-Darcy flow phenomena on the free convection
flow and heat transfer characteristics. It was found that the present problem depends on six parameters, namely, the local
thermal stratification parameter ξ, the boundary effect parameter Bp, the modified Grashof number Gr*, wall temperature exponent m, the curvature parameter ω, and the modified Rayleigh number based on pore diameter Ra
d
. The impacts of these governing parameters on the local heat transfer parameter are discussed in great detail. Also, representative
velocity and temperature profiles are presented at selected values of the thermal stratification parameter. In general, the
local heat transfer parameter is increased with increasing the values of m, ω, and Ra
d
; while it is decreased with increasing the values of ξ, Bp, and Gr*.
Received on 19 May 1998 |
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Keywords: | Non-Darcy natural convection Thermal stratification and Vertical cylinder |
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