Title
NATURAL CONVECTION IN AN ENCLOSURE WITH DISCRETE ROUGHNESS ELEMENTS ON A VERTICAL HEATED WALL.
Document Type
Conference Proceeding
Department
Mechanical Engineering
Conference Title
Heat Transfer, Proceedings of the International Heat Transfer Conference
Location
San Francisco, CA
Date of Presentation
1-1-1986
Abstract
Natural convection flow next to a heated wall with single and repeated, two-dimensional, rectangular roughness elements is studied numerically and experimentally. The objective is to determine how these roughness elements influence heat transfer rates from the wall. Each roughness element consists of a thermally conducting, horizontal cylinder of rectangular cross section attached to the heated, isothermal wall of an enclosure. The height of roughness is on the order of the boundary layer thickness. Dye flow visualization in water confirms the numerical prediction that the steady flow over these elements does not separate. Only at high Rayleigh numbers, when the boundary layer below the roughness is unsteady, is local instantaneous flow reversal observed. Although steady flow reversals near the wall are not predicted or observed, nearly stagnant regions are formed, particularly between closely spaced cylinders. The surface heat flux in these stagnant regions is relatively low, so the total heat transfer rate may be nearly the same as for a smooth wall in spite of the increased surface area.
Volume
4
First Page
1519
Last Page
1525
DOI
10.1615/ihtc8.3080
Recommended Citation
Shakerin, S.,
Bohn, M.,
&
Loehrke, R. I.
(1986).
NATURAL CONVECTION IN AN ENCLOSURE WITH DISCRETE ROUGHNESS ELEMENTS ON A VERTICAL HEATED WALL..
Paper presented at Heat Transfer, Proceedings of the International Heat Transfer Conference in San Francisco, CA.
https://scholarlycommons.pacific.edu/soecs-facpres/127
