Transient magnetoviscosity of dilute ferrofluids

Soto-Aquino, Denisse; Rinaldi, Carlos

doi:10.1016/j.jmmm.2010.11.038

Cited by 13 publications

(14 citation statements)

References 6 publications

(6 reference statements)

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“…This work is also helpful for future study of magnetically modulated optical transmission by magnetic nanoparticles suspended in fluids [13] which can be used in realizing magnetically tunable colloidal micromirrors [31]. The magnetoviscosity of dilute suspensions [19,20,30] of NFVs can be also investigated in the future works.…”

Section: Discussionmentioning

confidence: 92%

“…However, we can analytically estimate the error of the proposed analytical model by using (20) in the ∞ → t limit. To this end, we assume a Gaussian distribution for θ with the mean π/2 and the variance given by (20). So we can easily estimate 1− We also predict the effect of NFVs size on their response to the applied magnetic field.…”

Section: Limitation Of the Modelmentioning

confidence: 99%

“…There are also some experimental works indirectly investigating the rotational Brownian motion of NFVs under applied magnetic field [11,13]. The Brownian motion of different types of particles suspended in a Newtonian fluid has been numerically studied [16][17][18][19][20][21]. More recently, the numerical simulation of stochastic rotation of tri-axial ellipsoidal magnetic particles under constant and time-varying magnetic fields has been presented in [22].…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of magnetic nano-flake vortices in Newtonian fluids

Bazazzadeh

Mohseni

Khavasi

et al. 2016

Journal of Magnetism and Magnetic Materials

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We study the rotational motion of nano-flake ferromagnetic discs suspended in a Newtonian fluid, as a potential material owing the vortex-like magnetic configuration. Using analytical expressions for hydrodynamic, magnetic and Brownian torques, the stochastic angular momentum equation is determined in the dilute limit conditions under applied magnetic field. Results are compared against experimental ones and excellent agreement is observed. We also estimate the uncertainty in the orientation of the discs due to the Brownian torque when an external magnetic field aligns them. Interestingly, this uncertainty is roughly proportional to the ratio of thermal energy of fluid to the magnetic energy stored in the discs. Our approach can be implemented in many practical applications including biotechnology and multi-functional fluidics.Comment: 13 pages, 7 figure

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Section: Discussionmentioning

confidence: 92%

Section: Limitation Of the Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamics of magnetic nano-flake vortices in Newtonian fluids

Bazazzadeh

Mohseni

Khavasi

et al. 2016

Journal of Magnetism and Magnetic Materials

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“…One of many unique properties of ferrouids is their tunable viscosity by the external magnetic eld. This is called the magnetoviscous eect [2,3,4]. One of the most successful applications of thermophysical property of magnetic uid is audio speaker.…”

Section: Introductionmentioning

confidence: 99%

Viscosity Dependence of a Magnetic Fluid Nanoparticles Concentration

et al. 2014

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In this work we have studied the eect of temperature on the viscosity of magnetic uids (MFs) based on the transformer oil ITO 100. The volume concentration of suspended magnetic particles (MPs) changed from 0.25 to 1%. Rheological characterization of MFs was performed using a vibroviscometer at working frequency of 30 Hz. The temperature dependence of the viscosity was measured in the temperature range from 20 up to 50• C. The magnetization of dierent concentrations of MPs in MFs was determined by using the vibrating sample magnetometer.

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“…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. Recently, the dynamics of the transient magnetoviscous effect has received attention [33,34], with emphasis on response of ferrofluids to step changes in the applied magnetic or shear fields.…”

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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Transient magnetoviscosity of dilute ferrofluids

Cited by 13 publications

References 6 publications

Dynamics of magnetic nano-flake vortices in Newtonian fluids

Dynamics of magnetic nano-flake vortices in Newtonian fluids

Viscosity Dependence of a Magnetic Fluid Nanoparticles Concentration

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

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