Theoretical and experimental investigations have been
conducted to examine the behaviour of small icebergs and
bergy bits in unidirectional regular waves. A nonlinear
time-domain method based on the equivalent motion concept
and a corresponding computational algorithm are presented
for predicting the motion and trajectory of small ice masses
drifting in an open seaway and near a gravity base platform.
The general equations of motion of a rigid body are applied,
and the wave forces are determined as the sum of the
resultant of wave-induced pressures integrated over the
instantaneous wetted surface of the body (the Froude-Krylov
forces) and the flow disturbance induced by the presence of
the body as determined by the equivalent motion method. The
algorithm is used to predict the motion and trajectories of
free drifting and towed spherical models in small and large
amplitude waves. The computed values are found to be in
good qualitative and quantitative agreement with the
experimental measurements outside the heave resonance range
where the motions are over-predicted. The motions of the
ice mass are also simulated near a cylindrical gravity
platform taking into account the effect of the waves
diffracted by the structure. Large heave motions are
predicted in close vicinity of the platform. In addition to instances where collisions were predicted, the ice drifted
around or maintained a stationary position in front of the
structure. It is concluded that the method can be applied
to provide predictions of the kinematic parameters of motion
of small bodies drifting in waves
