The flow of particles, although seemingly random, can be characterized more effectively, according to work done by Virginia Tech’s Shane Ross of the engineering science and mechanics (ESM) department and his colleague Francois Lekien of École Polytechnique, Université Libre de Bruxelles, Belgium, who reported their findings in the publication Chaos. http://chaos.aip.org/chaoeh/v20/i1
Their research “will aid scientists and engineers in understanding and in controlling this type of global-scale phenomena, such as pollution dispersion in the atmosphere and the ocean, and large-scale transport of biological organisms, including airborne plant pathogens and respiratory disease agents,” said Ishwar Puri, head of the ESM department at Virginia Tech.
For example, the current British Petroleum oil spill in the Gulf of Mexico, might be modeled using Ross and Lekien’s findings to provide greater insight into how the particles might be dragged into the Gulf of Mexico’s Loop Current.
In explaining how they conducted their research on the flow of particles, Ross and Lekien said they employed existing scientific principles of Lagrangian coherent structures, which reveals the separation of the atmosphere into dynamically distinct regions, to investigate the shapes of geophysical flow patterns. http://www.esm.vt.edu/person.php?id=10139
They used the 2002 discovery of the Antarctic hole in their work because they viewed it as a “prototype atmospheric event” allowing for their studies on topological divisions on the mixing and transport of atmospheric tracers.
As the media worldwide broadly publicized the finding of the Antarctic hole, it became the focus of the atmospheric science community. As Ross described the event, when the ozone hole split in two, allowing one of its fragments or regions to reassert its position over the Antarctic Pole while the other one spread into the mid-latitude regions, it implied “a sudden stratospheric warming.”
This type of global warming occurs in roughly half of all winters in the Arctic. The scientific explanation, Ross said, is “they are produced by the dynamic momentum force resulting from the breaking and dissipation of planetary-scale Rossby waves in the stratosphere.”
This phenomenon had never been observed in the Antarctic prior to 2002, according to reliable records that go back some 50 years. Consequently, Ross and Lekien labeled it a “prototype” of rare atmospheric events.
Reviewing data from the event, they were able to determine that an isolated “blob of air” was slowly rotating over Antarctica. Lagrangian coherent structures, some which repel nearby air and some that attract it, formed inside the vortex. The vortex pinched off, sending the northwestern part of the ozone hole off into the mid latitude range while the southwestern portion returned to its regular position over the South Pole.
Consequently, they write, when there is more than one vortex flow on a sphere, such as the planet Earth, “complicated spatial structures can arise and evolve, such as the polar vortex split.” They were able to model this event, capturing some of its dynamic features.
“This model is very relevant both in atmospheric and oceanographic settings when one considers large-scale phenomena where the spatial geometry of the Earth’s surface becomes important. The full spherical geometry, as opposed to tangent plane approximations, is particularly important when considering global streamline patterns generated by a given vorticity distribution…These patterns, in turn, provide the dynamical templates by which one can begin to understand the chaotic advection of particles in a vortex-dominated flow.”
Virginia Tech’s College of Engineering is internationally recognized for its excellence in 14 engineering disciplines and computer science. As the nation’s third largest producer of engineers with baccalaureate degrees, undergraduates benefit from an innovative curriculum that provides a hands-on, minds-on approach to engineering education. It complements classroom instruction with two unique design-and-build facilities and a strong Cooperative Education Program. With more than 50 research centers and numerous laboratories, the college offers its 2,000 graduate students opportunities in advanced fields of study, including biomedical engineering, state-of-the-art microelectronics, and nanotechnology. http://www.eng.vt.edu/main/index.php
Lynn Nystrom | Newswise Science News
Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel
Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)
University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.
Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.
Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.
Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...
Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.
The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...
Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.
Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...
In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...
13.04.2018 | Event News
12.04.2018 | Event News
09.04.2018 | Event News
20.04.2018 | Physics and Astronomy
20.04.2018 | Interdisciplinary Research
20.04.2018 | Physics and Astronomy