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In this work, we study the effect of hydrophilic fumed silica nanoparticles with different mass fractions on the magneto-rheological properties of magnetic fluid, and reveal the mechanism by the coarse-grained molecular dynamics simulation. The magneto-rheological experimental results show that the viscosity of the magnetic fluid with silica nanoparticles will first decrease and then increase (larger than that of the pure magnetic fluid) as the mass fraction of silica nanoparticles increases. We use the molecular dynamics calculations to further explain the influence mechanism of the silica nanoparticles on the magneto-rheological properties of the magnetic fluid. We find that non-magnetic particles will hinder the formation of chains of magnetic particles and shorten the length of the chains under magnetic fields. Our research shows that the magneto-rheological properties of magnetic fluid can be optimized with appropriate hydrophilic fumed silica nanoparticles, which is of great significance in the fields of dynamic seals and microfluidics.

The liquid crystal alignments in the liquid crystal cell composed of the bare glass and indium tin oxide (ITO) regions are investigated based on birefringence. The experimental results by the proposed methods of circularly and linearly polarized light agree with the observation through the polarized optical microscope. The results show that the liquid crystal in the region of the bare glass is optical anisotropic and the liquid crystal director is almost parallel to the long side of the liquid crystal cell, while the liquid crystal in the region of ITO is isotropic. No other chemical components were found on the bare glass and ITO surfaces by the x-ray energy dispersive spectrometer, and the numerous random scratches on the bare glass were observed through the atomic force microscope. The self-consistent explanations for the different approaches and characteristic results are obtained. It is concluded that the bulk stress on the bare glass, rather than the local stress accompanied with the scratches, resulted in the liquid crystal alignment. Compared with the anisotropy of the bulk stress on the full bare glass, which formed during the preparation, the local stress on the scribed bare glass of the liquid crystal cell is isotropic. The scratch orientations are random, which cause the averaged local stress isotropic. The bulk stress on the long side is more significant than that on the short side of the cell. As a result, the liquid crystal director is almost parallel to the long side of the liquid crystal cell. The direction of the liquid crystal in the region of ITO is random, and the liquid crystal in that region is not birefringent.

In this research, conductive magnetic fluid is prepared using carbon nanotubes (CNTs) as enhancing phase. The fluid is a superparamagnetic material. Experimental results show that CNTs form conductive networks. Meanwhile, surface treatment of CNTs is not conducive to enhance the conductivity, which has been confirmed by our calculations. More interestingly, when we apply an external magnetic field, the conductivity of the magnetic fluid increases along the magnetic field direction, showing anisotropy. These unique properties of the conductive magnetic fluid make it very promising in microwave absorbers and electromagnetic shields.

This paper is concerned with the damping performance of a novel dynamic vibration absorber that exploits the first kind of levitation characteristics of ferrofluid. The dynamic vibration absorber consists of a nonmagnetic container, a copper block, a small amount of ferrofluid, and three permanent magnets (top magnet, bottom magnet, and annular magnet). Under the influence of gravity, the copper block will deviate from the center of the container and generate an initial eccentricity between itself and the container. The dependence of the mass of the ferrofluid on the initial eccentricity is investigated in detail. When an external vibration occurs, the initial eccentricity will cause an included angle with a range of 0 ∘ ∼ 90°. The damping performance of the ferrofluid dynamic vibration absorbers without and with the top magnet are tested by the free oscillation of a copper plate under two included angles: 0°and 90°, respectively. In addition, the mechanism of damping performance affected by the mass of the ferrofluid is discussed based on the ferrohydrostatic relation of ferrofluid.

A diffuse interface lattice Boltzmann model for thermocapillary flows with large density ratio and thermophysical parameters contrasts is developed in this paper. In this model, three distribution functions are used to describe the evolution of phase field, velocity field and temperature field. The conservative Allen-Cahn-based lattce Boltzmann equation which has good numerical stability in simulating multiphase flows at high density ratio is employed to capture the phase interface. The velocity-based lattice Boltzmann equation is utilized to capture the hydrodynamics with thermocapillary effect. In particular, a lattice Boltzmann scheme is proposed to solve the temperature field equation based on the diffuse interface concept, in which the source term is computed locally. Unlike previous lattice Boltzmann model for thermocapillary flows, the thermophysical parameters (heat capacitance and thermal conductivity) of two fluids are allowed to be different. The present model is validated by simulating several numerical examples. Numerical results indicate the reliability of proposed diffuse interface lattice Boltzmann model in simulating thermocapillary flows with large density ratio (up to 1000) and thermophysical parameters contrasts. Moreover, we also derive an unsteady solution for thermocapillary-driven flow in a heated microchannel with two superimposed planar fluids, which can be used to assess the numerical accuracy of numerical algorithm for thermocapillary flows.

