A novel intermittency distribution based transition model for low-re number airfoils

Abstract

A new correlation based transition model is proposed using a novel intermittency distribution function that relies on local information. The intermittency behavior of the transitional flows is reflected into computations by multiplying the production term of the Spalart-Allmaras turbulence model with the new intermittency factor. In this way, the model is in a sense similar to an algebraic model by using only an intermittency function rather than an intermittency transport equation, yet it carries transport equation character by means of the one-equation turbulence transport equation. Therefore, the present formulation being a local model yet bringing in the correlation data achieves a similar effect by using two less equations than similar transport equation based transition models like Menter's model. Validation of the new model with known flat plate test data of Schubauer & Klebanoff and Savill shows quite good agreement with the experiment. Model was also tested against some moderately high Reynolds number airfoil cases and some low Reynolds number airfoil cases with very promising results. The results imply that the new model may become a viable alternative for the higher order methods that is especially attractive in the design environment.