Electromagnetic Force Field Research Articles

A General Coupled Mathematical Model of Electromagnetic Phenomena, Two-Phase Flow, and Heat Transfer in Electroslag Remelting Process Including Conducting in the Mold

A transient three-dimensional finite-volume mathematical model has been developed to investigate the coupled physical fields in the electroslag remelting (ESR) process. Through equations solved by the electrical potential method, the electric current, electromagnetic force (EMF), and Joule heating fields are demonstrated. The mold is assumed to be conductive rather than insulated. The volume of fluid approach is implemented for the two-phase flow. Moreover, the EMF and Joule heating, which are the source terms of the momentum and energy sources, are recalculated at each iteration as a function of the phase distribution. The solidification is modeled by an enthalpy-porosity formulation, in which the mushy zone is treated as a porous medium with porosity equal to the liquid fraction. An innovative marking method of the metal pool profile is proposed in the experiment. The effect of the applied current on the ESR process is understood by the model. Good agreement is obtained between the experiment and calculation. The electric current flows to the mold lateral wall especially in the slag layer. A large amount of Joule heating around the metal droplet varies as it falls. The hottest region appears under the outer radius of the electrode tip, close to the slag/metal interface instead of the electrode tip. The metal pool becomes deeper with more power. The maximal temperature increases from 1951 K to 2015 K (1678 °C to 1742 °C), and the maximum metal pool depth increases from 34.0 to 59.5 mm with the applied current ranging from 1000 to 2000 A.

Modeling and Experiments on Electromagnetic Separation of Inclusions from Aluminum Melt under Combined Magnetic Field

Abstract Numerical simulation and experiment studies have been conducted to investigate the effect of inclusions separation under combined magnetic field (CMF) generated by synchronous application of a rotating magnetic field (RMF) and a downward traveling magnetic field (TMF). The experimental setup is constituted by two sets of equidistant coils systems fed by out-of-phase alternating currents. The electromagnetic force field and flow field were calculated via finite-element analysis. CMF combines the rotational effect of RMF and the transport effect of TMF. Volume fraction and particle trajectories were simulated to examine the mechanism of particle separating. Good agreement between experimental and numerical results has been achieved. The flow field and the Archimedes electromagnetic force are the two main factors responsible for particle motion. This type of CMF provides a highly efficient approach at eliminating inclusions.

Electromagnetic Stir Casting and its Process Parameters for the Fabrication and Refined the Grain Structure of Metal Matrix Composites – A Review

In numerous applications of casting, dendritic microstructure is not desirable as it results in poor mechanical properties. Enhancing the fluid flow in the mushy zone by mechanical stirring is one of the means to suppress this dendritic. Several manufacturing techniques have been invented for fabrication of metal matrix composites. One of the popular ways of generating non-dendritic microstructure is to stir the liquid metal during solidification using an electromagnetic force field. However, the main problem faced in the electro magnetic stir (EMS) casting is the selection of optimum combination of input variables for achieving the required physical, mechanical and tribological properties of composites. Therefore, in the present work an attempt has been made to review electromagnetic stir casting and its process parameters for the fabrication and refined the grain structure of metal matrix composites that possesses exceptionally good mechanical properties as well as tribological properties.

Simulation of Magnetohydrodynamic Multiphase Flow Phenomena and Interface Fluctuation in Aluminum Electrolytic Cell with Innovative Cathode

