Natural convection from a vertical or horizontal fin with repeated rectangular grooves under isothermal heating is studied experimentally.
A Mach-Zehnder interferometer is used in experiment and the local Nusselt numbers of each side in grooves are measured by analyzing the interferograms. Heat transfer rate of each side in the grooves is calculated by integrating this local Nusselt numbers over the surface area.
Nusselt number in greatest at the outer surface of the groove, while the Nusselt number at the inside surface shows complicated behavior depending on the geometry and inclination. Various flow patterns are expected to occur in the grooves. In some cases, the total heat transfer rate from a grooved surface may be smaller than that from a smooth surface.
