A hybrid approach to flooding and damaged ship dynamics

Strathclyde theses - ask staff. Thesis no. : T13131This thesis presents the development and application of a numerical tool that couples a Navier-Stokes (NS) solver and a seakeeping solver to study the behaviour of a damaged ship upon flooding. Firstly, an NS solver that combines the volume of fluid (VOF) method with dynamic mesh techniques was developed to calculate the interactive dynamics of a damaged ship and floodwater. The VOF method was used to capture the fluid interface. The dynamic mesh techniques were employed to update the mesh following transient ship motions. To validate its performance in addressing complex free surface motion, the solver was firstly applied to several simple test cases including dam break, tank sloshing and compartment flooding. The benchmarking studies confirm that the present method is effective in solving free surface flow problems even with strong non-linearity. Then the solver was used to simulate the flooding process of a damaged barge which was fixed or freely floated in calm water. In comparison with the experimental data, both the ship and floodwater motions are well predicted by the present method. Then, a hybrid method, which couples the present NS solver and another in-house seakeeping solver based on potential flow method, was developed to study damaged ship flooding in waves. The dynamics of water flooding and sloshing in the ship compartments were calculated by the NS solver, whereas the hydrodynamic forces induced by the sea on the external hull surface were calculated using the seakeeping solver. The hybrid approach was tested by simulating the roll decay of a damaged Ro-Ro ferry and free motion of the ferry in regular beam seas. Validation against experimental data shows that the proposed method ensures acceptable numerical accuracy in flooding simulations while reducing the computational cost. In addition, the interactive dynamics of ship, sea wave, water flooding and sloshing were analyzed using the hybrid method. In conclusion, the proposed hybrid method provides a reliable and efficient tool for analyzing flooding and damaged ship dynamics. Its application could assist in understanding of the intricate flooding mechanism that remains limited for ship researchers, designers and safety authorities.This thesis presents the development and application of a numerical tool that couples a Navier-Stokes (NS) solver and a seakeeping solver to study the behaviour of a damaged ship upon flooding. Firstly, an NS solver that combines the volume of fluid (VOF) method with dynamic mesh techniques was developed to calculate the interactive dynamics of a damaged ship and floodwater. The VOF method was used to capture the fluid interface. The dynamic mesh techniques were employed to update the mesh following transient ship motions. To validate its performance in addressing complex free surface motion, the solver was firstly applied to several simple test cases including dam break, tank sloshing and compartment flooding. The benchmarking studies confirm that the present method is effective in solving free surface flow problems even with strong non-linearity. Then the solver was used to simulate the flooding process of a damaged barge which was fixed or freely floated in calm water. In comparison with the experimental data, both the ship and floodwater motions are well predicted by the present method. Then, a hybrid method, which couples the present NS solver and another in-house seakeeping solver based on potential flow method, was developed to study damaged ship flooding in waves. The dynamics of water flooding and sloshing in the ship compartments were calculated by the NS solver, whereas the hydrodynamic forces induced by the sea on the external hull surface were calculated using the seakeeping solver. The hybrid approach was tested by simulating the roll decay of a damaged Ro-Ro ferry and free motion of the ferry in regular beam seas. Validation against experimental data shows that the proposed method ensures acceptable numerical accuracy in flooding simulations while reducing the computational cost. In addition, the interactive dynamics of ship, sea wave, water flooding and sloshing were analyzed using the hybrid method. In conclusion, the proposed hybrid method provides a reliable and efficient tool for analyzing flooding and damaged ship dynamics. Its application could assist in understanding of the intricate flooding mechanism that remains limited for ship researchers, designers and safety authorities