Dear Daniel,
Thank you very much! I can test my period boundary condition added truly. Your advision helps me a lot ! As my question is about periodic boundary condition like [image: 42.JPG] <about:invalid#zClosurez> just like Dirichlet boundary condition. But if "periodic boundary condition" means that all information of solution on periodic faces pair are equal, not only the value of solution (like Dirichlet boundary condition above), but also gradient value of solution (like Neuman boundary condition, as normal vector is opposite, so if grad_u_on_left = grad_u_on_right, for example, so n_left * grad_u_on_left + n_right * grad_u_on_right, top and bottom as well) . In my case, periodic boundary condition should include [image: 46.JPG] <about:invalid#zClosurez> Does deal.ii implement this kind of periodic boundary condition in fact? Is it different from what we have done above for periodic boundary condition like Dirichlet? Thank you very much! Best, Chucui -- 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.