The H-Rx method for predicting transition
Simple correlations for predicting transition of laminar boundary layers lack generality because they are often based on parameters that are not the best measure of stability. On the other hand, current data indicate the Exponent 9 method is the best all around method for predicting transition. In the present paper, the Exponent 9 method is used to compute the critical Reynolds number and the x-Reynolds number R(Exponent 9), where the disturbance amplitude is amplified by Exponent 9, for flat plate with pressure gradients, surface heating, and suction. The results are plotted as a function of the shape parameter H. The outcome is a universal H-R map that can be used very simply to predict transition for a wide class of flows, including bodies of revolution. A trace on this map of the development of R vs. H for a given body intersets the R(Exponent 9) loci at the transition Reynolds number.