An immersed boundary-lattice Boltzmann method for electro-thermo-convection in complex geometries is introduced in this paper. The modified governing equations with the additional source terms, including the Navier-stokes equations, the temperature field equation, the electric potential equation and the conservation equation of electric charge, are solved by the lattice Boltzmann method. Both Dirichlet-type and Neumann-type boundary conditions on curved boundaries are treated by the immersed boundary method. The numerical accuracy of the present method is verified by three simple cases with the curved boundary conditions. Moreover, the electro-thermo-convection problems with the prescribed wall temperature and wall heat flux for different geometric configurations are studied. The effects of the thermal Rayleigh number, the electric Rayleigh number, the aspect ratio and the Prandtl number on the streamlines, isotherms, charge density distribution and surface-averaged Nusselt number are investigated. The results indicate that increasing the electric Rayleigh number can enhance the heat transfer rate and change the flow field structure. The coexistence and competition of the buoyancy force and electric force can be also observed.

Magnetic fluid (MF) seals have typically been used under various vacuum and gaseous low-pressure conditions. However, there are only a few cases in which MF seals can be used in a liquid environmen...

Conventional ferrofluids are not satisfactory in special fields, especially in corrosive and extreme temperature conditions. In this study, perfluoropolyether based ferrofluid with outstanding performance was synthesized by high energy ball milling. The results of XRD, TEM and particle size analyzer show that the modified Fe3O4 is well crystallized, globular shaped and monodisperse. Magnetic particles in a narrow size distribution ranging from 8 nm to 15 nm and the average is approximately 10 nm. Characteristic peaks in FT-IR and XPS spectrum confirm that Fe3O4 MNPs are successfully decorated by perfluoropolyether carboxylic acid surfactant. Perfluoropolyether based ferrofluid exhibits superparamagnetism, and magnetization is 22.83 emu/g at 10 kOe. Surface tension of perfluoropolyether based ferrofluid is 25.18 mN/m at 25 °C; Viscosity decreases with temperature increasing, which can be fitted as I· = e a+bT+c T 2 . In heating progress from −20 °C to 25 °C, perfluoropolyether based ferrofluid is a non-Newtonian fluid, while from 25 °C to 100 °C, it is a Newtonian fluid with almost constant viscosity. Viscosity of perfluoropolyether based ferrofluid increases to 1825.7 mPa·s at −20 °C and is still flowing at −40 °C. Yield point occurs when deformation reaches to 10%, and increases along with electromagnetic field in magnetic rheological behavior.

To improve the pressure capability of ordinary ferrofluid seals with a large gap, a novel type of converging stepped ferrofluid seals was proposed. The leakage positions and the magnetic field distributions in the sealing gaps of the new device are studied computationally by means of the finite-element method. The theoretical pressure capabilities of the seal are calculated based on a new expression introduced for the particular new seal geometry and for different sealing gaps. Computational results for effects of the radial and axial sealing gaps on the pressure capabilities of the seal are compared to the experimental results obtained from measurements employing a prototype of the proposed new seal. A good agreement between theoretical and experimental results is obtained. It is found that the pressure capabilities of the new seal depend on the height of the radial sealing gap and on the width of the axial sealing gap.

With the development of science technology, ferrofluid seal has been intensively applied in mechanical industry, but more and more larger sealing stages are needed. At present, the literature mostly concentrated on numerical analysis with few pole pieces ferrofluid seals and focused on the critical pressure value in one-stage magnetic fluid seal, lacking of numerical simulation and experimental validation on the static pressure of multi-stage ferrofluid seals. On this basis, the analysis of larger number of sealing stages is presented. And numerical simulation along with experiment investigation was used to study the seal capacity of ferrofluids in different seal gaps and different seal stages in this paper. The results show that the theoretical value is well coincident with experimental value when the sealing gap is less than 0.2 mm. Increase the number of the pole tooth can significantly improve the seal capacity of ferrofluid seal, but the sealing pressure of ferrofluids does not increase linearly with the addition of the number of pole teeth. For the new structure, the pressure of one-stage pole tooth has more than doubled as the sealing clearance is 0.2 mm and 3.5 times increase when the sealing gap is 0.3 mm.

