CFD simulation of equilibrium shape and coalescence of ferrofluid droplets subjected to uniform magnetic field

•The equilibrium shape and coalescence behavior of ferrofluid droplets are simulated.•A simple coupled scheme of VOF and LS methods is implemented.•A new correlation is proposed to describe the deformation of ferrofluid droplets.•It was observed that the magnetic field can be useful in coalescence o...

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Bibliographic Details
Published in:Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2015-09, Vol.481, p.186-198
Main Authors: Ghaffari, Ali, Hashemabadi, Seyed Hassan, Bazmi, Mansour
Format: Article
Language:English
Subjects:
CFD simulation
Coalescence
Ferrofluid droplet
Interface tracking
VOF
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Summary:•The equilibrium shape and coalescence behavior of ferrofluid droplets are simulated.•A simple coupled scheme of VOF and LS methods is implemented.•A new correlation is proposed to describe the deformation of ferrofluid droplets.•It was observed that the magnetic field can be useful in coalescence of droplets. In this study a computational framework has been presented to simulate the equilibrium shape and coalescence behavior of suspended ferrofluid droplets subjected to uniform magnetic field. A finite volume based CFD Open source solver library (OpenFOAM®) is used for the simulations. Coupled flow field equations and magnetostatic equations are numerically solved and a coupled scheme of Volume of Fluid (VOF) and Level-Set (LS) methods called S-CLSVOF is implemented for interface capturing. The simulation results are compared with the experimental data reported in the literature. The effects of different parameters, such as magnetic field intensity, magnetic susceptibility, surface tension and initial size of droplet on the deformation of magnetic droplet are investigated. Aspect ratio of droplet at the equilibrium state is calculated and a cubic polynomial is proposed to formulate its dependency to the magnetic Bond number and magnetic susceptibility. Finally the coalescence of two falling ferrofluid droplets under the effect of uniform magnetic field is simulated. The results reveal that the application of magnetic field has a significant effect on the coalescence of droplets and it can be used as a promising method for emulsion breaking.
ISSN:0927-7757
1873-4359
DOI:10.1016/j.colsurfa.2015.04.038