Ferromagnetic Liquid Research Articles

Active and passive control of nanoparticles in ferromagnetic Jeffrey fluid flow

AbstractThe rheology of non‐Newtonian liquids has fascinated several researchers due to their wide‐ranging applications in manufacturing and engineering sectors like plastic processing, the mining industry, and lubrication. Also, the features of ferromagnetic non‐Newtonian fluids make it supportive for extensive usage in loudspeakers, magnetic resonance imaging, computer hard drives, directing of magnetic drugs, and magnetic hyperthermia. Owing to such potential applications, the current study is concerned with the heat and mass transfer analysis in a ferromagnetic Jeffrey liquid flow over a stretching sheet. In the flow problem, Brownian moment, magnetic dipole, and thermophoresis features are used. The active and passive control of nanomaterials is also considered in the modeling. Using appropriate similarity transformations, the modeling equations are converted to ordinary differential equations, then these equations are solved using the Runge–Kutta process and the shooting approach. The numerical and graphical solutions for the thermal profile, concentration profile, skin friction, rate of heat, and mass transfer characteristics are obtained. The significant results of the current study are that the thermal profile is strongly stimulated and increases faster for active control case than passive control case for augmented values of thermophoresis parameter. The heat transfer is strongly stimulated and decreases faster for passive control case than active control case for growing values of Deborah number. The mass transfer rate decreases faster for the active control case for increasing values of Schmidt number.

Evaluation of heat and mass transfer in ferromagnetic fluid flow over a stretching sheet with combined effects of thermophoretic particle deposition and magnetic dipole

The features of ferromagnetic fluids make it supportive for an extensive range of usages in directing magnetic drugs and magnetic hyperthermia. Owing to all such potential applications, the current study is concerned with the ferromagnetic liquid flow past a stretching sheet with thermophoretic particle deposition and a magnetic dipole. The equations of described flow are transformed into ordinary differential equations (ODEs) by selecting suitable similarity variables. These ODEs are later solved numerically by the fourth and fifth-order Runge–Kutta–Fehlberg (RKF-45) technique by using a shooting scheme. The influence of sundry parameters on velocity, thermophoretic diffusive deposition velocity, skin-friction, Nusselt number, Sherwood number, thermal and concentration profiles are illustrated graphically. The results reveal that the increase in ferromagnetic interaction parameter improves the thermal profile but declines the velocity and concentration profiles. The imposition of thermophoretic particle deposition results in declination of the mass transfer. The escalating values of the ferromagnetic interaction parameter decline the rate of heat transfer. Finally, the rise in values of the thermophoretic parameter and thermophoretic coefficient decays thermophoretic diffusive deposition velocity.

Learning spin liquids on a honeycomb lattice with artificial neural networks

Machine learning methods provide a new perspective on the study of many-body system in condensed matter physics and there is only limited understanding of their representational properties and limitations in quantum spin liquid systems. In this work, we investigate the ability of the machine learning method based on the restricted Boltzmann machine in capturing physical quantities including the ground-state energy, spin-structure factor, magnetization, quantum coherence, and multipartite entanglement in the two-dimensional ferromagnetic spin liquids on a honeycomb lattice. It is found that the restricted Boltzmann machine can encode the many-body wavefunction quite well by reproducing accurate ground-state energy and structure factor. Further investigation on the behavior of multipartite entanglement indicates that the residual entanglement is richer in the gapless phase than the gapped spin-liquid phase, which suggests that the residual entanglement can characterize the spin-liquid phases. Additionally, we confirm the existence of a gapped non-Abelian topological phase in the spin liquids on a honeycomb lattice with a small magnetic field and determine the corresponding phase boundary by recognizing the rapid change of the local magnetization and residual entanglement.

Introduction to Colloidal and Microfluidic Nematic Microstructures

In this brief review, we give an introduction to selected colloidal and microfluidic nematic microstructures, as enabled by the inherent anisotropy and microscopic orientational ordering in complex liquid crystalline materials. We give a brief overview of the mesoscopic theory, for equilibrium and dynamics, of nematic fluids, that provides the framework for understanding, characterization, and even prediction of such microstructures, with particular comment also on the role of topology and topological defects. Three types of nematic microstructures are highlighted: stable or metastable structures in nematic colloids based on spherical colloidal particles, stationary nematic microfluidic structures, and ferromagnetic liquid crystal structures based on magnetic colloidal particles. Finally, this paper is in honor of Noel A. Clark, as one of the world pioneers that helped to shape this field of complex and functional soft matter, contributing at different levels to works of various groups worldwide, including ours.

