Phase separating binary fluids under oscillatory shear

Abstract

We apply lattice Boltzmann methods to study the segregation of binary fluid mixtures under oscillatory shear flow in two dimensions. The algorithm allows to simulate systems whose dynamics is described by the Navier-Stokes and the convection-diffusion equations. The interplay between several time scales produces a rich and complex phenomenology. We investigate the effects of different oscillation frequencies and viscosities on the morphology of the phase separating domains. We find that at high frequencies the evolution is almost isotropic with growth exponents 2/3 and 1/3 in the inertial (low viscosity) and diffusive (high viscosity) regimes, respectively. When the period of the applied shear flow becomes of the same order of the relaxation time $T_R$ of the shear velocity profile, anisotropic effects are clearly observable. In correspondence with non-linear patterns for the velocity profiles, we find configurations where lamellar order close to the walls coexists with isotropic domains in the middle of the system. For particular values of frequency and viscosity it can also happen that the convective effects induced by the oscillations cause an interruption or a slowing of the segregation process, as found in some experiments. Finally, at very low frequencies, the morphology of domains is characterized by lamellar order everywhere in the system resembling what happens in the case with steady shear.

1 table and 12 figures in .gif format

References in corpus (3)

• Lattice Boltzmann simulations of contact line motion in a liquid-gas system
• Ordering of the lamellar phase under a shear flow
• Influence of confinement on the orientational phase transitions in the lamellar phase of a block copolymer melt under shear flow

Cited by in corpus (26)

• Lattice Boltzmann methods for multiphase flow and phase-change heat transfer
• Discrete Boltzmann multi-scale modeling of non-equilibrium multiphase flows
• Lattice Boltzmann Methods and Active Fluids
• Multiple-Relaxation-Time Lattice Boltzmann Approach to Compressible Flows with Flexible Specific-Heat Ratio and Prandtl Number
• Lattice Boltzmann study on Kelvin-Helmholtz instability: the roles of velocity and density gradients
• Phase separation of incompressible binary fluids with Lattice Boltzmann Methods
• Polar coordinate lattice Boltzmann modeling of compressible flows
• Lattice Boltzmann model for combustion and detonation
• Morphologies and flow patterns in quenching of lamellar systems with shear
• Phase separation in thermal systems: LB study and morphological characterization
• Finite-Difference Lattice Boltzmann Methods for binary fluids
• Scaling and hydrodynamic effects in lamellar ordering
• Large-scale grid-enabled lattice-Boltzmann simulations of complex fluid flow in porous media and under shear
• Multiple-relaxation-time lattice Boltzmann model for compressible fluids
• Entropy production in thermal phase separation: a kinetic-theory approach
• Two-dimensional finite-difference lattice Boltzmann method for the complete Navier-Stokes equations of binary fluids
• Kinetic modeling of multiphase flow based on simplified Enskog equation
• Complex fields in heterogeneous materials under shock: modeling, simulation and analysis
• Morphological characterization of shocked porous material
• FFT-LB modeling of thermal liquid-vapor systems
• Rheology of Lamellar Liquid Crystals in Two and Three Dimensions: A Simulation Study
• Structural transitions and arrest of domain growth in sheared binary immiscible fluids and microemulsions
• Stress response and structural transitions in sheared gyroidal and lamellar amphiphilic mesophases: lattice-Boltzmann simulations
• Cellular automata model for elastic solid material
• Switching dynamics in cholesteric liquid crystal emulsions
• Simulating liquid-vapor phase separation under shear with lattice Boltzmann method