Accurate physical and numerical modeling of complex vortex phenomena over delta wings

Abstract: With this contribution to the AVT-113/VFE-2 task group it was possible to prove the feasibility of high Reynolds number CFD computations to resolve and thus better understand the peculiar dual vortex system encountered on the VFE-2 blunt leading edge delta wing. Initial investigations into this phenomenon seemed to undermine the hypothesis, that the formation of the inner vortex system relies on the laminar state of the boundary layer at separation onset. As a result of this research, this initial hypothesis had to be expanded to account also for high Reynolds number cases, where a laminar boundary layer status at separation onset could be excluded. Furthermore, the data published in the same context shows evidence of secondary separation under the inner primary vortex. This further supports the supposition of a di?erent generation mechanism of the inner vortical system other than a pure development out of a possibly laminar separation bubble. The unsteady computations performed on numerical grids with different levels of re?nement led furthermore to the establishment of internal guidelines speci?c to the DES approach.