Dynamics of flexible active Brownian dumbbells in the absence and the presence of shear flow

The dynamical properties of a flexible dumbbell composed of active Brownian particles are analytically analyzed. The dumbbell is considered as a simplified description of a linear active polymer. The two beads are independently propelled in directions which change in a diffusive manner. The relaxation behavior of the internal degree of freedom is tightly coupled to the dumbbell activity. The latter dominates the dynamics for strong propulsion. As is shown, limitations in bond stretching strongly influence the relaxation behavior. Similarly, under shear flow, activity determines the relaxation and tumbling behavior at strong propulsion. Moreover, shear leads to a preferred alignment and consequently to shear thinning. Thereby, a different power-law dependence on the shear rate compared to passive dumbbells under flow is found. An active dumbbell under shear flow exhibits strong activity-enhanced alignment and shear thinning behavior.