Magnetic Particle Velocity Research Articles

Simulation and experimental study of tool passivation based on magnetic elastic abrasive particles

The presence of micro-cracks and serrations on the tool often leads to its premature failure. However, these microscopic defects can be mitigated through passivation treatment of the tool. Magnetoelastic abrasive particles are new composite particles formed by using abrasive phase particles, magnetic media phase particles and polymer matrix according to a certain ratio, the abrasive particles have both viscoelasticity and magnetic conductivity. The introduction of magnetoelastic abrasive grains into the dual-disk tool passivation equipment can effectively improve the surface quality of the tool and increase the passivation efficiency. At the outset, a model for tool passivation was crafted employing the ABAQUS simulation software. This model aimed to evaluate the effects of diverse passivation variables on the stress levels, the shape of the impact, and the depth of the impact experienced by the tool. Subsequently, by applying statistical theory combined with fitting function techniques, a mathematical model was constructed to determine the passivation volume of the tool subjected to multiple magnetic elastic abrasive particles. This model was then used to examine the impact count and passivation volume associated with each passivation factor. Finally, a tool passivation experiment was conducted using a dual-disk magnetic tool passivation device. The results showed that the smaller the impact velocity of magnetic elastic abrasive particles, the stress and impact depth of the cutting tool are decreasing, and the deformation of the cutting edge is caused by compressive stress. The error of impact depth calculated by simulation and mathematical model is within 20 %, which proves that the mathematical model can better calculate the impact depth of magnetic elastic abrasive particles on the cutting edge of the tool.

A magnetic anomaly and particle velocity array correlator for the detection of internal waves in the ocean

Related literature has shown that internal waves (IWs) observed in the ocean are capable of producing secondary magnetic fields with a small signal-to-noise ratio due to the flow of dissolved salts. It can be difficult to characterize these signals since they are relatively weak, highly transient, and capable of being multi-modal. Using data collected by an array of magnetometers and acoustic Doppler current profilers, a technique called magnetic anomaly and particle velocity array correlator was developed for the detection of IWs. By using a combination of filtering techniques and a multi-variate correlation step, peak correlations above 90% were shown between the magnetic and water particle velocity records of potential IWs.

Study of fractional-order model on Casson blood flow in stenosed artery with magnetic field effect

In this research work, the impacts of magnetic fields on Casson blood flow with stenosed artery are studied. The flow under investigation is affected by a magnetic field and an oscillating pressure gradient. The Caputo–Fabrizio fractional-order derivative was used to express the governing system of partial differential equations with imposed boundary and initial conditions. The governing problem is solved using Laplace and Finite Hankel transformations. The exact solution for blood velocity, magnetic particle velocity, and temperature profiles are defined. For better understanding of the various physical parameter, numerical results are obtained for blood velocity, magnetic particle velocity and temperature profiles and presented through the graphs. It is seen that the magnetic fields tend to reduce the blood viscosity which can be used for controlling the blood flow rate. It is also seen that Casson fluid parameter tends to improve the blood flow rate. From the results, it is illustrated that the heat transfer process improves with thermal radiation and heat generation parameter.

Numerical and experimental analysis of terminal settling velocity in the presence of magnetic field aligned with gravity for ferro-magnetite particles using coupled CFD+DPM method

ABSTRACT Based on the previous investigations, in the presence of a magnetic field aligned with the gravity, the terminal settling velocity (TSV) of magnetic particles is improved compared to that of non-magnetic particles. In this paper, the effects of magnetic fields with intensities of 0.03 and 0.05 T on the TSVs of spherical magnetite particles and steel balls of different sizes were simulated using combined computational fluid dynamics and discrete phase methods (CFD + DPM). Simulations showed that the application of a magnetic field with the mentioned intensities increased the TSVs of the steel balls and the magnetite spherical particles up to 16.16% and 13.88%, respectively. To validate simulation outputs, using synthetic samples and a Magneto-Gravity Settling Device (MGSD) designed and fabricated by the authors, a series of lab settling tests were performed under the same operational conditions as those of simulations. The results of the test work concluded that in the presence of magnetic fields of 0.03 and 0.05 T intensities, steel balls and spherical magnetite particles settled faster by 8.84% and 7.41%, respectively. This shows that, with an acceptable error, CFD + DPM simulation methods can well predict the influence of the magnetic field on the settling behaviour of magnetic particles.

