(45b) The Hydrodynamics of Active Suspensions

fascinating instances of fluid-structure interaction. Just as fascinating are the large-scale flows that result when there are not one but many locomoting bodies moving and interacting with each other through the fluid. Aside from their intrinsic importance to biology, such systems offer new approaches to micro-scale mixing and transport, as well as extraction of mechanical work, from active fluids. I will overview recent mathematical and simulational work in describing "active suspensions" here composed of many self-locomoting particles moving through a Stokesian fluid. This work ranges from using large-scale particle-based simulations of hydrodynamically interacting swimmers, to the development and application of continuum kinetic theories. Our analyses and simulations of these models demonstrate the existence of large-scale mixing and transport, dependent upon micro-mechanical swimming mechanisms and upon system scales, with these features associated with large-scale flow instability and the dynamics of quasi-periodic coherent structures.