A three-dimensional (3D) transient mathematical model has been developed to understand the effect of innovative cathode on molten cryolite (bath)/molten aluminum (metal) interface fluctuation as well as energy-saving mechanism in aluminum electrolytic cell with innovative cathode. Based on the finite element method, the steady charge conservation law, Ohm’s law, and steady-state Maxwell’s equations were solved in order to investigate electric current field, magnetic field, and electromagnetic force (EMF) field. Then, an inhomogeneous multiphase flow model of three phases including bath, metal, and gas bubbles, based on the finite volume method, was implemented using the Euler/Euler approach to investigate melt motion and bath/metal interface fluctuation. EMF was incorporated into the momentum equations of bath and metal as a source term. Additionally, the interphase drag force was employed to consider different phase interactions. Thus, present work owns three main features: (1) magnetohydrodynamic multiphase flow are demonstrated in detail both in aluminum electrolytic cell with traditional cathode and innovative cathode; (2) bath/metal interface fluctuation due to different driving forces of gas bubbles, EMF, and the combined effect of the two driving forces is investigated, which is critical to the energy saving; and (3) the effect of innovative cathode on melt flow and motion of gas bubbles. A good agreement between the predicated results and measurement is obtained. The velocity difference leading to the melt oscillation decreases due to more uniform flow field. The average velocity of metal in the cell with innovative cathode decreases by approximately 33.98 pct. The gas bubbles in the cell with innovative cathode releases more quickly under the effect of protrusion on the cathode. The average bubble release frequency increases from 1.1 to 1.98 Hz. Hence, the voltage drop caused by gas bubbles would decrease significantly. In addition, the two large vortices are broken into many small vortices due to the protrusion. The final disappearance of the small vortices as a result of viscous dissipation is conducive to the suppression of bath/metal interface fluctuation. The average interface amplitude in the cell with innovative cathode reduces to 75.95 pct of that in the cell with traditional cathode.

Coupled Numerical Simulation Study on Electromagnetic Field, Flow Field and Heat Transfer in ø210mm Round Billet Mold with M-EMS

aking the ∅210mm round billet M-EMS as study subject, a mathematical model coupling electromagnetic field, flow field and temperature field is established by use of Finite Element Analysis Software ANSYS. The distribution law of magnetic induction and electromagnetic force is investigated in mold; the effects of current intensity and frequency on magnetic induction, electromagnetic force, flow and temperature field is studied. The results show that: the values of magnetic induction and electromagnetic force reach its maximum near the edge of billet and became smaller towards the center; in the mold with EMS, the rotary flow is generated, and the flow pattern are upper recirculation zone, rotary zone and down recirculation zone, the location of hot area is moved up compared with the condition without EMS; in the considered parameters range, electromagnetic force and velocity of molten steel increase with the rise of current intensity and frequency.

Spinal cord stimulation for a woman with complex regional pain syndrome who wished to get pregnant

A woman with complex regional pain syndrome (CRPS) in the right lower extremity who wished to discontinue medications to get pregnant underwent implantation of a spinal cord stimulation system (SCS). An electrode lead was placed at Th(10-11) in the epidural space, accessed via the L(2-3) interspace with a paramedian approach, and a pulse generator was implanted in the left buttock. She kept the SCS on 24 h a day. After she had experienced several chemical abortions, finally she got pregnant via artificial insemination. She had an uneventful delivery of a healthy baby by cesarean resection under spinal anesthesia. In a patient with CRPS who has an implanted SCS system and wishes to get pregnant, the electrode lead into the low thoracic epidural space should be accessed via the high lumbar intervertebral space in consideration of a future requirement for spinal or epidural anesthesia for cesarean section. The generator should be placed in the buttock to prevent impairment of the SCS system being caused by the enlarged abdomen during pregnancy. Although we were apprehensive of adverse effects owing to the electromagnetic field force and change of blood flow in the pelvic viscera, our patient had a successful delivery. SCS is a favorable option for patients with CRPS who wish to get pregnant.

Homogenization of Electromagnetic Force Field During Casting of Functionally Graded Composites

The paper presents the analysis of the process of casting functionally graded composites under alternating electromagnetic field. The process utilizes the effect of electromagnetic buoyancy on nonconductive particles of the reinforcement in the conducting liquid (melted metal). The authors analyzed the possibilities of homogenizing the distribution of electromagnetic field in such a way as to obtain the desired direction of electromagnetic buoyancy and at the same time minimize the stirring of the molten metal, which makes it difficult to receive the optimal distribution of reinforcement in the casting. The suggested solution was to use the conductive elements of the mold to move the nonuniformity of the electromagnetic field outside the casting and a parabolic inductor to smooth the field distribution in the casting.

