Synopsis: Granular Flow of a Melting Avalanche

Motion in an ice avalanche is strongly affected by the feedback effect of melting.
Synopsis figure
Daniel Ucko

In September 2002, one hundred million cubic meters of rock and ice separated from the northern slope of the Kazbek massif in North Ossetia, Russia. Traveling at times at nearly 300 km/hour, the resultant avalanche killed dozens of people and caused widespread damage. Ice avalanches from collapsing glaciers are not common in populated areas, but that may change as global temperatures rise. The Ossetia avalanche alerted researchers to the urgency of gaining a better understanding of the processes that control such flows.

In a paper in Physical Review Letters, Barbara Turnbull at the University of Nottingham, UK, tells us how she measured the significant effect of melting on the behavior of ice flows, which therefore differ from dry granular shear flows. In a series of four seemingly simple yet carefully controlled experiments, the author recorded high-speed video of the motion of ice particles that partially fill a slowly rotating narrow drum. The observations appear to confirm that lubrication and capillary action resulting from melting and wetting provide a positive feedback to granular ice flow, like avalanches. Interfacial melting increases flow velocity, which in turn speeds up the melting. However, the real achievement of the reported experiments is that researchers now have a controlled setup with which to study an urgent real-world scenario that has always been difficult to measure. – Sami Mitra


Announcements

More Announcements »

Subject Areas

Nonlinear DynamicsSoft MatterInterdisciplinary Physics

Previous Synopsis

Atomic and Molecular Physics

First Out of the Gate

Read More »

Next Synopsis

Atomic and Molecular Physics

Laser Cooling Tuned to the UV

Read More »

Related Articles

Synopsis: Explaining Aftershock Clustering
Geophysics

Synopsis: Explaining Aftershock Clustering

A study of bursting phenomena like earthquakes suggests that events appear to cluster in time because of the way that small events like aftershocks are identified. Read More »

Viewpoint: Signs of a Gardner Transition in a Granular Glass
Soft Matter

Viewpoint: Signs of a Gardner Transition in a Granular Glass

Two-dimensional disk packings under compression and vibration display signatures of the Gardner phase transition that is thought to occur between the glass and jamming transitions. Read More »

Focus: Why Some Gels Shrink under Stress
Mechanics

Focus: Why Some Gels Shrink under Stress

The gel material that helps blood clot in a wound has anomalous material properties because of the interaction between the gel's fluid and its microscopic fiber network, according to experiments. Read More »

More Articles