Nautilus wind mill

Recently I found a promising new wind mill design for an urban wind turbine based on the magic of the nautilus (logarithmic) spiral.

http://www.gizmag.com/the-archimedes-liam-f1-urban-wind-turbine/32263/

To get some imagination about how the flow will behave in this kind of turbine I decided to do a quick flat design of that spiral and to print a CW and CCW version of it. The results were indeed surprising ...

This is a run of my counter rotating double wheel test mill:
http:/