Thanks morphling, but I was asking about the copper part!
As for masked geek's design, considering that it flows upwards (not downwards, morphling), I think it could be interesting, but I believe that it would perform better in reverse. Here's why:
I don't believe that you are likely to achieve a fast tornado in this design, but if you do, it would greatly increase the flow restriction: a circular motion (tornado) will have a tendancy to throw the coolant on the outside, due to centripedal force. Also, if there is a fast tornado, then you are inducing a further amount of friction, which will also increase flow restriction. I think that what you are more likely to achieve, is a whole bunch of small eddies, around a very slow tornado: the water may not even achieve a full rotation before exiting the block, it's going to depend on the flow rate.
If you want to force a tornado, then you're looking at a spiral design. Around a cone like yours, that's what morphling was thinking, but then he realized that it would required a fancier CNC...
