Magnetic Field Orientation Angle Research Articles

The Impact of Inclined Magnetic Field on Streamlines in a Constricted Lid-driven Cavity

The influence of oriented magnetic field on the incompressible and electrically conducting flow is investigated in a square cavity with a moving top wall and a no-slip constricted bottom wall. Radial basis function (RBF) approximation is employed to velocity-stream function-vorticity formulation of MHD equations. Numerical results are shown in terms of streamlines for different values of Hartmann number M, orientation angle of magnetic field ϴ and the height of the constricted bottom wall hc with a fixed Reynolds number. It is obtained that the number of vortices increases as either hc or M increases. However, the increase in ϴ leads to decrease the number of vortices. Formation of vortices depends on not only the strength and the orientation of the magnetic field but also the constriction of the bottom wall.

ИСПОЛЬЗОВАНИЕ ОРТОГОНАЛЬНЫХ СИЛЬНЫХ ЭЛЕКТРИЧЕСКИХ И МАГНИТНЫХ ПОЛЕЙ ДЛЯ СОЗДАНИЯ ЧАСТОТНО-ПРЕОБРАЗОВАТЕЛЬНЫХ УСТРОЙСТВ АВТОДИННОГО ТИПА

In the framework of the drift-diffusion model of carrier transport in the bulk of III–V typesemiconductors, under external action of strong constant electric and magnetic fields orthogonallyoriented relative to each other, a new principle for applying the discovered effects is proposed, whichtake into account the nonlinearities of the output parameters of the working chip, which leads to thepossibility creation of new semiconductor structures controlled by a magnetic field (SSCMF). Previously,the diffusion component of the output current density was not taken into account as a separateeffect arising under the orthogonal action of strong electric and magnetic components, which was atfirst time considered in this paper. It is shown that this component is a part of the inductive transverseoutput current and can be considered as an independent effect. The proposed practical applicationis based on the classical relations that describe the component spatial representation of the effectivemass energy dependence and the parameters of the kinetic equations for the carriers drift andheating in the bulk of highly mobile III–V type semiconductors structures. (The energy dependence ofthe reciprocal effective mass value was obtained under the assumption that this parameter becomesheavier in the framework of the two-valley representation. However, the mechanism of such increasingis not considered in detail, but is taken into account as a result of expansion in a Taylor series.)At the same time, some new phenomena were also hypothetically discovered: a diffusion detectoreffect and a transverse induction effect controlled by a magnetic field, similar in its manifestation tothe Gunn effect observed in this direction. The results obtained open the prospect for creating fundamentallynew frequency-converting devices based on the above SSCMF, such as autodyne-type converters(mixers), one of the designs of which is also proposed in this work in a waveguide version. Inthe case of experimental confirmation of the discovered effects, which can be investigated using theblock diagram of the measuring setup proposed in the work, we can conclude that there are promisingnew applications of magnetically controlled semiconductor structures. In addition, equipmentdevelopers will be interested in the possibility of using the magnetic field orientation angle to controlthe output parameters of such structures as part of converters

Thermosolutal hydromagnetic mixed convective hybrid nanofluid flow in a wavy walled enclosure

This paper deals with the effects of an inclined magnetic field and hybrid nanoliquid on thermosolutal mixed convection in a partially heated wavy walled enclosure. Two distinct flow features are considered by performing a variant of heating and concentrating locations in both the vertical walls. The upper border is in motion with the same speed in the right direction. The governing Navier–Stokes equations are modeled to describe thermosolutal phenomena. These equations are solved by reconstructing a recently developed compact scheme. Results are displayed in terms of streamlines, isotherms, iso-concentrations, average Nusselt and Sherwood numbers to evoke the thermosolutal phenomena for various physical parameters. Furthermore, the significance of well-defined parameters influencing the fluid rotation and thermosolutal transfer, namely Richardson number (0.1≤Ri≤10), Lewis number (1≤Le≤5), thermal Grashof number (GrT=104), Buoyancy ratio (−1≤N≤1), Hartmann number (0≤Ha≤40), orientation angle of magnetic field (00≤γ≤900) and solid volume fraction (0.0≤ϕhnp≤0.04) of the hybrid nanofluid are performed generously. Results reveal that the heating areas and the angle γ play a vital role in flow topology, thermal and solutal transport inside the wavy enclosure. In addition, thermal and solutal transfer enhancement are noted with increasing values of γ while thermal and solutal transfer reduction are noted with the increasing Hartmann number. We have noticed that for the change in the concentration of Cu-Al2O3/water hybrid nanofluid (ϕhnp) from 1% to 4%, average Nusselt number is enhanced by 7.46% in Case-I and 5.09% in Case-II whereas average Sherwood number is decreased by 2.42% and 1.58% for Case-I and Case-II respectively. It is also concluded that the single nanofluid is more effective than the hybrid nanofluid in the case of thermosolutal transport phenomena.

