October 24, 2008
The Physics of Star-Forming Clouds, Spider Webs, Sand Dunes, Tears, Flames, and the Urban Environment
From the collapse of star-forming clouds to the flow of the molten Earth's core, from the combustion of gasoline in your car engine to the coursing blood in your veins, from the aerodynamics of flight to the concentration of microscopic animals in the ocean, many of nature's most fascinating phenomena are forms of fluid flow.
The 61st Annual Meeting of the American Physical Society's Division of Fluid Dynamics, which takes place from November 23-25 at the San Antonio Convention Center in Texas, is the largest scientific meeting of the year devoted to the dynamics of such fluids. It brings together researchers from across the globe to present work with applications in astronomy, engineering, alternative energy, and medicine.
Reporters are invited to attend the conference free of charge. Registration instructions and other information may be found at the end of this news release. Brief highlights of the invited talks and some of the more than 1,522 additional presentations at the meeting are listed below.
Contents of this Release
- Highlights of Invited Talk
- Brief Highlights of Scientific Program
- Registration for Journalists and Other Meeting Information
1. Highlights of Invited Talk
FLUID MECHANICS OF URBAN ENVIRONMENTS
The rapid urbanization of the Earth has led to highly populated cities that act as concentrated centers of human stressors on the natural environment. The degradation of environmental quality due to such stressors, in turn, greatly impacts human behavior. In San Antonio, Harindra J. Fernando (Arizona State University) will discuss efforts to understand and model fluid motions in urban areas, to identify environmental impacts of urbanization, and to predict how these impacts affect quality of life and sustainability of urban areas.
STATE-OF-THE-ART SPACECRAFT THRUSTERS
The Hall-effect thruster is an advanced propulsion system that uses electrical power provided by a spacecraft to generate thrust by ionizing and accelerating propellant to high velocities. Alec Gallimore (University of Michigan) will discuss the fundamental physics and state-of-the-art of these thrusters, which are now being considered for a variety of missions in deep space.
SUPERSONIC TURBULENCE AND STAR FORMATION
For more than 100 years, astronomers have built their theories of star formation around gravitational instability in star-forming clouds. New work over the last decade by Paolo Padoan (University of California at San-Diego) and others has pointed to an important connection between turbulence in these clouds and gravitational instability. In San Antonio, Padoan will present results of large-scale 3D numerical simulations that investigate the properties of supersonic magneto-hydrodynamic turbulence in star-forming clouds.
THE DYNAMOS AT THE CORES OF STARS
Deep within the interiors of some planets and stars there are turbulent flowing fluids that induce strong magnetic fields. In San Antonio, Stephan Fauve (Ecole Normale Superieure, Paris) will review the mechanisms of such "dynamos" and their relevance for planetary and stellar magnetic fields. He will also present the results of a recent experiment displaying the generation of magnetic field by a fully turbulent flow of liquid sodium. This field can switch polarities at random, thus mimicking Earth's magnetic field reversals.
COMPUTING ATMOSPHERIC WINDS
Atmospheric winds are highly complex and difficult to predict accurately, especially in the part where humans live, the "atmospheric boundary layer" adjacent to the earth's surface. To predict the winds at the highest levels of detail requires the largest computers and a numerical approach called "large-eddy simulation," or LES. However since the first LES was done nearly two decades ago, it has been found that the simulation goes badly wrong in the first 200 meters above the surface in some fundamental way that has defied understanding. James Brasseur (Penn State University) will present recent research that appears to explain much of the underlying reasons for the errors, and he will discuss a "framework" in which LES can be developed to improve the LES process of atmospheric modeling.
COMBUSTION WAVE TRANSITION -- LAMINAR TO TURBULENT FLAMES, AND THEN TO DETONATION
When a detonation occurs, a combustion wave becomes strong and extremely powerful. In San Antonio, Elaine Oran (Naval Research Laboratory) will describe the processes of wave transition in which an initially small, laminar flame, as might be caused by a spark, can evolve into a turbulent flame that produces high compression and strong shock waves. The shocks, in turn, may couple with the flame to form unsteady, propagating shock-flame complexes that may transition to a detonation.
TURBULENT MIXING IN FUSION IMPLOSIONS
The phenomenon known as Rayleigh-Taylor instability occurs when a dense fluid rests on top of a light fluid in a gravitational field. It also occurs when a pressure gradient accelerates an interface between fluids of different density, such as in inertial confinement fusion implosions. In San Antonio, David Youngs (Aldermaston, UK) will show that 3D simulations of Rayleigh-Taylor instability have made major advances in
understanding this process over the last decade.
