Transition from Turbulent Natural to Turbulent Forced Convection Adjacent to an Isothermal Vertical Plate

Turbulent mixed convection adjacent to an isothermal vertical flat plate was numerically examined by exploring the effect of small velocity on turbulent natural convection flow. A low Reynolds number k-∈ turbulence model, equivalent to the one used by Jones and Launder (1973), was employed in the simulation. The effect of increasing the free stream velocity on the velocity and temperature distributions, wall heat transfer, turbulent kinetic energy and its dissipation rate were examined. Results are presented for fluids with Prandtl number Pr - 0.7 at free stream velocities of u∞=0, 0.05, 0.25, 0.75 and 2.00 m/s for a Grashof number Grx = 1.0×1011. The introduction of small free stream velocity on turbulent natural convection flow suppresses the turbulence and decreases the heat transfer from the wall. As the free stream velocity continues to increase, the flow characteristics change to turbulent forced convection flow. Correlations to predict the heat transfer for the different convective flow regimes are presented