On the Prediction of Separation-Induced Transition by Coupling Delayed Detached-Eddy Simulation with y-Transition Model

Abstract

Powerful hybrid RANS/LES methods are gaining more attention for the prediction of transitional turbomachinery flow although the combination of these two worlds (hybrid RANS/LES and transition) is not well considered yet. Therefore, we propose a coupling of DDES and the y-transition model. The intention behind this coupling is explained and illustrated with two test cases, namely the academic flat plate boundary layer test case with adverse pressure gradient and the T106C turbine cascade, which represent transitional flow with separation-induced transition. The fundamental behavior of the coupled DDES-y is assessed by the flat plate test case. Further reaching analysis is done with the turbomachinery test case T106C. Both test cases helped to understand the model coupling and yield promising results for the DDES-y model, while we showed, that the fully-turbulent DDES failed to capture relevant features of the transitional flow for low free-stream turbulence.