MARGINAL ICE-ZONE RHEOLOGY - COMPARISON OF RESULTS FROM CONTINUUM-PLASTIC MODELS AND DISCRETE-PARTICLE SIMULATIONS

Computer simulations of ice behaviour in the marginal ice zone (MIZ) a re described. Two cases were studied, a constant velocity wind blowing at certain angle with respect to the coast in what can be considered a simplified MIZ problem, and a vortex-wind force field. The viscous-p lastic approach of Hibler has been used to model the ice theology. We study the effects of adopting two different rheologies: cavitating flu id and Mohr-Coulomb. The introduction of shear strength effects throug h a Mohr-Coulomb yield criterion plays an important role in determinin g ice drift velocities in the MIZ. The effects that ice floe collision s can have in determining the ice rheological behavior have been teste d by using: discrete-particle simulations. In order to do so, simulati ons for the MIZ were performed using different mean flee sizes, as wel l as different MIZ widths and wind conditions. The predictions of the discrete-particle simulations are in general agreement with the result s obtained by using the Mohr-Coulomb rheology in the viscous-plastic m odel. The continuum models were solved by using a fully Lagrangian met hod known as smoothed particle hydrodynamics (SPH). The method has the advantage of the Lagrangian techniques in avoiding problems of numeri cal diffusion. An additional advantage of SPH in comparison with class ical Lagrangian approaches is that SPH does not need grids, and this m akes it well suited to handle problems of large deformations.