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 heate d plate with a single attached and separated square solid element was numer ically and experimentally examined, Experiment was optically performed by u sing a Mach-Zehnder interferometer. An attached solid element tends to incr ease the thermal boundary layer thickness in the upstream region of the rea ttachment point of the separated flow. As the results, the local heat trans fer 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 an d the solid element, the flow is accelerated and the local heat transfer is remarkably enhanced. The effect of thermal conductivity of the solid eleme nt is also examined.