Ferromagnetic Liquid Droplet on a Superhydrophobic Surface for the Transduction of Mechanical Energy to Electricity Based on Electromagnetic Induction.

Ferromagnetic liquids undergo reversible magnetization changes upon varying external magnetic field levels. The movement of ferromagnetic liquid droplets across a coil under an external magnetic field holds promise as an energy transducer from mechanical force to electricity; however, it suffers from an adhesive issue between the ferromagnetic liquid and the solid pedestal. We introduce a superhydrophobic support that uses antiwetting surfaces to remarkably reduce adhesion during the movement of ferromagnetic liquid droplets. Maxwell numerical simulation was utilized to analyze the working mechanism and improve further electrical outputs. By controlling the droplet size, the strength of the magnetic bottom and the tilting speed of the test condition, we generated a ferromagnetic liquid droplet-based superhydrophobic magnetoelectric energy transducer (FLD-SMET) that can convert vibrational energy to electricity. When a 100 μL ferromagnetic liquid droplet was used for FLD-SMET under a 13 mT magnetic field, an electrical voltage response of 280 μV and electrical current response of ∼7.5 μA were generated using a shaking machine with a tilting speed of 9.5°/s. We thus show that such a device can serve as a self-powered light buoy floating on a water surface. Our study presents an applied concept for the design of droplet-based energy harvesters to convert surrounding vibrational energy to electricity.

INVESTIGATION OF THE ELECTROMAGNETIC EFFECT ON THE PROCESS OF OIL DISPLACEMENT FROM BITUMINOUS SANDSTONE USING A FERROMAGNETIC FLUID

In Azerbaijan, due to natural oil, there are large reserves of bituminous rocks. Absheron-Gobustan district has 11 bituminous sandstone deposits with reserves of 12,673,6600 tons [1-3]. The largest reserves are concentrated in the Balakhan part of the Kirmaki Mountains, the reserves of which amount to more than 50 million tons. For the purpose of extraction of oil from bituminous rocks different methods and methods are used. The results of the study of electromagnetic effects on the process of displacement of oil from bituminous sand with the use of ferromagnetic liquid are given in this work. Keywords: bituminous sands, oil extraction, ferromagnetic liquid.

Individual effects of sinusoidal and non-sinusoidal gravity modulation on Rayleigh-Bénard convection in a ferromagnetic liquid and in a nanoliquid with couple stress

Individual effects of sinusoidal and non-sinusoidal gravity modulation on Rayleigh-Bénard convection in a ferromagnetic liquid and in a nanoliquid with couple stress

Study of double-diffusive convection in a rotating couple-stress ferromagnetic fluid in the presence of varying gravitational field and horizontal magnetic field saturating in a porous medium

The results of double-diffusive convection on the liquid coatings of ferromagnetic liquids is studied by researchers by various theoretical and hydrodynamics concepts of hydrodynamics. However this study is done in presence of varying gravitational field. The study of such couple-stress ferromagnetic fluids in presence of fluctuating gravitational field is still not explored. As we know that gravitational field varies on different points on the earth; for this reason the study of couple-stress ferromagnetic liquids in presence of variable gravity fields is highly required. In this paper we studied the impact of medium permeability, stable solute gradient, couple-stress, rotation, magnetic field, and magnetization of a couple-stress ferromagnetic fluid in presence of variable gravitational field. For this study a coating of couple-stress ferromagnetic fluid saturating in a porous medium when fluid layer is heated and soluted. We examined the results of the magnetic field on couple-stress ferromagnetic fluids, its thermosolutal instability during rotation. A linearized concept and normal mode technique are used to acquire the dispersion relation. For the case of stationary convection, medium permeability, couple-stress, and magnetic field have both stabilizing and destabilizing results under certain conditions. A stable solute gradient has a stabilizing result on the system. Also, the rotation has a stabilizing result for λ>0 and destabilizing result for λ 0 and λ<0. The critical Rayleigh number for the onset of instability is decided numerically and graphically also. The principle of exchange of stabilities is observed to keep genuine in the absence of rotation, magnetic field, and stable solute gradient under certain conditions.

