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ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
A Computational Analysis and Validation of a Laminar-Turbulent Transition Model Including Crossflow Effects
Submission Author:
Aline Righi , SP
Co-Authors:
Aline Righi, Gustavo Luiz Olichevis Halila, João Luiz F. Azevedo
Presenter: Aline Righi
doi://10.26678/ABCM.ENCIT2022.CIT22-0030
Abstract
For quite some time now, Computational Fluid Dynamics (CFD) techniques have been used for academic or industrial purposes in the aerospace industry. Although such techniques have been improved throughout the years, some challenges still remain. One of such challenging areas is the appropriate treatment of laminar-turbulent transition. In order to be able to represent transitional flows, a few transition models have been developed. Among those models, the present work is particularly concerned with the Langtry-Menter transition model. This model uses two transport equations and it is compatible with modern CFD techniques, {\em i.e.}, with unstructured grids and parallel processing. The Langtry-Menter transition model, coupled with the SST model for turbulence closure, is already implemented in an in-house code, BRU3D\@. The BRU3D code has been developed throughout the years and it is capable of representing aerospace-type flows with the use of different turbulent models. The code also uses parallel processing and all usual computational enhancements typical of current CFD codes. It is important to point out that transition can be triggered through different mechanisms, such as, bypass transition, the amplification of Tollmien-Schlichting waves and crossflow vortices. However, the form in which the Langtry-Menter model was previously implemented in the code would only allow the prediction of transition caused by the amplification of Tollmien-Schlichting waves or by the bypass process. This limitation came from the empirical correlations implemented, which would only support these two transition mechanisms. Therefore, in order to be able to represent transition caused by crossflow vortices, a new empirical correlation was recently added to the code. The empirical correlation is based on the local helicity in the flow. The present work is concerned with the validation study for this implementation, as well as the study of the impact of the newly added equations in the numerical convergence. For our investigations, the flow over a prolate spheroid is used, which is a well-know test case for crossflow transition in the literature. Hence, it is expected that the main contributions of the work will include the availability of the capability of simulating crossflow transition and the study of the impact of the newly added equations in the numerical convergence. Furthermore, our investigation will also include an analysis of the influence of the freestream turbulence properties on the transition location.
Keywords
Laminar-turbulent transition, Langtry-Menter model, Numerical Convergence, Crossflow Instabilities
