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Annual Report 2016
SAMCoT
The ice is located on the left, depicted by the teal line.
The floating structure is depicted by the red line.
In 2016, PhD candidate Marnix van den Berg resolved the
remaining research questions regarding the combina-
tion of lattice modelling and the non-smooth discrete
element method (NDEM) to model structure-floe ice
interactions. Using NDEM, compared to other discrete
element methods, may lead to reduced calculation time.
Accuracy is achieved by implicit time integration. van den
Berg is currently in the process of validating the different
components of the model with promising results.
In July, van den Berg joined the Oden icebreaker to parti-
cipate in an engine trial. He used this trip to check if his
modelling assumptions were realistic. Since there was no
possibility to go on the ice during this trip, he used visual
Visual impression of a lattice-NDEM simulation showing
a ship breaking through floe ice.
PhD candidate Chris Keijdener studies the qualitative
effects of nearby level ice on the response of a floating
body using a 2D model.
Below a certain onset frequency, the amplitude of the
reflected waves is insignificant and consequently the
body remains unaffected by the ice. This frequency is
only sensitive to the ice thickness, with thinner ice
resulting in a higher onset frequency. Above the onset
frequency the reflected waves cause quasi-standing wa-
ves between the body and ice. For frequencies at which
the surface wavelength is approximately an integer
multiple of twice the gap length, the amplitude of the
standing waves is greatly amplified. This can result in
(anti-) resonance depending on the phasing between the
reflected waves and the body’s motion.
In addition, Keijdener is working on creating a model
that can isolate the effects of dynamic fluid pressure
on the interaction between level ice and sloping-faced
structures. The ultimate aim of this work is two-fold:
the first goal is to gain a qualitative understanding of
how the dynamic pressure influences the interaction
between level ice and a sloping structure, while the
second goal is to assess for which interaction speeds
the effects are negligible, hence allowing the dynamic
pressure to be ignored.
EFFECTS OF HYDRODYNAMICS ON STRUCTURE-LEVEL ICE INTERACTION
MODELLING OF STRUCTURE-FLOE ICE INTERACTIONS
observations for his tasks. An important observation was
that there is significant variability in ice conditions, even
on relatively small spatial scales.
During most of the trip, the ice consisted of a very
uneven floe field in which first year ice was mixed with
some multi-year ice inclusions. A high number of ridges
and rubble fields were present, as well as icebergs. The
first-year ice was often very weak and ‘rotten’, while the
multi-year ice was much stronger and much thicker. The
observed variability was in line with descriptions in the
existing literature. It confirms once more that full-scale
Arctic summer ice conditions cannot be approximated by
an assumed constant ice thickness in a numerical model.