Ice Resistance Calculation in Pack Ice Conditions

Abstract

With the decline of the Arctic sea ice cover, more and more marine transportation and oil production are moving into ice-covered waters. Pack ice conditions may be the most common scenario for the ice-going ships in airworthiness seasons, except the icebreaker. During the ship advancing in pack ice conditions, the ice pieces will contact with the hull, interact with the water and even break or crush due to the bend stress, which is a complex process for the numerical simulation. In this study, the ice resistance of ship under the pack ice condition has been estimated using Multi-Material Arbitrary Lagrangian Eulerian formulation and penalty-based fluid structure interaction technique in LS-DYNA. Emphasis in present research has been placed on the hydrodynamic loads occurring during the ship-ice interaction in the numerical model without significant simplification. Validation of the employed fluid structure interaction model was given, especially focusing on the buoyancy and hydrodynamic behaviors of an ice cube. The ice pieces and the ship hull were assumed to be rigid. In addition, an ice filed generation algorithm to generate randomly distributed pack ices was adopted. Finally, the ice resistance of an oil tanker has been calculated and validated by comparing with the empirical formula. Moreover, the necessity to consider water effect in the interaction between ship and ice was discussed. When the hydrodynamic influence of ship is neglected, the ice resistance will be large obviously. In order to simulate the fracture behavior of ice, the material model such as cohesive element model was also considered.