Simplified Stability-Based Transition Transport Modeling for Unstructured Computational Fluid Dynamics

Abstract

Inspired by the gamma-Re_thetat model framework, a new gamma-based model was developed and implemented into an unstructured Reynolds-averaged Navier–Stokes (RANS) code. The new model applies a modified version of the gamma-transport equation of the gamma-Re_thetat model. This new implementation applies an alternative local formulation for the pressure-gradient parameter lambda_theta that allows the local assessment of the transition criterion within the boundary layer and, thereby, simplifies the model and increases the accuracy of the transition onset location. The resulting prediction approach is robust, user-friendly, and suitable for unstructured RANS solvers with high parallelization. To attain a wide application range of the prediction method, while keeping the simplicity of the approach, a physical path-independent transition criterion was adopted, which was calibrated based on linear stability theory results. The approach was successfully validated against experimental data for various relevant test cases. In addition, results were also compared with results obtained with the gamma-Re_thetat model and, for some cases, with the eN method, which showed a strong similarity in the predictions of the eN method and the new gamma model.