Divergence Theorem (Gauss’, Ostrogradsky’s) to Measure Flow

Example showing that the volume integral of the divergence of f = surface integral of the magnitude of f normal to the surface (f dot n)

%% Divergence Theorem to Measure the Flow in a Control Volume (Rectangular Prism)
% Example Proof: flow = volume integral of the divergence of f (flux density*dV) = surface integral of the magnitude of f normal to the surface (f dot n) (flux*dS)
% by Prof. Roche C. de Guzman