Cobalt was applied to a generic aircraft wing-body configuration and assessed for accuracy in predicting drag. Cobalt distinguished itself in predicting drag accurately in comparison to a wide range of codes at the 2nd AIAA Drag Prediction Workshop.
Cobalt became the standard among CFD codes for drag prediction accuracy at the 2nd AIAA Drag Prediction Workshop. While the configuration was simplistic in geometric terms, the corresponding flow exhibited complex, separated physics that demanded a robust, accurate flow solver.
The configuration modeled was a generic transport with and without nacelles. The grid consisted of prismatic and tetrahedral elements and was created rather quickly. A grid resolution study was performed by adjusting one parameter in VGRID, thereby creating larger grids that exhibited similar global qualities throughout the domain.
With quantitative and qualitative experimental data available for comparison, Cobalt produced the best comparison with lift and drag coefficients and was the only flow solver to accurately predict the pitching moment. Furthermore, Cobalt was the only code to capture the separated region on the upper wing at the trailing edge.
Convergence speed was similar or better than other codes. But when grid generation speed is taken into account, the overall time to solution is much reduced when compared to structured methods. When speed and accuracy count, the unstructured capability in Cobalt is very difficult to beat.
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