Estimation of sway force and yaw moment acting on ship in drift motion in shallow water

Abstract

Currently, the ship size is increased dramaticaly to meet the demand for cargo transportation in the world. However, the maneuverability of a large ship will become more difficult, especially when the ship moves in shallow water area. Hence, the influence of water depth on the hydrodynamic forces and moments acting on the ship should be considered more. Many studies have conducted the research on hydrodynamic forces and moments of the ship in deep water, while the effect of shallow water on the ship is being focused on recent years. The article presents the results of the sway force and yaw moment acting on the ship's hull and rudder when the ship moves horizontally based on the computational fluid dynamics method. The sway forces and yaw moments acting on the ship in drifting motion at different speeds and water depths will be analyzed. The results show that the coefficients of the sway force and yaw moment are in good agreement with the experimental data. As the water depth decreases, the sway force and yaw moment acting on the ship also increases. The Y'v coefficient of a ship operating in shallow water with h/T=1.5 and h/T=2.0 increases by 8.5 times and 2.6 times, respectively, compared to the Y'v value of the ship operating in deep water. The coefficient N'v of the ship in shallow water with h/T=1.5 and h/T=2.0 also increased 5.2 times and 2.7 times in comparison with the corresponding of the ship in deep water. Also, the coefficients Y'vvv and N'vvv of the sway force and yaw moment also increase significantly compared to these coefficients of the ship in unrestricted waters.