Electromagnetic field simulation and crack analysis of electromagnetic forming of Magnesium alloy tube

The AZ31 magnesium alloy tube was used for electromagnetic forming experiment of three kinds of input voltages. The stress-strain state of tube forming was analyzed. It was shown that the cause of oblique crack of tube was σr of axial inhomogeneous distribution and σz, and the cause of longitudinal crack was σr and σe of inhomogeneous distribution in circumferential direction. Moreover, the electromagnetic field and force field during electromagnetic forming was simulated by ANSYS software. The experiment proved the simulation result.

Lattice Boltzmann simulation of thermofluidic transport phenomena in a DC magnetohydrodynamic (MHD) micropump

A comprehensive non-isothermal Lattice Boltzmann (LB) algorithm is proposed in this article to simulate the thermofluidic transport phenomena encountered in a direct-current (DC) magnetohydrodynamic (MHD) micropump. Inside the pump, an electrically conducting fluid is transported through the microchannel by the action of an electromagnetic Lorentz force evolved out as a consequence of the interaction between applied electric and magnetic fields. The fluid flow and thermal characteristics of the MHD micropump depend on several factors such as the channel geometry, electromagnetic field strength and electrical property of the conducting fluid. An involved analysis is carried out following the LB technique to understand the significant influences of the aforementioned controlling parameters on the overall transport phenomena. In the LB framework, the hydrodynamics is simulated by a distribution function, which obeys a single scalar kinetic equation associated with an externally imposed electromagnetic force field. The thermal history is monitored by a separate temperature distribution function through another scalar kinetic equation incorporating the Joule heating effect. Agreement with analytical, experimental and other available numerical results is found to be quantitative.

Two Dimension Value Simulation of Plasma Powder Deposition Process in Electromagnetic Field

A two dimension value simulation was carried out for studying the electromagnetic force effect on melting pool in plasma powder deposition process. As the process is a layer-laminated deposition process, the gravity and the fluid motion of molten metal in melting pool during the layer-laminated deposition process without supporting, it will difficult to form complex shape parts. So a new scheme which using the magnetic field to restrict the melting metal flow was proposed. The method designed a restricted equipment of magnetic field in order to prevent and reduce the fluid flow and collapse of the melting pool. Compared with traditional method, as the height of the deposition shape increased, the process restricted with electromagnetic force can make the shape of parts more complex and more accurate. The changes of the electromagnetic force field were simulated with the finite element analysis, while the effects of electromagnetic force on forming process were discussed. Simulation show that the method is feasible and practicable. The electromagnetic force will decrease the post-treatment procedure and could contribute to the process of plasma powder deposition manufacture.

Calculation of electromagnetic force in electromagnetic forming process of metal sheet

Electromagnetic forming (EMF) is a forming process that relies on the inductive electromagnetic force to deform metallic workpiece at high speed. Calculation of the electromagnetic force is essential to understand the EMF process. However, accurate calculation requires complex numerical solution, in which the coupling between the electromagnetic process and the deformation of workpiece needs be considered. In this paper, an appropriate formula has been developed to calculate the electromagnetic force in metal work-piece in the sheet EMF process. The effects of the geometric size of coil, the material properties, and the parameters of discharge circuit on electromagnetic force are taken into consideration. Through the formula, the electromagnetic force at different time and in different positions of the workpiece can be predicted. The calculated electromagnetic force and magnetic field are in good agreement with the numerical and experimental results. The accurate prediction of the electromagnetic force provides an insight into the physical process of the EMF and a powerful tool to design optimum EMF systems.

