Field Lorentz Force Research Articles

Computational work of casson rheology on 3D swirling plate employing yamada-ota and xue models

This article emphasizes the findings of comparative thermal enhancement in Casson fluid using bases fluid as blood and Xue and Yamada-Ota hybrid nano-structures model towards a 3D swirling plate. Nanofluid flow is a widely investigated topic in engineering and industry, particularly in the cooling of electronic devices. Its proven ability to save energy makes it a viable option for improving cooling systems and sustainability initiatives. Thermal energy incorporates solar radiation, Soret and heat sources while transportation of species happens utilizing activation energy and Dufour impact. It was estimated that the system (partial differential equation) is converted into Odes employing finite element methodology. Such a complicated model is resolved efficient method named as finite element method. By enhancing impacts of chemical reaction and Dufour numbers, mass diffusion is enhanced but opposite behavior is noticed in mass diffusion with the change of Schmidt number. By increasing values of Lorentz force and velocity field inclines. Further, thickness (MBLs) increase with variation of Lorentz force and Casson parameter.

Brownian fluctuations of kinetic energy under Lorentz force

In stochastic thermodynamics, significant attention has been given to studying the statistical behavior of thermodynamic quantities, such as heat and work. However, fluctuations in other quantities, such as kinetic energy and internal energy, can also exhibit intriguing statistical properties. In this study, we investigate the fluctuations of kinetic energy within an initially equilibrated underdamped Brownian particle subsequently exposed to a Lorentz force, comprising both electric and magnetic fields, and provide insights through the examination of the characteristic function, central moments, and kinetic energy distribution.

Porous Medium Influenced Dissipative Hybrid Casson Nanofluid Flow over a Nonlinearly Stretching Sheet under Inclined Ohmic Lorentz Force Field

Porous Medium Influenced Dissipative Hybrid Casson Nanofluid Flow over a Nonlinearly Stretching Sheet under Inclined Ohmic Lorentz Force Field

Enhancing forming accuracy in aluminum alloy variable-diameter tubes through dual-coil controllable electromagnetic forming

High-accuracy forming of aluminum alloy variable-diameter tubes imposes strict requirements on force field design. Although electromagnetic forming has shown unique advantages in enhancing the formability of aluminum alloy materials, its shortcomings lie in the single and difficult-to-adjust force field, which limits its application in variable-diameter tubes. To address this challenge, a novel dual-coil electromagnetic forming approach with good controllability of force field is proposed. Numerical simulations and experiments are both conducted to showcase the superiority of this approach in forming variable-diameter aluminum alloy tubes. The results demonstrate that the forming accuracy of AA6061-O variable-diameter tubes has significantly improved compared to a traditional single-coil system, in which the maximum die-fitting gap is reduced from approximately 2 mm to less than 0.22 mm. Furthermore, it is identified the force field produced by the single-coil system causes a local cavity gap between the tube and the die, which adversely affects the forming accuracy. In contrast, the improved force field produced by the dual-coil system facilitates bottom-to-top deformation of the tube, thereby avoiding undesirable cavity gaps and achieving high forming accuracy. Importantly, the dual-coil forming system offers significant controllability of the Lorentz force field by adjusting the coil discharge, making it suitable for variable-diameter tubes of different sizes without changing the coil structure. This work represents a substantial advancement in controllable tube forming, offering a new approach to force field design and holding promise for extensive applications in the forming of variable-diameter tubes.

Dissipative Lorentz force influence on mass flow over a micro‐cantilever sensor sheet under magnetic Ohmic heating

AbstractThe novelty and main aim of the present numerical analysis is to explore the magneto‐thermo‐fluid characteristic features of incompressible, time‐dependent electrically conducting second‐grade fluid flow about a micro‐cantilever sensor sheet suspended in a squeezed regime between two parallel plates under the influence of Lorentz force field and viscous dissipation effects. Pertaining to this physical situation, the primitive forms of produced coupled nonlinear partial differential equations are rendered to non‐dimensional ordinary differential equations through appropriate scaling transformations. The resultant coupled nonlinear boundary value physical problem is solved by deploying a robust BVP4C Matlab function. The key features of the emerged different fluid flow parameters are documented in terms of extensive graphical visualization and tabular discussion. The current numerical investigation showed that, the increasing second‐grade fluid parameter significantly decreases the flow field and enhances the thermal and mass diffusion fields. Magnifying permeable velocity number decreases the velocity and increases the heat and concentration transport process. The thermal distribution over a sensor region is boosted with increasing Eckert number through viscous dissipation and magnetic Ohmic heating. Further, the elevating squeezing number decreases the skin friction and enhancing second‐grade fluid number boosted the skin‐friction coefficient. In addition to this, the increasing Schmidt and squeezing parameters decreases the local Sherwood number. Finally, a reasonable agreement between the present numerical solutions with the former results is presented.

