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November 2012 - Baltimore, Maryland
The APS Division of Fluid Dynamics held its 64th annual meeting in Baltimore, Maryland from November 20 through 22. Over 2,400 physicists attended more than 2,000 presentations on topics covering all aspects of fluid physics. Researchers offered new insights into wind turbine designs, mechanical heart valves, what happens at the instant an explosion detonates, and even the physics of wine swirling.
Building better wind turbines was featured in four focus sessions and a total of 36 presentations on how researchers are using fluid dynamics to better harness energy from wind. One research team at Caltech, led by John Dabiri, has been adapting the way schools of fish swim in the ocean to improve the efficiency of wind farms. Dabiri said that the way fish draft off each other smoothes the flow of water through the school, letting each fish expend less energy when swimming than if it was by itself. Dabiri’s experiments in a remote part of Los Angeles County have shown that arranging wind turbines like a school of fish cuts down on turbulence and can improve efficiency of the farms.
Volatile fiery explosions are dramatic, but powerful concussive detonations can be much more damaging. Researchers have long studied how a slow burning fiery deflagration can turn into a powerful detonation in enclosed spaces. At the meeting, researchers showed that detonations can also happen in an unconfined area. Alexei Poludnenko and his team, at the US Naval Research Laboratory and Sandia National Laboratories, showed that it was possible, under the proper turbulent conditions, for a detonation to happen in an unenclosed space. The conditions they described are similar to theoretical models of the interiors of white dwarf stars, which offer a possible explanation for the cause of type 1a supernovae.
The shapes of heart valves have gotten much scrutiny of late, and Marija Vukicevic of the University of Trieste showed that some of their inherent asymmetries might hold the key to better blood flow out of the heart. She and her research partner Gianni Pedrizzetti, also from the University of Trieste, built valves where one flap was as much as 70 percent bigger than the other, which more closely resembles the valves in a human heart. After tests in a silicon aorta model, the team found that blood flowed more smoothly in the asymmetrical valves, rather than the industry standard symmetrical valves.
The physics of how swirling a glass of fine port helps release its floral scents was calculated for the first time by Mohamed Farhat from the École Polytechnique Fédérale de Lausanne in Switzerland. Using high-speed video, he recorded the propagation of waves in wine while swirling wine at different speeds and briskness. He found that for each glass shape there is an optimal “shaking diameter and rotation speed” to get the most oxygenation which releases the wine’s character. He said also that the research can find industrial use in biopharmaceuticals manufacturing where large machines have to swirl vats of biological matter to culture growing cells.
Julian Hunt, a fluid physicist at University College, London and a member of Britain’s House of Lords, encouraged physicists to get more involved with public policy debates. He said that scientists have a lot of expertise to offer on important issues facing the world, and wanted to see more researchers and scientific organizations speak up and take an active, engaged role in pushing science-based solutions to issues like energy, climate change and natural disaster response.
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Editor: Alan Chodos