The hydrodynamics of active fluids

Active fluids are a novel example of soft matter. We will introduce a continuum theory which attempts to describe the basic physical and flow properties of these systems. The practical examples of active fluids I will make contact with are solutions of actin and myosin, a molecular motor, and concentrated suspensions of bacterial swimmers or propellers. We have recently studied, via lattice Boltzmann simulations, the hydrodynamics and the rheology of an active fluid. I will report some results on these studies. Mainly I will discuss the fact that spontaneous flow can occur in this system, comparing the pattern with experimental ones, and discuss the rheology of active fluids, which display massively non-Newtonian features. Finally, I will discuss the comparison of our continuum theory simulations with simulations of the rheology of fully resolved self propelled particles.