A numerical study on the added resistance and motion of a ship in bow quartering waves using a soft spring system

The prediction of resistance performance in oblique waves have been a key issue for the accurate estimation of added resistance of ships in the actual operating state. Therefore, in this paper, the added resistance of a large tanker in the bow quartering waves (180 degrees, 150 degrees, 120 degrees) was studied by applying a computational fluid dynamics (CFD) solver based on the unsteady Reynolds-averaged Navier-Stokes equations. In addition, the forces and motion responses in bow quartering waves according to the captive test (heave, roll, and pitch free) and soft spring test (6 DOF) were investigated. To validate the CFD results, it was compared with the model test results showing good agreement. The maximum value of the added resistance was observed between 180 degrees and 150 degrees, and it decreased sharply at 120 degrees. The peak of the added resistance moved to a shorter wave region. The differences in added resistance, heave, and pitch motions in oblique wave according to the degree of freedom were insignif-icant. However, the discrepancy in roll motion occurred due to the forces and moments differences caused by the degree of freedom. The tendency of added resistance in the bow quartering waves and the forces and motion responses according to the degree of freedom were also investigated.