Forced convection heat transfer to supercritical helium

We studied numerically the heat transfer for a turbulent flow of supercritical helium. A finite difference model is constructed with three different models of turbulence: the mixing length,k- andk-ε model. The stationary results compared to experimental data reveal that the mixing length model gives the best prediction of turbulence in this situation. A severe deterioration from the widely used Nusselt correlation by Giarratano is observed for cases near the pseudocritical temperature, while a far better correspondance is found with the more recent Yaskin correlation. The maxima and minima in the heat transfer curves can be understood by interpretation of the wall and bulk temperature together with the strong changes in density.