Phase Separation Dynamics and Active Turbulence in a Binary Fluid Mixture

Abstract: Active matter, encompassing natural systems, converts surrounding energy to sustain autonomous motion, exhibiting unique non-equilibrium behaviors such as active turbulence and motility-induced phase separation (MIPS). In this study, we present a novel two-fluids model considering dynamics of the Cahn-Hilliard (CH) model for phase separation with Beris-Edwards nematohydrodynamics equation for orientational order and two distinct momentum equations for active and passive fluids coupled by viscous drag. A phase field-based lattice Boltzmann method is used to investigate the existence of active turbulence and phase separation in the binary mixture. We analyze micro-phase separated domain under extensile and contractile stresses, long the statistical properties of turbulent flow. Key parameters, like active parameter, tumbling parameter and elastic constant, affect the characteristic scale of flow. Our findings show that the interaction of active stress and two-fluid hydrodynamics leads to complex non-equilibrium pattern formation. This offers insights into biological and synthetic active materials.