Numerical modeling of ice loads on an icebreaking tanker: Comparing simulations with model tests

Abstract

A numerical model is presented to simulate the dynamic ice loads acting on an icebreaking tanker in level ice, considering the action of ice in the vicinity of the waterline caused by breaking of intact ice and the effect of submersion of broken ice floes. The numerical simulations are also compared with ice tank tests. For these tests, ice rubble accumulation contributes to a high ice load and thus was taken into consideration in the simulations in addition to the ice-breaking forces. In the simulations, an icebreaking tanker fixed by artificial high stiffness mooring lines was towed through an intact ice sheet. The setup of the numerical simulation was as similar to the ice tank setup as possible. The ice loads were compared between model tests and simulations by varying the ice drift speed, the relative ice drift angles and ice properties. The results show that the simulated ice loads are in good agreement with the experimental results in terms of the mean values, standard deviations, and maximum and extreme force distributions, although there are some deviations between the predicted and measured results for certain cases. Some of the possible reasons that may explain the differences have been presented. The numerical model can be applied to predict the ice loads on moored or dynamic structures with station-keeping operations in level ice with a constant drift direction, and it can be extended to variable relative ice drift directions.