"A surprising pattern, much like the meshed teeth of a zipper, is frequently seen when floating ice sheets collide," said John Wettlaufer, professor of geology & geophysics and of physics at Yale. He and his colleague Dominic Vella of Cambridge University in England demonstrated the underlying principle for the observation. Further, they suggest that the process can work for any materials that share particular physical characteristics of thickness and flexibility.
"When two elastic sheets floating on a liquid collide, intuition leads us to expect one of two results — one sheet might be 'subducted' under the other, as we observe with the earth's crust, or the two might crush each other forming a field of rubble, as we observe in thick ice floes," said Wettlaufer.
The researchers describe a third possibility in their study published in Physical Review Letters. They show that sheets of ice, or in their experiments, sheets of wax, form a series of interlocking blocks -– termed "finger rafting" — that alternately ride over and under one another. It is a curiosity that has vexed scientists for over 50 years.
The natural patterns look like meter-wide rectangular zigzags, and only occur when both sheets of ice are roughly the same thickness. Their theoretical analysis was confirmed experimentally using flexible layers of wax on water to simulate the phenomenon. They demonstrated the relationship between the width of the resulting fingers and the material's mechanical properties.
"We show that this striking observation is a general and robust mechanical phenomenon that we can reproduce in the laboratory with floating materials other than ice," he said. "Our experimental results were consistent with the field observations."
According to Wettlaufer, the findings are relevant for a host of physical systems and, "The same principles might be used for designing nanomachine gears from appropriate materials." He points out that Tuzo Wilson, one of the founders of the theory of plate tectonics, was inspired by the resemblance of structures on floating polar ice sheets to the transform faults and other features of the Earth's moving plates.
Janet Rettig Emanuel | EurekAlert!
SF State astronomer searches for signs of life on Wolf 1061 exoplanet
20.01.2017 | San Francisco State University
Molecule flash mob
19.01.2017 | Technische Universität Wien
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Awards Funding
20.01.2017 | Materials Sciences
20.01.2017 | Life Sciences