In this paper, a lattice Boltzmann model with dynamic grid refinement is proposed for immiscible ternary flows, which is capable of conserving the total mass and preserving the volume of each phase. The application of interpolation schemes in adaptive mesh refinement (AMR) techniques results in the violation of the total mass of the fluids system within the lattice Boltzmann method (LBM) framework. In the present model, a source term with two free parameters is introduced into the interface capturing equation, which can be determined by the mass conservation and the volume preservation properties. A piecewise constant function has been deliberately incorporated into the source term in order to avoid the appearance of an unphysical fluid at the interface of other two fluids. Based on a block-structured AMR method, the governing equations for phase-field variables and flow hydrodynamic properties are solved by the finite-difference multiple-relaxation-time (MRT) LBM. Simulations of several typical problems are performed in order to evaluate the accuracy and applicability of the proposed model. The numerical results demonstrate that the present model can conserve both mass and volume at the same time as well as reduce numerical dispersion in the bulk region.

In this paper, we present an improved lattice Boltzmann model for fluid–fluid–solid (FFS) flows with a high viscosity ratio. The bounce-back particle model is combined with the Shan–Chen (SC) multicomponent model. We extend the bounce-back scheme based on velocity interpolation and a fresh-node initialization approach with second-order accuracy to moving particles within the framework of the multicomponent model. An improved virtual solid density model for wetting boundary conditions is employed to implement contact angles on curved boundaries. We examine the factors that lead to the violation of mass conservation, and an easy redistributing method is developed to fix the mass leakage issue. The combined multiphase particle model is able to simulate FFS flows with a high viscosity ratio of up to 1000 while preserving the total mass of the two fluids. The performance of the approach is tested by a variety of numerical experiments. The dynamic behaviors of moving contact lines on the curved boundary are validated by a droplet wetting on a solid particle. The model is then applied to simulate dynamic FFS problems, such as particle wetting at the fluid interface and particle motion through a fluid–fluid interface. According to the simulation results, the present model is capable of capturing the total force exerted on a particle by the fluid and the interface. However, the SC-type fluid–solid interaction force does not equal the capillary force in the present model. Finally, the self-assembly process of two floating particles on a liquid–liquid interface is investigated.

Compressed air energy storage is a well-used technology for application in high voltage power systems, but researchers are also investing efforts to minimize the cost of this technology in medium and low voltage power systems. Integration of this energy storage requires a robust control of the power electronic converter to control the power injection due to the dynamic behavior of the system. The conventional linear control design requires a thorough knowledge of the system parameters, but the uncertain disturbances caused by the mechanical properties of the energy storage is neglected in the design and the system fails in presence of such instances. In this paper an adaptive control-based boost converter and sliding mode control-based three phase inverter for a grid integrated compressed air energy storage system of up to 1 kW has been presented that can mitigate any uncertain disturbances in the system without prior knowledge of the system parameters. The experimental results along with the simulation results are also presented to validate the efficiency of the system.

To address the problem of building accurate and coherent models for large-scale terrains from incomplete and noisy sensor data, this paper proposes a novel framework that can efficiently infer terrain structures by divisionally providing the best linear unbiased estimates for the elevation values. To avoid data ambiguity caused by the uncertainty of sensor data, the proposed method introduces elevation filtering to extract the terrain surfaces, which reduces the amount of data greatly while the contained terrain information is basically unchanged. Then, for the large-scale terrains, the Gaussian mixture model is used to divide the interested regions, which remarkably improves the prediction accuracy and speed. Finally, for each subregion, a gaussian process regression model based on the static kernel is used to create a multiresolution terrain representation, which can deal with incompleteness of sensor data by considering the spatial correlations of the terrain. Evaluations of the proposed technique were conducted on diverse large-scale field terrains, including the quarry, planetary emulation terrain and highland, showing that the proposed method outperforms the state-of-art terrain modeling techniques in terms of the prediction accuracy, computation speed and memory consumption. As a practical application, the path planning problem was explored based on this terrain modeling technique to produce a better path.

