These days I was looking for information about whirlpools. Here some links:
I found some threads in the forums and was playing arround this subject. By now I have not great results but think it is quite easy to get interesting results using vortex and DSplines daemons.
First test I did was with partcle base fluids, the problem is you need a lot of particles.
These are some tests using HYBRIDO where you can generate a lot of particles, in this tests I have used few cells so they are not showing a lot. In the first example I used a simple vortex, the other three a DSpline gives you more control and let you play with several configurations, animating parameters and its layers. Now I am working on the other layers of the simulation, splashes , spray, foam, etc.
Some test scenes.