Rheology of active emulsions with negative effective viscosity

Abstract

We numerically study by lattice Boltzmann simulations the rheological properties of an active emulsion made of a suspension of an active polar gel embedded in an isotropic passive background. We find that the hexatic equilibrium configuration of polar droplets is highly sensitive to both active injection and external forcing and may either lead to asymmetric unidirectional states which break top-bottom symmetry or symmetric ones. In this latter case, for large enough activity, the system develops a shear-thickening regime at low shear rates. Importantly, for larger external forcing a regime with stable negative effective viscosity is found. Moreover, at intermediate activity a region of multistability is encountered and we show that a maximum entropy production principle holds in selecting the most favorable state.

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Cited by in corpus (5)

• Yield-stress transition in suspensions of deformable droplets
• Phase behaviour and dynamics of three-dimensional active dumbbell systems
• Entropy production of active Brownian particles going from liquid to hexatic and solid phases
• Fluctuation Theorems for Heat exchanges between passive and active baths
• Transverse Self-Propulsion Enhances the Aggregation of Active Dumbbells