Browsing by Author "Langtry, Robin Blair"

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A correlation-based transition model using local variables for unstructured parallelized CFD codes
(2006) Langtry, Robin Blair; Casey, Michael (Prof.)
A new correlation-based transition model has been developed that is based strictly on local variables. As a result, the transition model is compatible with modern CFD techniques such as unstructured grids and massive parallel execution. The model is based on two transport equations, one for intermittency and one for a transition onset criterion 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 transition correlations into general-purpose CFD methods. The transition model has been extensively validated for predicting transition in both aerodynamic and turbomachinery flows. An incremental approach was used to validate the model, first on simple flat plate experiments, 2D airfoils/blades and then on progressively more complicated 3D test cases such as a low-aspect ratio compressor, a transonic wing, a full helicopter configuration and an actual wind turbine blade. In all cases good agreement with the available experimental data was observed. The author believes that the current formulation is a significant step forward in engineering transition modeling, as it allows the combination of transition correlations with general purpose CFD codes. There is a strong potential that the model will allow the 1st order effects of transition to be included in everyday industrial CFD simulations.