syntax for velocity profile
 

Hi all,
i want to modify the inlet velocity in a 3D pipe (cylinder).
This is the U file:

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{


inlet
{
type fixedValue;
value uniform (0 0 1);
}

outlet
{
type inletOutlet;
inletValue $internalField;
value $internalField;
}

"(walls|bfV_zone0)"
{
type fixedValue;
value uniform (0 0 0);
}
}

I want to change it from a uniform field to a parabolic profile.
If the z axis is the direction of the flow in the pipe, which is the correct way to express the velocity profile of the circular section (z= cost.) corresponding to the inlet?

Thanks