Abstract:
Sea waves inside harbors can affect scheduled port operations. Hence it is
important to correctly predict and characterize the wave field inside ports and to describe the
movements of the ship and forces acting upon it. A classical approach is to assume that shipwave
interaction is linear, [1]. Then it is possible to decompose it in the so-called radiation
and diffraction problems. Numerical models that solve such problems have been developed
and used by the offshore industry for quite a while, [2], to study the interaction of sea-waves
with floating objects. However, these models cannot be used to solve the diffraction problem
of ships inside harbor basins where nearby reflecting boundaries and shallow depths create
very complex nonlinear wave fields.
A new set of procedures using coupled models is proposed in this work. First, a Boussinesqtype
finite element wave propagation model is used to determine the wave field in the
numerical domain containing the harbor. Then the velocity potentials are evaluated at the
ship’s hull and finally, the Haskind relations [3] are used to determine the wave forces on the
ship along the six modes of motion (heave, sway, surge, roll, pitch and yaw). This new
methodology for the evaluation of diffraction forces on a ship inside a harbor basin is
presented and tested in this paper. Movements of the moored ship and tensions on the
mooring system are obtained using a numerical solver for the motion equations of a moored
ship. An application to an open coast harbor is presented.