Velocity measurement of magnetic particles simultaneously affected by two-phase flow and an external magnetic field using dual-sided SPIM-µPIV

Micro-particle image velocimetry (µPIV) measurement in gas–liquid flow is a challenging task mainly due to the volume illumination of the laser light. A special solution frequently adopted is the use of a thin laser sheet with a reduced macro-scale 2D-PIV illumination method. In this study, a novel dual-sided single-plane illumination microscopy-micro particle image velocimetry (SPIM-µPIV) technique was developed and successfully applied to multi-phase flow. The velocity of magnetic particles in a power-generation unit using waste heat simultaneously affected by two-phase flow and an external magnetic field was measured. This technique illuminates a light source in a thin sheet form, thus reducing errors due to particle overlap. Both sides of the laser sheet were illuminated to prevent particle shadowing and amplify the fluorescence signal. The velocity distributions of the wall and center were measured simultaneously. The average magnetic particle diameter was 200 nm; the excitation and emission wavelengths were 530 and 650 nm, respectively. The central magnetic force of the external magnetic field was 0.23 T. The velocity of the magnetic particles was measured under bubbly and slug flows, where magnetic particles are disturbed and power can be generated. For the bubbly flow, the velocity and vorticity were reduced by 11.89% and 32.29%, respectively, and by 34.70% and 8%, respectively, for the slug flow. The bubbly and slug flows showed opposite results in terms of velocity and vorticity reduction.

Theoretical study of the blood flow in arteries in the presence of magnetic particles and under periodic body acceleration

Abstract In this article, the dynamics of blood with suspended magnetic particles in coronal and femoral arteries are investigated. The flow of blood is examined in the presence of external magnetic field, periodic body acceleration and a pressure gradient of an oscillating type. Expressions for the velocity of blood and velocity of magnetic particles will be yielded by employing integral transforms. The analytical results will be expressed in terms of steady-state and transient parts. Moreover, to get insight of the control of the material parameters such as amplitude, the lead angle, frequency of body acceleration, magnetic field and particles’ concentration parameter, numerical simulations and graphical illustrations will be used and useful consequences will be summarized.

Rotating magnetic particles for lab-on-chip applications - a comprehensive review.

Magnetic particles are widely used in lab-on-chip and biosensing applications, because they have a high surface-to-volume ratio, they can be actuated with magnetic fields and many biofunctionalization options are available. The most well-known actuation method is to apply a magnetic field gradient which generates a translational force on the particles and allows separation of the particles from a suspension. A more recently developed magnetic actuation method is to exert torque on magnetic particles by a rotating magnetic field. Rotational actuation can be achieved with a field that is uniform in space and it allows for a precise control of torque, orientation, and angular velocity of magnetic particles in lab-on-chip devices. A wide range of studies have been performed with rotating MPs, demonstrating fluid mixing, concentration determination of biological molecules in solution, and characterization of structure and function of biomolecules at the single-molecule level. In this paper we give a comprehensive review of the historical development of MP rotation studies, including configurations for field generation, physical model descriptions, and biological applications. We conclude by sketching the scientific and technological developments that can be expected in the future in the field of rotating magnetic particles for lab-on-chip applications.

