We end up with a group of large predator vortices preying on smaller ones, which in turn prey on smaller ones still, forming a food chain of vortices.
You have a large vortex spinning around, with a smaller one inside. The large vortex has a shearing effect on the smaller one, like cake batter being stirred. The large-scale vortex acts like a giant mixer, stretching and thinning out the smaller one, transferring its energy into the larger vortex. The large-scale vortex actually acts like a vampire, sucking the energy out of the smaller one.