7th International Ship Stability Workshop, 1-3 November 2004, Shanghai, China
green water; water on deck; water discharge
Water collected on decks due to waves or result of accidental structural damages cause loss of stability by what is known as the free surface effects. This study focuses on the modeling of the discharge of the collected water in order to establish relationships between the geometrical characteristics of an open deck or damaged hull - its beam, height of the gap (e.g. freeing port) - and wave parameters such as wave length and wave height. A two-dimensional model of the discharge was constructed to visualize the free surface and to measure the flow discharge from a flat bottom. In this study, lengths corresponding to the flooded width of the ship, initial water height corresponding to the collected amount of water on deck and discharge gap height corresponding to the freeing port opening were varied systematically. The time domain discharge flow pattern and free surface form were recorded with a digital camera. The digitized frames were captured on a computer and the location and the form of the free surface were computed. The change in volume, discharge rate velocity at the freeing port and various parameters of the discharge kinematics were calculated from knowledge of the free surface. Additionally, CFD solutions to the problem were carried out. This paper reports some of the findings related to the variation of the discharge gap height and tank length.
7th International Ship Stability Workshop [Proceedings].