Dissipative magnetic ohmic heating influence on radiative nanofluid flow about a permeable stretching sheet under a porous medium with heat source

The present numerical analysis describes the influence of dissipative magnetic Ohmic heating on the radiative magnetised nanofluid flow about a permeable stretching sheet under porous medium and thermal source/sink effects numerically. Produced steady-state Navier-Stokes conservation equations are highly nonlinear, coupled and which are rendered non-dimensional through appropriate similarity transformations. A Runge–Kutta scheme with shooting technique is implemented to produce the similarity solutions. Increased Lorentz force field decreases the velocity field. Nanofluid velocity significantly decreasedadjacent to the solid sheet for the increasing porous parameter. Enhancing thermal absorption number decreases the thermal boundary layer thickness. The novelty of the current investigation is to generalise the former studies by incorporating the magnetic Ohmic heating; viscous dissipation, radiation, porous number, Brownian motion and thermophoresis parameters and producing more refined nanofluid flow definition. A comparative study with former results also included to quantify the guarantee of the produced similar results.

Numerical method to depict the time-varying Lorentz force field under harmonic magnetic field

The time-varying Lorentz force field(tvLFf), induced by harmonic magnetic field, is widely used in materials pocessing, one of its typical applications is electromagnetic stirring in continuous casting. However, knowledge about the tvLFf is quite limited, only its time-averaged component is studied, and the profile of its time-varying component is unknown up to now. In this paper, the author develops a method to depict the tvLFf using 11 features, which are classified into 3 categories: Strength features, Morphology features and Tide features. All 11 features are created or extracted based on an analysis of the time-varying force ellipse, ruled by the amplitudes and initial phase angles of the induced eletromagnetic field. The elliptical characteristics of the time-varying Lorentz force are derived mathematically and via necessary numerical calculations, by which the effect of stirring or driving is clarified. The author finds that, the amplitudes of the induced eletromagnetic field are proportional to the magnitude of the exciting current, and that Strength features are proportional to the square of the magnitude of the exciting current, while the initial phase angles, Morphology features, and Tide features do not change with the magnitude of the exciting current, when frequency is fixed and the physical properties are constant. Finally, the author presents a model to illustrate the analyzing process, and a detailed visualization of the tvLFf is presented, with revealed features in conformity to the published results.

Influence mechanism of magnetic field direction on magnetic drag of reentry vehicle and better magnetic field direction

The magnetic field condition has a great influence on the magnetic control drag of reentry vehicle, so it is an important research topic to select appropriate magnetic field condition to control the drag force of vehicle. This paper analyzes the magnetic control drag by solving the hypersonic magnetohydrodynamic equations and combining the magnetic field working conditions, studies the influence of the axisymmetric magnetic field direction on the drag, supplements the mechanism of Lorentz force, pressure and conductivity on the axisymmetric magnetic control drag, and compares the drag value and drag composition ratio under different magnetic field directions. The problem is solved numerically for a particular model of a dipole magnetic field. Under different dipole magnetic fields, the magnitude and distribution shape of Lorentz force are different. There are several dividing lines where the Lorentz force is 0, and the Lorentz force directions on both sides are opposite, and this line divides the Lorentz force field into multiple parts. In addition, it is found that the change of the angle between the axis of the aircraft and the direction of the magnetic field will cause the change of the aircraft resistance, which will reduce or increase it.

