How to define the edge after Boolean Operation
 

How to define the edge after Boolean operation

I have three circles with the same centre point, C1, C2, and C3, from which three faces are made, F1, F2, F3. Then I made the Boolean operation:

1). F3 subtract F2 (F2 retained); then new edge of Edge.5 and now face F3 occur. 2) F2 subtract F1 (F1 un-retained); then new edge of Edge.6 and new face F2 occur.

Now, Edge.5 and C2 are in the same position.

Then I made the mesh for F3 and F2;

In Solver, I select Fluent5/6. Then define the boundary conditions:

1） Edge.6 is Velocity inlet 2） C3 is Pressure outlet 3） C2 and Edge.5: (I don't know how to define them). I tried to define C2 and Edge.5 as Wall, or Interior or Interface, or Pressure outlet for F2 & Pressure Inlet for F3. but at the end when I export the mesh, I always got the same Error Message as following：

Continuum or Boundary Condition specified on Entity F3 is invalid for fluent 6.

However when I went through the Ttutorial 8 (blower) in Fluent 6, I noticed there were Wall-2 & Wall-2-shadow. It seems a similar case as C2 and Edge.5. I just could not get them. Why?

Your kind help in this matter would be highly appreciated.