For the special case where the tensor product operation is a contraction of one index and the gradient operation is a divergence, and both F and G are second order tensors, we have ∫ ∫ Ω Ω F ⋅ ⋅ ( ∇ ∇ ⋅ ⋅ G ) d Ω Ω = ∫ ∫ Γ Γ n ⋅ ⋅ ( G ⋅ ⋅ F T ) d Γ Γ − − ∫ ∫ Ω Ω ( ∇ ∇ F ) : G T d Ω Ω .