Accurate Drag Prediction Using Cobalt

The technical objective of the Second AIAA Computational Fluid Dynamics (CFD) Drag Prediction Workshop is to assess the state-of-the-art computational methods as practical aerodynamic tools for aircraft force-and-moment prediction of increasingly complex geometries. With more emphasis being placed on CFD methods to evaluate aircraft designs early in the design process, the ability to accurately predict the forces and moments, specifically drag, on an airliner configuration is important. Using the CFD code Cobalt, force-and-moment calculations are obtained on a civil transport geometry with and without engine nacelle and pylon.Comparisons with experimental data show consistent agreement with forces and moments, wing Cp data, and qualitative data. Installation drag for the nacelle/pylon is well predicted. Relevance of the importance of the grid and robustness of the flow solver to the overall accuracy of the results is discussed.