EPTT 2022

13th Spring School on Transition and Turbulence

A Study on the Effects of Mesh Refinement for Transitional Flows Including Crossflow-Triggered Transition

Submission Author: Aline Righi , SP
Co-Authors: Aline Righi, Gustavo Luiz Olichevis Halila, João Luiz F. Azevedo
Presenter: Aline Righi

doi://10.26678/ABCM.EPTT2022.EPT22-0001

 

Abstract

Computational Fluid Dynamics (CFD) techniques have been used now for many decades in different applications for academic or industrial purposes. For example, the aerospace industry has been using CFD methods for design and development processes for some time now, and the methods have been improving considerably. However, there are still some challenges that warrant further research. For instance, the appropriate treatment of the laminar-turbulent transition over general configurations and the correct prediction of the transition location are among those aspects that require further development. The approach here uses the Langtry-Menter transition model coupled with the SST model for turbulence closure. The Langtry-Menter transition model uses two equations of transport for correctly predicting the laminar-turbulent transition. Moreover, the model is compatible with current CFD techniques, such as the use of unstructured grids and parallel processing. Transition can be triggered through different mechanisms as, for example, the amplification of Tollmien-Schlichting waves or the so-called bypass transition. The original version of the Langtry-Menter model was capable of correctly predicting both mechanisms through the use of empirical correlations. However, more recently, the Langtry-Menter model was extended in order to be able to predict transition due to crossflow vortices. There are different forms of developing an empirical correlation in order to take into account the crossflow instabilities and, in particular, the present work is concerned with an empirical correlation based on the flow helicity. Hence, the work will present a study of the effects of mesh refinement and of some other numerical parameters on the capability of accurately predicting transition due to crossflow instabilities. The main test case addressed here is the flow over a prolate spheroid.

Keywords

Laminar-turbulent transition, Langtry-Menter model, Mesh refinement, Empirical Correlations, Crossflow Instabilities

 

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