Modelling of thermal wall boundary conditions with temperature-dependent material properties for use in RANS

The present work extends a recently proposed P-function based model for describing the near-wall variation of temperature in forced convective turbulent flow to the case with temperature-dependent material properties. The extension essentially modifies the model formulations for describing the local variation of the turbulent mixing length and the turbulent Prandtl number. Direct Numerical Simulations (DNS) and experimental measurements are carried to provide comprehensive validation data for a wide range of Reynolds numbers, considering molecular Prandtl numbers well beyond unity. The observed good agreement of the predictions with the DNS data and experiments proves the present extended model as a well-suited approach for prescribing reliable thermal boundary conditions in Reynolds Averaged Navier-Stokes (RANS) simulations, assuming temperature-dependent material properties.