Thats not really correct. The winglets have absolutely no effect on the vorticies. The winglets are an attempt to get the wing closer to its optimum length, without increasing the wingspan
Vorticies are not created by the tips, but the entire wing. The vorticies rollup at the tips, but that is the combination of the air flow from the bottom, combining with the airflow over the top, and of course, the end of the influence.
The fuselage and center wing also contribute, as well as the engines.
The winglets help reduce drag with the thin section, and that is likely where most of the benefit comes from
Last edited by FlightPathOBN; 15th Jun 2012 at 20:29.