Comprehensive study of thermophoretic diffusion deposition velocity effect on heat and mass transfer of ferromagnetic fluid flow along a stretching cylinder

The aim of this current investigation is to discuss the flow of a ferromagnetic viscous liquid with thermophoretic particle deposition over a stretching cylinder on taking account of a uniform heat source/sink. The non-dimensional form of equations for described flow is attained by using appropriate similarity variables. The solution of the resultant governing system is obtained by Runge-Kutta-Fehlberg’s fourth-fifth order method by adopting the shooting technique. The outcomes of dimensionless quantities are discussed on velocity, temperature, and concentration fields by using suitable graphs. Result reveals that the upshot in values of ferromagnetic interaction parameter increases the thermal gradient but a converse trend is detected for inclined values of heat source/sink parameter. An increase in thermophoretic parameter and thermophoretic coefficient declines the thermophoretic particle deposition velocity. The imposing of magnetic dipole and particle deposition has a receding impact on the rate of heat and mass transfers respectively. Excellent comparison is established through a tabular description to validate the adopted numerical procedure.

Ferromagnetic liquid droplets with adjustable magnetic properties

The assembly and jamming of magnetic nanoparticles (NPs) at liquid-liquid interfaces is a versatile platform to endow structured liquid droplets with a magnetization, i.e., producing ferromagnetic liquid droplets (FMLDs). Here, we use hydrodynamics experiments to probe how the magnetization of FMLDs and their response to external stimuli can be tuned by chemical, structural, and magnetic means. The remanent magnetization stems from magnetic NPs jammed at the liquid-liquid interface and dispersed NPs magneto-statically coupled to the interface. FMLDs form even at low concentrations of magnetic NPs when mixing nonmagnetic and magnetic NPs, since the underlying magnetic dipole-driven clustering of magnetic NP-surfactants at the interface produces local magnetic properties, similar to those found with pure magnetic NP solutions. While the net magnetization is smaller, such a clustering of NPs may enable structured liquids with heterogeneous surfaces.

Nonlinear analysis of the effect of viscoelasticity on ferroconvection

AbstractThis paper concerns a nonlinear analysis of the effects of viscoelasticity on convection in ferroliquids. We consider the Oldroyd model for the constitutive equation of the liquid. The linear stability analysis yields the critical value of the Rayleigh number for the onset of oscillatory convection in Maxwell and Jeffrey ferroliquids. The use of a minimal mode double Fourier series in the nonlinear perturbation equations yields a Khayat–Lorenz model for the ferromagnetic liquid, and that is scaled further to get the classical Lorenz model as a limiting case. The scaled Khayat–Lorenz model thus obtained is solved numerically and the solution is used to compute the time‐dependent Nusselt number, which quantifies the heat transport. The results are analyzed for the dependence of the time‐averaged Nusselt number on different parameters.

Магнитный аналог вращения Квинке

Opportunity to observe magnetic analog of the Quincke rotation effect, namely, spontaneous rotation of a spherical particle in homogeneous DC magnetic field (B), is analyzed. Two experimental versions: nonmagnetic particle suspensioned in ferromagnetic liquid and, second, - diamagnetic sphere levitated in vacuum, are considered. In the first case spontaneous rotation is possible in the fields B &lt; 0.1 T for relaxation times of the particle magnetization ~ 10-3 s. Indispensible condition of accelerated spinning of the diamagnetic sphere is confinement of its rotation degree of freedom by only one rotation axis orthogonal to the vector B.

Study of double-diffusive convection in a rotating couple-stress ferromagnetic fluid in the presence of varying gravitational field and horizontal magnetic field saturating in a porous medium

