|The project is focused on the erosion at the toe of the mooring structures, caused by the ship propellers during the maneuvering and mooring phases. This problem is becoming very important nowadays due to the evolution of the shipping industry and to the intensification of the use not only of stern main thrusters (conventional or azimuthal) but also lateral bow and stern ones, to maneuver independently without the help of a tugboat. As consequence several harbors have experienced problems at the toe of the existing docks.
The project aims to characterize the flow pattern of the propellers and the erosive potential considering the effect of the pier and ship, using a Lagrangian numerical model (SPH) and physical model tests. The project also allows design and evaluation of protective measures.
The latest recommendations for the design of protection systems of the docks toe based on the determination of the velocities induced at the bottom by the propeller shows significant differences. One of the main problems is the interpretation of parameters related to propellers, but also the fact of not considering important aspects such as different types of propeller (especially hydro-jets), maneuvering practices for docking and undocking, propeller orientation or the confinement effect generated by the dock itself (and the shelter of the vessel).
The research foresees to use and coordinate the following approaches/tools:
• Numerical modeling (leader: UVigo)
• Physical modeling (leader:UPC)
In its preliminary stage, a proper characterization of the representative fleet, related propelling systems and their functional regime during the mooring phases are requested to set up the physical model tests to be carried out at UPC. Then, three scenarios will be investigated by means of numerical and physical modeling:
1. Unconfined case: investigation of effects of jet or turbine propulsion on a soft bottom at different angles and speed/power.
2. Semi-confined: the ship maneuver takes place close to a wall and effects of the propulsion on a soft bottom at different angles and speed/power will be investigated.
3. Double-confined: the ship maneuver takes place close to a hook (end dock) and effects of propulsion on a soft bottom at different angles; speed/power will be investigated.
Finally measures to protect the structures (foot) from undesired effects characterized during phase one and recommendations for ship operability/ maneuvering will be produced based on results of the previous phase.
The project fosters the development of the DualSPHysics model (already in use at FHR) applied to sediment transport and bottom erosion, with a correct treatment of the sediment properties. There is interest in such kind of improvement to apply DualSPHysics in those cases of wave structure interaction with mobile bed (e.g. Geobags, scouring).
It could be eventally applied to lock modelling.