Application of an Intermittency-based Transition Transport Model to the NASA CRM-NLF Configuration

Abstract

For the numerical simulation of aircraft configurations with transitional boundary layers using computational fluid dynamics (CFD) tools it is reasobale to have different transition prediction approaches available. Depending on the complexity of the geometry and the flow field and on the specific simulation task it may be worthwhile to chose an approach that satisfies the needs of the user with regard to the scope of performance, the predictive accuracy, the ease of use and the pre- and post-processing efforts before and after the computation. In the DLR TAU code transition transport models (TTM) are available in addition to the traditional streamline-based application of the eN-method in conjunction with the two-N-factor strategy that relies on an appropriate NTS-NCF transition limiting curve. While the eN-method has a theoretical foundation and has turned out to be able to yield very accurate predictions it sometimes needs expert knowledge especially in complex flows cases. In contrast, transition transport models can be applied much more easily. However, in many cases they are based on more or stronger approximations. Thus, any new transport model must be validated carefully against experimental data and other prediction approaches that are less approximate.