### Abstract

algorithm to realize the interfacial tension effect and phase separation respectively, is adopted to systematically study droplet deformation and breakup in confined conditions. The effects of capillary number, viscosity ratio of the droplet to the carrier liquid, and confinement ratio are studied. The simulation results are compared against the theoretical predictions, experimental and numerical data available in literature. We find that increasing confinement ratio will enhance deformation, and the maximum deformation occurs at the viscosity ratio of unity. The droplet is found to orient more towards the flow direction with increasing viscosity ratio or confinement ratio. Also, it is noticed that the wall effect becomes more significant for the confinement ratios larger than 0.4. Finally, the critical capillary number, above which the droplet breakup occurs, is found to be mildly affected by the confinement for the viscosity ratio of unity. Upon increasing the confinement ratio, the critical capillary number increases for the viscosity ratios less than unity, but decreases for the viscosity ratios more than unity.

Original language | English |
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Number of pages | 19 |

Journal | Journal of Computational Science |

Early online date | 15 Mar 2016 |

DOIs | |

Publication status | E-pub ahead of print - 15 Mar 2016 |

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### Keywords

- lattice Boltzmann method
- droplet dynamics
- deformation
- confinement
- breakup

### Cite this

*Journal of Computational Science*. https://doi.org/10.1016/j.jocs.2016.03.009

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*Journal of Computational Science*. https://doi.org/10.1016/j.jocs.2016.03.009

**Droplet dynamics in confinement.** / Ioannou, N.; Liu, H.; Zhang, Y. H.

Research output: Contribution to journal › Article

TY - JOUR

T1 - Droplet dynamics in confinement

AU - Ioannou, N.

AU - Liu, H.

AU - Zhang, Y. H.

PY - 2016/3/15

Y1 - 2016/3/15

N2 - This study is to understand confinement effect on the dynamical behaviour of a droplet immersed in an immiscible liquid subjected to a simple shear flow. The lattice Boltzmann method, which uses a forcing term and a recoloringalgorithm to realize the interfacial tension effect and phase separation respectively, is adopted to systematically study droplet deformation and breakup in confined conditions. The effects of capillary number, viscosity ratio of the droplet to the carrier liquid, and confinement ratio are studied. The simulation results are compared against the theoretical predictions, experimental and numerical data available in literature. We find that increasing confinement ratio will enhance deformation, and the maximum deformation occurs at the viscosity ratio of unity. The droplet is found to orient more towards the flow direction with increasing viscosity ratio or confinement ratio. Also, it is noticed that the wall effect becomes more significant for the confinement ratios larger than 0.4. Finally, the critical capillary number, above which the droplet breakup occurs, is found to be mildly affected by the confinement for the viscosity ratio of unity. Upon increasing the confinement ratio, the critical capillary number increases for the viscosity ratios less than unity, but decreases for the viscosity ratios more than unity.

AB - This study is to understand confinement effect on the dynamical behaviour of a droplet immersed in an immiscible liquid subjected to a simple shear flow. The lattice Boltzmann method, which uses a forcing term and a recoloringalgorithm to realize the interfacial tension effect and phase separation respectively, is adopted to systematically study droplet deformation and breakup in confined conditions. The effects of capillary number, viscosity ratio of the droplet to the carrier liquid, and confinement ratio are studied. The simulation results are compared against the theoretical predictions, experimental and numerical data available in literature. We find that increasing confinement ratio will enhance deformation, and the maximum deformation occurs at the viscosity ratio of unity. The droplet is found to orient more towards the flow direction with increasing viscosity ratio or confinement ratio. Also, it is noticed that the wall effect becomes more significant for the confinement ratios larger than 0.4. Finally, the critical capillary number, above which the droplet breakup occurs, is found to be mildly affected by the confinement for the viscosity ratio of unity. Upon increasing the confinement ratio, the critical capillary number increases for the viscosity ratios less than unity, but decreases for the viscosity ratios more than unity.

KW - lattice Boltzmann method

KW - droplet dynamics

KW - deformation

KW - confinement

KW - breakup

UR - http://www.journals.elsevier.com/journal-of-computational-science/

U2 - 10.1016/j.jocs.2016.03.009

DO - 10.1016/j.jocs.2016.03.009

M3 - Article

JO - Journal of Computational Science

JF - Journal of Computational Science

SN - 1877-7503

ER -