Multi-scale control of active emulsion dynamics

Abstract

We numerically study the energy transfer in a multi-component $2d$ film, made of an active polar gel and a passive isotropic fluid in presence of surfactant favoring emulsification. We show that by confining the active behavior into the localized component, the typical scale where chemical energy is transformed in mechanical energy can be substantially controlled. Quantitative analysis of kinetic energy spectra and fluxes shows the presence of a multi-scale dynamics due to the existence of a flux induced by the active stress only, without the presence of a turbulent cascade. An increase in the intensity of active doping induces drag reduction due to the competition of elastic and dissipative stresses against active forces. Furthermore we show that a non-homogeneous activity pattern induces localized response, including a modulation of the slip length, opening the way toward the control of active flows by external doping.

8 pages, 6 figures

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• Phase behaviour and dynamics of three-dimensional active dumbbell systems
• Hydrodynamic Enhancement of $p$-atic Defect Dynamics
• Rheology of active emulsions with negative effective viscosity
• Activity induced isotropic-polar transition in active liquid crystals
• Coexistence of defect morphologies in three dimensional active nematics
• Defect turbulence in a dense suspension of polar, active swimmers
• Hydrodynamic stability and pattern formation in hexatic epithelial layers
• Motility and self propulsion of active droplets