In the present study, the magnetic field induced self-assembly processes of magnetic microparticles in an aqueous liquid (the pure magnetic fluid) and nonmagnetic microparticles in ferrofluid (the inverse magnetic fluid) are experimentally investigated The microparticles are formed into chain-like microstructures in both the pure magnetic fluid and the inverse magnetic fluid by applying the external magnetic field The fluorescence parameters of these self-assembled chain-like microstructures are measured and compared to those without the effect of magnetic field It is found that the fluorescence in the pure magnetic fluid is weakened, because the scattering and illuminating areas are reduced in the microstructures On the contrary, the fluorescence in the inverse magnetic fluid is enhanced, because more fluorescent nonmagnetic microparticles are enriched and become detectable under the effect of the magnetic dipole force and the magnetic levitational force, and their unnecessary scattering can be absorbed by the surrounding ferrofluid The average enhancement of the fluorescence area ratio in the inverse magnetic fluid with 3 μm nonmagnetic microparticles reaches 112 92% The present work shows that the inverse magnetic fluid has advantages such as low cost, no scattering effect, stable fluorescence intensity, and relatively low magnetic resistance In the end, a prototype design for the novel detection of coronavirus disease 2019 based on the magnetic field induced self-assembly in the inverse magnetic fluid is proposed, which could support the epidemic prevention and control © 2021 Author(s)

Magnetic fluid is a liquid magnetic material which could reflect the changes of magnetic field rapidly. For application research, the characteristics of magnetic fluid such as supermagnetism, lubricity and fluidity were introduced and analyzed. A gas flow sensor was designed and researched utilizing the magnetic fluid as a sensing medium. The combination of the magnetic fluid and magnet was designed as the magnetic core in the flow sensor. The structure of the flow sensor was designed and analyzed. The measuring work principle of the gas flow sensor with magnetic fluid was studied. By calculating and analyzing, the flow for measuring is related to the parameters including the elasticity coefficient of the spring, the motion distance of the magnetic core, the moving time of the magnetic core, the cross section area of the magnetic core, and the cross section of the measuring pipe for the gas passing through. The gas flow sensor with magnetic fluid is efficient and feasible.

We report on the experimental observation of the diffraction pattern formed in the far-field region when a high-power continuous-wave laser convergent or divergent Gaussian beam passes through a cuvette with ferrofluid. Two different types of diffraction rings with opposite light-intensity distribution are shown in the far field. The difference between the diffractive patterns is attributed to the interaction of the strong spatial self-phase modulation caused by the refractive index change of the medium with wavefront curvature of the input Gaussian beam. The observed behavior of the diffraction pattern dynamics is interpreted theoretically based on the Fresnel–Kirchhoff integral. The negative polarity of nonlinear refraction can be identified by the central interference profiles and the diffraction pattern. At the same time, the self-defocusing phenomena of the ferrofluid can be determined by the type of pattern. The nonlinear refraction coefficients of the ferrofluid were estimated to be ∼ − 2.89 × 10 − 5 c m 2 / W (convergent Gaussian beam) and ∼ − 3.53 × 10 − 5 c m 2 / W (divergent Gaussian beam). In addition, the corresponding third-order nonlinear optical susceptibility of the sample was also estimated as ∼ 1.43 × 10 − 5 e s u and ∼ 1.75 × 10 − 5 e s u , respectively. The experimental results imply a novel potential application of ferrofluid in nonlinear phase modulation devices.

Wind power connected to the power grid has been continuously increasing over the last decade. However, wind power is naturally unpredictable, which impacts on the stability of the power system. This paper reports a new method for the Doubly Fed Induction Generator (DIIG) wind turbine to gain the capability of participating in the primary frequency control service. The proposed method combined with inertia control and pitch angle control makes wind turbine release active power reserves. The paper presents a DFIG wind turbine mathematical model which is based on the parameters and structure of the 3.2 MW wind turbine from CSSC Haizhuang Windpower Co., Ltd. The simulation results show that the proposed method can provide additional active power during the period of grid frequency drops, which meets the state grid technical requirements for the wind turbine.

Background There are different surgical approaches used for repairing a supracardiac total anomalous pulmonary venous connection (TAPVC), with different results. This retrospective study evaluated the outcomes of surgical repair for supracardiac TAPVC through the combined superior approach in neonatal patients. Methods Medical records were retrospectively reviewed and 21 neonates who underwent supracardiac TAPVC repair with the combined superior approach between July 2014 and January 2020 were identified. There were 13 males and eight females. Results The patients’ median age was 20.6±8.9 days (range, 3–27). The median weight was 3.1±0.39 kg (range, 2.5–3.7) The median aortic cross-clamp and cardiopulmonary bypass times were 49.3±19.5 minutes (range, 27–86) and 91.1±23.7 minutes (range, 57–146). They were two deaths during the intensive care unit stay. One (1) patient died 2 months after discharge, the other remaining patients had no pulmonary venous obstruction (PVO) at the 6-month and intermediate-term follow-ups. Conclusions The combined superior approach is a useful method for repair of neonatal critical supracardiac TAPVC. This technique may be more helpful in preventing early postoperative anastomotic stenosis and contribute to an improved patient outcome.

