Study of Transition Prediction with the Langtry-Menter Model in the Tau Rans Flow Solver

Abstract

[EN] In this report a new approach for transition prediction is reviewed. The Langtry-Menter model is a new approach that is based only in local variables what makes it easy to use in modern CFD parallelised codes with unstructured grids. A complete review of the model, the mathematical formulation and the coupling with the turbulent model is presented. The extension of the model to 3D cases with crossflow and previous work done on the Langtry-Menter transition model is summarised. The methodology to run the Langtry-Menter transition model coupled with the tur bulent model k −ω SST is developed and the Best Practice is established. Experimental data for a natural laminar flow wing, model M2355, is used to validate the model and the limits of the transition model in the TAU flow solver are checked. The original transition model is developed with a 2D boundary layer profile so a 0° sweep angle case is chosen as an appropriate example. The input, key parameters and mesh sensitivity are studied with three different meshes and how to set up the key parameters is reviewed. Different variables like first cell high, surface mesh size or farfield mesh maximum size are changed in the base mesh to com pare both results and see its influence on the final result. The sensitivity of the model to the mesh and key parameters is shown and how that sensitivity affects the accuracy and robustness of the final solution is presented. A detailed analysis of the model has been performed investigating the behavior of certain flow features that appear in the solution, specially when the transition model is switched on