Influence of floe-floe interactions on wave damping in marginal ice zones

Numerous observations show that in spite of relative motions of floes caused by wave propagation in marginal ice zone (MIZ) direct contacts between them don’t occur. Nevertheless, relative motions of floes may influence formation of oscillating water currents between them which take and dissipate the energy of incoming waves. Full-scale and laboratory experiments were performed to investigate characteristics of water currents between interacting floes. The experiments included the investigation of vertical and horizontal oscillating motions of floes in ice environment. During the experiments we recorded floe accelerations, water pressure and water velocity. Main goal of the experiments was to estimate effective viscosity of water in gapes between interacting floes, describe floe-floe forces caused by the floe accelerations, and estimate the influence of slush formation on the effective viscosity of water. The floe motion was initiated by mechanical pooling, towing with a rope and by original pendulum rig. The experiments were performed in the Van-Mijen Fjord of Spitsbergen in winter seasons of 2018 and 2019, and in the wave flume at UNIS. A lubrication theory was used to describe the dependence of water pressure between interacting floes from their relative speed and the distance between approaching surfaces. Comparison of numerical simulations with experimental records showed that the action of water pressure and the formation of flow jets can prevent direct collision of approaching floes. Obtained analytical formulas are used for the formulation of rheological equations describing the behavior of broken ice in MIZ.