Rotating field induced torque on ferrofluid emulsion with deformable dispersed phase microdrops

Zakinyan, Arthur

doi:10.1016/j.sna.2020.112347

Cited by 7 publications

(1 citation statement)

References 51 publications

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“…[48,49]), the formation of chained structures of ferrofluid droplets, [50] and the effect of these structures on the emulsion electrical properties [51]. Finally, it is worth mentioning the recent work of Zakinyan and Zakinyan [52] who succeed on producing an emulsion of ferrofluid microdrops using a rotating magnetic field and showed that the resulting magnetic torque of the emulsion can be enhanced with respect that observable in the pure ferrofluid.…”

Section: Introductionmentioning

confidence: 99%

Shear rheology of a dilute emulsion of ferrofluid droplets dispersed in a nonmagnetizable carrier fluid under the influence of a uniform magnetic field

Capobianchi

Lappa

Oliveira

et al. 2021

Journal of Rheology

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The effect of a spatially uniform magnetic field on the shear rheology of a dilute emulsion of monodispersed ferrofluid droplets, immersed in a non-magnetizable immiscible fluid, is investigated using direct numerical simulations. The direction of the applied magnetic field is normal to the shear flow direction. The droplets extra stress tensor arising from the presence of interfacial forces of magnetic nature is modeled on the basis of the seminal work of G. K. Batchelor, J. Fluid Mech., 41.3 (1970) under the assumptions of a linearly magnetizable ferrofluid phase and negligible inertia. The results show that even relatively small magnetic fields can have significant consequences on the rheological properties of the emulsion due to the magnetic forces that contribute to deform and orient the droplets towards the direction of the applied magnetic vector. In particular, we have observed an increase of the effective (bulk) viscosity and a reversal of the sign of the two normal stress differences with respect to the case without magnetic field for those conditions where the magnetic force prevails over the shearing force. Comparisons between the results of our model with a direct integration of the viscous stress have provided an indication of its reliability to predict the effective viscosity of the suspension. Moreover, this latter quantity has been found to behave as a monotonic increasing function of the applied magnetic field for constant shearing flows ("magneto-thickening" behaviour), which allowed us to infer a simple constitutive equation describing the emulsion viscosity.

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Section: Introductionmentioning

confidence: 99%

Shear rheology of a dilute emulsion of ferrofluid droplets dispersed in a nonmagnetizable carrier fluid under the influence of a uniform magnetic field

Capobianchi

Lappa

Oliveira

et al. 2021

Journal of Rheology

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Fluid droplet deformation in ferrofluid exposed to a rotating magnetic field

Cha

Wang

Prodanović

et al. 2022

Journal of Magnetism and Magnetic Materials

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Rheology and magnetorheology of ferrofluid emulsions: Insights into formulation and stability

Gómez-Sanabria,

Contreras-Mateus,

Chaves-Guerrero

et al. 2024

Physics of Fluids

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The integration of surfactants and nanoparticles in emulsion formulations has attracted significant attention due to their potential synergistic effects, improving stability and enabling the development of stimuli-responsive materials. The objective of this study was to investigate the stability, bulk rheological, and magnetorheological properties of oil in water (o/w) emulsions, composed of Fe3O4 kerosene-based ferrofluids dispersed in surfactant solutions (hexadecylpyridinium chloride, and nonylphenol polyethoxylate—ethylene oxide = 40, known as Tergitol NP-40), as a function of concentration and nature of the emulsifying agents. The results demonstrated the formation of stable systems (>2 months), featuring an average droplet size below 4 μm, with the primary stabilization mechanism attributed to the reduction of interfacial tension by surfactant activity. The emulsions exhibited shear thinning and viscoelastic solid-like behavior, which were enhanced by increasing the concentrations of both emulsifiers. Emulsions stabilized with hexadecylpyridinium exhibited a higher structural rigidity, with dynamic moduli an order of magnitude higher than Tergitol formulations. In the presence of a perpendicular magnetic field, it was demonstrated that incorporating ferrofluid as a dispersed phase in an o/w emulsion potentiates the magnetoviscous effect, compared to that observed with neat ferrofluid at the same concentration. A maximum relative increase in viscosity of up to 17-fold was observed in emulsions stabilized with 2.5 w/v% of hexadecylpyridinium and 10 000 ppm of nanoparticles when exposed to a linearly increasing magnetic field up to 796.73 mT at 1 s−1. The observed magnetoviscous effect remained reproducible for up to one year after formulation, highlighting the potential of these systems for multiple applications.

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Rotating field induced torque on ferrofluid emulsion with deformable dispersed phase microdrops

Cited by 7 publications

References 51 publications

Shear rheology of a dilute emulsion of ferrofluid droplets dispersed in a nonmagnetizable carrier fluid under the influence of a uniform magnetic field

Shear rheology of a dilute emulsion of ferrofluid droplets dispersed in a nonmagnetizable carrier fluid under the influence of a uniform magnetic field

Fluid droplet deformation in ferrofluid exposed to a rotating magnetic field

Rheology and magnetorheology of ferrofluid emulsions: Insights into formulation and stability

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