COMPLEX FLUIDS ON THE MICRO-SCALE
"Microfluidics" seeks to observe the flows of liquids and gases in tiny silicon, glass, or plastic systems, and it has lots of exciting applications and industrial challenges. In San Antonio, Patrick Tabeling (MMN-ESPCI, Paris) will discuss experiments he and his colleagues have carried out over the last three years to measure microscopic fluid slip and flow along walls, study complex fluids, and observe the dynamical behavior of tiny droplets in microfluid channels.
2. Brief Highlights of Scientific Program
The following is a sampling of some of the 1,522 abstracts to be presented at the meeting.
TIDES AND WINDS
The role of tides in moving ocean water on Earth or triggering volcanos on Io or holding the Moon’s face perpetually toward Earth is well studied; a new study looks at the role of tides in driving winds on planets and stars.
"Solid foams are commonly used to absorb shocks. We consider here the efficiency of liquid foams as kinetic energy absorbers..."
THE PHYSICS OF AUTOMOTIVE AIR FILTERS
"A model was developed to predict the removal of aerosol particles by automotive air filters..."
SAND DUNE MOTION
"Particle image velocimetry on the surface of moving dunes reveals the flux of creeping sand, while measurement of sand grains flying through the air quantifies the key mechanism that moves sand by wind: saltation..."
THE PHYSICS OF HUMAN TEARS
"We present recent progress in the understanding of the dynamics of the human tear film on the complex eye-shaped geometry..."
ANATOMY OF A SPLASH
"The impact of a drop onto a liquid layer and the subsequent splash has important implications for diverse physical processes such as air-sea gas transfer, cooling, and combustion..."
SWIMMING AND FLYING ANIMALS DO THE TWIST
"Free swimming and flying animals twist their wings. But why? We have carried out force and efficiency measurements with twistable finite fins in water..."
"We present the results of a combined theoretical and experimental investigation of spider capture thread. While the radial threads in a spider web are simply cylindrical, the circumferential threads are pre-wound helices immersed in a viscous fluid..."
HURRICANE SEASON ON JUPITER
"Jupiter's atmosphere has been active during the last year with the Great, Little, and Oval Red Spots merging, almost merging, or repelling each other. These jovian storms are all anticyclonic vortices..."
ANATOMY OF A JAM
Granular materials jamming in a chute or tube is a million-dollar issue; this work looks at the redesigning hopper geometry.
3. Registration for Journalists and Other Meeting Information
The 61st Annual Division of Fluid Dynamics Meeting will be held at the Henry B. Gonzalez Convention Center in San Antonio, Texas. All meeting information, including directions to the Convention Center is at: http://dfd2008.tamu.edu/index.html.Useful Links
Credentialed full-time journalist and professional freelance journalists working on assignment are invited to attend the conference free of charge.
Onsite Meeting Press Room
The onsite Pressroom will be located in the Gonzales Convention Center. Pressroom hours are Monday-Thursday, 8:00-5:00 p.m. The location is to be determined. Press announcements and other news will be available in the pressroom.
Virtual Press Room
The Virtual Press Room for the 61st Annual Division of Fluid Dynamics Meeting will contain tips on dozens of stories as well as stunning graphics and lay-language papers detailing some of the most interesting results at the meeting. Lay-language papers are roughly 500 word summaries written for a general audience by the authors of individual presentations with accompanying graphics and multimedia files. The Virtual Press Room will serve as starting points for journalists who are interested in covering the meeting but cannot attend in person. In mid-November, the Virtual Press Room will be launched and another news release will be sent out at that time.
Gallery of Fluid Motion
Every year, the American Physical Society's Division of Fluid Dynamics hosts posters and videos that show stunning images and graphics from either computational or experimental studies of flow phenomena. The outstanding entries, selected by a panel of referees for artistic content, originality and ability to convey information, will be honored during the meeting, placed on display at the Annual APS Meeting in March of 2009, and will appear in the annual Gallery of Fluid Motion article in the September 2009 issue of Physics of Fluids.
This year, selected entries from the 26th Annual Gallery of Fluid Motion will be hosted as part of the Virtual Press Room for the 61st Annual DFD Meeting . In mid- November, when the Virtual Press Room is launched, another announcement will be sent out.