New analytical solutions for the inextensible Heisenberg ferromagnetic flow and solitonic magnetic flux surfaces in the binormal direction

Maxwellian electromagnetism describes the wave features of the light and related subjects. Its original formulation was established 150 years ago. One of the four Maxwell’s equations is Gauss’s law, which states significant facts regarding magnetic flux through surfaces. It was also observed that optical media provides surface electromagnetism around 60 years ago. This observation leads to improve new techniques on nano-photonics, metamaterials, and plasmonics. The goal of this manuscript is to suggest novel accurate and local conditions for defining magnetic flux surfaces for the inextensible Heisenberg ferromagnetic flow in the binormal direction. The theoretical accuracy of the methodology is verified through the evolution of magnetic vector fields and the anti-symmetric Lorentz force field operator. On the other hand, the numerical accuracy and efficiency is developed in detail by considering the conformable fractional derivative method when these fields are transformed under the traveling wave hypothesis.

Numerical simulation and experimental validation of multiphysics field coupling mechanisms for a high power ICP wind tunnel* *Project supported by the National Natural Science Foundation of China (Grant No. 11705143), the Open Foundation for Key Laboratories of National Defense Science and Technology of China (Grant No. 6142202031901), and the Foundation for Research and Development of Applied Technology in Beilin District

We take the established inductively coupled plasma (ICP) wind tunnel as a research object to investigate the thermal protection system of re-entry vehicles. A 1.2-MW high power ICP wind tunnel is studied through numerical simulation and experimental validation. The distribution characteristics and interaction mechanism of the flow field and electromagnetic field of the ICP wind tunnel are investigated using the multi-field coupling method of flow, electromagnetic, chemical, and thermodynamic field. The accuracy of the numerical simulation is validated by comparing the experimental results with the simulation results. Thereafter, the wind tunnel pressure, air velocity, electron density, Joule heating rate, Lorentz force, and electric field intensity obtained using the simulation are analyzed and discussed. The results indicate that for the 1.2-MW ICP wind tunnel, the maximum values of temperature, pressure, electron number density, and other parameters are observed during coil heating. The influence of the radial Lorentz force on the momentum transfer is stronger than that of the axial Lorentz force. The electron number density at the central axis and the amplitude and position of the Joule heating rate are affected by the radial Lorentz force. Moreover, the plasma in the wind tunnel is constantly in the subsonic flow state, and a strong eddy flow is easily generated at the inlet of the wind tunnel.

Strip Size Optimization for Spiral Type Actuator Coil Used in Electromagnetic Flat Sheet Forming Experiment

Flat spiral coil for electromagnetic forming system has been modelled in FEMM 4.2 software. Copper strip was chosen as material for designing the actuator coil. Relationship between height to width ratio (S-factor) of the copper strip and coil’s performance has been studied. Magnetic field intensities, eddy currents and Lorentz force were calculated for the coils that were designed using six different 'S-factor' values (0.65, 0.75, 1.05, 1.25, 1.54 and 1.75), keeping the cross-sectional area of strip same. Results obtained through simulation suggest that actuator coil with S-factor ~ 1 shows optimum forming performance as it exerts maximum Lorentz force (84 kN) on work piece. The same coils was fabricated and used for electromagnetic sheet forming experiments. Aluminum 6061 sheets of thickness 1.5 mm have been formed using different voltage levels of capacitor bank. Smooth forming profiles were obtained with dome heights 28, 35 and 40 mm in work piece at 800, 1150 and 1250 V respectively.

Modeling and analysis of coagulation coefficient of bipolarly charged particles in a composite magnetoelectric field

To improve the efficiency of submicron-scale dust coagulation and removal further, a method for the magnetoelectric coagulation of submicron dust is proposed for the first time. When positively and negatively charged particles enter a compound field composed of magnetic field and direct current (DC) electric field at a certain speed (under the combined action of the Lorentz force and electric field force), they undergo spiral motion then collide and coagulate. The mathematical model of the coagulation of bipolarly charged particles in a composite magnetoelectric field is established, and the expression for the coagulation coefficient is obtained. Through the simulation of the coagulation coefficient, it is concluded that for PM1, the coagulation coefficient in the composite magnetoelectric field is increased by more than 20% compared with that in the DC electric field. The coagulation coefficient of bipolarly charged particles in the composite magnetoelectric field is positively correlated with the electric field strength, magnetic induction, and time for collision to occur, while it is negatively correlated with the particle density.

