Form the aforementioned global flow parameters it is seen, that any of the applied non-linear turbulence closure outperforms the standard (linear) eddy-viscosity approach even when truncated to their linear variants. A closer inspection of the turbulence details (cf. Fig. 10), however, reveals an inconsistent poor representation of the turbulence intensity in the wake of the obstacle. In contrat to this, the total energy is captured with much better success, which grounds for suspicion that the calculation is extremly sensitive to the imposed inlet condition. The adjusted level of turbulent length-scale at the inlet triggers the total energy in the wake, which grossly controls the shedding mechanism. Hence, as demonstrated by Figure (11), the predictive success of the applied non-linear closure relies on the appropriate choice of inlet turbulence.

Fig. 10: Turbulence energy along the centerline Fig. 11: Sensitivity of the global flow parameters to imposed inlet length scale
Fig.10: Turbulence and total energy in the wake Fig.11: Sensitivity of lift and drag to inlet length scale
Vortex Shedding behind a Square Cylinder at Re=22 000

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Last modified: Mon Apr 26 14:32:10 CEST 1999