Odd Transport in Active Fluids

Active fluids, which are composed of self-propelled particles, are known to exhibit novel transport properties. Familiar laws such as those of Fourier, Fick, and Newton -- describing the linear constitutive behavior governing heat, mass, and momentum transport, respectively -- must be revisited in this context. In particular, the breaking of time-reversal symmetry at the particle scale can dramatically affect transport at the continuum scale. One example is the emergence of so-called odd viscosity in two dimensional chiral active fluids. In this talk, we describe how the statistical mechanical origins of odd viscosity are encapsulated in a set of Green-Kubo relations, which we verify in simulations of a model fluid composed of self-rotating active dumbbells. In this same spirit, we describe consequences of time-reversal symmetry breaking for diffusive transport, identifying common features which span a range of physically-distinct diffusive active systems.