Topology of vortex–wing interaction

A trailing vortex incident upon a wing can generate different modes of vortex–wing interaction. These modes, which may involve either enhancement or suppression of the vortex generated at the tip of the wing, are classified on the basis of the present experiments together with computations at the Air Force Research Laboratory. Occurrence of a given mode of interaction is predominantly determined by the dimensionless location of the incident vortex relative to the tip of the wing and is relatively insensitive to the Reynolds number and dimensionless circulation of the incident vortex. The genesis of the basic interaction modes is clarified using streamline topology with associated critical points that show compatibility between complex streamline patterns in the vicinity of the tip of the wing. Whereas formation of an enhanced tip vortex involves a region of large upwash in conjunction with localized flow separation, complete suppression of the tip vortex is associated with a small-scale separation–reattachment bubble bounded by downwash at the wing tip.