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Janiaud, E.; Elias, F.; Bacri, J.-C.; Cabuil, V.; Perzynski, R.

doi:10.1023/a:1010444923379

Cited by 24 publications

(19 citation statements)

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“…The typical values of α obtained range from 2 to 5 dyn/cm. This is comparable to many common fluids and three orders of magnitude higher than the unusually small interface tension characteristic for the micro-drops used in the experiments reported in [7,12,17]. As usual it is quite hard to determine the interface tension reliably.…”

Section: Methodsmentioning

confidence: 61%

“…This is in marked contrast to the experiments with microdrops reported in [7,17] and allows for the first time a detailed comparison between theory and experiment for the non axis-symmetric state. For a setup with parameters as specified in Table 1 The error in the measurement of the semi-axes is below 1% as long as there are no peaks at the periphery.…”

Section: Methodsmentioning

confidence: 80%

“…For intermediate values of the magnetic field strength various transient non axis-symmetric shapes like "worms" and "loops" where found. In later experiments [17] even more exotic forms of "S"-,"O"-, and "8"-shapes where reported. On the theoretical side (see also [18]) it was noted that for intermediate values of the magnetic field the axis-symmetric state may become unstable if the susceptibility of the ferrofluid exceeds χ 0.56.…”

Section: Introductionmentioning

confidence: 75%

“…However, for the parameter values used in our experiments the viscous torques turn out to be irrelevant for the shape of the drop for all occurring values of the semi-axes ratios b and c . On the other hand, for the micro-drops studied in [7,17] the viscous stresses become comparable to the magnetic and capillary ones for large elongations of the drops. The motion of the drop and the associated fluid flow then start to influence the drop shape.…”

Section: Preliminary Remarksmentioning

confidence: 89%

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Rotating Ferrofluid Drops

Engel

Lebedev

Morozov

2003

Zeitschrift Für Naturforschung A

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We study the stationary shapes and the rotational motion of drops of magnetic fluids floating in a non-magnetic liquid of equal density and spun up by an externally applied rotating magnetic field. For a sufficiently large magnetic susceptibility of the drop fluid transitions to non axial-symmetric shapes take place when the field amplitude is increased. We give a detailed theoretical account of the character of these shape bifurcations, of the resulting stationary drop forms, and of the slow rotational motion of the drop and compare our findings with results obtained in an experimental realization of the system. Quantitative agreement between theory and experiment can be obtained when saturation effects in the magnetization curve of the ferrofluid are taken into account.

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Section: Methodsmentioning

confidence: 61%

Section: Methodsmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 75%

Section: Preliminary Remarksmentioning

confidence: 89%

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Rotating Ferrofluid Drops

Engel

Lebedev

Morozov

2003

Zeitschrift Für Naturforschung A

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“…1. We argue that this point maybe responsible for the fact that depending on conditions in experiments the splitting of a magnetic thread in two or three parts is observed [2]. Here the formation of ''S'' like shapes near the critical frequency of a rotating field is studied by the numerical solution of Eq.…”

Section: Viscous Elongated Dropletsmentioning

confidence: 94%

Dynamics of elongated magnetic droplets and elastic rods in magnetic field

Cēbers

2005

Journal of Magnetism and Magnetic Materials

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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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Cited by 24 publications

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Rotating Ferrofluid Drops

Rotating Ferrofluid Drops

Dynamics of elongated magnetic droplets and elastic rods in magnetic field

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

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