A numerical simulation method for transient behavior of damaged ships associated with flooding

In order to secure the survivability of damaged ships in flooding situations, time-domain simulation is necessary for the quantitative safety assessment, which can predict ship's transient behavior associated with flooding. A numerical simulation method for damaged ships, solving equations of motion with hydrodynamic forces estimated by the semi-implicit MPS (Moving Particle Simulation) for damaged parts and by the potential flow theory for intact parts, has been proposed by the authors (Hashimoto et al., 2013). The validity of the proposed method was demonstrated through comparisons with model experiments in 2-D flooding situations. However it is difficult to apply this simulation method directly to realistic flooding situations because number of particles increases tremendously in 3-D MPS simulation. In this research, the semi-implicit MPS is replaced with the explicit MPS to reduce the CPU cost. In addition, GPGPU (General Purpose computing on Graphics Processing Units) technology is introduced to accelerate the MPS simulation, in which parallel computing runs on GPUs instead of CPUs, so that sufficient number of particles can be used to perform complicated 3-D flooding simulations. In order to validate the developed simulation method, dedicated model experiments are newly conducted. One is a forced roll test for a flooded car-deck compartment and the other is a ship flooding test using a PCTC (Pure Car and Truck Carrier) model. Through comparisons between the model experiment and the numerical simulation, it is well demonstrated that the explicit MPS has good ability to simulate complicated floodwater flows in the car-deck compartment and the developed simulation method can well reproduce ship's transient behavior associated with water flooding.