The compression of floating ice fields

The compression of ice fields made up of thin floes is central to the processes of ice jam formation in northern rivers, pressure ridge formation in northern seas, and the dynamics of ice fields in Arctic and Antarctic marginal seas. This work describes the results of computer simulations in which a floating layer of circular floes, confined in a rectangular channel, is compressed by a pusher plate moving at a constant speed. The accuracy of the simulations is assessed by comparison with a series of similar physical experiments performed in a refrigerated basin. Following this comparison, the computer model is used to perform an extensive series of simulations to explore the effect of variations in channel length and width, the ratio of floe diameter to thickness, floe on floe friction coefficients, and the distribution of floe diameters on the force required to compress the floes. The results show that reducing the aspect ratio of the floes or increasing the friction coefficient increases the force needed to compress the floes. Both changes increase the force by changing the dominant failure mechanism in the layer of floes from rafting to underturning .Increasing channel width reduced the compressive force (per unit channel width) by reducing the relative importance of frictional drag at the channel edges. Last, the results of a simulation using a distribution of floe diameters was indistinguishable from those of a simulation using floes with a single diameter equal to the average diameter of the distribution.