Jamming of Ice Mélange: Using Particle Rafts to Model Ice Mélange Dynamics
Mentor:Michael Dennin, Professor, Physics & Astronomy, University of California Irvine
An ice mélange consists of the ice pieces floating on the water in a fjord (channel) in front of a glacier. The interaction between the glacier, ice mélange, and water is of great interest, but the dynamics of this system are difficult to study in the field due to their massive system size. Therefore, we tested the validity of modeling this system by using a plastic raft model system. In the model, plastic beads float on the air/water interface to represent the ice mélange and the force is measured with a spring-loaded system. The plastic beads are placed in a reservoir between two walls (the channel) and are pushed at various velocities. The sides of the reservoir are lined with sandpaper to simulate a rough surface. We have used rectangular shapes for the particles because this shape approximates pieces of ice with sharp corners. The spring pushed on the plastic rafts and we observed the impact on the particles. This created a jamming force measured by the spring system. As the particles were pushed, they jammed and some fraction of the particles stop moving because of the friction in the particle raft which created a large jamming force. Once the force reaches a critical value, the system unjams, and flows again. The average number of jamming events for each run was 2.5. The average jamming force was the same at every speed except the critical speed. At the critical speed, the average jamming force is at a substantially higher value than at any other speed.