Reversing magnet polarity to increase/decrease Eddy currents? I have a cast iron wheel with magnets around the inner radius as a braking mechanism. If I were to add additional magnets around the outer radius, would the amount of Eddy currents increase or crease if the polarity of the outer magnets was opposite?
EDIT:
Here's a diagram

where black circle, red and green rectangles depict the wheel, existing magnets and new magnets, respectively. The existing magnets have the S side facing the wheel. So my question is, if the green magnets have the N side facing the wheel, will Eddy currents increase or decrease? What if the S sides face the wheel? In fact, do the polarities of any of the magnet matter?
 A: If the magnets in the two sets were facing each other (i.e., if green outer magnets were shifted to the $6$ o'clock position), it would be pretty obvious that, in order to increase eddy currents, the outer magnets would have to be installed with their north poles facing the wheel, so that the magnetic fields of the two sets boosted each other rather than canceled each other.
When the outer magnets are located as shown on the diagram (at about $3$ o'clock), the interaction of the magnetic fields of the two sets is not as significant. 
If the wheel was made out of aluminum or other non-ferromagnetic material, we could say that the polarity of the outer magnets would not matter, i.e., in either case, they would generate roughly the same additional eddy currents and similarly increase braking action. 
In your example, through, the wheel is made out of cast iron, a ferromagnetic material, and, as such, it would bend magnetic lines and increase the interaction between the two sets. It is hard to predict the degree of this interaction, but, to be sure (and since it costs nothing), it makes sense to install the outer magnets with their north poles facing the wheel.
