AN EXPERIMENTAL-STUDY ON NATURAL CONVECTIVE HEAT-TRANSFER FROM A VERTICAL WAVY SURFACE HEATED AT CONVEX CONCAVE ELEMENTS

Natural convective heat transfer from a vertical wavy surface has been studied experimentally. The wavy surface has isothermally heated convex or concave semicircular cylinders. Such a problem involves the effect of complex geometries and heat conduction in unheated elements on natural convection flow. In this problem, the clarification of the interaction between the fields of fluid convection and heat conduction in the unheated elements is the most important part of explaining the heat transfer behavior. Therefore, a new proposed parameter S (= BR/GrD 1 4) was introduced through a vectorial dimensional analysis, taking into account the thermal properties of the material of the unheated elements. Heat transfer characteristics for cases of both convex and concave heating surface are discussed on the basis of the parameter S and visual observations of the velocity and temperature fields. Empirical formulas for the cases of convex and concave heating have been derived to correlate the heat transfer characteristic Nu/GrD 1 4 and the parameter S. © 1990.