How can I enter a parabolic inlet profile in Comsol for 3D tube modeling?

[alireza.b]

hello everyone
is anybody here using comsol multiphysics?
i'm trying to model a tube which the inlet is a fully developed fluid
but the problem is how to enter a parabolic inlet profile for velocity
in 2d axisymmetric it is very simple. but my model is 3d
i've entered "r" as a variable in definitions{r=sqrt((x^2)+(y^2))} and another variable for velocity, using "r". but the solution is not converged
how can i give the correct parabolic inlet?

 

[Greg Bernhardt]

I'm sorry you are not generating any responses at the moment. Is there any additional information you can share with us? Any new findings?

 

[alireza.b]

not yet
i fixed it by extrude the inlet plane to make sure that the inlet velocity profile is parabolic.
but no progress in giving parabolic profile to the software.