This question is throwing me for a loop.
Q: If u = x^2 in the square S = \{ -1<x,y<1\} , verify the divergence theorem when \vec w = \Nabla u :
\int\int_S div\,grad\,u\,dx\,dy = \int_C \hat n \cdot grad\,u\,ds
If a different u satisfies Laplace's equation in S , what is the net flow...