Summary of Data from the Fifth Computational Fluid Dynamics Drag Prediction Workshop

Kurzfassung

Results from the Fifth AIAA Computational Fluid Dynamics Drag Prediction Workshop are presented. As with past workshops, numerical calculations are performed using industry-relevant geometry, methodology, and test cases. This workshop focused on force/moment predictions for the NASA Common Research Model wing-body configuration, including a grid refinement study and an optional buffet study. The grid refinement study used a common grid sequence derived from a multiblock topology structured grid. Six levels of refinement were created, resulting in grids ranging from 0 . 64 × 10 6 to 138 × 10 6 hexahedra, a much larger range than is typically seen. The gridswerethentransformedintostructuredoversetandhexahedral,prismatic,tetrahedral,andhybridunstructured formats all using the same basic cloud of points. This unique collection of grids was designed to isolate the effects of grid type and solution algorithm by using identical point distributions. This study showed reduced scatter and standarddeviationfrompreviousworkshops.Thesecondtestcasestudiedbuffetonsetat M � 0 . 85 usingthemedium grid ( 5 . 1 × 10 6 nodes) from the sequence described earlier. The prescribed alpha sweep used finely spaced intervals through the zone where wing separation was expected to begin. Some solutions exhibited a large side of body separationbubblethatwasnotobservedinthewind-tunnelresults.Anoptionalthirdcaseusedthreesetsofgeometry, grids, and conditions from the Turbulence Model Resource website prepared by the Turbulence Model Benchmarking Working Group. These simple cases were intended to help identifypotential differences in turbulence model implementation. Although a few outliers and issues affecting consistency were identified, the majority of participants produced consistent results.