The results of double-diffusive convection on the liquid coatings of ferromagnetic liquids is studied by researchers by various theoretical and hydrodynamics concepts of hydrodynamics. However this study is done in presence of varying gravitational field. The study of such couple-stress ferromagnetic fluids in presence of fluctuating gravitational field is still not explored. As we know that gravitational field varies on different points on the earth; for this reason the study of couple-stress ferromagnetic liquids in presence of variable gravity fields is highly required. In this paper we studied the impact of medium permeability, stable solute gradient, couple-stress, rotation, magnetic field, and magnetization of a couple-stress ferromagnetic fluid in presence of variable gravitational field. For this study a coating of couple-stress ferromagnetic fluid saturating in a porous medium when fluid layer is heated and soluted. We examined the results of the magnetic field on couple-stress ferromagnetic fluids, its thermosolutal instability during rotation. A linearized concept and normal mode technique are used to acquire the dispersion relation. For the case of stationary convection, medium permeability, couple-stress, and magnetic field have both stabilizing and destabilizing results under certain conditions. A stable solute gradient has a stabilizing result on the system. Also, the rotation has a stabilizing result for λ&gt;0 and destabilizing result for λ&lt;0 the system. It is likewise observed that in the absence of a stable solute gradient, magnetization has a stabilizing result on the system for both λ&gt;0 and λ&lt;0. The critical Rayleigh number for the onset of instability is decided numerically and graphically also. The principle of exchange of stabilities is observed to keep genuine in the absence of rotation, magnetic field, and stable solute gradient under certain conditions.

Wide-range current transformers with non-contact regulation

Several designs of wide-range current transformers (TT) have been developed. The analysis of their work has established that the most complete requirements of control and control systems are met by TT, in which the wide range is implemented by the implementation of a spiral core in the form of an Archimedean spiral. This leads to an increase in the stability of the TT. The developed TT consists of a fixed hollow core 1 in the form of a spiral made of non-magnetic and non-conductive material, a primary winding 2 applied according to the required functional law to a fixed core 1, a movable ferromagnetic magnetic core 3 that can rotate around a common axis 4 with the help of a holder 5, a secondary winding 6 located in the inner cavity of a movable ferromagnetic core 3 and a ferromagnetic liquid 7 filling the parts of a spiral hollow tube covered by a movable ferromagnetic core 3 of 1.

Nonlinear Thermal Buoyancy on Ferromagnetic Liquid Stream Over a Radiated Elastic Surface with Non Fourier Heat Flux

The current article discusses the heat transfer characteristics of ferromagnetic liquid over an elastic surface with the thermal radiation and non-Fourier heat flux. In most of the existing studies, the heat flux is considered as constant, but whereas we incorporated the non-Fourier flux to get the exact performance of the flow. Also, we excluded the PWT and PHF cases to control the boundary layer of the flow. The governing equations related to our contemplate are changed into non-linear ordinary differential equations (ODE’s) by utilizing appropriate similarity changes, which are at the point enlightened by Runge–Kutta based shooting approach. The equations are broken down concerning boundary conditions and to be explained prescribed wall temperature (PWT) and prescribed heat flux (PHF) cases. The impacts of diverse non-dimensional physical parameters on velocity and temperature profiles are laid out graphically. Also, the assortment of skin friction and local Nusselt number for both PWT and PHF cases for various assessments of non-dimensional parameters have been sorted out. Towards the wrap-up of the examination, we suspect that the friction factor coefficient is higher in the PWT case compared to the PHF case. This result helps to conclude that the flux conditions are useful for cooling applications.

Fractionalized spin excitations in the ferromagnetic edge state of graphene: Signature of the ferromagnetic Luttinger liquid

The elementary excitations from the conventional magnetic ordered states, such as ferromagnets and antiferromagnets, are magnons. Here, we elaborate a case where the well-defined magnons are absent completely and the spin excitation spectra exhibit an entire continuum in the itinerant edge ferromagnetic state of graphene arising from the flatband edge electronic states. Based on the further studies of the entanglement entropy and finite-size analysis, we show that the continuum other than the Stoner part results from the spin-1/2 spinons deconfined from magnons. The spinon continuum in a magnetically ordered state is ascribed to a ferromagnetic Luttinger liquid in this edge ferromagnet. The investigation is carried out by using the numerical exact diagonalization method with a projection of the interacting Hamiltonian onto the flat band.

