Lord,
That illustration is interesting, but studies have shown that is not correct. Using LIDAR and SODAR, we can now measure the trailing vortices, not just model them. Comp fluid dynamics just really doesnt work as well as you think, as water cannot be compressed and air can. Most models either model a thin section of the wing, or perhaps the wing itself, but very, very few model the wing, fuselage, center wing combination, let alone the significant effect of the engine on rollup.
The winglets, in reducing the vortices over the top of the wing that create the drag, actually tend to concentrate the airflow, which creates a faster velocity on the wake vortex creation. This creates what is called a small core vortex, which is very powerful, and a large core, which is not as powerful, but due to the zone of influence lasts longer.
This is why the vortex off the back of a 737-400 is a only a large core, while the 737-800 is a small and a large core. You dont want to get caught in the small core.
In board flaps and flap settings have significant effect as well on vortex creation.