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The artificial ice particles were placed in the channel by hand


test programme was done with a model with the original and the new coating. With each coating, four repeat runs were conducted at three model velocities (0.15, 0.30 and 0.50 m/s). The new coating reduced the sub- mersion resistance by up to 21% depending on the velocity. As a result, the difference between the artificial ice tests and the Lindqvist formulation was below 8% for higher velocities. For the 0.15 m/s runs the difference was still 37%. Artificial ice can therefore not be regarded as a substitute for the refrigerated ice used during model tests in ice tanks.


Despite the difference in measured submersion resistance, artificial ice serves as a very good validation opportunity for simulations that were carried out simultaneously with MARIN’s in-house simulation tool XMF, of which aNySIM is one of the modules. With this hydrody- namic tool, ice is simulated as numerous rigid bodies interacting with each other and with a floating structure. By simulating the exact setup of the artificial ice tests in XMF (using artificial ice rather than ice as a material), the flow and friction processes in the simulations can be compared with the tests. Complex ice breaking processes are


Model towed through the channel of artificial ice particles.


not present in either the tests or the simula- tions, which makes the comparison easier.


To facilitate having a large number of rigid bodies in the simulations, XMF’s functionality has been extended to integrate a Physics Engine (PE), i.e. a constrained dynamics engine. MARIN has already successfully adopted a third-party PE line module for the lifting of heavy loads. In the simulations with ice particles, the PE accounts for the collision interaction between the vessel and ice.


Confidence going forward The results from the test campaigns and the simulation, combined with the fair comparison found between them, gives MARIN sufficient reason and confidence to proceed with the artificial ice measurements and to perform feasibility studies for Arctic offshore operations.


Following on from the research that has been initiated, MARIN intends to launch the ServICE JIP, an Arctic Joint Industry Project on simulations, focusing on linking the engineering and operational approaches, such that both the technical and operational feasibility of working in ice can be assessed.


1


Bergsma, J.M., Bouhuys, C.M., Schaap, T., Spaargaren, A.F., van der Zalm, M., van der Werff, S.E., 2014, “On the Measurement of Submersion Ice Resistance of Ships Using Artificial Ice”, Proceedings of the 24th International Offshore and Polar Engineering Conference, Busan, Korea


2


S.E. van der Werff, J. Brouwer, G. Hagesteijn, “Ship Resistance Validation Using Artificial Ice”, June 2015, Proceedings of the ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering


3


Lindqvist, G., 1989, “A Straightforward Method for Calculation of Ice Resistance of Ships”, Proceedings of the 10th International Conference on Port and Ocean Engineering under Arctic Conditions (POAC), Lulea, Sweden, Vol.4, pp 722-736


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