Analysis of blood flow with nanoparticles induced by uniform magnetic field through a circular cylinder with fractional Caputo derivatives

The magneto hydrodynamic blood flow in the presence of magnetic particles through a circular cylinder is investigated. To calculate the impact of externally applied uniform magnetic field, the blood is electrically charged. Initially the fluid and circular cylinder is at rest but at time t=0+, the cylinder starts to oscillate along its axis with velocity fsin(Ωt). To obtain the mathematical model of blood flow with fractional derivatives Caputo fractional operator is employed. The solutions for the velocities of blood and magnetic particles are procured semi analytically by using Laplace transformation method. The inverse Laplace transform has been calculated numerically by using MATHCAD computer software. The obtained results of velocities are presented in Laplace domain in terms of modified Bessel function I0(·). The obtained results satisfied all imposed initial and boundary conditions. The hybrid technique that is employed here less computational effort and time cost as compared to other techniques used in literature. As the limiting cases of our results the solutions of the flow model with ordinary derivatives has been procured. Finally, the impact of Reynolds number Re, fractional parameter α and Hartmann number Ha is analyzed and portrayed through graphs. It is worthy to pointing out that fractional derivatives brings remarkable differences as compared to ordinary derivatives. It also has been observed that velocity of blood and magnetic particles is weaker under the effect of transverse magnetic field.

Shock Initiation of the CL-20-Based Explosive C-1 Measured with Embedded Electromagnetic Particle Velocity Gauges

Hexanitrohexaazaisowurtzitane (CL-20) is a high-energy material with high shock sensitivity. The evolution of shock into the detonation of CL-20 deserves academic attention and research. An embedded electromagnetic particle velocity gauge was used to study the shock initiation of detonation in a pressed solid explosive formulation, C-1, containing 94 wt-% epsilon phase CL-20 and 6 wt-% fluororubber (FPM). In conventional experiments, the magnetic field was generated using a pair of electromagnets with a complex structure and operation. A new device was designed to solve complex problems. This device comprised NdFeB magnets, pole shoes and magnetic yokes; using this technique, a uniform magnetic field could be created. A series of shock initiation experiments on high-explosive C-1 was performed, and the explosive samples were initiated at different intensity input shocks by an explosive driven flyer plate. In situ magnetic particle velocity gauges were utilized to detail the growth from an input shock to detonation, and the attenuation of particle velocity in unreacted C-1 was also obtained in low-intensity shock initiation experiments. Hugoniot data for C-1 in the form of shock velocity D vs. particle velocity Up were obtained. A simulation model for shock initiation of C-1 was established, and the particle velocity data from several experiments were used to determine the parameters required for the unreacted equation of state and ignition and growth reactive flow model for C-1. These coefficients were then applied in the calculation of the initial shock pressure−distance to detonation relationship (Pop-plot) for the explosive. Based on the results of experiments and simulations, the shock sensitivity characteristic of C-1 was described.

Directed Magnetic Particle Transport above Artificial Magnetic Domains Due to Dynamic Magnetic Potential Energy Landscape Transformation.

An approach for a remotely controllable transport of magnetic micro- and/or nanoparticles above a topographically flat exchange-bias (EB) thin film system, magnetically patterned into parallel stripe domains, is presented where the particle manipulation is achieved by sub-mT external magnetic field pulses. Superparamagnetic core-shell particles are moved stepwise by the dynamic transformation of the particles' magnetic potential energy landscape due to the external magnetic field pulses without affecting the magnetic state of the thin film system. The magnetic particle velocity is adjustable in the range of 1-100 μm/s by the design of the substrate's magnetic field landscape (MFL), the particle-substrate distance, and the magnitude of the applied external magnetic field pulses. The agglomeration of magnetic particles is avoided by the intrinsic magnetostatic repulsion of particles due to the parallel alignment of the particles' magnetic moments perpendicular to the transport direction and parallel to the surface normal of the substrate during the particle motion. The transport mechanism is modeled by a quantitative theory based on the precise knowledge of the sample's MFL and the particle-substrate distance.

Magnetic field effect on flow parameters of blood along with magnetic particles in a cylindrical tube

Abstract In this paper, the effect of external uniform magnetic field on flow parameters of both blood and magnetic particles is reported through a mathematical model using magnetohydrodynamics (MHD) approach. The fluid is acted upon by a varying pressure gradient and an external uniform magnetic field is applied perpendicular to the cylindrical tube. The governing nonlinear partial differential equations were solved numerically and found that flow parameters are affected by the influence of magnetic field. Further, artificial blood (75% water+25% Glycerol) along with iron oxide magnetic particles were prepared and transported into a glass tube with help of a peristaltic pump. The velocity of artificial blood along with magnetic particles was experimentally measured at different magnetic fields ranging from 100 to 600 mT. The model results show that the velocity of blood and magnetic particles is appreciably reduced under the influence of magnetic field, which is supported by our experimental results.

