Study of CFD variation on transport configurations from the second drag-prediction workshop

Abstract: This paper describes and analyzes a series of nearly 90 CFD test cases performed as a contribution to the second Drag Prediction Workshop, held in Orlando, Florida in June 2003. Two configurations are included: DLR-F6 wing-body and wing-body-nacelle-pylon. The ability of CFD to predict the drag, lift, and pitching moment from experiment––including the “delta” arising from the addition of the nacelle and pylon––is assessed. In general, at a fixed angle of attack CFD overpredicts lift, but predicts the ΔCL reasonably well. At low lift levels (CL<0.3), ΔCD is 20–30 drag counts (30–45%) high. At the target lift coefficient of CL=0.5, ΔCD is overpredicted by between 11 and 16 counts. However, the primary contribution of this paper is not so much the assessment of CFD against experiment, but rather a detailed assessment and analysis of CFD variation. The series of test cases are designed to determine the sensitivity/variability of CFD to a variety of factors, including grid, turbulence model, transition, code, and viscous model. Using medium-level grids (6–11 million points) at the target lift coefficient, the maximum variation in drag due to different grids is 5–11 drag counts, due to code is 5–10 counts, due to turbulence model is 7–15 counts, due to transition is 10–11 counts, and due to viscous model is 4–5 counts. Other specific variations are described in the paper. [Copyright &y& Elsevier]