Thanks for the clarification, Dr. Bangerth. I think I will use the zero boundary condition to test whether finite element spaces are appropriate.
Best, Zhuoran On Tue, Jun 8, 2021 at 12:19 AM Wolfgang Bangerth <[email protected]> wrote: > On 6/6/21 10:35 PM, Zhuoran Wang wrote: > > I'm now trying to use WG(P1,P1) to solve Darcy. For WG(P0,P0), I used > FE_DGQ > > and FE_FaceQ which are the same as FE_DGP and FE_FaceP. But for higher > > elements, I need to use FE_FaceP. > > If the face dof is correctly figured out, I suppose I can assign the > D.B.C to > > constraints by myself. Is that correct? > > The issue is that FE_DGP is not interpolatory (i.e., the basis functions > do > not have the phi_i(x_j)=delta_ij property), and consequently the > VectorTools::interpolate_boundary_values function does not work. > > But you can do the equivalent work yourself: > for (cell=...) > for (face=...) > if (face->at_boundary()) > { > get the DoF indices for that face, which in your case will only > correspond to the FE_FaceP component > determine which values these DoFs need to have > add the corresponding constraints to the AffineConstraints > object > } > > The second step in the inner loop might be the difficult one if you have > nontrivial boundary values since then you probably want to compute the > projection of these boundary values onto the finite element space on that > face. But if you have zero boundary values, for example, then you'd just > set > all DoFs to zero in that loop. > > Best > W. > > > -- > ------------------------------------------------------------------------ > Wolfgang Bangerth email: [email protected] > www: http://www.math.colostate.edu/~bangerth/ > > -- > 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 a topic in the > Google Groups "deal.II User Group" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/dealii/TX_xy-KFDMQ/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/1ef2ff40-d865-dba5-847f-d5ad859ab04a%40colostate.edu > . > -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/dealii/CAO_HR-j7Bhq6vYoW-%3DNwr6bcUTn160NN2D6N6yvbYXF%2B8pyu9A%40mail.gmail.com.