Electromagnetic Field Simulation and Experiment of Electromagnetic Forming of Magnesium Alloy Tube

The AZ31 magnesium alloy tube was used for electromagnetic forming experiment of three kinds of input voltages. The stress-strain state of tube forming was analyzed. It was shown that the cause of oblique crack of tube was of axial inhomogeneous distribution and , and the cause of longitudinal crack was and of inhomogeneous distribution in circumferential direction. Moreover, the electromagnetic field and force field during electromagnetic forming was simulated by ANSYS software. The experiment proved the simulation result.

Modeling of electromagnetic separation of inclusions from molten metals

The presence of inclusions greatly influences the mechanical and the corrosion resistance of metallic alloys. These influential effects become more crucial when using metallic scrap, due to the high levels of inclusions and other contaminants such as non-metallic and oxides particles. Metal cleanliness requirements are becoming more striking, enforcing higher demands on the efficiency and flexibility of refining methods. Recently electromagnetic separation technique has been considered as a new method for the production of metals free from inclusions. In this study, a mathematical model has been developed to simulate the flow of molten metal through a channel in the presence of electromagnetic force field generated by interaction between a stationary electromagnetic field and DC current passing through the melt. A generalized model based on Newton's second law of motion was developed for the motion of inclusions in the melt flowing through the channel of separator by considering different forces acting on particle including electromagnetic force. A physical model was designed and constructed to visualize the inclusion separation phenomena and to verify the mathematical model. The predicted particle trajectories and separation in the physical model were compared with those obtained from experiments which showed reasonably good agreement. Parametric studies were performed using the mathematical model to evaluate the effects of various parameters, such as electromagnetic force strength, particle size and melt inlet velocity on the inclusion removal efficiency.

Multiscale Laminar Flows with Turbulentlike Properties

By applying fractal electromagnetic force fields on a thin layer of brine, we generate steady quasi-two-dimensional laminar flows with multiscale stagnation point topology. This topology is shown to control the evolution of pair separation (Delta) statistics by imposing a turbulentlike locality based on the sizes and strain rates of hyperbolic stagnation points when the flows are fast enough, in which case Delta(2) approximately t(gamma) is a good approximation with gamma close to 3. Spatially multiscale laminar flows with turbulentlike spectral and stirring properties are a new concept with potential applications in efficient and microfluidic mixing.

Solvent activity and its vapor pressure over a nonvolatile substance solution

295 Solvation effects in solutions are usually considered qualitatively with the reference to the enthalpy and entropy of mixing or diluting [1]. In the condensedstate physics, an interaction between particles is typically described in terms of the electromagnetic force field: the way one particle acts on some other is treated not as a direct interaction between them, but rather via the field effect E micr that causes polarization of molecules [2]. If the system is affected also by some external field E ext , the summary vector field is a superposition of the two fields: ∆ E = E micr + E ext . By the fundamental laws of electrodynamics [3], the specific polarization work of an environment molecule is

Electromagnetic field effect on separation of nucleotide sequences and unwinding of a double helix during DNA replication

