Due to the effects of global warming, the Arctic is rapidly transforming into a navigable ocean. During the navigable months, Arctic sea ice along the shipping routes are observed to be dominated by unconsolidated ice floes. Therefore, ice resistance must be considered for ships sailing in the Arctic regions. In this paper, we aim to use the discrete element method to analyze the ice resistance of ships in ice floes. In addition, the influence trend of ship speed and other parameters on ice resistance is analyzed, and the parameters are sorted according to the degree of influence.
Due to the effects of global warming, the Arctic is rapidly transforming into a navigable ocean. For shipping companies, the Northwest Passage (NWP) and the Northern Sea Route (NSR), are shorter alternative routes to connect Europe, North America and Asia than the traditional routes via the Panama and Suez Canals, resulting in up to 40% savings in distance as well as time, fuel, and emissions (Smith and Stephenson, 2013). Despite the reduction in ice cover in the polar seas, Arctic waters are only navigable for non-icebreaking commercial ships in the summer season, i.e., between July and October. During these months, Arctic sea ice along the shipping routes are observed to be dominated by unconsolidated ice floes. The interaction between ship and ice floes results in increase of the ship's resistance. Ice resistance is an important factor that affects the ship's fuel consumption. Therefore, ice resistance of ships sailing in the Arctic region needs to be studied.
Ship resistance in ice floes has been studied by Hansen and Løset （1999）, who used a two-dimensional disc to replace the floe ice and used the discrete element method (DEM) to study the ship-ice force in ice floes, laying a foundation for the later ship-ice interaction research. Later, three-dimensional objects were also used in DEM to simulate the destruction process of sea ice under the action of ships and obtain ship resistance (Lau and Lawrence et al., 2011). Su and Riska et al. (2011) used numerical simulation to study the resistance of the ship in the ice area and the maneuverability of the ship. Kim and Lee et al. (2013) used the finite element software LS-DYNA to simulate the resistance of the broken ice channel, and then compared the simulation results with the experimental results of the Korean ice pool, and the two results met the error requirements. Based on the Lattice Boltzmann fluid solver, Janßen and Mierke et al. (2017) simulated the complex fluid-ship-ice interaction. The fluid-structure interaction (FSI) method is used to study the ice resistance caused by the interaction of ship ice during ship navigation, and the results are compared with the results of model ship tests conducted in a towing tank with ice to discuss the feasibility of the FEM (Guo and Zhang et al., 2018). In addition, the energy dissipation caused by the collision of ice floes was numerically simulated using the DEM method (Herman, 2018; Herman and Cheng et al., 2019). Kim and Kim et al. (2019) used the discrete element method to simulate the interaction between fixed structures and ice floe, and studied the numerical simulation of ice abrasion caused by unbreakable ice floe. In addition, model test in pack ice conditions is carried out (Huang and Li et al., 2016; Guo and Xie et al., 2018). Guo and Xie et al. conducted a model test, with floating paraffin wax blocks acting as ice on the water, and measured the resistance of the advancing ship. They decomposed the resistance into two parts, the resistance in open water and the ice resistance due to contact with ship ice.