periodic boundary condition

Murali

I have a symmetry model and i tried to define a rotational periodic bc to the it.i was able to link the faces togather and then do the volume mesh, but when i take the file to fluent and define the flow direction and rotational periodicity and say solve, it comes with an error saying divergence detected in amg solver and if i use coupled solver it say floating point error(underflow detected)....

could any one help me on this...

thanks in advance Murali