New Insights Into the Flooding Sequence of the Costa Concordia Accident

Abstract

The tragic accident of the Costa Concordia in January 2012 was one of the most severe large passenger ship accident in Europe in recent times followed by a tremendous public interest. We present the results of an in-depth technical investigation of the flooding sequence which lead to the heeling and grounding of the ship. A fast and explicit numerical flooding simulation method has been developed in the last years to better understand accidents like this one caused by complex and large scale flooding events. The flooding simulation is validated with the help of results from model tests and has been successfully applied to the investigation of several other severe ship accidents. It is based on a quasi-static approach in the time domain which evaluates the hydrostatic equilibrium at each time step. The water fluxes through the openings are computed by a hydraulic model based on the Bernoulli equation. Large and partly flooded openings are taken into account as well as conditional openings like the opening, closing and breaking of doors. The fluxes are integrated in the time domain by a predictor-corrector integration scheme to obtain the water volumes in each compartment involved in the flooding sequence. Due to the fact that the accident happened in calm water at moderate wind speeds close to the shore of the island Giglio this quasi-static numerical flooding simulation can be applied. The results of the technical investigation of the Costa Concordia accident obtained with the help of the developed method are presented. These results match well with the heel and trim motions observed during the accident and the chain of events which lead to the final position of the vessel on the rocks in front of the island Giglio. The explicit and direct approach of the method leads to a fast computational run-time of the numerical method. This allows to study several possible accident scenarios within a short period to investigate for example the influence of the opening and closing of watertight doors and to identify a most likely flooding scenario which lead to this tragic accident.