Flow reversal in turbulent mixed convection

Metais and Eckert (1964) have considered a plot to map the three convection regions for both laminar and turbulent flow. By plotting the Reynolds number against the dimensionless group, regimes were defined for free, forced, and mixed convection for flow in vertical tubes. In the present investigation, this mapping is examined for opposed turbulent flow, taking into account an identification of criteria under which flow reversal could occur. Experiments were conducted with the aid of a flow reversal apparatus. Heated water from a constant head tank was supplied to the bottom of a long vertical section of acrylic plastic pipe of the same internal diameter as the test section. The results indicate that the conditions for reversal in turbulent mixed convection were reproducible. The conditions at flow reversal for upward flowing water were defined.