FEM Discretization of Moltres Equation

[habibhrk]

Hi @smpark7 Sir! i need help to understand the FEM-DISCRETIZATION of (moltres coupled equations), like explained in moose framework "https://mooseframework.inl.gov/workshop/index.html#/8/6", from strong form to weak form and relate it with moltres/src/kernels.

[smpark7]

Hey @habibhrk, sorry for the late reply. Unfortunately, we currently don't have the weak forms in our current documentation. We're working on it so you can check back in a few weeks. In the meantime, you can find them in the kernel source code under the computeQpResidual member functions. Those expressions correspond to the mathematical weak forms.

[habibhrk]

Dear @smpark7 ,I hope this message finds you well. I wanted to inform you that I've been working on developing the weak form for Moltres, as indicated in the attachment below. I've sought assistance from the Moose FEM implementation during this process. I kindly request your expertise in reviewing my work to ensure its correctness. If you happen to identify any issues or discrepancies, I would greatly appreciate your guidance in rectifying them on my end. Additionally, I have conducted a comparison using the computeQpResidual for each corresponding term.
FEM_MOLTRES_WEAK_FORM.pdf

[smpark7]

Hey @habibhrk, this is a good summary of the Moltres finite element implementation. The weak forms seem mostly correct. The neutron diffusion term should have a boundary contribution similar to your approach for MatDiffusion. The boundary contributions should then be summed up like the volumetric contributions as shown on mooseframework.inl.gov/workshop/index.html#/10/5.