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Felderhof, B. U.

doi:10.1023/a:1010401108357

Cited by 17 publications

(14 citation statements)

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“…Both they are in a good agreement with experimental data of many authors and with computational results provided by direct numerical integration of the Fokker-Planck equation in linear approximation in Ωτ [17]. Quite recently Felderhof [18] solved this linearized equation by the Galerkin method using a large number of trial functions (the associated Legendre functions). Comparing his "exact result" for the rotational viscosity with (30) and (17), he wrote that "the result of Martsenyuk, Raikher and Shliomis [5] is quite a good approximation, but the result of Shliomis [2] deviates up to 17 percent".…”

Section: Magnetization Equation Derived Microscopicallysupporting

confidence: 86%

“…(the saturation) when rolling of the particle is replaced by slipping: the field of sufficiently large intensity guarantees constancy of the particle's orientation, not allowing it to twist with the fluid. Note that the result (18) does not depend on a concrete form of the magnetization equation but follows directly from the equation of fluid motion (5). Actually, in the limit under consideration ω p = 0 , so that Eq.…”

Section: Phenomenological Magnetization Equationmentioning

confidence: 99%

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Comment on “Magnetoviscosity and relaxation in ferrofluids”

Shliomis

2001

Phys. Rev. E

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It is shown and discussed how the conventional system of hydrodynamic equations for ferrofluids was derived. The set consists of the equation of fluid motion, the Maxwell equations, and the magnetization equation. The latter was recently revised by Felderhof [Phys. Rev. E 62, 3848 (2000)]. His phenomenological magnetization equation looks rather like our corresponding equation, but leads to wrong consequences for the dependence of ferrofluid viscosity and magnetization relaxation time on magnetic field.

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Section: Magnetization Equation Derived Microscopicallysupporting

confidence: 86%

Section: Phenomenological Magnetization Equationmentioning

confidence: 99%

Comment on “Magnetoviscosity and relaxation in ferrofluids”

Shliomis

2001

Phys. Rev. E

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“…(16), (18), and (38) into (37) and keeping only the first term in the regular perturbation solution, we obtaiñ…”

Section: A Regular Perturbation Solutionmentioning

confidence: 99%

“…The magnetorheology of ferrofluids has been an active area of experimental [1][2][3][4][5][6] and theoretical [7][8][9][10][11][12] research for decades. The focus of most work has been the steady-state response of dilute and semidilute ferrofluids to imposed constant shear and magnetic fields [2,3,[13][14][15][16][17][18][19][20][21]. There has also been some work on the response of ferrofluids to oscillating [3,14,[22][23][24][25][26] and rotating [14,[27][28][29][30][31][32] magnetic fields; however, here again a steady flow has been considered.…”

Section: Introductionmentioning

confidence: 99%

Oscillatory shear response of dilute ferrofluids: Predictions from rotational Brownian dynamics simulations and ferrohydrodynamics modeling

2011

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Ferrofluids are colloidal suspensions of magnetic nanoparticles that exhibit normal liquid behavior in the absence of magnetic fields but respond to imposed magnetic fields by changing their viscosity without loss of fluidity. The response of ferrofluids to constant shear and magnetic fields has received a lot of attention, but the response of ferrofluids to oscillatory shear remains largely unexplored. In the present work we used rotational Brownian dynamics to study the dynamic properties of ferrofluids with thermally blocked nanoparticles under oscillatory shear and constant magnetic fields. Comparisons between simulations and modeling using the ferrohydrodynamics equations were also made. Simulation results show that, for small rotational Péclet number, the in-phase and out-of-phase components of the complex viscosity depend on the magnitude of the magnetic field and frequency of the shear, following a Maxwell-like model with field-dependent viscosity and characteristic time equal to the field-dependent transverse magnetic relaxation time of the nanoparticles. Comparison between simulations and the numerical solution of the ferrohydrodynamic equations shows that the oscillatory rotational magnetoviscosity for an oscillating shear field obtained using the kinetic magnetization relaxation equation quantitatively agrees with simulations for a wide range of Péclet number and Langevin parameter but has quantitative deviations from the simulations at high values of the Langevin parameter. These predictions indicate an apparent elastic character to the rheology of these suspensions, even though we are considering the infinitely dilute limit in which there are negligible particle-particle interactions and, as such, chains do not form. Additionally, an asymptotic analytical solution of the ferrohydrodynamics equations, valid for Pe<<2, was used to demonstrate that the Cox-Merz rule applies for dilute ferrofluids under conditions of small shear rates. At higher shear rates the Cox-Merz rule ceases to apply.

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“…Experiments demonstrate that magnetodipolar interparticle interaction changes significantly both the equilibrium [2] and dynamical [3] properties of ferrofluids. Theoretical models of dynamical properties of dilute ferrofluids with vanishing interparticle interactions have been proposed in [4,5,6,7]. These models lead to very accurate results for very dilute ferrofluids but can not explain properties and behavior of ferrofluids where the interparticle interaction is significant.…”

Section: Introductionmentioning

confidence: 99%

Magnetization dynamics of non-dilute ferrofluids

Berkov

Iskakova²,

Zubarev³

2009

J. Phys.: Conf. Ser.

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The paper is devoted to the theoretical investigation of the magnetodipolar interparticle interaction effect on remagnetization dynamics in moderately concentrated ferrofluids. We consider a homogenous (without particle aggregates) ferrofluid consisting of identical spherical particles and employ a rigid dipole model, where magnetic moment of a particle is fixed with respect to the particle itself. In particular, for the magnetization relaxation after the external field is instantly switched off, we show that the magnetodipolar interaction leads to the increase of the initial magnetization relaxation time. For the complex ac-susceptibility ( ) ( ) ( ) i χ ω χ ω χ ω

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Cited by 17 publications

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Comment on “Magnetoviscosity and relaxation in ferrofluids”

Comment on “Magnetoviscosity and relaxation in ferrofluids”

Oscillatory shear response of dilute ferrofluids: Predictions from rotational Brownian dynamics simulations and ferrohydrodynamics modeling

Magnetization dynamics of non-dilute ferrofluids

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