Drift of icebergs affected by wave action

Abstract

The wave drift force acting on freely floating icebergs has been analysed. This wave drift force was included together with other environmental forces acting on an iceberg for drift modelling to predict its drift patterns. -- The wave drift force was calculated using the wave diffraction theory and the singularity distribution method. By distributing singularities over the underwater surface of the iceberg, the velocity potential due to wave diffraction was computed using the Green's function method, and then added to the incoming wave velocity potential to form the total velocity potential. It was assumed that the potential due to the oscillatory motion of an iceberg was negligible. The wave drift force was derived by taking the time average of the second-order wave forces on the iceberg. -- The computed wave drift force was then added to other environmental forces acting on the iceberg to form the differential equations of motion for translation in a horizontal plane. The iceberg trajectory can be found by solving the equations of motion numerically with the time step integration technique. -- This study has shown that the wave drift force acting on an iceberg is significant and has the same order of magnitude as other environmental forces. Including the wave drift force in the drift model has improved the accuracy of predicted paths of icebergs. This was verified by comparing the observed and predicted trajectories of two icebergs with and without the wave drift effect.