Understanding Abrupt Wing Stall with Computational Fluid Dynamics.

We describe the computational-fluid-dynamics efforts and lessons learned during the four-year Abrupt Wing Stall national research program. The paper details the complex nature of the transonic flows encountered by modern U.S. fighter and attack aircraft during transonic maneuvering conditions. Topics include grid resolution, computational memory and processor requirements, turbulence modeling, steady and unsteady calculations, and Reynolds-averaged Navier-Stokes solutions compared with detached-eddy simulations for this highly complex, viscously dominated, shock-induced, massively separated class of flow. Examples include results obtained for F/A-18C, AV-8B, preproduction F/A-18E, and F-16C aircraft undergoing transonic maneuvering conditions. Various flap settings have been modeled and the computational results compared with extensive wind-tunnel data