Simulation of the Averaged Flow of a Metal Melt in an Alternating Magnetic Field with Variable Amplitude and Frequency

The movement of a metal melt in an inhomogeneous high-frequency magnetic field is considered. A system of equations with boundary conditions defining the diffusion of the magnetic field and the heat conduction in such a melt in the Boussinesq approximation with account of the Joule heat released in the melt and the volume Lorentz forces acting in it is presented. The correctness of the mathematical model proposed is demonstrated. The amplitude distributions of the magnetic fields of the eddy currents induced in a metal melt, the velocity distributions of the heat flows in it, and the distribution of temperatures in the melt were calculated for the control parameters of its flow determined by the frequency and amplitude of the alternating magnetic field acting on it. The conditions under which the structure of this flow is completely determined by the parameters of the magnetic field and the problem on determination of the heat and mass transfer in the metal melt can be reduced to the calculation of its forced convection in the Lorentz force field and the temperature distribution in the melt at a definite velocity of its flow were determined.

Stable Fano-like plasmonic resonance: its impact on the reversal of far- and near-field optical binding force

Even for a 100 nm interparticle distance or a small change in particle shape, optical Fano-like plasmonic resonance mode usually vanishes completely. It would be remarkable if stable Fano-like resonance could somehow be achieved in distinctly shaped nanoparticles for more than 1 μm interparticle distance, which corresponds to the far electromagnetic field region. If such far-field Fano-like plasmonic resonance can be achieved, controlling the reversal of the far-field binding force can be attained, like the currently reported reversals for near-field cases. In this work, we have proposed an optical set-up to achieve such a robust and stable Fano-like plasmonic resonance, and comparatively studied its remarkable impact on controlling the reversal of near- and far-field optical binding forces. In our proposed set-up, the distinctly shaped plasmonic tetramers are half immersed (i.e. air–benzene) in an inhomogeneous dielectric interface and illuminated by circular polarized light. We have demonstrated significant differences between near- and far-field optical binding forces along with the Lorentz force field, which partially depends on the object’s shape. A clear connection is shown between the far-field binding force and the resonant modes, along with a generic mechanism to achieve controllable Fano-like plasmonic resonance and the reversal of the optical binding force in both far- and near-field configurations.

Multi-Physics and Multi-Scale Meshless Simulation System for Direct-Chill Casting of Aluminium Alloys

This paper represents an overview of the elements of the user-friendly simulation system, developed for computational analysis and optimization of the quality and productivity of the electromagnetically direct-chill cast semi-products from aluminium alloys. The system also allows the computational estimation of the design changes of the casting equipment. To achieve this goal, the electromagnetic and the thermofluid process parameters are coupled to the evolution of Lorentz force, temperature, velocity, concentration, strain and stress fields as well as microstructure evolution. This forms a multi-physics and multi-scale problem of great complexity, which has not been demonstrated before. The macroscopic fluid mechanics, solid mechanics, and electromagnetic solution framework is based on local strong-form meshless formulation, involving the radial basis functions and monomials as trial functions, and local collocation or weighted least squares approximation. It is coupled to the micro-scale by incorporating the point automata solution concept. The entire macro-micro solution concept does not require meshing and space integration. The solution procedure can be easily and efficiently automatically adapted in node redistribution and/or refinement sense, which is of utmost importance when coping with fields exhibiting sharp gradients, which occur in the phase-change problems. The simulation system is coded from scratch in modern Fortran. The elements of the experimental validation of the system and the demonstration of its use for round billet casting in IMPOL Aluminium Industry are shown.

Magnetohydrodynamic electro-osmotic flow of Maxwell fluids with patterned charged surface in narrow confinements

We study the magnetohydrodynamic electro-osmotic flow of Maxwell fluids through two microparallel plates with patterned charged surfaces. The combined influences of two imposed time periodic electric fields (one along the lateral direction and the other along the axial direction) and an external vertical magnetic field are taken into account. The flow is driven by Lorentz force and electric field force and is 2D due to charge modulated surfaces. Upon the assumptions of the Debye–Hückel linearization, the analytical solutions of the stream function and velocity field are derived. The variations in velocity with the dimensionless relaxation time De, the Hartmann number Ha, and the oscillating Reynolds number Re are depicted graphically. Furthermore, the parameters that influence the generation of vortexes in the flow field are also discussed.

Piezoelectric-on-Silicon MEMS Lorentz Force Lateral Field Magnetometers.

