WATER-ON-DECK PROBLEM: 2D INVESTIGATION AND MAIN FINDINGS

Present work summarizes the water-on-deck studies performed in the last years by the authors. It is based on the assumptions of head sea waves, no forward motion and 2D flow conditions along the ship centreplane. Experimental, theoretical and numerical investigations are used to draw the main green-water scenarios in terms of the incoming wave steepness and of the ratio between the incoming wave vertical velocity and the vertical velocity at the bow. The following scenarios are identified: dam-breaking (DB) type event, initial plunging followed by a large scale dam-breaking (PDB) type event, plunging wave (PW) type event, hammer fist (HF) type event, flip through without water on deck or with 'white water' (WW). From the experimental evidence PDB is the most common water shipping, while the HF represents the most dangerous. The former is associated with an initial and possibly a later plunging phenomenon, leading to air entrapment, and has a global dam-breaking behaviour. The latter corresponds to a blunt mass of water hitting the deck with possible formation of small cavities and results in more complex water interactions with the superstructures. Flow features and green-water loads are studied for PDB and HF events. PDB events are also examined in terms of hydroelasticity excitation as a consequence of impacts, air-entrapment and related influence on the green-water loads and water-front velocity.