Detached-Eddy Simulation of the F-15E at High Alpha

Abstract

Detached-eddy simulation (DES) is used to predict the massively separated flow around an F-15E at 65-deg angle of attack. The calculations are performed at flight conditions corresponding to a chord-based Reynolds number of 13.6 × 10 6 and Mach number of 0.3. Flowfield solutions are obtained using unstructured grids with the commercial solver Cobalt: the average mesh spacing from solid surfaces to the first cell center from the wall under one viscous unit. The influence of the mesh size is assessed using a series of three grids ranging from 2.85 × 10 6 cells to 10 × 10 6 cells. In addition, the influence of the time step is investigated using three simulations with varied time steps. DES predictions are assessed via comparison to Boeing's stability and control database as well as to solutions of the Reynolds-averaged Navies-Stokes (RANG) equations. These are steady, with the Spalart-Allmaras model. Both RANS and DES predictions of integrated forces exhibit a relatively weak dependence on the grid density for the range examined. In the DES the wake region is characterized by complex and chaotic three-dimensional structures with direct resolution of a reasonable range of length and timescales