Hi Julian Thanks for the tips. My code is actually based on Step 46, but the difference is that in my case I am not solving for a completely new set of variables in each part of the domain. Based on what you are suggesting, wouldn't that mean that the total number of variables/components that I would be solving for is 5 (by summing the multiplicities) instead of 3? That's at least what I inferred from Step 46. Also, is there a more intuitive approach to follow? Because your suggestion means that variables u1 and u2 belong to the first base element in this FESystem
FESystem[FE_Q(1)^3-FE_Nothing^2] but they belong to a completely different base element in the other FESystem FESystem[FE_Nothing^3-FE_Q(1)^2] I think the way the logic is conveyed in Step 46 is more intuitive because Stokes variables which exist in the first base element in one FESystem still exist in the first base base element in the other FESystem but are represented by FE_Nothing instead of FE_Q elements. Thanks, Mohamad On Sun, Apr 7, 2024 at 11:52 PM julian...@gmail.com <julianroth...@gmail.com> wrote: > Hi Mohamad, > > You need to create the two FESystems as follows: > FESystem[FE_Q(1)^3-FE_Nothing^2] and FESystem[FE_Nothing^3-FE_Q(1)^2]. > This way the first three variables u1, u2 and u3 will be only defined in > the first domain and in the second domain we define u1 and u2 as the last > two variables. > For more information on FE_Nothing look at step 46 of the deal.II > tutorials. > Additionally, I also have some code online that uses FE_Nothing: > https://github.com/mathmerizing/TemporalMultirateFEM/blob/main/src%2Fmonolithic_heatwave%2Fmain.cc > Kind regards, > > Julian > On Sunday, April 7, 2024 at 12:24:53 AM UTC+2 mgha...@ualberta.ca wrote: > >> Hello, >> >> I am solving a problem in which I use the FE_Nothing class to represent >> variables that do not exist in parts of the physical domain. My domain is >> split into two parts: In the first part, I solve for all three variables >> (I'll call them u1, u2, and u3) and in the second part of the domain I >> solve for u1 and u2 only. >> For my problem, I use two FESystem objects in the parameter file as >> follows: >> *FESystem[FE_Q(1)^3]* for the first part of the domain >> *FESystem[FE_Q(1)^2-FE_Nothing^1]* for the second part of the domain. >> >> However, this results in the following assertion error: >> >> >> >> >> >> >> >> >> >> >> >> >> >> *An error occurred in line <2478> of file >> <../deal.II/src/source/fe/fe_system.cc> in function >> dealii::FiniteElementDomination::Domination dealii::FESystem<dim, >> spacedim>::compare_for_domination(const dealii::FiniteElement<dim, >> spacedim>&, unsigned int) const [with int dim = 2; int spacedim = 2]The >> violated condition was: this->n_base_elements() == >> fe_sys_other->n_base_elements()Additional information: You are trying >> to use functionality in deal.II that is currently not implemented. In >> many cases, this indicates that there simply didn't appear much of a >> need for it, or that the author of the original code did not have the >> time to implement a particular case. If you hit this exception, it is >> therefore worth the time to look into the code to find out whether you >> may be able to implement the missing functionality. If you do, please >> consider providing a patch to the deal.II development sources (see the >> deal.II website on how to contribute).* >> >> But when I changed the first FESystem into: >> *FESystem[FE_Q(1)^2-**FE_Q(1)^1**]* >> it worked fine because the number of base elements in both FESystems is >> now the same. My question is then, is this assertion necessary? >> >> Thank you, >> Mohamad >> > -- > 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/csAJHjYuK88/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > dealii+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/dealii/0f0b1e5b-5e10-40b9-a5ed-bf6eba6f4d4en%40googlegroups.com > <https://groups.google.com/d/msgid/dealii/0f0b1e5b-5e10-40b9-a5ed-bf6eba6f4d4en%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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 on the web visit https://groups.google.com/d/msgid/dealii/CAP2_OwEcTkCjE54g7QP54PijhcGci4fZfuCFhLH3Ah1Ngw2-2w%40mail.gmail.com.
