Laminar and turbulent liquid-liquid dispersions: a lattice Boltzmann study

• Author / Creator

  Komrakova, Alexandra E.

• A numerical approach based on a diffuse-interface free energy lattice Boltzmann equation method is developed
  to gain fundamental insight in liquid-liquid dispersions. The approach relies on detailed resolution of the
  interaction of the dispersed and continuous phases at the microscopic level, including drop breakup and
  coalescence. Several studies have been performed. A study of the gravity-driven motion of a single n-butanol
  drop in water demonstrates that the method handles complex drop deformations, including shape-oscillating
  motion of drops. Simulations of a single liquid drop in simple shear flow were used to assess the impact of
  numerical parameters on drop deformation levels. At higher capillary numbers the simulations capture endpinching
  and capillary wave breakup mechanisms. The method handles a range of shearing conditions from
  near-creeping flow, to drop Reynolds of 50, also a viscosity ratio range (dispersed phase over continuous phase
  viscosity) of 0.1-3.0. The feasibility of direct numerical simulations of turbulently agitated liquid-liquid dispersions
  is demonstrated. Three-dimensional simulations are carried out in fully-periodic cubic domains with grids of size
  500^3 and 1000^3 and the resolution of the Kolmogorov length scale in the range 1-10 lattice units. The process
  of dispersion formation is visualized, revealing the details of breakup and coalescence. However, several
  numerical issues are encountered: appearance of spurious currents over liquid-liquid interface, dissolution of
  small drops, and easy coalescence of drops. The effects of each drawback on the results are discussed.

• Subjects / Keywords

  • Turbulent dispersion
  • Drop breakup and deformation
  • Numerical simulation
  • Lattice Boltzmann
  • Liquid-liquid dispersion
  • Free energy model

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3FB4WV2S

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.