The yielding behaviors of the ferrofluids are vital for many applications. However, previous studies have mainly focused on the magnetoviscous effect under relatively high shear rates and rarely involved the yielding process of ferrofluids under very low shear rates. In this study, ferrofluid samples of different particle volume concentrations were prepared and their shear thinning behaviors within a wide shear stress range were systematically studied under various magnetic field strengths and temperatures. The very shear thinning phenomenon of ferrofluids was first observed and its microscopic mechanism was analyzed. A precipitous fall-off stage as the mark of yielding appeared between the low shear and high shear plateaus in the viscosity curves of ferrofluids. The precipitous fall-off stage in the viscosity curves became steeper with the increase of the magnetic field strength or decrease in the temperature. For ferrofluids with relatively low particle volume concentrations, the high viscosity limit under the low shear region disappeared when temperature exceeded a certain value and was interpreted as the disappearance of the equilibrium columnar structures under high Brownian thermal interaction level. A composite Ellis model was proved to be suitable for the fitting of different types of yield stresses and a structural number, Sn was proposed for the dimensionless analysis of the shear thinning behaviors of ferrofluids. The findings in this study contribute to a better understanding of the microscopic mechanism of yielding behaviors of ferrofluids and also provide guidance for many practical applications.

The magnetic fluid seal is one of the best known and widely used technical applications of magnetic fluid. However, the boundary and the flow regime with the rotation shaft cannot be observed by the experiment method. This paper presents a novel numerical simulation method to obtain the boundary and the velocity of the fluid in seals. The magnetic field of the seal is solved by the finite-element method, and the Navier–Stokes equations of the magnetic fluid based on the influence of magnetic force are solved by the finite-volume method. The two-phase flow is solved by the volume of fluid method. The seal capacities of the rectangle tooth and the trapezoid tooth with different rotation velocities are obtained. The result shows that the seal capacity decreases with the increase in the rotation velocity.

SummaryAn effective path planner is critical for autonomous traversal of unmanned ground vehicles (UGVs) in harsh environments. This paper describes a novel path planning method considering Bézier curves and a two-layer planning framework. In the two-layer framework, a road centerline (RCL) estimator located on the upper layer works as a global planner to obtain the local target for the bottom local planner. The RCL is estimated from a series of candidate Bézier curves based on a safety criterion. In the bottom layer, an optimal trajectory planner and a speed planner make up the local planner to obtain the desired steering turning angle and linear speed. The criteria for optimal trajectory selection are designed for comfortable driving. Road safety is considered in the speed planner for robust driving. Three sets of simulations are used to evaluate and quantify the relative performance of variations of our path planning algorithm. The proposed path planning method is implemented on a modified Polaris RZR 800 UGV, too. Two experiments based on this UGV are set up in the country road environment to demonstrate the viability of the proposed method.

Using an altering chemically induced transition route, magnetic nanoparticles as well as nanoparticles modified with oleic acid have been prepared. The modified nanoparticles have been used to synthesize a high-quality kerosene-based ferrofluid, in which the mass fraction percentage of particles consisting of a γ-Fe2O3 core and an oleic acid coating, ϕm, amounted to 55%. Ferrofluids having lower concentrations of particles were obtained by diluting the mother ferrofluid. Magnetization measurements showed the as-synthesized ferrofluids to have excellent dispersity of the particles and field-induced inter-particle interactions. Optical transparency measurements confirmed that the ferrofluids showed a sensitive field-induced effect of chain-like aggregation, with redispersion of the particles after removing the magnetic field. According to results concerning both particle structure and ferrofluid density, the volume fraction percentage of particles, including both the γ-Fe2O3 core and the oleic acid coating, ϕ′v, as well as that of the γ-Fe2O3 alone, ϕv, can be deduced.

The self-levitation of permanent magnet in magnetic fluid has been widely used in sensors, actuators, dampers, bearings, and lubrication in micromechanical systems. In this paper, the magnetic self-levitation force (MSLF) experienced by a permanent immersed in magnetic fluid is studied, and the formula for calculating the MSLF is derived. To measure MSLF experimentally, a nonmagnetic rod is used to connect the magnet and dynamometer. The experimental error caused by the nonmagnetic rod is studied theoretically, and nonmagnetic Cu rods with different radii are used in the experiments to verify the theoretical analysis. With nonmagnetic Cu rod sticking on the top surface of the magnet, the experimental error caused by the nonmagnetic rod is negligible when the magnet moves down from center of the container. However, the experimental error can’t be ignored when the magnet moves up. In addition, the simulation results are in good agreement with the experimental results when the magnet moves down.

