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Nonlinear Dynamics of Active Fluids and Transition to Active Turbulence

Prof. Piyush Grover, University of Nebraska-Lincoln

Dr. Mike Norton, Rochester Institute of Technology

Active fluids, or flowing active matter, refers to dense suspensions of self-propelled and often anisotropic constituent particles. Examples include bacteria, microtubule networks driven by molecular motors, and artificial swimmers. The constituents consume energy at small scales to propel themselves, and their collective motion results in large-scale spatiotemporal patterns. It is known that certain active fluids confined to two- and three-dimensional geometries can exhibit diverse, large-scale spatiotemporal dynamics, which are characterized by structures in both their flow fields and the orientation field of the active constituents. For instance, in active nematic channel flows, increasing the strength of the active stresses instigates a sequence of transitions from a stationary state to a defect-less laminar flow state, an ordered vortex pattern with motile topological defects in the nematic orientation field, and, eventually, mesoscale (low Reynolds number) turbulence whose signature is chaotic defect motion and a disordered distribution of vortices. The purpose of this mini-symposium is to gather researchers applying topological, statistical, and geometric tools of dynamical systems theory to study active fluids.