I have solved a PDE and would like to confirm that the neumann boundary conditions are correctly applied. Solution post How to check that the Neumann boundary condition is correctly applied - #4 by nate gives a way to do this in old dolfin. The syntax changed in non-intuitive manner. Anyone knows how to translate the solution to dolfinx?
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How to compute boundary integrals are for instance covered in:
https://jorgensd.github.io/dolfinx-tutorial/chapter2/ns_code2.html#verification-of-the-implementation-compute-known-physical-quantities