Time: Friday, September 26, 2003
Room: 4:00pm NSH 184

Speaker: Dr. Christian Huepe Minoletti, Northwestern University

Title: Phase Transitions, Intermittency and Clustering in a Simple Model for Swarming: A Network Approach

Abstract:
I will discuss different aspects of the non-equilibrium dynamics of a system of many self-driven interacting particles. The system is described by a minimal swarming model introduced by Vicsek et al. [Phys. Rev. Lett. (75), 1226 (1995)]. In this model, each particle moves with constant speed in the direction (plus noise) of the mean velocity of the particles within a given interaction range. I will show that the phase transition to the ordered phase (in which most particles move in the same approximate direction) can be understood by using a network approach. I will also show that this phase displays intermittent bursts during which the order is lost. The intermittency will be characterized and its statistical properties found analytically for a reduced two-particle system. On large systems, the particles aggregate into clusters. The role of these clusters in the system dynamics will be explained and their description using a network approach will be discussed.