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Polar Patterns In Active Fluids, Luca Giomi, M. Cristina Marchetti

Physics - All Scholarship

We study the spatio-temporal dynamics of a model of polar active fluid in two dimensions. The system exhibits a transition from an isotropic to a polarized state as a function of density. The uniform polarized state is, however, unstable above a critical value of activity. Upon increasing activity, the active fluids displays increasingly complex patterns, including traveling bands, traveling vortices and chaotic behavior. The advection arising from the particles self-propulsion and unique to polar fluids yields qualitatively new behavior as compared to that obtain in active nematic, yielding traveling-wave structures. We show that the nonlinear hydrodynamic equations can be mapped …