About your plan to define the linear form in general, it is a nightmare. It is probably better to wait for future updates of FF that could manage with line elements in 3d!
I was afraid this would be the answer. The phenomena I try to model rely on this particular transport mechanism. Initially, I wasn’t sure if FEM formulation will allow me to model it this way, I was relying on the intuition that it will. So the good news is, your help on the model example proved it can be done and works as expected.
Do you know if there are plans to bring this functionality in future versions? In one of the topics from 2 years ago prof. Hecht was rather skeptical about introducing 1D integral into 3D models https://community.freefem.org/t/int1d-th-label-on-a-3d-mesh/1892/4, but I don’t know what is the team’s stand on that currently. Maybe I can suggest new functionality somewhere?
You get that u is the basis function of the dof of index j in triangle k.
That will be useful, thank you.