One-dimensional plate impact experiments on the cyclotetramethylene tetranitramine (HMX) based explosive EDC32

Eight one-dimensional plate impact experiments have been performed to study both the Shock to Detonation Transition and Hugoniot state in the cyclotetramethylene tetranitramine (HMX) based explosive EDC32. The experiments covered shock pressures ranging from 0.59 to 7.5 GPa with sustained shocks, double shocks, and short pulse shocks. Experiments were instrumented with embedded magnetic particle velocity gauges. Results include; (1) wave profiles of particle velocity vs. time vs. depth in the explosive, (2) time-distance coordinates for onset of detonation vs. initial shock pressure (aka the Pop-plot), (3) a reactants Hugoniot, and (4) measurement of the Hugoniot Elastic Limit of 0.22.GPa.

SHOCK HUGONIOT RELATION OF UNREACTED HETEROGENEOUS EXPLOSIVES

There is a continuing interest in determining the characteristics of unreacted plastic bonded explosives (PBXs). In this work, a Particle Velocity Comparing Method to determine the unreacted Hugoniot of heterogeneous explosive using magnetic particle velocity gauge is described. The Hugoniot for the PBXs has been measured using flyer driven by planar wave lens. A superposition principle considering unreacted explosives as composite and porous materials is presented, the unreacted Hugoniot of explosives is calculated, and the results of calculation are compared with the experiment results.

Effect of patterned micro-magnets on superparamagnetic beads in microchannels

The trapping response of patterned micro-magnets (PMMs) was studied based on the parameters affecting superparamagnetic beads in microfluidic channels. Using replica moulding and electroplating technologies, the PMMs were fabricated on the microchannel bottom, which generated sufficient magnetic forces to bias the moments of magnetic particles in a flowing stream. A simplified physical principle was used to analyse the relative velocity of the magnetic particle in the confined space of a microchannel. The results revealed that the magnetic force contributed to the fluidic flow rate as well as to the hydrodynamic drag force. The relative velocity of magnetic particles was dependent on the frequency under an external magnetic field driven by an alternate current (ac) source. It showed that the magnetic gradient induced hysteresis characteristics of the transmission spectrum, associated with the interaction of superparamagnetic beads and magnetic field.

Quartz to stishovite: Wave propagation in the mixed phase region

This work reports on phase transition kinetics and wave propagation in Arkansas novaculite, a fine-grained polycrystalline α quartz rock, when it is subject to high-pressure dynamic loading and relief. The stress region studied is between 150 and 400 kbar, where the polymorphic phase transition from α quartz to stishovite is believed to occur. Particular emphasis was focused on the unloading behavior in the mixed phase region. High-pressure loading is provided by conventional explosive methods. Measurements of the transient flow field are obtained with in-material manganin stress gages or magnetic particle velocity gages. Results showed partial transformation to the high-density phase occurring in the shock front, the degree of transformation depending on peak driving stress. A continuing transformation rate behind the shock front is very small, i.e., at least 3 orders of magnitude slower than the initial transformation rate. Unloading from stress-volume points in the mixed phase region is observed to occur along, or close to, paths of frozen phase concentration down to approximately 80 kbar. Below this stress the data indicate a transition of the high-density phase to a lower-density phase.

The generation and effect of electrostatic fields during an auroral disturbance

The equations of motion of electrons and ions in the presence of electric, magnetic, and neutral particle velocity fields are derived for conditions likely to exist in an auroral arc. The electric field resulting from charge separation is computed. Electron densities, charged-particle motion, and electric currents are also computed. It is shown how these computations can account for magnetic bays, electron drifts, and electric field fluctuation observed during auroral disturbances. Analytical expressions for electric field strengths and neutral plasma drift velocities are derived.