Nicholas T. Ouellette
Professor and Associate Department Chair
Kenneth and Barbara Oshman Faculty Scholar
Department of Civil and Environmental Engineering
Will present a talk titled:
“Animal Groups as Active Materials”
Abstract: Aggregations of social animals are beautiful examples of self-organized behavior far from equilibrium. Understanding these systems, however, has proved to be quite challenging. Determining the rules of interaction from empirical measurements of animals is a difficult inverse problem. Thus, researchers tend to focus on the macroscopic behavior of the group instead. Because so many of these systems display large-scale ordered patterns, it has become the norm in modeling to focus on this order. Large-scale pattern alone, however, is not sufficient to characterize the dynamics of animal aggregations, and does not provide a stringent enough condition to benchmark models. Instead, I will argue that we should borrow ideas from materials characterization to describe the macroscopic state of an animal group in terms of its response to external stimuli. I will illustrate these ideas with recent experiments on swarms of the non-biting midge Chironomus riparius, where we have developed methods to apply controlled perturbations and measure the detailed swarm response. Our results allow us to begin to describe swarms in terms of state variables and response functions, bringing them into the purview of theories of active matter, and point towards new ways of characterizing and hopefully comparing collective behavior in animal groups.
Bio: Nicholas Ouellette is a Professor of Civil and Environmental Engineering at Stanford University. He is broadly interested in the behavior of complex systems far from equilibrium, and in particular in the dynamical self-organization that is ubiquitous in such systems. He works both to understand the physical principles that govern the spontaneous emergence of low-dimensional structure in high-dimensional systems and to harness this self-organization for engineering applications. Ouellette’s current research interests include hydrodynamic turbulence; the transport of inertial, anisotropic, and active particles by fluid flows; the strength and failure of granular materials; and collective behavior in insect swarms, bird flocks, and other animal groups. Ouellette graduated from Swarthmore College in 2002 with majors in Physics and Computer Science, earned his Ph.D. in Physics from Cornell University in 2006, and did postdoctoral research at the Max Planck Institute for Dynamics and Self-Organization and in the Physics Department at Haverford College. Before coming to Stanford, he spent seven years on the faculty in Mechanical Engineering and Materials Science at Yale University.
SC166
Friday, September 24th 2021
12:00 pm
