### Abstract

Original language | English |
---|---|

Pages (from-to) | 314-322 |

Number of pages | 9 |

Journal | Chemical Engineering Journal |

Volume | 302 |

Early online date | 14 May 2016 |

DOIs | |

Publication status | Published - 15 Oct 2016 |

### Fingerprint

### Keywords

- surface charge
- droplet
- coalescence
- Poisson-Boltzmann equation
- shear flow
- simulation
- lattice Boltzmann method

### Cite this

*Chemical Engineering Journal*,

*302*, 314-322. https://doi.org/10.1016/j.cej.2016.05.054

**Simulations of charged droplet collisions in shear flow.** / Shardt, Orsen; Mitra, Sushanta K. ; Derksen, J J .

Research output: Contribution to journal › Article

*Chemical Engineering Journal*, vol. 302, pp. 314-322. https://doi.org/10.1016/j.cej.2016.05.054

}

TY - JOUR

T1 - Simulations of charged droplet collisions in shear flow

AU - Shardt, Orsen

AU - Mitra, Sushanta K.

AU - Derksen, J J

N1 - Acknowledgments This research has been enabled by the use of computing resources provided by WestGrid, the Shared Hierarchical Academic Research Computing Network (SHARCNET: www.sharcnet.ca), and Compute/Calcul Canada. O.S. thanks NSERC for an Alexander Graham Bell Canada Graduate Scholarship.

PY - 2016/10/15

Y1 - 2016/10/15

N2 - Collisions of charged droplets in the shear flow of an electrolyte were simulated to investigate the effects of surface charges and double layers on the critical conditions for coalescence. A lattice Boltzmann method phase field flow solver was coupled with an iterative finite-difference solver for the linearized Poisson-Boltzmann equation describing electric double layers. The simulations resolve both the phase field diffuse interface and electric double layer. The critical capillary numbers for coalescence were determined under varying strengths of the electric interactions. Critical capillary numbers between 0.03 and 0.2 were found for droplet radii spanning 25 to 50 lattice nodes (12.5 to 25 times the characteristic interface thickness), with lower critical values for larger droplets. The droplet interfaces had a constant potential. Once electric repulsion becomes comparable to the viscous shear force on the drops, the critical capillary numbers decrease, and the decrease is smaller for longer Debye lengths. Though the ratio of droplet size and Debye length that can be achieved in the simulations is constrained by high computational demands, the simulations provide insight into the effects of surface charge on the interactions between interfaces in multiphase flows.

AB - Collisions of charged droplets in the shear flow of an electrolyte were simulated to investigate the effects of surface charges and double layers on the critical conditions for coalescence. A lattice Boltzmann method phase field flow solver was coupled with an iterative finite-difference solver for the linearized Poisson-Boltzmann equation describing electric double layers. The simulations resolve both the phase field diffuse interface and electric double layer. The critical capillary numbers for coalescence were determined under varying strengths of the electric interactions. Critical capillary numbers between 0.03 and 0.2 were found for droplet radii spanning 25 to 50 lattice nodes (12.5 to 25 times the characteristic interface thickness), with lower critical values for larger droplets. The droplet interfaces had a constant potential. Once electric repulsion becomes comparable to the viscous shear force on the drops, the critical capillary numbers decrease, and the decrease is smaller for longer Debye lengths. Though the ratio of droplet size and Debye length that can be achieved in the simulations is constrained by high computational demands, the simulations provide insight into the effects of surface charge on the interactions between interfaces in multiphase flows.

KW - surface charge

KW - droplet

KW - coalescence

KW - Poisson-Boltzmann equation

KW - shear flow

KW - simulation

KW - lattice Boltzmann method

U2 - 10.1016/j.cej.2016.05.054

DO - 10.1016/j.cej.2016.05.054

M3 - Article

VL - 302

SP - 314

EP - 322

JO - Chemical Engineering Journal

JF - Chemical Engineering Journal

SN - 1385-8947

ER -