Anisotropic friction induced stabilization and motion in isotropic active fluids

Active fluids convert energy at the particle scale to emergent, macroscopic stresses at the system scale. This leads to a diverse range of behaviors in both biological and synthetic active matter. A recent research direction has been to exploit inherent broken symmetries in active fluids by coupling them to external or environmental features to induce novel exotic behaviors and even control the dynamics of the active fluid. Here, we study how active fluids with no inherent broken symmetries interact with a broken symmetry in the environment. We numerically model an isotropic, compressible, active fluid with patterned anisotropic friction. We show that regions patterned as topological defects may act as accumulation centers, similar to recent experiments of cellular monolayers on patterned substrates. We also show that local asymmetry in the friction patterning may induce motion in active fluid clusters, the direction of which may be controlled by the type of patterning. Our results highlight the important role the environment plays in the motion and organization of active and biological matter, even when the underlying material is isotropic.