UFR 2-11 Evaluation: Difference between revisions
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Revision as of 10:09, 7 September 2011
High Reynolds Number Flow around Airfoil in Deep Stall
Flows Around Bodies
Underlying Flow Regime 2-11
Evaluation
Comparison of CFD Calculations with Experiments
A dramatic improvement in solution fidelity for DES compared to URANS, first reported by Shur et al. [22], was observed in the extensive cross-validation exercise carried out in the EU FLOMANIA project [4]. Figure 4 depicts the relative deviation from experimental drag achieved by DES and URANS within this work.
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| Figure 4: Comparison of URANS and DES for the prediction of mean drag coefficient for the NACA0012 airfoil at α = 60°. Results of 11 different simulations conducted by different partners with different codes and turbulence models within the EU FLOMANIA project [4]. Experimental data cited by Hoerner [6] are used as reference. |
The effect of spatial and temporal numerical schemes on DES was
investigated for the NACA0012 case at α = 45° by
Shur et al. (2004)
[23]. Using a localised "hybrid" convection
scheme [29] (in which 4th
order central differences are applied within the vortical wake region)
and a 2nd order temporal integration was seen to resolve fine turbulent
structures to a scale near to that of the local grid spacing. Switching
the convection scheme to 3rd order upwind or, to a lesser extent, the
temporal scheme to 1st order was seen to strongly damp the fine
vortices in the wake (Figure 5). Correspondingly, a strong under-
prediction of the Power Spectral Density (PSD) of the drag and lift
forces at higher frequencies was observed. The effect on the mean
forces and pressure distributions was however comparatively mild for
this case.
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| Figure 5: Effect of different spatial and temporal numerical schemes on the resolved wake structures of the NACA0012 at α = 45° [23]. "Hybrid" refers to the localized blending between 4th order central and 3rd or 5th order upwind convection schemes proposed by Travin et al. [29] | ||
Contributed by: Charles Mockett; Misha Strelets — CFD Software GmbH and Technische Universitaet Berlin; New Technologies and Services LLC (NTS) and Saint-Petersburg State University
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