Maybe there are something wrong on the boundary condition on phi

[candy29333]

Hello, I’ve been using this software to write programs recently. On a whim, I printed out the values of the electric potential on the upper and lower surfaces. To my surprise, I found that they differ significantly from the prescribed fixed values (0 and 5). Could you please advise whether there might be an issue somewhere in the code?

[ajnonaka]

Are those values from the cell-centers adjacent to the boundary? If so this could make sense as the Dirichlet values are imposed exactly on the boundary (the face). So the cell-centered values will move off of the prescribed values by a little bit.