Detached-eddy simulation of the separated flow over a rounded-corner square

Detached-eddy simulation (DES) is used to study the massively separated flow over a rounded-corner square. The configuration is an idealization of the flow around a forebody cross section rotating at high angle of attack. Simulations are performed at sub- and supercritical Reynolds numbers, between which experimental measurements show a reversal of the side force. DES predictions are evaluated using experimental measurements and contrasted with unsteady Reynolds-averaged Navier-Stokes (URANS) results. The computations are also subjected to a moderate grid refinement, a doubling of the span-wise period, an enlargement of the domain in the other directions, and the removal of any explicit turbulence model. The sub- and supercritical flows are computed at Reynolds numbers of 10 ⁵ and 8 × 10 ⁵, respectively, and with the freestream at 10 deg angle of attack. Boundary-layer separation characteristics (laminar or turbulent) are established via the initial and boundary conditions of the eddy viscosity. Following boundary layer detachment, a chaotic and three-dimensional wake rapidly develops. For the supercritical flow, the pressure distribution is close to the measured values and both the streamwise and side forces are in adequate agreement with measurements. For the subcritical flow, DES side-force predictions do not follow the experimental measurements far enough to achieve reversal.