No abstract

Global warming has caused significant changes in the environment of the Arctic. Due to the shipping economy and efficiency, the number of ships sailing in the Arctic region has been increasing recently. Since pack ice is a common ice condition in the Arctic, studying the ship-ice interaction in the pack ice area is significant to the ship navigation in this area. This paper applies the fluid-ice coupling method combining Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM) to establish the numerical model for investigating the ship-ice interaction in the pack ice area, considering the influence of flow field. Based on the CFD-DEM coupling method, the ship-ice interaction is simulated for the KRISO Container Ship (KCS). Through the comparison with the results of empirical formulae and experimental measurements, it is found that the numerical model can not only predict the ice resistance more accurately, but also simulate the typical phenomena of ship-ice interaction. Besides, the influences of ice concentration and ship speed on the ice resistance, and the impact of ship-generated waves on the motion of pack ice are studied.

When a ship sails in pack ice area, it not only collides with the ice but also interacts with the water, generating ship-generated waves. The role and influence of ship-generated waves on the ship-ice-water interaction have not been thoroughly studied. In this study, a numerical model with ship-generated waves is established using a coupled Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM), and an appropriate contact model is selected for numerical simulations. Meanwhile, a simplified numerical model without ship-generated waves is proposed. By comparing the simulation results under the same simulation conditions with and without ship-generated waves, the effects of ship-generated waves on the phenomena of ship-ice-water interaction, longitudinal and lateral contact forces between the ship and pack ice, and ice resistance are analysed, along with the underlying mechanisms. The results indicate that the ship-generated waves can mitigate and reduce the collision intensity and contact frequency between the ship and pack ice, resulting in a decrease in the contact forces and ultimately achieving a significant reduction in ice resistance. Furthermore, this mitigation effect becomes more pronounced with increasing ship speed.

For a ship navigating in waterways covered by pack ices, the ice load including resistance prediction is a critical issue at the design stage, which is directly related to the safety of the ship, and it is of great significance to the research of ship propulsion efficiency. This paper adopts a coupled numerical method to simulate the ship-ice interaction under pack-ice conditions: the fluid flow is solved by Computational Fluid Dynamics (CFD) method, while the governing equations of ice is solved and the ship-ice and ice-ice collisions are simulated by the Discrete Element Method (DEM). In addition, this method is also capable of building a random pack ice field. The DEM-based ice particles are established according to the model test conditions and the parameters in a published reference. The comparison between the present results with the model test data and the results in another study by the Finite Element Method (FEM) under the same conditions shows that the numerical model established in this paper has higher accuracy in predicting ice resistance. On this basis, the influence of ship speed on the ice resistance under different concentrations of pack ice is investigated.