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.