Effective Viscosity of Bacterial Suspensions

We discuss the transition from the well developed modeling and analysis of passive suspensions to active suspensions (namely, bio-suspensions). Modeling of bacterial suspensions and, more generally, of suspensions of active microparticles has recently become an increasingly active area of research. The focus of our work is on the development and analysis of a mathematical PDE model for the multiscale problem of bacterial suspensions. In particular, we discuss recent results on the effective viscosity of dilute bacterial suspensions (with Aronson, Berlyand and Karpeev).