Analysis of Scale Adaptive Approaches Based on the Rotta Transport Equation
A zonal formulation of the scale adaptive simulation (SAS) approach for wall bounded shear flows based on the Rotta’s transport equation for integral length scale is contrasted with the \(SST-SAS\) model of Menter and Egorov (Flow Turbul Combust 85(1):113–138, 2010) with local triggering (seamless formulation). It is known that the SAS approach does not trigger to a scale resolving mode in attached/mildly separated flows even if grid supports the transition Menter et al. (4th Symposium on Hybrid RANS-LES Methods, Beijing, China, September, 2011). This work addresses the question whether a zonal formulation of SAS (\(k-\varepsilon \) formulation along with different norm for second derivative of velocity) could improve the triggering process from URANS to LES-like mode in attached/mildly separated flows. In order to study the effects of different formulations, both models were applied to different flow configurations ranging from fully attached to strongly separated, including stationary streamwise-homogeneous turbulent channel flow, flow over an S809 airfoil and swirling flow through a sudden expansion. We find that, in both formulations, even when grid is sufficiently fine to resolve the integral scale motions, the simulation only transitions to scale-resolving mode when the base URANS flow is naturally unstable.
KeywordsTurbulent Kinetic Energy Large Eddy Simulation Flow Turbul Combust Eddy Viscosity Sudden Expansion
The authors acknowledge the funding of this work by Deutsche Forschungsgemeinschaft (DFG) under Grant No. ME4126/2-1.
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