AN EXTENDED KAYS AND CRAWFORD TURBULENT PRANDTL NUMBER MODEL

For theoretical predictions of turbulent heat transfer in boundary lay ers and in duct flows, the knowledge of the turbulent Prandtl number i s crucial. This is especially true for fluids with low molecular Prand tl numbers (liquid metals). The present formulation, which is an exten ded Kays and Crawford (Convective Heat ann Mass Transfer, 3rd edn. McG raw-Hill, New York, 1993) turbulent Prandtl number model, can be used for accurately predicting the heat transfer for liquid metal flows. Th e Nusselt numbers calculated with the modified model for Pr, are found to be in good agreement with experimental data for fully-developed pi pe flows as well as for thermally developing pipe flows for various wa ll boundary conditions. The present model reduces to the one given in the above reference for liquids and gases with higher molecular Prandt l numbers. (C) 1997 Elsevier Science Ltd.