Why does fluid behave this way in polygon-shaped vortices?

[CaptainBarbosa]

http://www.physorg.com/news66924222.html%22

Why does the fluid act like this? I'm truly stumped... I would read the published results paper, but I can't pay for it.

 

[ZapperZ]

There you go!

http://arxiv.org/abs/physics/0511251

Zz.

 

[freerangequark]

It occurs in nature too...

http://www.msnbc.msn.com/id/17816192/

 

[CaptainBarbosa]

There you go!

http://arxiv.org/abs/physics/0511251

Zz.

That's the whole thing that you normally have to pay for?!