Comparative Assessment of Hybrid LES/RANS Models in Turbulent Flows Separating from Smooth Surfaces
Several hybrid LES/RANS (LES - Large-Eddy Simulation; RANS - Reynolds- Averaged Navier-Stokes) models have been assessed in computations of separated flows over smooth-contoured, wall-mounted hills, including flow control. The models considered include DES (Detached Eddy Simulation; Spalart et al. 1997, Travin et al. 2002), DDES (Delayed DES; Spalart et al. 2006), a zonal hybrid LES/RANS scheme (HLR; Jakirlic et al. 2006) and an Instability-Sensitized (IS) k-ε model. We report on models performance in the two configurations: periodic flow over a symmetric 2-D hill at moderate Reynolds number (Re b =10595; LES: Fröhlich et al.,2005; Breuer et al., 2005) and flow over a 2-D hump at high Re number( Re c ≈ 106,Exp.: Greenblatt et al., 2004). In the latter case the separation was controlled by steady suction through a narrow opening at the natural separation line in addition to the baseline flow. The computational results obtained confirm a crucial role of the LES/RANS interface treatment.
KeywordsZonal Hybrid Separate Shear Layer Interface Position Detach Eddy Simulation RANS Model
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