报告题目：The Dynamics of Active Matter Particles on Disordered Landscapes: Jamming, Clogging, and Avalanches
Center for Nonlinear Studies and Theoretical Division
报告简介：There has been tremendous growth in studying nonequilibrium systems in which the individual units are internally driven and are self-mobile. Such dynamics can effectively describe certain biological systems such as run-and-tumble bacteria or crawling cells, as well as non-biological systems such as self-driven colloids or artificial swimmers. These systems are now being grouped into a new class of matter called active matter. They exhibit a wealth of novel nonequilibrium behaviours, such as clustering, flocking, and phase separation. In non-active systems there are numerous examples of collections of interacting particles that can be driven over random and periodic substrates such as vortices in type-II superconductors, colloids on periodic optical lattices, models of friction, and particle flows through porous media. Here we examine the dynamics of active matter systems interacting with random or periodic substrates. We show that active particles can exhibit a number of distinct dynamical phases when moving or driven over random or periodic substrates. We find that in some cases, increasing the activity or the self-propulsion of the particles can increase the transport across the substrate; however, there are also regimes in which increased activity can lead to enhanced pinning or jamming of the systems. For non-active systems we show that in the presence of random arrays the flow and density become highly heterogeneous. For intermediate activity the flow becomes uniform, and at high activity the flow once again becomes heterogeneous leading to strong clogging effects. In the dense particle limit, we find that active matter systems can show interesting motion of dislocations, grain boundaries and other topological structures distinct from those found in purely thermally driven systems or systems with external drives.
告人简介：Dr. Charles Reichhardt received his PhD degree in Physics from the University of Michigan in 1998. Later, he received the prestigious Richard P. Feynman Distinguished Postdoctoral Fellowship, working in theoretical and computational studies of condensed matter and complex systems in Los Alamos National Laboratory since then. Now, he is a technical staff member in the theoretical division of Los Alamos National Laboratory, who has an extensive knowledge of collective behaviors of many-particle interacting systems. He has already published > 200 publications, including 41 papers on Phys. Rev. Lett., and some on Science and Nature series, with about 5000 citations, and an h-index of 37 (from Web of Science). In 2011, he was elected as the APS Fellow with the citation of “For seminal work on the dynamics of collectively interacting particles on random or periodic substrates, including superconducting vortices, colloids, electron crystals and Bose-Einstein condensates.”