Direct numerical simulation benchmarks for the prediction of boundary layer bypass transition in the narrow sense*

We report a comprehensive set of direct numerical simulation benchmark statistics of bypass transition in the narrow sense with inlet freestream turbulent intensity levels 0.75%, 1.5%, 2.25%, 3.0% and 6.0%, respectively. Detailed descriptions of length scales and the rate of viscous dissipation are provided. Additionally, an intermittency correlation formula is proposed and compared with literature data, and the classical Abu-Ghannam and Shaw correlation (J. Mech. Eng. Sci. 1980) is found to describe the beginning, rather than the completion, of the late transitional stage. Further, accompanying RANS simulations were performed using OpenFOAM as a representative solver. Strong sensitivities are observed in the choice of the turbulence length scale used in the boundary condition for the k − ω SST and γ − Reθ models. Finally, we also found that the boundary layer freestream turbulence has a decay rate and length scales similar to those of its counterpart in a stand-alone spatially developing isotropic turbulence flow without the wall.