Identity for $\nabla w .\nabla w$ How can I expand/find an identity for $\nabla w .\nabla w$ so that I get div ($\nabla.$) in the expansion?
Thanks!

$\nabla\cdot(w\nabla w) = \nabla w\cdot\nabla w + w\nabla\cdot\nabla w$, thus
$\nabla w\cdot\nabla w = \nabla\cdot(w\nabla w) - w\nabla\cdot\nabla w$ for instance.