A quantum correlation test of quantum criticality in transverse-field Ising chain with Dzyaloshinskii-Moriya interaction

Usually, the zero temperature quantum critical point (QCP) induces a QC regime at low temperature due to the competition between quantum and thermal fluctuations, which is characterized by power-law temperature dependence of thermodynamics. Herein, focusing on the quantum phase transition (QPT) of transeverse-field Ising chain with Dzyaloshinskii-Moriya (DM) interaction, the quantum correlation exhibits temperature scaling. In the absence of magnetic field, the competition between DM interaction and Ising spin coupling manifested by θ angle, gives rise to different ground states such as Ising-type ferromagnetic (xFM), antiferromagnetic (xAFM) and Tomonaga-Luttinger liquid (TLL). As temperature emerges, the TLL phase is crossover into QC regimes with a crossover temperature connecting to a universal linear line T*~|θ-θc1,2| that ends at θc1,2 upon cooling down to 0 K, providing a new clue to capture QCP. Around QCP, the thermal QC scaling is demonstrated by analyzing quantum correlations and specific heat to extract the critical exponents (δ, β, γ and α) that fulfill the Widom and Essam-Fisher scaling laws, which is further verified by scaling hypothesis equations. As a magnetic field is turned on, an additional field-induced transverse ferromagnetic (zFM) phase with gapped low-lying excitation is unveiled. In particular, the Ising-like quantum criticality turns out to be gapless, which is different from the TLL-like one.

Magnetically Tunable Liquid Crystal-Based Optical Diffraction Gratings

We present a theoretical analysis of optical diffractive properties of magnetically tunable optical transmission gratings composed of periodically assembled layers of a polymer and a ferromagnetic liquid crystal (LC). The orientational structure of the LC layers as a function of an applied magnetic field is calculated by minimization of the Landau-de Gennes free energy for ferromagnetic LCs, which is performed numerically and also analytically by using the one-constant approximation and the approximations of the high and the low magnetic fields. Optical diffractive properties of the associated diffraction structure are calculated numerically in the framework of rigorous coupled-wave analysis (RCWA). The presented methodology provides a basis for designing new types of diffractive optical element based on ferromagnetic LCs and simulating their operation governed by the in-plane magnetic field.

Ferromagnetic and antiferromagnetic liquid crystal suspensions: Experiment and theory

In this paper, the complete theoretical and experimental studies of electrically and magnetically induced orientational transitions in suspensions of goethite nanorods in a nematic liquid crystal 4-(trans-4-n-hexylcyclohexyl)-isothiocyanato-benzene (6CHBT), known as ferronematics are presented. Two types of samples with different magnetic properties are prepared and observed. A compensated ferronematic with zero initial magnetization is obtained after cooling of the sample from isotropic to nematic phase in the absence of a magnetic field. A magnetized ferronematic with nonzero initial magnetization is prepared during application of magnetic field. The magnetically induced transitions demonstrated two different types of orientational behavior of the samples. The Fréedericksz transition in the compensated ferronematic occurred in higher magnetic field in comparison with pure nematic while the magnetized ferronematic shown well measurable response in capacitance to the applied magnetic field, even much below the Fréedericksz threshold in usual 6CHBT. Full theoretical descriptions of such behaviours of compensated and magnetized ferronematic samples are presented and all observed dependencies of the cells capacitance on magnetic field are numerically calculated. A comparative analysis shows very well qualitative and quantitative agreement between theoretical results and experimental data. Due to this, the material parameters of the investigated ferronematic system with goethite nanoparticles are estimated.

Role of fractal–fractional derivative on ferromagnetic fluid via fractal Laplace transform: A first problem via fractal–fractional differential operator

A deformity of magnetic field discloses that different particle of ferrofluid exhibits different pattern to accumulate more closely with strong magnetic properties; this is because of the existence of a homogeneous ferromagnetic liquid. In this context, the Newtonian fluid (ordinary liquid) is magnetized by dispersing into porous media. A mathematical model for ferromagnetic fluid is developed by means of fractal–fractionalderivative based on the power law. A powerful technique of Laplace transform is invoked on the fractal-fractionalized MHD Newtonian fluid model embedded in porous medium based within power law kernel. The solution is investigated for velocity field by particularizing the format of mathematical special function so called Fox-H function Hα,β+11,αF. The Fox-H function Hα,β+11,αF is employed among solution for the elimination of gamma functions. In order to generate the physical insight of fractal-fractionalized ferrofluid, a novel behaviors of velocity field based on the power law has disclosed several similarities and differences through the embedded rheological parameters. In short, It is worth noting that there is no previous paper related to ferrofluid involved with fractal–fractional​ derivative based on the power law.