I'm currently studying a numerical scheme which preserves the divergence through time, i.e $div(A^{n+1}) = div(A^{n})$ where $A$ any vector field in $\mathbb{R}^n$ and $n, n+1$ time stations. This is true in Cartesian coordinates but I was wondering if it could be altered using other kind of coordinate systems, I guess not (using a diffeorphism as a coordinate transform) but what's the theoretical background ?
Thx