An Adaptive Turbulence Model for Swirling Flow

Paper in proceeding, 2006

Swirling flows are very common in technical applications, especially in hydraulic machinery, and they require rather sophisticated modeling. At present, an applicative method for simulating unsteady flows is Very Large Eddy Simulation (VLES). In VLES, large turbulence structures are resolved in time and space, while the small scales are modeled with an adequate turbulence model. Therefore the turbulence model must be able to distinguish between the resolved and the unresolved scales. In order to accomplish this the method used in this work employs an adaptive and dynamic filtering technique that restricts the turbulence model to only predict the effect of non-resolvable turbulent scales. The results obtained from using the standard k-ε model is compared to those using the extended model of Chen and Kim, with and without the filtering approach. The modified k-ε model of Reif et al. is also investigated together with the filtering approach. The models are implemented in the FENFLOSS and the CALC-PMB CFD codes. The chosen test cases are swirling flow in a straight pipe and swirling flow through a straight conical diffuser.