Physical Mathematics Seminar Emergent Patterns in Active Polar Suspensions

Aggregates of self-propelling entities such as flocks of birds, schools of fish, bands of bacteria and motors in motility assays exhibit a zoo of striking, large scale collective behavior. Advances in the imaging of small scale biological systems (bacteria, cells) and increased computational power enabling the tracking of large-scale coherent structures (birds, insects) have led to a resurgence of interest in the theoretical modeling of such active, polar suspensions. In my talk, I will first discuss how a classical model from soft condensed matter physics the XY theory for spins can be adapted for these systems by incorporating additional physical effects namely, convection due to self-propulsion, excluded volume interactions and alignment inducing nonlinear couplings. I will then present results demonstrating the emergence of large scale patterns such as soliton-like waves, roving comets and stationary asters from the interplay between these effects. TUESDAY, MAY 3, 2011 2:30 PM Building 2, Room 105 Refreshments at 3:30 PM in Building 2, Room 290