![Screenshot_20200205-175120|250x500] Hi guys, My colleague wants me to run this code for him on my laptop, however the Fenics used in the book is very old syntax (pre 2013) and the code isn’t all there. It’s just snippets. Does anybody have the entire code for that problem in modern syntax or can…

I can’t see your screenshot, but do you mean this demo ?

I’m very sorry about my screenshot not working! Unfortunately as a new user I can only post one picture. Here is the picture of the book page with the problem I’m looking at. The code is given in snippets with parts missing and I’m not finding it easy filling the blanks. I think the problem goes on …

Here is my problem that is similar to the book problem. [1]

The demo I linked you to is the basic example of how to find the cutoff frequency in a rectangular waveguide. Hopefully you can figure out the syntax and where you need to go from there to apply it to your specific problem.

Thanks for the reply. Is there a way to change your boundary conditions in the code? I can’t seem to spot any.

It’s been a long time since I’ve looked at waveguide problems. But here’s an example with assumed perfect conductor BCs You need vtkplotter if you want the plotting, installed via pip3 install vtkplotter --user. Otherwise just remove the plotting lines. Just plotting the first 4 propagating modes. …

This is brilliant. Thank you so much. I’ve showed it to my professor and he verified it. It works excellent thank you. Is there a way to do neumann conditions? I’m guessing I just have to change the DIRICHLETBC function?

Yes, just use natural assembly without a DirichletBC. Perhaps you should examine the FEniCS demos . With regards to Maxwell’s equations for a beginner: Take a lot of time to understand what’s going on when you solve a simple Poisson equation with various boundary conditions here . Now take this kno…

Ah, so neumann bc are default in DOLFIN. So the only thing that changes is the mesh being used and a couple of values. Other than that I’d solve like I would for any other mesh?

There is no “default”. FEniCS’s philosophy is finite element matrix assembly of a specified weak formulation. I recommend the demos, and getting to grips with the basics of finite element theory.

Rectangular waveguide problem chapter 34 Fenics book

francesco-ballarin May 21, 2024, 8:27am 16

Please do not duplicate posts. I am going to close this one in favor of Assembling Process.

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Rectangular waveguide problem chapter 34 Fenics book

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