turbulent velocity profiles at cylinder exit

shaheeb

After creating a structured 3d cylinder mesh and solving with a k-e model, i continue to get an incorrect velocity profile at the exit.

FLUENT seems to be treating the cylinder as two halves. I think the problem is to do with the trielement vertex type. I am using periodic boundary conditions for the inlet and outflow faces.

How can i obtain the correct turbulent profile? Many thanks in advance.