Dynamic orifice flow model and compartment models for flooding simulation of a damaged ship

Abstract When a damaged ship floods, flows of water and air move from one compartment to another, or to and from the outside. There are two main difficulties in simulation of such flooding. One is the effect of air, and the other is the calculation of pressure in a complex system of openings involving a large number of compartments. The air plays a crucial role in the flooding of some compartments, and the presence of air slows the rate of flooding in vented compartments. However, taking into account the effect of air results in ‘ripples’ of pressure fluctuation. Some other unusual difficulties arise, when many compartments are flooded. In this paper, new models for vented compartments and an accumulator model were proposed, which can adjust the inner pressure automatically, even for systems with many compartments and openings, especially for fully flooded compartments. The dynamic-orifice equation was investigated for use in the case of large openings, so that the ripples in the air pressure that had been caused by the square-root singularity of the existing orifice equation could be eliminated. Application to a recent real accident showed the usefulness of the proposed models.