URANS assessment of ship extreme roll event in irregular stern quartering sea

Abstract

Abstract In this study, the extreme roll events of a free-running ONR Tumblehome model in stern quartering seas are predicted by an unsteady Reynolds-averaged Navier–Stokes (URANS) solver coupled with a dynamic overset grid approach. The validation study is first performed for the prediction of ship extreme roll amplitude in regular waves, indicating satisfactory agreement with an average difference of less than 3% between the simulation and experimental results. The URANS approach is then applied to the assessment of the extreme roll events as the ship is sailing in irregular seas. The ship is free to 6 degrees of freedom (DOF) motions with a course-keeping control. It is concluded that the ship’s yaw motion plays an important role in the occurrence of ship extreme roll events in an irregular stern quartering sea. A rapid increase of yaw angle is observed for the ship coupled with the occurrence of the extreme roll, even leading to the capsizing.