Discrete fluidization of dense monodisperse emulsions in neutral wetting microchannels
arXiv:1910.01978 · doi:10.1039/C9SM02331C
Abstract
The rheology of pressure-driven flows of two-dimensional dense monodisperse emulsions in neutral wetting microchannels is investigated by means of mesoscopic lattice simulations, capable of handling large collections of droplets, in the order of several hundreds. The simulations reveal that the fluidization of the emulsion proceeds through a sequence of discrete steps, characterized by yielding events whereby layers of droplets start rolling over each other, thus leading to sudden drops of the relative effective viscosity. It is shown that such discrete fluidization is robust against loss of confinement, namely it persists also in the regime of small ratios of the droplet diameter over the microchannel width. We also develop a simple phenomenological model which predicts a linear relation between the relative effective viscosity of the emulsion and the product of the confinement parameter (global size of the device over droplet radius) and the viscosity ratio between the disperse and continuous phases. The model shows excellent agreement with the numerical simulations. The present work offers new insights to enable the design of microfluidic scaffolds for tissue engineering applications and paves the way to detailed rheological studies of soft-glassy materials in complex geometries.
arXiv comment8 pages, 8 figures
References in corpus (24)
- Simulation of non-ideal gases and liquid-gas phase transitions by lattice Boltzmann equation
- Rheology of Soft Glassy Materials
- Lattice Boltzmann methods for multiphase flow and phase-change heat transfer
- Yield Stress Materials in Soft Condensed Matter
- Discontinuous Shear Thickening of Frictional Hard-Sphere Suspensions
- Shear thickening in concentrated suspensions: phenomenology, mechanisms, and relations to jamming
- Discontinuous shear thickening without inertia in dense non-Brownian suspensions
- Microscopic mechanism for the shear-thickening of non-Brownian suspensions
- Deformation and flow of a two-dimensional foam under continuous shear
- Yielding and flow in adhesive and non-adhesive concentrated emulsions
- Shearing or Compressing a Soft Glass in 2D: Time-concentration superposition
- Modeling realistic multiphase flows using a non-orthogonal multiple-relaxation-time lattice Boltzmann method
- Three-dimensional cascaded lattice Boltzmann method: improved implementation and consistent forcing scheme
- Consistent forcing scheme in the cascaded lattice Boltzmann method
- Three-dimensional non-orthogonal multiple-relaxation-time lattice Boltzmann model for multiphase flows
- Lattice Boltzmann modeling of self-propelled Leidenfrost droplets on ratchet surfaces
- The emergence of supramolecular forces from lattice kinetic models of non ideal fluids: applications to the rheology of soft glassy meterials
- Mesoscopic lattice Boltzmann modeling of flowing soft systems
- Flow of deformable droplets: discontinuous shear thinning and velocity oscillations
- Discontinuous shear-thickening in Brownian suspensions
- Modeling pattern formation in soft flowing crystals
- Plastic deformations in crystal, polycrystal, and glass in binary mixtures under shear: Collective yielding
- Mesoscopic model for soft flowing systems with tunable viscosity ratio
- Discontinuous shear-thinning in adhesive dispersions