Dear Wolfgang, Maybe I had not make my question clear. I dont think the question we encountered is not graphical output, instead, I think the the problem we encountered is numerical issue in Deal II. For example, when we take thermal conductivity as 1e6 (the real value of the problem), there always exhibit erroneous results in the figure (see the figure below), in temperature distribution, as high as 24 degree centigrate in the figure, but as theoretical calculation, all the temperatures within the figure should range between 0 and -50 degree. On the contrary, when thermal conductivity was taken as 1e2, the simulation results work well. Moreover, when we make the simulation via Matlab, the simulation results work well even thermal conductivity was taken as 1e6. So we suspect that the high magnitude of thermal conductivity in coupled equation significantly affects the simulation results. But we are really not sure where is the problem and how to fix it, any other suggestions?
We also found in other step (e.g. step 34), temperature-displacement-pressure multi-field problem was implemented by decoupling the temperature field. Best regards! Rongwei Dr. Rongwei Yang (杨荣伟) School of Civil Engineering, Tianjin University, 135 Yaguan Rd, Jinnan District, Tianjin 300350, China P.R. Email: [email protected] *http://jgxy.tju.edu.cn/teachers.asp?id=221 <http://jgxy.tju.edu.cn/teachers.asp?id=221>* [email protected] <[email protected]> 于2024年9月6日周五 09:19写道： > Thanks，Prof. Bangerth, we have used uniform mesh, and the errors appeared > also. We will check and verify the questions you posed. Thanks a lot for > your kindly reply! best regards Yours sincerely Rongwei > > > ---- 回复的原邮件 ---- > 发件人 Wolfgang Bangerth<[email protected]> <[email protected]> > 日期 2024年09月06日 00:19 > 收件人 [email protected] > 抄送至 > 主题 Re: [deal.II] Errors for temperature field occur in a multiphysics > problems > > On 9/5/24 01:07, 杨荣伟 wrote: > > We implemented the work based on Step26 (We really appreciated > > that). Now the problem we encountered is that there still exist > > unexpected errors on the temperature field in Deal II solution (see > > the figures (circles) enclosed in attachment ). We suspect that the > > errors arise from the large magnitude of thermal conductivity (K_T in > > the equations in the attachment), which is equal to 10^6, which will > > render the stiffness matrix being errous. Does anyone can help us to > > figure out the critical errors and make any suggestions? > > At the end of the day, you will have to develop the skills to debug > these sorts of problems -- this will not be the last time you wonder > about the correctness of your program :-) > > In your case, I think you are using an adaptive mesh. Make the problem > simpler: Does the solution look correct if you are using a uniformly > refined mesh? If yes, are you using a higher-order element (e.g., > quadratic shape functions)? If so, go back to linear elements and make > sure the solution is correct. If so, you can try quadratic elements > again, but make sure that what you are visualizing is an adequate > representation of the actual solution -- see > > > https://github.com/dealii/dealii/wiki/Frequently-Asked-Questions#in-my-graphical-output-the-solution-appears-discontinuous-at-hanging-nodes > > There are many more directions one can go into, but these are perhaps > good starting points already. > > Best > W. > > -- > 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/NeV2zRU_aVY/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/95b639b8-7bed-4937-8e87-a3041519510d%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/CAGJ%2BbAFh1U0477KxfCUJQgoGx8aw%3DF5Xi1y1-2iNGMhyh3yicw%40mail.gmail.com.
