Sorry I feel I have not explained myself correctly. Here is a drawing of
With Ux may be a profile or a constant.
Initially I had set-up that case with Ux as a Poiseuille flow profile and
the Top and Bottom as no slip boundary conditions. In that case I got the
solution I was expecting. Convergence was good and the solution was what I
had in mind.
Then what I wish to do is set Ux as a constant and apply slip at the top
and bottom boundary conditions. When I do this is when I am unable to reach
convergence in my iterative solution, yet I do not understand why because
the problem should be well posed.
I don't think that leaving my right boundary as a free traction boundary
condition is problematic since it is by all mean an outlet boundary. This
worked well for instance in a backward facing step case.
Thank you for your time, sorry for the confusion.
On Monday, 19 February 2018 10:50:48 UTC-5, Timo Heister wrote:
> > Does the order in which I apply the nonzero and zero constraints matter?
> These are two independent objects, so no.
> > Currently I apply the inlet and then the no-slip in the
> > thus the bottom and top wall appear after the inlet. Afterward the
> > is put in the zero constraints.
> I don't understand. You need boundary conditions in
> nonzero_constraints and zero_constraints for all boundaries. The
> reason for these two sets is that one is used for the initial solve,
> while the second one is used for the Newton updates.
> Timo Heister
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