Tuning the viscosity and jamming point in dense active non-Brownian suspensions

Abstract

Using particle-based simulations, we study the rheology of dense, frictional, non-Brownian suspensions containing active particles. We find that the viscosity and the shear jamming point of the suspension can be tuned by varying the activity strength of the active particles. Microscopically, variations in the number of frictional contacts and the formation of a more isotropic force-chain network due to the presence of active particles underlie the viscosity changes. We introduce an effective temperature, defined through the control parameters of the active particles, that uniquely governs the viscosity of the suspensions. We also find that while activity drives the system away from jamming by hindering force-chain formation, unjamming an already jammed state by breaking existing force chains requires higher activity strength.