dolfin team mailing list archive

[ndl@xxxxxxxxxxxxxx]

On Monday 16 June 2008, Anders Logg wrote:
> On Mon, Jun 16, 2008 at 05:40:00PM +0100, Nuno David Lopes wrote:
> > Is this problem really solved?
>
> No, it looks awful here as well. It used to look much better.
>
> > I'm get oscillating spikes  all over the boundary.
> > The same for a standard 2d cavity.
>
> For which element types are you getting the spikes?
in 2D the same as in demo: triangle 
Lagrange 2 for velocities and Lagrange 1 for pressure.

>
> > Also in 3d experiments.
> > I'm getting  the feeling that only the the dofs associated with the
> > triangle vertices are getting the boundary conditions, (or something like
> > that is happening.)
>
> Can you check for which degrees of freedom we are enforcing
> boundary conditions? Are we missing any?
I will try to get into that  first thing tomorow. I hope i'll understand it!!!
I think I've seen  something similar some time ago, don't remember if it was 
in my old hand-made c++  codes, using Uzawa methods, 
or in FreeFem++ also with Uzawa methods, 
 but i've solved it and I really don't remember what was the problem. 




-- 
Nuno David Lopes