Abstract
Mixed convection heat transfer from a horizontally placed upward-facing semi-infinite plate to a uniform downward forced flow is numerically analyzed. The Reynolds and the modified Grashof numbers are 500 and 5×10^7, respectively. Characteristic longitudinal vortical structure, which was observed in the recent experimental study, is successfully simulated. The typical structure appears near the plate as a pair of counter-rotating vortices, which is elongated over the plate. Special attention is focused on the relationship between this structure and the heat transfer. After the emergence of the vortices, overall Nusselt number, which shows irregular unsteadiness, rises up by more than 30 percent on average. Time series of the overall Nusselt numbers and the average heights of the vortices have a significant negative correlation, which means that the longitudinal vortices near the plate enhance the overall heat transfer at that moment, and vice versa.
