Viscous flow simulations at high Reynolds numbers without wall functions: Is y+≃1 enough for the near-wall cells?

The results show that the numerical accuracy of the simulations is dependent on the selected turbulence model. For y+<1, there is no significant effect of the near-wall cell height on the numerical uncertainty of the selected flow quantities for the Spalart & Allmaras and k-kL models and so y+≃1 is sufficient to obtain numerical uncertainties of friction resistance coefficients smaller than 1% . On the other hand, with the SST k-ω model, y+≃1 leads to numerical uncertainties of friction resistance coefficients larger than 5% for all the present test cases. To attain the same uncertainty of the other turbulence models with the SST k-ω, one must use y+≃0.1.