Numerical evaluation of a new high pressure water jet interference method for bridge pier protection against vessel collision

Ship-bridge collisions happen from time to time globally, and the consequences are often catastrophic. Therefore, this paper proposes a new high-pressure water jet interference (HPWJI) method for bridge pier protection against vessel collision. Unlike traditional methods that absorb energy by anti-collision devices to mitigate the impact force of ships on bridges, this method mainly changes the direction of ship movement by lateral high-pressure water jet impact, so that the ship deviates from the bridge piers and avoids collision. This paper takes China's Shawan River as the background and simulates the navigation of a ship (weighing about 2000 t) in the HPWJI method in the ANSYS-FLUENT software. The simulation results show that the HPWJI method has a significant impact on the direction of the ship's movement, enabling the ship to deviate from the pier, which is theoretically feasible for preventing bridge-ship collisions. The faster the ship's speed, the smaller the lateral displacement and deflection angle of the ship during a certain displacement. When the ship speed is less than 7 m/s, the impact of water flow on the ship's trajectory is more significant. Finally, this paper constructs a model formula for the relationship between the lateral displacement and speed, and surge displacement of the selected ship. This formula can be used to predict the minimum safe distance of the ship at different speeds.