ABSTRACT
This paper presents a numerical prediction of the hydrodynamic forces on a container ship under ship-bank interaction. The hydrodynamic forces in the horizontal plane and ship squat are predicted for different water depths and ship-to-bank distances. Results show that the change of sway force direction, from a suction force to a repulsive force, is closely related to water depth and ship speed. The detailed force distributions and wave profiles explain that the wave action between the ship and the bank leads to the repulsive sway force as well as the large yaw moment in the condition of very shallow water or high speed.
When a ship sails parallel close to the wall of a quay or a canal, a hydrodynamic interaction between the ship and the wall occurs, which is known as bank effect. For a long time, researchers have been focusing on the bank effect on low-speed displacement ships. With the trend in building high-speed vessels of ever-increasing size, for example, ultra-large container ships, the gap of confronting extreme confined water is reduced for ships today, like operating a ship in shallow water with a under keel clearance (UKC) of 20% of draft. Different from the hydrodynamic loads on a low-speed ship under bank effect, of which the sway force is a suction force towards the wall, on a high-speed ship the sway force changes direction and becomes a repulsion force. Besides, the conclusion drawn from early studies, like Norrbin (1974), was that the bank induced sway force and the bow-out moment (a yaw moment pushing the bow away from the bank) are proportional to the square of speed. However, later experiments show that the loads will increase with speed to an order higher than two for very shallow conditions, see Dand (1981), Li et al. (2001) and Lataire (2014).
