Re: gradient of divergence

Thanks Pu.
We have:
grad div F = [F1xx+F2yx, F1xy+F2yy]; (1)
div(c*grad F) = [c11*(F1xx+F1yy)+c12*(F2xx+F2yy), c21*(F1xx+F1yy)+c22*(F2xx+F2yy)] (2)
where c=[c11, c12; c21, c22], hence, it seems to me that mixed partial derivative terms in (1) never appear no matter how to choose the coefficient c if we use the Coefficient Form PDE to represent the gradient of divergence. Am I correct?

Thanks,
Tony