Bulletin of the American Physical Society
APS March Meeting 2014
Volume 59, Number 1
Monday–Friday, March 3–7, 2014; Denver, Colorado
Session M40: Invited Session: Onsager / Lilienfeld / UG Inst / Apker 1 Prize session |
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Sponsoring Units: DCMP GSNP Chair: Bulbul Chakraborty, Brandeis University Room: Mile High Ballroom 2B-3B |
Wednesday, March 5, 2014 11:15AM - 11:51AM |
M40.00001: Lars Onsager Prize: Topological Defects in Condensed Matter Phases Invited Speaker: Vladimir Mineev Circulation quantization in superfluid 4He and superconductors. General principles of classification of topologically stable defects in ordered media. Superfluid phases of 3He. Topology at different scales of length. Superfluids under rotation. Biaxial nematics. Nonabelian disclinations. Half-quantum vortices: 3He-A, Sr2RuO4, exciton-polariton condensates, FFLO, Super Solid. [Preview Abstract] |
Wednesday, March 5, 2014 11:51AM - 12:27PM |
M40.00002: Julius Edgar Lilienfeld Prize: Chaotic Dynamics in the Physical Sciences: Some Comments and Examples Invited Speaker: Edward Ott Chaos was first discovered by Poincare in his famous 1887 work on the motion of N \textgreater 2 bodies interacting through gravitational attraction. Although steady progress was made by mathematicians following Poincare's work, widespread impact and development of chaos in the physical sciences is only comparatively recent, i.e., approximately starting in the 1970's. This talk will review this history and give some examples illustrating the types of questions, problems and results arising from perspectives resulting from widespread participation of physical scientists. [Preview Abstract] |
Wednesday, March 5, 2014 12:27PM - 1:03PM |
M40.00003: Prize to a Faculty Member for Research in an Undergraduate: Chaotic mixing and front propagation Invited Speaker: Tom Solomon We present results from a series of experiments -- all done with undergraduate students -- on chaotic fluid mixing and the effects of fluid flows on the behavior of reaction systems. Simple, well-ordered laminar fluid flows can give rise to fluid mixing with complexity far beyond that of the underlying flow, with tracers that separate exponentially in time and invariant manifolds that act as barriers to transport. Recently, we have studied how fluid mixing affects the propagation of reaction fronts in a flow. This is an issue with applications to a wide range of systems including microfluidic chemical reactors, blooms of phytoplankton in the oceans, and the spreading of a disease in a moving population. To analyze and predict the behavior of the fronts, we generalize tools developed to describe passive mixing. In particular, the concept of an invariant manifold is expanded to account for reactive burning. ``Burning invariant manifolds'' (BIMs) are predicted and measured experimentally as structures in the flow that act as one-way barriers that block the motion of reaction fronts. We test these ideas experimentally in three fluid flows: (a) and chain of alternating vortices; (b) an extended, spatially-random pattern of vortices; and (c) a time-independent, three-dimensional, nested vortex flow. The reaction fronts are produced chemically with variations of the well-known Belousov-Zhabotinsky reaction. [Preview Abstract] |
Wednesday, March 5, 2014 1:03PM - 1:39PM |
M40.00004: Using 3D Printing and Stereoscopic Imaging to Measure the Alignment and Rotation of Anisotropic Particles in Turbulence Invited Speaker: Guy Marcus We have developed a general methodology to experimentally measure the time-resolved Lagrangian orientation and solid body rotation rate of anisotropic particles with arbitrary aspect ratio from standard stereoscopic video image data. We apply these techniques to particles advected in a $R_\lambda \approx 110$ fluid flow, where turbulence is generated by two grids oscillating in phase. We use 3D printing technology to design and fabricate neutrally buoyant rods, crosses (two perpendicular rods), and jacks (three mutually perpendicular rods) with a largest dimension of 7 times the Kolmogorov length scale, which makes them good approximations to tracer particles. We have measured the mean square rotation rate, $\dot{p}_i \dot{p}_i$, of particles spanning the full range of aspect ratios and obtained results that agree with direct numerical simulations. Our measurements of the full solid-body rotation of jacks, in particular, are of broad experimental relevance because they demonstrate a new and extensible way to directly probe the Lagrangian vorticity of a fluid. Lastly, we will present our direct measurements of the alignment of crosses with the direction of their solid body rotation rate vector, demonstrating how turbulence aligns particles along their longest dimension. [Preview Abstract] |
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