Modeling, Validation and Implementation of Turbulence Models for 21st Century Aircraft

Advances in numerical and grid-generation techniques in CFD codes as they are applied to aerodynamic designs must be accompanied by a corresponding development of accurate turbulence models. In the last decade, advances in both computer and numerical method technologies have dramatically affected the development of new and improved turbulence models. However, the proliferation of these new models, combined with the lack of information about their performance under various flow conditions, has contributed to additional uncertainties and risks in the design process. A clear definition of standard criteria for evaluating turbulence models can minimize these risks. To this end, in order to understand the capabilities and limitations of current turbulence models, it is first necessary to validate and test the models against benchmark experiments. Unified and effective evaluation criteria for turbulence models are required to accurately predict complex turbulent flows. This process involves the defining and updating of metrics with regard to specific testing and validation procedures. The aim of this work is to develop a methodology for the validation of current turbulence models that can then be used to develop and test new, advanced models. The outcome of this study will serve at least two purposes: the first is to evaluate the performance of existing Reynolds-Stress models; the second is to establish standard numerical solutions for the models. The former enables a user to select a desirable turbulence model for his application, while the latter enables modelers and users to determine criteria and metrics required to produce code and grid-independent numerical solutions. The benchmark results obtained should thus be reproducible by other general-purpose application computer codes. The establishment of a well-controlled solution enables CFD code developers to validate their implementations of the turbulence model in their own application codes. The experience in establishing reliable CFD solutions is necessary to achieve a useful CFD tool for design of 21st century aircraft.