Hybrid turbulence model simulations of internal and external flows

The large computational expense of direct numerical simulations provides motivation for the continuous development of new and improved turbulence models. In our research the standard k-ω and k-ε two-equation turbulence models were modified by limiting the turbulence length scale. The resulting hybrid models and a renormalization group hybrid model were tested for a plane channel flow at Re_τ = 395 and for the Stanford asymmetric diffuser. All three models were then employed for investigating the separated flow on the suction side of a wing section with a modified NACA64₃-618 airfoil for Re=300,000 and α=15deg. As a reference, in addition to the hybrid simulations, a direct numerical simulation was carried out. Although plausible results were obtained for the plane channel flow, the diffuser flow simulations were inconclusive. For the wing section, very good agreement with the DNS data was obtained with the RG model. For the two-equation hybrid models, the turbulent suction side boundary layer separated too early compared to the DNS.