Numerical study on the 6-DOF motions of ship turning in waves.

Ships are often disturbed by waves when they are sailing on sea, and the influence is usually not negligible. When a ship is manoeuvering in waves, the wave will seriously threaten the ship’s navigation safety. Therefore, it is of great significance to study the manoeuverability of a ship in waves, and the study is a hot research topic in recent years. In this paper, the viscous CFD method is used to directly simulate the 6-DOF manoeuvering-seakeeping coupling motions of the series 175 (S-175) container ship model in regular waves. The turning motions of the ship in different wave cases are simulated in the time domain. The Unsteady Reynolds-Averaged Navier-Stokes (URANS) method is adopted to solve the viscous flow around the ship, and the overset grid method is adopted to deal with the rotation of the rudder. Based on the open water characteristic curves, the body force propeller method is used to mimic the propeller behaviour to reduce the calculating cost. The time history of the ship’s force, the characteristic parameters related to manoeuvrability, and some details of the flow field in the typical manoeuvring motion are obtained. At the same time, the model tests of the S-175 container ship turning in waves were carried out in the ship seakeeping/manoeuvrability tank, and the numerical results were compared with the experimental results. The comparison indicates the direct numerical simulation method adopted is a reliable method for predicting ship manoeuvrability in waves.