where F and G are differentiable tensor fields of arbitrary order, n is the unit outward normal to the domain over which the tensor fields are defined, ⊗ ⊗ represents a generalized tensor product operator, and ∇ ∇ is a generalized gradient operator. When F is equal to the identity tensor, we get the divergence theorem ∫ ∫ Ω Ω ∇ ∇ G d Ω Ω = ∫ ∫ Γ Γ n ⊗ ⊗ G d Γ Γ .