With the development and utilization of ocean resources, maritime transportation is becoming increasingly busy. Stopping ability has great effect on the safety of ship maneuvering for those large ships. In this paper, naoe-FOAM-SJTU solver with 6DOF motion module with a hierarchy of bodies developed by Wan Decheng's research team in Shanghai Jiao Tong University is used to numerically investigate complex ship motion problem in stopping maneuver. The simulation starts from the steady state of self-propulsion and the propeller is controlled to a reverse speed to achieve the ship stopping condition. Detail information of the flow field during stopping maneuver are presented and analyzed to explain the stopping effect. The predicted results for the stopping maneuver in calm water are compared with the corresponding experimental data. The comparison is satisfactory and shows that the naoe-FOAM-SJTU solver is feasible for the direct simulation of stopping maneuvers. And the calculation results can provide suggestions when designing a ship or choosing stopping method.
In recent years, ships tend to become larger for reducing the cost of shipping and improving the transport efficiency. Since the large size worsens the maneuverability, accidents can easily occur in the crowded ports and channels. Therefore, it is significant to study the stopping ability of large ships to prevent the ship from collision and to ensure the safety of the ship sailing near the port.
Generally, reversing the propeller is still the most common operation when a large ship needs to brake to prevent collision. In the procedure of stopping manuever, the bow will turn left or right because of the side forces at the aft caused by reversing propeller. The existence of the transversal force caused by reversing propeller is determined by Chislett and Smitt (1972) through a ship model test. The stopping trajectory is shown in Fig. 1. Good stopping ability means minimum stopping distance, horizontal distance and yaw angle.