High-Fidelity Computations of the Prandtl-D Flying Wing

A complete, multifidelity numerical study is undertaken to investigate the loads and flow structure on the Prandtl-D, a low-speed flying-wing demonstrator designed to operate with a bell-shaped lift distribution. The Prandtl-D is simulated using implicit large-eddy simulation (ILES) at a mean-chord Reynolds number ([Formula: see text]) of [Formula: see text] at the design condition of [Formula: see text] to provide the full, three-dimensional unsteady flow topology. The flowfield at the wing’s design point was characterized by a laminar separation bubble that extended across the majority of the wing, open separation near the wingtip, and the absence of a tip vortex. The flow structure over the wing contrasted with previous Reynolds-averaged Navier–Stokes (RANS) results at a slightly higher [Formula: see text] but exhibited similarities with experiments at the same [Formula: see text]. The wake sheet contained a vortical structure inboard of the wingtip that originated from the open-separation zone. Examination of loads and flow structure at different fidelities demonstrated favorable agreement between the ILES and RANS augmented by the Amplification Factor Transport transition model, though the inviscid method was a sufficient level of fidelity for engineering purposes to capture the net and sectional loads near the design condition as a means of developing fidelity thresholds for this nontraditional platform.