Heat transfer enhancement or depression of natural convection by a single square solid element on or separated from a vertical heated plate

The characteristics of natural convective heat transfer on a vertical heated plate with a single attached and separated square solid element was numerically and experimentally examined, Experiment was optically performed by using a Mach-Zehnder interferometer. An attached solid element tends to increase the thermal boundary layer thickness in the upstream region of the reattachment point of the separated flow. As the results, the local heat transfer is depressed in this region and it is improved in the downstream region of the reattachment point. When a space exists between the heated plate and the solid element, the flow is accelerated and the local heat transfer is remarkably enhanced. The effect of thermal conductivity of the solid element is also examined.