Vortex characterization in multiple-vortex systems of wing model wakes

In the wake of an aircraft large-scale vortical structures organize in multiple vortex systems with their vortex axes aligned approximately parallel to the wake axis. Equal-strength counter-rotating vortex pairs of 2–vortex wakes are known to be stable for rather high vortex ages until growing long-wavelength instabilities may lead to mutual interaction and final disintegration. Contrarily, unequal-strength counter-rotating vortex pairs eventually will grow short-wavelength cooperative instabilities and will undergo a rapid three-dimensional reorganization of the vortex system, as has recently been shown from numerical simulation [2, °3] and evidenced experimentally. By enforcing the generation of vortices that are prone to severe vortex interactions the wake vortex system could be diffused significantly faster. Such optimal perturbation by passive control of the wake could contribute to minimize aircraft separation distances necessary for air safety reason