A Correlation-Based Transition Model Using Local Variables: Part I

TLDR

Part I presents the mathematical formulation of a correlation‑based transition model and demonstrates its basic validation using a 2‑D turbine‑blade case. The model employs two transport equations—one for intermittency and one for transition onset based on momentum‑thickness Reynolds number—to provide a framework for integrating correlation‑based models into general‑purpose CFD, with Part I detailing the formulation and Part II outlining extensive turbomachinery and aerodynamic validation. The authors show that the new local‑variable correlation‑based transition model is compatible with modern CFD techniques such as unstructured grids and parallel execution, representing a significant advance for engineering transition modeling.

Abstract

A new correlation-based transition model has been developed, which is based strictly on local variables. As a result, the transition model is compatible with modern CFD approaches such as unstructured grids and massive parallel execution. The model is based on two transport equations, one for intermittency and one for the transition onset criteria in terms of momentum thickness Reynolds number. The proposed transport equations do not attempt to model the physics of the transition process (unlike e.g. turbulence models), but form a framework for the implementation of correlation-based models into general-purpose CFD methods. Part I (this part) of this paper gives a detailed description of the mathematical formulation of the model and some of the basic test cases used for model validation, including a 2-D turbine blade. Part II of the paper details a significant number of test cases that have been used to validate the transition model for turbomachinery and aerodynamic applications. The authors believe that the current formulation is a significant step forward in engineering transition modeling, as it allows the combination of correlation-based transition models with general purpose CFD codes.