Natural Boundary Condition for Potential?

[ghost]

What is the natural boundary condition for potential? My best guess is that the dV/dx = 0 at the boundary.

[csdechant]

Just to double check, by natural boundary condition, you mean at a boundary where the potential is not restricted (e.g. a boundary that represents open air). If so, then yes, the BC would be grad(V) = 0.

[ghost]

At a given boundary, grad(V) = 0 holds even if the plasma species have specified BCs on that boundary unless a BC for the potential specifically is provided?

[csdechant]

Could you please give an example of when one might want to define a BC for the plasma species, but not the potential? (Are you still using one of Zapdos's flux BC for the plasma species, or are you defining the species with a new BC)