Numerous experimental and analytical investigations have been undertaken on the subject of heat transfer in thecombined free and forced, or mixed convection regime. This paper focuses on the topic heat transfer for aiding turbulent flow. Aiding flow is when byoyancy forces act in the same direction as the forced flow (heated upflow or cooled downflow( while opposing flow is when the byoyancy force is in the opposite direction of the forced flow (cooled upflow or heated downflow). For opposing flow t he buoyancy always increases the rate of heat transfer over the forced convection value, while for aiding flow, first a reduction in heat transfer is encountered, than an enhancement. Correlatioins for turbulent mixed convection in a vertical pipe, and criteria for the onset of mixed convectioin effects are reviewed. Numerous correlations were found which predict specific data sets, but a correlation which accounts for flow development effects in the regime of degraded turbulent heat transfer is lacking. A new correlation for turbulent mixed conveection for aiding flow in a vertical piple is porposed.
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