Pergamon Int. Comnt HeatMass Transfer, Vol. 23, No. 3, pp. 417-426, 1996 Copyright © 1996 Elsevier Science Ltd Printed in the USA. All rights reserved 0735-1933/96 $12.00 + .00 PII S0735-1933(96)00027-9 NATURAL CONVECTION HEAT TRANSFER FROM A DISCRETE PROTRUDING SURFACE M. Nitin Darbhe and K. Muralidhar Indian Institute of Technology Department of Mechanical Engineering Kanpur 208016, India (Communicated by P.J. Heggs and A.R. Balakrishnan) ABSTRACT Steady heat transfer from a two dimensional discrete protruding copper block mounted on a vertical wall has been experimentally studied here. The buoyant flow around the block has been visualized using an interferometer. The average Nusselt number for the heater is found to be considerably larger than values reported in the literature. Local Nusselt numbers derived from the interferograms, however justify the magnitude of the average Nusselt number. Introduction Buoyancy-driven flow in the vicinity of a protruding heated copper block placed on a vertical wall and exposed to the ambient is experimentally studied here. The copper block is of height h, protrusion b and a length L which is much larger than h and b. It is located on a vertical bakelite board with its longest dimension L lying in the horizontal plane. All measurements are carried out at steady state. Average Nusselt number as a function of Rayleigh number has been reported in this work. The thermal wake above the heated block as visualized by a Mach- Zehnder interferometer is also presented in this study. The problem addressed here arises frequently in the thermal design of high performance electronic components such as integrated chips in mainframe computers. An overall review of 417