Giorgos, there can be several reasons for this: 1. You forgot a ConstraintMatrix::distribute() call (after solving) 2. Your ConstraintMatrix is inconsistent (for example if you manually set boundary ids or values in the ConstraintMatrix) 3. If you do some kind of nonlinear iteration, you might not treat residuals of constrained entries correctly. 4. It might be a visualization artifact (you do not transfer the ghost values over correctly).
This is an annoying thing to debug. Good luck. On Thu, Feb 15, 2018 at 5:10 AM, Giorgos Kourakos <gio...@gmail.com> wrote: > Hi deal.ii experts, > > I have the following issue and I'd like if you could give me directions > what to look for. > > I'm attaching a figure from two consecutive iterations: > The black line shows how the triangulation is split to different > processors. > The red line indicates a Dirichlet boundary condition that happens to > start > exactly at the edge of the cell and spans almost half cell (of the 1st > iteration). > > ITERATION 1 > > > <https://urldefense.proofpoint.com/v2/url?u=https-3A__lh3.googleusercontent.com_-2DtFrSyl1GugA_WoVYmCxSgFI_AAAAAAAAFu4_BfqET6F0me4SpGLa9gUHgPQtfns7XqMlgCEwYBhgL_s1600_Iter1.png&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=FXNP1TzxXyujwfeH30hq_c08Gw_Elq8I27NRMvHfhSo&s=mSs_5YSCWmj6dXUjBuHtDAt2lgF8lxKKthyAfKmPlzA&e= > > > > > ITERATION 2 > > > <https://urldefense.proofpoint.com/v2/url?u=https-3A__lh3.googleusercontent.com_-2DfVK1tw5ifWM_WoVY77uLAtI_AAAAAAAAFu8_EN2VpOEiOZYPi9lf5Iocjf9ego3-2DFMhnwCLcBGAs_s1600_Iter2.png&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=FXNP1TzxXyujwfeH30hq_c08Gw_Elq8I27NRMvHfhSo&s=0so5FiG8ExQe6sNy3sd11WRW3vTLrynubIFB2KB2bDE&e= > > > > > You can see that there is an artifact in the solution right where the > border between the processors and the edge of the boundary conditions is. > If I change slightly the boundary conditions e.g. expand it to the left > then the solution is getting smooth. > > Any advice? > > Thank you > > Giorgos > > > > -- > The deal.II project is located at > https://urldefense.proofpoint.com/v2/url?u=http-3A__www.dealii.org_&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=FXNP1TzxXyujwfeH30hq_c08Gw_Elq8I27NRMvHfhSo&s=XbXGlLUFFDbIPBMwMupIaGv8DRL-hOQ-hF_Lf6R-dNE&e= > > For mailing list/forum options, see > https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=FXNP1TzxXyujwfeH30hq_c08Gw_Elq8I27NRMvHfhSo&s=JcywWm3IbaPXDhLbQThfRGdhiH0yy7CL9yt0jiWtsGQ&e= > > forum/dealii?hl=en > --- > You received this message because you are subscribed to the Google Groups > "deal.II User Group" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to dealii+unsubscr...@googlegroups.com. > For more options, visit > https://urldefense.proofpoint.com/v2/url?u=https-3A__groups.google.com_d_optout&d=DwIBaQ&c=Ngd-ta5yRYsqeUsEDgxhcqsYYY1Xs5ogLxWPA_2Wlc4&r=4k7iKXbjGC8LfYxVJJXiaYVu6FRWmEjX38S7JmlS9Vw&m=FXNP1TzxXyujwfeH30hq_c08Gw_Elq8I27NRMvHfhSo&s=UC01YylZx5IunNqH7OX7-0a-V1zRp9t1_64E4cNepGw&e= > . > -- Timo Heister http://www.math.clemson.edu/~heister/ -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
