Let $\Omega\subset\mathbb{R}^3$ be a bounded domain with boundary $\Gamma$. Assume that $F\in\mathbb{H}(\text{div}; \Omega)$ is a vectorial function. Denote by $n$ the exterior normal direction to $\Gamma$. The divergence theorem states that $ \int_{\Omega}\text{div}\, F\, d\Omega = \int_{\Gamma}F\cdot n\, d\Gamma. $