Hi, I am using Fenics to perform Finite-Element simulations for coupled magneto-mechanical problems (stationary) and have a problem with the calculation of postprocessing quantities for visualization in Paraview. In my case, the domain contains subdomains with different material parameters. Assigni…

[image] Flifff: self.file.write(self,time) Are you using XDMF and write_checkpoint instead of write function ?

I tried XDMF and pvd files. The results did not change… But I never tried to use the write_checkpoint function, only the write function. I will give it a try and see, if that already answers my question

OK, this did the trick. Now the solutions look more reasonable. As a follow-up question: I still have problems writing my primary fields to an xdmf-file. Currently I am using periodic boundary conditions to determine the fluctuations for my primary field which is approximated by CG2 ansatz function…

So what happens if you only try to project dot(FMacro-I, x) and visualize it with write_checkpoint? As you have not given a minimal example illustrating what FMacro is, there isn’t much I can do. Also, what happens if you only project u into its own space? Does that work?

Sorry, I should have uploaded more of the code… Yes, I checked projecting only u or dot(FMacro-I,x) and both give similar results to what is shown in the picture above. If I just use u without projecting and write it to a .pvd-file, the solution looks as expected. It’s a little bit tricky to really …

[image] Flifff: parameters ["form_compiler"]["quadrature_degree"] = 2 The quadrature degree is too low. Removing this parameter makes everything behave as normal.

OK, thank you! I am currently checking if my results are better without this parameter. I will let you know, if this solves my problem. But shouldn’t a quadrature degree of 3 be OK for Langrangian polynomials of order 2 (if I recall it correctly, 9 Gauss-points are needed for the exact integration f…

Three sounds reasonable. In general FEniCS is quite generous with quadrature points, as it is better to over-estimate than under estimate. I would always start by using fenics automatic choice, then reduce it until you see discrepancies in the result. (Especially since you are setting this parameter…

OK, thanks a lot - for both of my problems!

Preserve Material discontinuities in projection for postprocessing

dokken June 12, 2020, 9:07pm 3

To add some context, see for instance: Access function in time dependent XDMFFile

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Preserve Material discontinuities in projection for postprocessing

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