Natural convection heat transfer is numerically studied in a vertical parallel-walled channel with a single square obstruction at Rayleigh numbers up to 10000. The channel walls are maintained at a uniform temperature which exceeds the ambient temperature. The working fluid is air. It can be seen that the average Nusselt number curve for the obstructed channel represents five flow regimes; while the one for the unobstructed channel represents three flow regimes only. The presence of an obstruction reduces the average Nusselt number to the unobstructed channel at Ra′ > 10; while it increases it at small Rayleigh numbers (Ra′ <10). For a very low Rayleigh numbers (Ra < 10) the average Nusselt number approaches a constant value. The average Nusselt number depends on Rayleigh number, aspect ratio, length of the obstruction and height of the obstruction from the channel entrance. The effects of all these parameters are studied and reported. Also a comparison is made between the results of the present study and those for a vertical parallel-walled channel with a single semi-circular obstruction having the same surface area as the square one.
|Number of pages
|American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD
|Published - 1990
ASJC Scopus subject areas
- Mechanical Engineering
- Fluid Flow and Transfer Processes