Drag Prediction for the Common Research Model Using CFL3D and OVERFLOW

Abstract

In response to the fourth AIAA CFD Drag Prediction Workshop, the NASA Common Research Model wing–body and wing–body–tail configurations are analyzed using the Reynolds-averaged Navier–Stokes flow solvers CFL3D and OVERFLOW. Two families of structured, overset grids are built. Grid Family 1 consists of a coarse (7.2 million), medium (16.9 million), fine (56.5 million), and extra-fine (189.4 million) mesh. Grid Family 2 is an extension of the first and includes a super-fine (714.2 million) and an ultra-fine (2.4 billion) mesh. The medium grid anchors both families with an established build process for accurate cruise drag prediction studies. This base mesh is coarsened and enhanced to form a set of parametrically equivalent grids that increase in size by a factor of roughly 3.4 from one level to the next denser level. Both CFL3D and OVERFLOW are run on Grid Family 1 using a consistent numerical approach. Additional OVERFLOW runs are made to study effects of differencing scheme and turbulence model on Grid Family 1 and to obtain results for Grid Family 2. All CFD results are post-processed using Richardson extrapolation, and approximate grid-converged values of drag are compared. The medium grid is also used to compute a trimmed drag polar for both codes.