Published online by Cambridge University Press: 07 June 2016
The results obtained from exact numerical solutions to the laminar boundary layer equations are compared with those given by the approximate method of Luxton and Young and the comparison shows that the latter method may be used for cases involving non-constant wall temperatures. This satisfactory result arises essentially from the fact demonstrated by the calculations that the skin friction is relatively insensitive to wall temperature gradients. It is also shown from these results that there is a lag in the propagation of wall temperature changes through the boundary layer. In consequence the Stanton number is a heat transfer parameter of doubtful value in cases of non-uniform wall temperature.