Hi Everyone,
I hope you're all doing well. I was wondering if anyone might have some insight into why this isn't working. I've also reviewed the videos on applying non-Dirichlet boundary conditions in deal.II, and everything seems to align with the code. Despite that, the issue still persists! Thank you in advance for your time and help. On Thursday, March 20, 2025 at 9:51:50 AM UTC+1 Alex wrote: > Dear Prof. Wolfgang, > > Thank you very much for your kind response. > > I sincerely appreciate your insights. However, I believe this aspect has > already been addressed in step-44 through the conditions mentioned below. > // Since the constraints are different at different Newton iterations, > we > // need to clear the constraints matrix and completely rebuild > // it. However, after the first iteration, the constraints remain the > same > // and we can simply skip the rebuilding step if we do not clear it. > if (it_nr > 1) > return; > const bool apply_dirichlet_bc = (it_nr == 0); > > > To verify this, I printed the values of the constraints at each iteration. > Based on my observations, the constraints are populated with values only at > Iteration "0," and in all subsequent iterations, they remain zero. > > Please let me know if you have any thoughts or if I might have overlooked > anything. I truly appreciate your guidance. > > > > On Thu, Mar 20, 2025 at 3:10 AM Wolfgang Bangerth <bang...@colostate.edu> > wrote: > >> On 3/19/25 00:51, Jean-Paul Pelteret wrote: >> > >> > You might want to try either reformulating your boundary conditions as >> updates >> > to the BCs applied at the previous timestep (i.e. constrain the >> increment) or >> > you should refactor the code (assembly, constraints creation + >> something >> > before the Newton iterations start) such that you apply the constraints >> > directly to the solution vector itself. >> >> There is also a discussion on boundary values for Newton methods in >> step-15 >> that you might want to read through. In short, you likely only want to >> apply >> Dirichlet boundary conditions to the first Newton iteration, and then use >> zero >> boundary conditions after that. >> >> Best >> W. >> >> -- >> ------------------------------------------------------------------------ >> Wolfgang Bangerth email: bang...@colostate.edu >> 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 the Google Groups >> "deal.II User Group" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to dealii+un...@googlegroups.com. >> > To view this discussion visit >> https://groups.google.com/d/msgid/dealii/d229e447-a652-4877-8b03-5659c14b83f5%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 dealii+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/dealii/9cbddc6b-c031-4ef1-b5e9-7756c1272fb4n%40googlegroups.com.
