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COBEM 2021
26th International Congress of Mechanical Engineering
A Numerical Study on the Effects of Mesh Refinement, Artificial Dissipation and Freestream Turbulence on Laminar-Turbulent Transition Predictions
Submission Author:
Aline Righi , SP
Co-Authors:
Aline Righi, Leonardo Motta Maia de Oliveira Carvalho, Gustavo Luiz Olichevis Halila, João Luiz F. Azevedo
Presenter: Aline Righi
doi://10.26678/ABCM.COBEM2021.COB2021-0167
Abstract
The aerospace industry has been using CFD methods as an integral part of its design and development processes for quite some time and, as expected, the methods and the protocols for their use have matured considerably. There are, however, a few areas within aerospace applications for which some challenges for the more widespread use of CFD remain. One of such challenging areas concerns the appropriate treatment of laminar-turbulent transition in high Reynolds number flows over general configurations. The present work is concerned with the study of the impact of mesh refinement and numerical parameters on the accuracy of transition predictions for high Reynolds number flows. The approach adopted here uses a Reynolds-averaged Navier--Stokes formulation, with the SST model for turbulence closure. The SST model is further coupled to the Langtry--Menter transition model. Our investigation goals include the understating of the mesh influence over solutions for bypass and Tollmien-Schlichting (TS) transition mechanisms when using the Langtry--Menter model and the influence of the freestream viscosity ratio over the numerical solutions for both transition mechanisms. The Langtry-Menter model is implemented in an in-house code named BRU3D. Test cases include a flat plate geometry and the NLF(1)-0416 airfoil. For the TS-wave transition mechanism, the main conclusion is that increasing the freestream eddy viscosity ratio and decreasing the artificial dissipation lead to an upstream movement of the transition front, while the opposite behavior is observed for the bypass mechanism. Similar conclusions are drawn for the NLF(1)-0416 airfoil test case, except that there is no sensitivity in the results related to the effects of artificial dissipation.
Keywords
CFD, Laminar-turbulent transition, Langtry-Menter model, Mesh refinement