This paper describes the realization of piezoelectric-on-silicon lateral field Lorentz force magnetometers (LFMs) that target operation in ambient pressure instead of vacuum. Specifically, we describe two device topologies based on the out-of-plane resonant vibration modes. The first is based on a classic cantilever while the other is based on a corner-flapping square plate. In both topologies, piezoelectric transduction is exploited to enhance the sensitivity of the device compared to prevailing approaches to microelectromechanical system (MEMS) LFMs based on capacitive output interfaces. We show that the responsivity of the corner-flapping square plate topology (12026 ppm/T) is 8.5 times higher than a state-of-the-art lateral field LFM based on a capacitive output interface even without relying on vacuum. We here define responsivity as the output sense current per unit magnetic field density normalized over the input excitation current.

The Eruption of a Small-scale Emerging Flux Rope as the Driver of an M-class Flare and of a Coronal Mass Ejection

Abstract Solar flares and coronal mass ejections are the most powerful explosions in the Sun. They are major sources of potentially destructive space weather conditions. However, the possible causes of their initiation remain controversial. Using high-resolution data observed by the New Solar Telescope of Big Bear Solar Observaotry, supplemented by Solar Dynamics Observatory observations, we present unusual observations of a small-scale emerging flux rope near a large sunspot, whose eruption produced an M-class flare and a coronal mass ejection. The presence of the small-scale flux rope was indicated by static nonlinear force-free field extrapolation as well as data-driven magnetohydrodynamics modeling of the dynamic evolution of the coronal three-dimensional magnetic field. During the emergence of the flux rope, rotation of satellite sunspots at the footpoints of the flux rope was observed. Meanwhile, the Lorentz force, magnetic energy, vertical current, and transverse fields were increasing during this phase. The free energy from the magnetic flux emergence and twisting magnetic fields is sufficient to power the M-class flare. These observations present, for the first time, the complete process, from the emergence of the small-scale flux rope, to the production of solar eruptions.

Differences between Doppler velocities of ions and neutral atoms in a solar prominence

In astrophysical systems with partially ionized plasma the motion of ions is governed by the magnetic field while the neutral particles can only feel the magnetic field's Lorentz force indirectly through collisions with ions. The drift in the velocity between ionized and neutral species plays a key role in modifying important physical processes like magnetic reconnection, damping of magnetohydrodynamic waves, transport of angular momentum in plasma through the magnetic field, and heating. This paper investigates the differences between Doppler velocities of calcium ions and neutral hydrogen in a solar prominence to look for velocity differences between the neutral and ionized species. We simultaneously observed spectra of a prominence over an active region in H I 397 nm, H I 434 nm, Ca II 397 nm, and Ca II 854 nm using a high dispersion spectrograph of the Domeless Solar Telescope at Hida observatory, and compared the Doppler velocities, derived from the shift of the peak of the spectral lines presumably emitted from optically-thin plasma. There are instances when the difference in velocities between neutral atoms and ions is significant, e.g. 1433 events (~ 3 % of sets of compared profiles) with a difference in velocity between neutral hydrogen atoms and calcium ions greater than 3sigma of the measurement error. However, we also found significant differences between the Doppler velocities of two spectral lines emitted from the same species, and the probability density functions of velocity difference between the same species is not significantly different from those between neutral atoms and ions. We interpreted the difference of Doppler velocities as a result of motions of different components in the prominence along the line of sight, rather than the decoupling of neutral atoms from plasma.

Investigations on the Effects of Vortex-Induced Vibration with Different Distributions of Lorentz Forces

The control of vortex-induced vibration (VIV) in shear flow with different distributions of Lorentz force is numerically investigated based on the stream function–vorticity equations in the exponential-polar coordinates exerted on moving cylinder for Re = 150. The cylinder motion equation coupled with the fluid, including the mathematical expressions of the lift force coefficient C l , is derived. The initial and boundary conditions as well as the hydrodynamic forces on the surface of cylinder are also formulated. The Lorentz force applied to suppress the VIV has no relationship with the flow field, and involves two categories, i.e., the field Lorentz force and the wall Lorentz force. With the application of symmetrical Lorentz forces, the symmetric field Lorentz force can amplify the drag, suppress the flow separation, decrease the lift fluctuation, and then suppress the VIV while the wall Lorentz force decreases the drag only. With the application of asymmetrical Lorentz forces, besides the above-mentioned effects, the field Lorentz force can increase additional lift induced by shear flow, whereas the wall Lorentz force can counteract the additional lift, which is dominated on the total effect.