Simple Poiseuille flow

Maggie

I am having problems with simulating a simple Poiseuille flow in a small pipe. At the boundary 'Inlet' I prescribe the velocity in 3 directions (0 in both y- and z-direction and 2*Vaverage*(1-r^2/R^2) in x-direction). At the outlet the relative static pressure is set to 0 Pa, and at the wall a 'no slip' condition is priscribed. As a result velocities of about 4e-3 m/s in y- and z-direction are created by CFX 5.6. How can I create a Poiseuille velocity field in the entire pipe (so velocities in y- and z-direction becomes 0 or in the order of 1e-6)?