Our previous pre-clinic experimental results have showed that the bacterium infection can be suppressed and the epithelialization can be enhanced by the externally applied rectangular pulsed electrical current stimulation (RPECS). The results are clinically significant for patients, especially for those difficult patients whose skin wounds need long periods to heal. However, the results also raise questions: How does the RPECS accelerate the epithelium cell proliferation? What is the relationship among the bacterium infection, the epithelialization and the RPECS? To answer these questions, we have previously modeled mitosis and cytokinesis mechanisms for animal cells and amitosis for bacteria at a cellular level and in a view of physics. In this paper, we model the separation of nucleotide sequences and the unwinding of a double helix during DNA replication at a molecular level and also in wild types of cells. Firstly, we define a new concept of nucleotide (NT) electromagnetic field (EMF) box (sequence) which carries genetic information: The continuous NT EMF boxes compose a nucleotide strand. Then, we hypothesize the symmetry, repulsion and attraction of NT EMF boxes: If a pair of NT EMF boxes are (quasi) mirror or complementary symmetric about a plane (curve) or point, they repulse or attract from each other because there is a repulsive or attractive EMF force between them. Our models suggest, the repulsive EMF force from children DNA strands simultaneously separates the children DNA strands, splits the hydrogen bonds of parental base pairs, and unwinds the parental double helix while DNA polymerases are synchronously synthesizing the new children DNA strands. To understand the mechanism of epithelialization enhanced with the externally applied RPECS at a molecular level, we hypothesize that the normal separation of nucleotide sequences and unwinding of a double helix during DNA replication could be suppressed in the bacteria but not in the epithelium cells because: (a) the spontaneous EMF in the epithelium could be 1000 times stronger than that in bacteria; (b) the epithelium cells have one more non-conducting envelope (nuclear membrane) to protect the normal separation and unwinding; (c) based on our previous experimental data, the RPECS amount received by the bacteria are three times as much as the amount the epithelium cells receive. Therefore, the epithelium cellular proliferation may be directly, as well as indirectly (e.g., somatic reflex) accelerated by the RPECS.

Modeling of transport phenomena in continuous casting of non-dendritic billets

A macroscopic model for simulating the phase change process and transport of solid fraction is developed for the case of solidification during direct chill continuous casting of a non-dendritic Al-alloy billet, in presence of electromagnetic stirring. Maxwell’s equations are solved to obtain the electromagnetic force field, which is incorporated in the momentum conservation equations as body force source terms. Thereafter, the complete set of equivalent single-phase governing equations (mass, momentum, energy, species conservation and transport of solid fraction) are solved using a pressure-based finite volume method. A variable viscosity approach is employed to model fluid flow in presence of phase change. The model is first validated against some experimental and numerical results available in the literature, pertaining to the case of conventional continuous casting without any externally imposed stirring. The model predicts the temperature, velocity, species and most importantly, the solid fraction distribution in the mold. These predictions are then used for studying the influence of initial superheat, stirring intensity and cooling rate on the macroscopic behavior of the system.

Electromagnetic flow control leading to a strong drag reduction of a sphere

We consider the flow of an electrically conducting fluid around a sphere with some internal source of alternating magnetic field. The resulting electromagnetic forces of this inductive scheme lead to a thrust of the sphere and a changed drag coefficient which balance each other in the self-moved regime. Allowing for a free choice of physically meaningful field distributions, the inverse problem is addressed of looking for such magnetic fields which result in a low drag. A gradient-type optimization is applied in the Stokes limit, and the same electromagnetic force fields are then applied at higher Reynolds numbers. Without claiming to have found a global optimum, we present some examples of electromagnetic forces providing strong reductions of the sphere drag by factors of 10 3 ... 10 4 compared to the non-magnetic case. Numerical results up to Re = 1000 are given, the corresponding modifications of surface pressure and vorticity are discussed.

Nonlinear viscoelasticity of polymer melts in electromagnetic vibration force field

The nonlinear viscoelastic behavior of polymer melts in electromagnetic vibration force field can be shown instantaneously by making use of a new capillary dynamic rheometer to measure their transient responses.

A New Interactive Visualization System With Force Feedback Device in 3-D Electromagnetics

This paper describes an interactive visualization system with force feedback device in three-dimensional (3-D) electromagnetics. We present an extension and improvement of the previously developed two-dimensional (2-D) interactive visualization system used for visualization of various 2-D field distribution maps with arbitrarily movable objects inside the analyzed region. We improve our 2-D visualization system to deal with real 3-D models. Moreover, we knew that perceiving electromagnetic force along with observing various 3-D field distribution maps could significantly help users to better understand the complex electromagnetic phenomenon. Driven by these ideas, we have developed a 3-D interactive visualization system with force feedback device for fast and easy perception of the electromagnetic force and electromagnetic field distribution maps for 3-D models with movable objects.