Magnetic fluid is a new type of functional materials. The seal of reciprocating shaft is a typical application of the magnetic fluid. However, there is little research on the magnetic fluid reciprocating seals, thus improving the sealing life and seal capacity is the key problem of studying the reciprocating seals. This paper presents a structure of the seal to test the sealing life and other characteristics. The magnetic field of the seal is estimated using the finite-element method. The thickness of the magnetic fluid on the surface of reciprocating shaft and the flow rate of magnetic fluid are obtained theoretically. The experimental result shows that the static seal capacity is related to the fluid volume. The static seal capacity obtained by experiment is approximately equal to the value through the simulation with sufficient magnetic fluid. The relationship between sealing life and the motion of the reciprocating shaft is obtained experimentally. The sealing life decreases rapidly with the increase of the stroke and velocity.

A self-made saturable absorber (SA) based on hybridized graphene oxide (GO) and ${{\rm Fe}_{3}}{{\rm O}_{4}}$Fe

Kerosene-based ferrofluid (FF) loaded with multiwalled carbon nanotubes (MCNTs) is prepared and characterized to enhance heat conduction and furthermore for potential application in high-speed ferrofluid seals. The present study investigates kerosene-based ferrofluid loaded with MCNTs for the thermal conductivity and magnetization behaviors by varying temperature, weight fractions of MCNTs, and functional groups of MCNTs. The thermal conductivity is then measured by using a transient hot wire method, and magnetization behaviors are measured by using vibrator sample magnetometers. Microstructures among MCNTs and microstructures between MCNTs and magnetic nanoparticles in nanofluids are analyzed by optical microscopy and transmission electron microscopy. Experiments are carried out in the temperature range of 20–50 °C, MCNT weight fraction range of 0–1% for kerosene-based ferrofluid loaded with pristine MCNTs (p-MCNTs), MCNTs functionalized with carboxylic groups (MCNTs-COOH), and MCNTs functionalized with hydroxyl groups (MCNTs-OH). Results show that thermal conductivity and magnetization of FF + MCNTs nanofluids decrease with the increase in temperature. The addition of MCNTs increases the thermal conductivity and decreases the magnetization of the original ferrofluid, especially in the FF + p-MCNTs nanofluids. Furthermore, the addition of 1 wt % p-MCNTs increases the thermal conductivity and decreases the magnetization of the original ferrofluid by 12.47 and 7.73%, respectively. Moreover, the FF + 1 wt % p-MCNTs nanofluid can be stable for at least eleven weeks, which might be basically applied to high-speed ferrofluid seals.

The application of magnetic fluid (MF) in microfluidics such as micropump and microvalve has been a hot topic recent years. Furthermore, the researches and the applications of MF seal are relatively mature and systematic. However, the seal capacity, which significantly influences the performance of micropump and microvalve, has not been studied specifically and overly. This paper focuses on the theoretical and experimental study about the seal capacity of MF seal in capillary tube. Furthermore, the influence of the clearance between the heads of steel poles, the inner diameter of the capillary tube, and the length of MF plug is investigated numerically and experimentally. In the simulation work, the conventional calculation model of magnetic pressure is applied to the occasion under the presence of low magnetic field and the simulation of magnetic field in the capillary tube is also conducted. Subsequently, the experiments are conducted and compared with our theoretical simulation results. In order to improve the prediction of the theory, the influence of viscosity is considered and the optimized theoretical results are compared with conventional theoretical results, which revealed that the viscosity cannot be ignored in the study of MF seal in capillary tube.

The influence of temperature on the inertial structures in magnetic fluid was previously assumed to be based on a single mechanism. In this work, specialized rheological experiments were performed and their results have shown that different structural evolution paths can take place under the function of hydrodynamic and thermal interaction. The widely adopted Mason number was proved to be unsuitable to describe the magnetoviscous effect of magnetic fluids under different temperatures. To give a proper description on the combined effect of magnetic dipolar interaction, hydrodynamic interaction and thermal interaction in magnetic colloidal system, a novel structural number S was proposed and found to be applicable to superimposed the data under various temperatures onto a master curves.