An exact solution of the laminar boundary-layer equations for free convection from a vertical plate having uniform surface heat flux has been obtained. Heat-transfer parameters have been calculated for Prandtl numbers in the range 0.1 to 100. The results have been extrapolated to a Prandtl number of 0.01.
Experimental results are compared with the theory and the agreement is found to be good. Heat-transfer results obtained from the von Kárm n-Pohlhausen method also are shown to be in good agreement with those from the exact solution. It is demonstrated that when average Nusselt numbers are calculated for a plate with uniform surface heat flux using the temperature difference halfway along the height, the results are very close to those for a uniform temperature plate.