The research project PrICE is motivated by the reduction of arctic sea ice which triggered an increase in maritime operations in the Arctic. As an alternative to standard shipping routes between Europe and Southeast Asia, the Northern Route can save significant amounts of time and reduce fuel expenses. Supplementary, offshore operations and cruise shipping in arctic regions will increase significantly. As a consequence, accurate and efficient models to predict the loads on vessels that transit regions, which are fully or partially covered by level ice, are required to ensure a safe and economic performance. Nowadays, model tests at ice research facilities are a crucial part of the design process of arctic structures and ice-going ships. However, numerical simulations of ship-ice interaction are believed to become an important part of future design processes.
When attention is directed to the breaking of level ice, several failure mechanisms occur, such as bending, crushing and buckling. Moreover, ice-ice collisions and ice sliding along the hull as well as the hydrodynamic interplay between floating objects are of relevance for the performance of the ship before the ice will eventually be cleared away. Sea ice is a very complex material which is governed by multiple physical phenomena. A direct modelling of the ice mechanics in conjunction with a simulation to assess the ice-transit performance of vessel – possibly also looking at ice clearance aspects – is deemed to cause prohibitive computational cost, thus an alternative engineering approach is seeked.
The present approach simplifies the ice as an homogeneous and isotropic material while focusing on bending. Contact forces between ship and ice are computed depending on contact areas. Varying types of load models and failure criteria can then be used to simulate the breaking process of the ice. The physics engine Open Dynamics Engine is used to compute the collision reaction of all bodies. This includes ship-ice interaction as well as collisions between the ice floes. The coupling of the rigid-body system with the in-house Lattice Boltzmann based free surface flow solver elbe supplements the hydrodynamic forces to update the positions of the ice floes and the hull.
The following example refers to a downward breaking cone representing a typical offshore structure which is colliding with an intact level ice.
The project is funded by the German Ministry of Economics and Technology under the aegis of the BMWi-project PrICE. The work is performed in collaboration with Pella Sietas, Rolls Royce, the Norwegian University of Science and Technology and the Institute for Ship Structural Design and Analysis of TUHH.