Validation of large-eddy simulation of strongly curved stationary and rotating U-duct flows

Numerical predictions of the developing turbulent flow through stationary and rotating U-ducts with strong curvature are presented using large-eddy simulation (LES). The primary aim is to validate LES in a strongly curved U-duct for three different cases: stationary (non-rotating), positive and negative rotational cases. Selected flow models have provided a challenging test for the methodology adopted in terms of boundary conditions, wall functions and subgrid-scale (SGS) models, which are still regarded as crucial research topics within the context of LES. The agreement between the predictions and experimental data is quite satisfactory considering the coarse grid adopted. Discrepancies are observed to diminish near the lateral walls due to the relatively fine grid resolution. It is seen that LES performs better than the two-component-limit (TCL) RANS model in predicting the quantitative features of the turbulent flow through a U-duct with a non-conforming mesh adaptation.