Diffraction patterns in ferrofluids: Effect of magnetic field and gravity

Radha, S.; Mohan, Shalini; Pai, Chintamani

doi:10.1016/j.physb.2014.04.050

Cited by 23 publications

(7 citation statements)

References 26 publications

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“…Thus, in comparison to the problem in quasistationary theory, we now have three more parameters:  1 ,  1 and  which influence the stability problem. We note that if we set  1 = 0 in (26) and  = 0 in (28) and rearrange the terms we recover the equations studied by Finlayson [13]. There are, however, no counterparts to equation (27), the angular momentum equation, and the magnetization equation (29…”

Section: Governing Equationsmentioning

confidence: 85%

“…The effect of the magnetic field in low Reynolds numbers was higher, and a maximum of 27.6% enhancement in the convection heat transfer was observed. Radha et al [26] reported the experimental observation of diffraction patterns in a ferrofluid under the effect of magnetic field and gravity. The diffraction pattern showed a variation at different depths of the sample in the absence of the magnetic field and when the magnetic field is applied.…”

Section: Introductionmentioning

confidence: 99%

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Rayleigh-Bénard Convection in Ferrofluids in the Microgravity Environment

Jasmine

2016

J. Sci. Res.

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We have investigated stability of a ferrofluid in microgravity environment. We consider the effect of the spin viscosity, vortex viscosity, and magnetization relaxation. The eigenvalue problem is solved by employing the Chebyshev pseudospectral method and the results are discussed for all three boundary conditions: free-free, rigid-free and rigid-rigid. In the microgravity environment, the ferrofluid is more resilient to convection and, in general, for all boundary conditions requires higher temperature gradient for the threshold of the convection. It is found that a ferrofluid in microgravity environment is more stable, not only as compared to the case when gravity is present, but also in the pure viscous case.

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Section: Governing Equationsmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Rayleigh-Bénard Convection in Ferrofluids in the Microgravity Environment

Jasmine

2016

J. Sci. Res.

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“…In the absence of an external magnetic field, MF displays a Newtonian behavior. Whereas it shows a two-fold shift with the application of field and displays non-Newtonian characteristics [23,24]. The viscosity of these fluids remains constant at fixed temperature and does not depend on external factors such as applied shear strain, loading, oscillation, or angular frequency in the absence of the applied field [25].…”

Section: Introductionmentioning

confidence: 99%

Facile Synthesis, Static, and Dynamic Magnetic Characteristics of Varying Size Double-Surfactant-Coated Mesoscopic Magnetic Nanoparticles Dispersed Stable Aqueous Magnetic Fluids

et al. 2021

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The present work reports the synthesis of a stable aqueous magnetic fluid (AMF) by dispersing double-surfactant-coated Fe3O4 magnetic nanoparticles (MNPs) in water using a facile ambient scalable wet chemical route. MNPs do not disperse well in water, resulting in low stability. This was improved by dispersing double-surfactant (oleic acid and sodium oleate)-coated MNPs in water, where cross-linking between the surfactants improves the stability of the AMFs. The stability was probed by rheological measurements and all the AMF samples showed a good long-term stability and stability against a gradient magnetic field. Further, the microwave spin resonance behavior of AMFs was studied in detail by corroborating the experimental results obtained from the ferromagnetic resonance (FMR) technique to theoretical predictions by appropriate fittings. A broad spectrum was perceived for AMFs which indicates strong ferromagnetic characteristics. The resonance field shifted to higher magnetic field values with the decrease in particle size as larger-size MNPs magnetize and demagnetize more easily since their magnetic spins can align in the field direction more definitely. The FMR spectra was fitted to obtain various spin resonance parameters. The asymmetric shapes of the FMR spectra were observed with a decrease in particle sizes, which indicates an increase in relaxation time. The relaxation time increased with a decrease in particle sizes (sample A to D) from 37.2779 ps to 42.8301 ps. Further, a detailed investigation of the structural, morphological, and dc magnetic properties of the AMF samples was performed. Room temperature dc magnetic measurements confirmed the superparamagnetic (SPM) characteristics of the AMF and the M-H plot for each sample was fitted with a Langevin function to obtain the domain magnetization, permeability, and hydrodynamic diameter of the MNPs. The saturation magnetization and coercivity of the AMF samples increased with the increase in dispersed MNPs’ size of the samples. The improvement in the stability and magnetic characteristics makes AMFs suitable candidates for various biomedical applications such as drug delivery, magnetic fluid hyperthermia, and biomedicines.

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“…The effect of the magnetic field in low Reynolds numbers was higher, and a maximum of 27.6% enhancement in the convection heat transfer was observed. Radha et al [13] reported the experimental observation of diffraction patterns in a ferrofluid under the effect of magnetic field and gravity. The diffraction pattern showed a variation at different depths of the sample in the absence of the magnetic field and when the magnetic field is applied.…”

Section: Introductionmentioning

confidence: 99%

Thermoconvective Stability of a Ferrofluids in Presence of Magnetic Field

Jasmine

2016

J. Sci. Res.

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We have carried out a theoretical analysis of the linear thermoconvective stability of a ferrofluid, which is confined between two horizontal plates maintained at different constant temperatures and which is subject to an external uniform magnetic field in the vertical direction. The effects of the spin viscosity, vortex viscosity and magnetization relaxation are considered and discussed. The eigenvalue problem is solved by employing the Chebyshev pseudospectral method. It is found that the presence of magnetic field complements the buoyancy force in destabilizing the fluid at lower values of the magnetic field only and when the applied field is increased, the effect is reversed and the flow becomes more stable.

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Diffraction patterns in ferrofluids: Effect of magnetic field and gravity

Cited by 23 publications

References 26 publications

Rayleigh-Bénard Convection in Ferrofluids in the Microgravity Environment

Rayleigh-Bénard Convection in Ferrofluids in the Microgravity Environment

Facile Synthesis, Static, and Dynamic Magnetic Characteristics of Varying Size Double-Surfactant-Coated Mesoscopic Magnetic Nanoparticles Dispersed Stable Aqueous Magnetic Fluids

Thermoconvective Stability of a Ferrofluids in Presence of Magnetic Field

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