Large-eddy simulation of aircraft wake evolution from roll-up until vortex decay

The evolution of aircraft wake vortices from the roll-up until vortex decay is studied by large-eddy simulation. An aircraft model and the surrounding flow field obtained from high-fidelity Reynolds-averaged Navier-Stokes simulation are swept through a ground-fixed computational domain to initialize the wake. After the wake initialization a large-eddy simulation of the vortical wake is performed until vortex decay. In this paper the methodology is tested with a NACA 0012 wing and applied to the DLR-F6 wing-body model in cruise condition and a long-range aircraft model in high-lift configuration which was used in the European Aircraft Wing with Advanced Technology Operation project. The correlation between the detailed roll-up process of the vorticity sheet shedding from the main wing and the characteristics of the rolled-up vortex pair such as vortex circulation, core radius, and separation is investigated with and without ambient turbulence. In both the DLR-F6 wing-body and the long-range aircraft models, the behavior of the formed vortex pair appears similar to that of a vortex pair defined by an analytical vortex model including the impact of ambient turbulence on vortex linking and decay. The velocity profile of a fully rolled-up vortex pair at around t∗ = 1.0 agrees well with the Rosenhead-Burnham-Hallock vortex model.