Ferrofluids and magnetically guided superparamagnetic particles in flows: a review of simulations and modeling

Afkhami, Shahriar; Renardy, Yuriko

doi:10.1007/s10665-017-9931-9

Cited by 26 publications

(16 citation statements)

References 63 publications

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“…In this paper, we review experimental, theoretical, and computational studies on the structural transformations in ferrofluids, as well as their effects on the magnetic and dynamic properties of these systems. Discussions of the methods of ferrofluid synthesis, a basic introduction into the physics of these systems, and their practical applications can be found in books [1][2][3][4][5][6] and reviews [7][8][9][10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Chain Formation and Phase Separation in Ferrofluids: The Influence on Viscous Properties

Иванов

Zubarev

2020

Materials

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Ferrofluids have attracted considerable interest from researchers and engineers due to their rich set of unique physical properties that are valuable for many industrial and biomedical applications. Many phenomena and features of ferrofluids’ behavior are determined by internal structural transformations in the ensembles of particles, which occur due to the magnetic interaction between the particles. An applied magnetic field induces formations, such as linear chains and bulk columns, that become elongated along the field. In turn, these structures dramatically change the rheological and other physical properties of these fluids. A deep and clear understanding of the main features and laws of the transformations is necessary for the understanding and explanation of the macroscopic properties and behavior of ferrofluids. In this paper, we present an overview of experimental and theoretical works on the internal transformations in these systems, as well as on the effect of the internal structures on the rheological effects in the fluids.

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Section: Introductionmentioning

confidence: 99%

Chain Formation and Phase Separation in Ferrofluids: The Influence on Viscous Properties

Иванов

Zubarev

2020

Materials

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“…Different studies have addressed the modeling of droplet formation, using different flow rates for the CP and DP. [21][22][23] A majority of reported numerical studies on ferrofluid droplets are devoted to the investigation of motion and alteration of a single droplet, while it is exposed to a magnetic field. [24][25][26] However, most of these studies are focused on droplet elongations under uniform magnetic fields, because of simpler mathematical description.…”

Section: Introductionmentioning

confidence: 99%

“…The VOF method is simple, efficient, and robust for tracking topologically complex evolving interfaces. Among its advantages are strict conservation of mass and discretization of the surface tension force, which make it a valuable and competitive method for modeling flows with moving and deforming interfaces 23,30 . The advantage of this model is the reduced computational cost while tracking the interface between DP and CP through a microchannel.…”

Section: Introductionmentioning

confidence: 99%

Formation and manipulation of ferrofluid droplets with magnetic fields in a microdevice: a numerical parametric study

et al. 2020

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“…Static fixed finite, or "control," volumes-aligned to a cartesian grid for example 23,24 and also known as "volume-of-fluid" schemes-are usually coupled together with an interface surface tracker such as the ("particle") level set method whereby tracer points for the surface are allowed to advect with the flow as it is calculated within the fixed grid/mesh to capture the evolution of the interface between droplet and surrounding medium. 23,25,26 These methods have many advantages for free surface problems in their ease of implementation and ability to track complex or convoluted boundaries.…”

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confidence: 99%

“…For more discussion on the relative merits of different numerical schemes for such FHD free surface problems, the reader is referred to reviews 24,28 and the references therein.…”

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confidence: 99%

Numerical study of ferro‐droplet breakup initiation induced by a slowly rotating uniform magnetic field

Radcliffe

2020

Engineering Reports

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The fully three-dimensional start-up deformations and accelerations of initially spherical magnetically susceptable linearly magnetizable ferrofluid droplets, driven by a rotating uniform magnetic field, are investigated through the use of coupled finite element/boundary element computer simulations. For given magnetic susceptability, a critical viscosity is suggested, proportional to both magnetic field strength and rotation speed, below which the deformations of the initially spherical droplet inevitably lead to breakup, but above which a simple persistent spheroidal solid body rotation is attained. K E Y W O R D Sdroplet deformations, ferrofluids, finite/boundary elements, rotating magnetic field INTRODUCTIONA ferrofluid is a non-electrically conducting, stable colloidal suspension of magnetic particles in a Newtonian carrier liquid that makes the latter sensitive to the presence of a magnetic field. 1 Such "ferrohydrodynamics" (FHD) are distinguishable from the "magnetohydrodynamics" (MHD) of electrically conducting fluids by the complete absence of electric currents and the Lorentz forces they might otherwise induce. The particles typically have sizes of about 10 nm and are often coated with a stabilizing dispersing agent (surfactant) to avoid particle agglomeration 2 -even in the presence of strong magnetic field gradients. Additionally, if the particles are also "magnetically soft," with a magnetization relaxation time of the order 10 −7 seconds, then hysteresis effects may also be neglected, as will be done here.Finally, a ferrofluid in droplet form gives a rich and varied phenomenology of physical behavior through the competition between magnetic and surface tension forces on the surface, in an analogous manner to that seen between electric and surface tension forces in electrohydrodynamics. [3][4][5] There have been many experimental 6-8 and numerical [8][9][10][11][12] studies of the simple axisymmetric prolate spheroid equilibrium shapes ferrodrops achieve inside static uniform applied magnetic fields analogous to those of dielectric drops in an electric field, [13][14][15][16] where the prolate elongation from a sphere aligns with the applied field direction and assumes a stable equilibrium configuration directly proportional to the field strength.However, if the external magnetic field rotates, then two distinct classes of behavior emerge, dependent on the rotation speed.

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Ferrofluids and magnetically guided superparamagnetic particles in flows: a review of simulations and modeling

Cited by 26 publications

References 63 publications

Chain Formation and Phase Separation in Ferrofluids: The Influence on Viscous Properties

Chain Formation and Phase Separation in Ferrofluids: The Influence on Viscous Properties

Formation and manipulation of ferrofluid droplets with magnetic fields in a microdevice: a numerical parametric study

Numerical study of ferro‐droplet breakup initiation induced by a slowly rotating uniform magnetic field

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