The winter blanket of snow covering the Alps is stunningly beautiful– and incredibly dangerous. In 2004-2005, 26 people died in avalanches in Switzerland alone. The victims range from occasional snow-boarders catching some powder off-piste to backcountry ski guides with years of experience. In this mountainous country, avalanches also pose a serious public danger. They can bury people in their homes, cut off access roads or even flatten whole villages. Scientists have put great effort into trying to understand the physical mechanisms at work in avalanches, particularly in the domain of fluid mechanics, in an attempt to improve our ability to predict and manage avalanche danger. But progress is limited because the computer models that simulate complex fluid movement are still quite rudimentary.
EPFL professor Christophe Ancey, an expert in rheology, or flow phenomena, is working to improve that situation. His team is building an installation that will generate avalanches in the comfort of the laboratory. Unlike natural avalanches, no two of which are alike, and all of which are quite uncomfortable in scale and force, all the variables involved in these slides can be controlled and the same avalanche can be studied repeatedly. The simulation data will be used to construct a new numerical model capable of describing the avalanche’s dynamic behavior.
The laboratory system Ancey is developing is based on the “dam-break” concept, in which a viscous fluid is poured onto a steeply inclined plane. The blue ooze flowing down the slope may not look like snow, but it deforms in the same way an avalanche does, and shares the same physics – the highly complex, non-equilibrium, non-linear flow that is characteristic of heavy snow and mud. “No existing numerical model can reproduce what’s happening in even this simple setup,” explains Ancey. “As a first step, we need to be able to reproduce what we observe, and with a model that takes only hours, not days, to run.”
Christophe Ancey | alfa
Successful calculation of human and natural influence on cloud formation
04.11.2016 | Goethe-Universität Frankfurt am Main
Invasive Insects Cost the World Billions Per Year
04.10.2016 | University of Adelaide
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
06.12.2016 | Materials Sciences
06.12.2016 | Medical Engineering
06.12.2016 | Power and Electrical Engineering