Thank you for your help, I really appreciate it. I thought regarding the second one we can also compute the lump, because we have m_i = sigma (m_ij) = int(phi_i dx) and M_l = diag(m_1,m_2,...,m_N).
Regards Shahin <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> Virus-free. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> On Fri, May 21, 2021 at 9:27 PM Bruno Turcksin <bruno.turck...@gmail.com> wrote: > Shahin, > > The two codes are not equivalent and I think that they are both wrong. The > second code is not lumping anything, you just keep the diagonal of the > matrix and that's it. The first code set lump = 0.0 at the wrong place and > you forgot a += or you need to reorder the loops. I think you want > something like this: > > for(unsigned int i = 0; i<dofs_per_cell; ++i) > > { > > double lump = 0.; > > for(unsigned int j = 0; j<dofs_per_cell; ++j) > > { > > for(unsigned int q_index = 0 ; q_index < n_q_points ; ++q_index) > > { > > lump += fe_values.shape_value(i, q_index) > *fe_values.shape_value(j, q_index) * fe_values.JxW(q_index); > > } > > } > > lump_cell_matrix(i,i) = lump; > > } > > > > Best, > > Bruno > > Le ven. 21 mai 2021 à 14:54, Shahin Heydari <sh1990.heyd...@gmail.com> a > écrit : > >> Dear Bruno >> >> Thank you so much for your reply, It was very helpful. Regarding the mass >> lumping question, I just compute it as follows: >> >> for(unsigned int q_index = 0 ; q_index < n_q_points ; ++q_index) >> >> { >> >> double lump = 0.0; >> >> for(unsigned int i = 0; i<dofs_per_cell; ++i) >> >> for(unsigned int j = 0; j<dofs_per_cell; ++j) >> >> lump += fe_values.shape_value(i, q_index) * >> >> fe_values.shape_value(j, q_index) * >> >> fe_values.JxW(q_index); >> >> >> lump_cell_matrix(i,i) = lump; >> >> } >> >> >> >> or another way can be >> >> for(unsigned int q_index = 0 ; q_index < n_q_points ; ++q_index) >> >> { >> >> for(unsigned int i = 0; i<dofs_per_cell; ++i) >> >> for(unsigned int j = 0; j<dofs_per_cell; ++j) >> >> if(i==j) >> >> lump_cell_matrix(i,j) += fe_values.shape_value(i, q_index)* >> >> fe_values.JxW(q_index) ; >> >> else >> >> 0; >> >> } >> but I am not sure if it always works, what if I want to use Q2, I feel >> like it's not correct. I would be happy to hear your opinion or advice. >> >> Regards >> Shahin >> >> >> On Thu, May 20, 2021, 14:49 Bruno Turcksin <bruno.turck...@gmail.com> >> wrote: >> >>> Shahin, >>> >>> I think this does what you want >>> https://dealii.org/current/doxygen/deal.II/namespaceGridTools.html#addb822f0e3068e48640ecc981ee6c1e6 >>> I am not sure I understand what's your question about lumping. >>> >>> Best, >>> >>> Bruno >>> >>> On Thursday, May 20, 2021 at 4:11:47 AM UTC-4 sh1990....@gmail.com >>> wrote: >>> >>>> Dear all >>>> Hello, hope you are safe and healthy. >>>> >>>> I am trying to use deal.ii for my work but I have encountered some >>>> difficulties during implementation and I would highly appreciate it if you >>>> can help me with it. >>>> >>>> I want to use flux corrected transport scheme, and for this I should >>>> go through all the neighbouring of a certain node and compute the fluxes to >>>> that node, there is also a flux limiter which is depend on this flux, so I >>>> can't go cell by cell as many of the tutorial in dealii has suggested, >>>> instead I need to go through a patch consist of all neighbouring cells, now >>>> I am just wondering whether there is any class in dealii which can do this >>>> process, I would really appreciate any help and feedback from you. >>>> >>>> On the other hand there is a part in which I should compute a lump >>>> matrix and add it to the scheme, but I feel like this is also wrong and >>>> should not be done over a cell(please see the attachment). >>>> >>>> I am trying to implement some initial conditions, whenever I run each >>>> part of the code separately I can get the picture but when I am trying to >>>> put it all together in a loop it won't work (please see the attachment). I >>>> would be thankful if you could let me know how I can fix it. >>>> >>>> I am looking forward to hearing from you. >>>> Sincerely >>>> Shahin Heydari >>>> >>>> -- >>> 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/c77c7def-c89e-4bdb-8f2d-6cc23fc1eec8n%40googlegroups.com >>> <https://groups.google.com/d/msgid/dealii/c77c7def-c89e-4bdb-8f2d-6cc23fc1eec8n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> >> >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=icon> >> Virus-free. >> www.avast.com >> <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail&utm_term=link> >> <#m_7582570965796856719_m_1817937648256189538_m_-1766663769396021098_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >> >> -- >> 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/0B1nGC0O1Tc/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/CALUbCFwGm8duazCftHqU%2BOUzkOxHxgsm%2B4EgZZk1r9Thf%3DiTQA%40mail.gmail.com >> <https://groups.google.com/d/msgid/dealii/CALUbCFwGm8duazCftHqU%2BOUzkOxHxgsm%2B4EgZZk1r9Thf%3DiTQA%40mail.gmail.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/CAGVt9ePyAxprvkxEEwOG4du9_hp7bcQFq%2B2mHBfntA7rY4-p7g%40mail.gmail.com > <https://groups.google.com/d/msgid/dealii/CAGVt9ePyAxprvkxEEwOG4du9_hp7bcQFq%2B2mHBfntA7rY4-p7g%40mail.gmail.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. 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