I performed a simulation of hydrogen transport in W/Cu/CuCrZr in 2D. I used big mesh size to make the computation quick. The exported chemical_pot_conservation derived_quantities file show the result. As is seen in the picture below, the total retention in volume 7 and 8, the flux on surface 15 are missing. Can anyone tell me that what might cause this problem and how to solve it? Thank you!
It is a bit hard to tell without more information.
Are you certain that you have volumes 7 and 8 and surface 15 in your model?
To verify this, open your XDMF mesh files in Paraview.
If you are certain that one of the surfaces is tagged with the ID 15, then what boundary condition did you put on surface 15?
If you haven’t set any BC on this subdomain than the default is “no flux” which would explain why this column is zero.