The Green function of the theory of diffraction radiation of time-harmonic (regular)
waves by an offshore structure, or a ship at low speed, in deep water is considered. The Green
function G and its gradient ∇G are expressed in the usual manner as the sum of three com- ponents
that correspond to the fundamental free-space singularity, a non-oscillatory local flow, and waves.
Simple approximations that only involve elementary continuous functions (algebraic,
exponential, logarithmic) of real arguments are given for the local flow components in G and
G. These approximations are global approximations valid within the entire flow region, rather
regions as can be found in the literature