On the analysis of magnetohydrodynamics and magnetic field-dependent viscosity effects on thermogravitational convection of hybrid nanofluid in an enclosure with curved walls

This work deals with the impact of magnetic field-dependent viscosity and magnetohydrodynamics on the natural convection heat transfer of Ag–MgO (50%–50%) water hybrid nanoliquid in a complicated enclosure. The considered cavity with concave or convex horizontal boundaries has been differentially heated and cooled by multiple heat sources and heat sinks. The governing equations (Navier–Stokes equations) constituting stream function (ψ)-vorticity (ζ) formulation with energy equation are solved by adopting a compact finite difference scheme. Meanwhile, the flow domain that is influenced by several factors including Hartmann number (0≤Ha≤60), hybrid nanoparticles volume fraction (0≤ϕhnp≤0.02), Rayleigh number (103≤Ra≤106), orientation angle of magnetic field (00≤γ≤900), magnetic number (0≤δ0≤1), different cases (Case-I to III), and internal heat generation or absorption (−2≤Q≤2) is analyzed generously. Experimentally based correlations for thermal conductivity and dynamic viscosity have been used throughout the study. The outcomes show that the geometric parameters can be used as an excellent controller of the thermal performance inside the wavy chamber.

Brownian motion of magnetonanofluid flow in an undulated partially heated enclosure

This paper is framed to analyze mixed convection flow features of a CuO - H11H2O2O nanoliquid within a partially heated wavy enclosure. The enclosure is embraced by the inclined magnetic field. In addition, the impact of Brownian motion is assimilated into the nanoliquid. Two models, namely the viscosity and the thermal conductivity depending on the Brownian motion of nanoliquid are used. The numerical solutions of the control equations constituting Navier-Stokes equations are carried out by adopting a compact finite difference scheme. Our computed results using some experimental data are compared to the results available in the literature and a nice resemblance is obtained. Numerical results for the specified problem are investigated by controlling the key characteristics such as nanoparticle concentration (0≤ϕ≤0.04), Richardson number (0.1≤Ri≤20), Reynolds number (50≤Re<750), Grashof number (Gr=5×104), Hartmann number (0≤Ha≤60), orientation angle of magnetic field (00≤γ≤900), number of undulations (0≤λ≤3) and amplitude of wavy surface (A=0.05). It is established that the angle γ and the position of the heating area play a crucial role in the liquid motion and heat transport inside the wavy cavity. The energy transfer rate can be augmented or diminished in presence of nanoparticles along with variations of Hartmann and Richardson numbers as well as the number of waviness of the bottom surface of the enclosure.

Constraints on axion-like particles with different magnetic field models from the PKS 2155–304 energy spectrum

Axion-like particles (ALPs) are a promising kind of dark matter candidate particle that are predicted to couple with photons in the presence of magnetic fields. The oscillations between photons and ALPs traveling in the magnetic fields have been used to constrain ALP properties. In this work, we obtain some new constraints on the ALP mass ma and the photon-ALP coupling constant g with two different magnetic field models through TeV photons from PKS 2155–304. The first is the discrete-φ model in which the magnetic field has the orientation angle φ that changes discretely and randomly from one coherent domain to the next, and the second is the linearly-continuous-φ model in which the magnetic field orientation angle φ varies continuously across neighboring coherent domains. For the discrete-φ model, we can obtain the best constraints on the ALP mass m1 = ma/(1\\ neV) = 0.1 and on the photon-ALP coupling constant g11 = g/(10−11 GeV−1) = 5. The reasonable range of the ALP mass m1 is 0.08 ∼ 0.2 when g11 = 5, and the only reasonable value of the photon-ALP coupling constant is g11 = 5 when m1 = 0.1. For the linearly-continuous-φ model, we can obtain the best constraints on the ALP mass m1 = 0.1 and on the photon-ALP coupling constant g11 = 0.7. The reasonable range of the ALP mass m1 is 0.05 ∼ 0.4 when g11 = 0.7, and the reasonable range of the photon-ALP coupling constant g11 is 0.5 ∼ 1 when m1 = 0.1. All of the results are consistent with the upper bound (g < 6.6 × 10−11 GeV−1, i.e., g11 < 6.6) set by the CAST experiment.

Highly Demagnetization Performance IPMSM Under Hot Environments

This paper examines how changing the magnetic orientation of permanent magnets in concentrated winding interior permanent magnet synchronous motors (IPMSMs) affects their demagnetization resistance. We evaluated a prototype for demagnetization at 180 °C that consists of a 130° V-shaped rotor core in which parallelogram magnets with oblique orientation are arranged and confirmed by finite element analysis where the demagnetization resistance increases as magnetic field orientation angle $\alpha $ becomes larger. For demagnetization evaluation of the prototype, it is easier to change the rotor core shape of a two-pole test rotor of a multipole IPMSM than a multipole rotor, and the demagnetization evaluation is performed using a small number of magnets.

Analysis of heatlines and entropy generation during double-diffusive MHD natural convection within a tilted sinusoidal corrugated porous enclosure

The natural convection and entropy generation during double-diffusive MHD natural convection in a tilted sinusoidal corrugated porous enclosure is investigated numerically in this work by using heatline visualization technique. The top and bottom horizontal walls are assumed as adiabatic and non-diffusive, while the left and right vertical corrugated sidewalls are maintained at a constant hot and cold temperatures and concentrations respectively. The flow in the enclosure is subjected to an inclined magnetic field. The enclosure is filled with an electrically conducting fluid [Pr = 0.024] saturated with a porous media. The numerical computations are presented for various values of Rayleigh number (Ra), Hartmann number (Ha), Lewis number (Le), Darcy number (Da), buoyancy ratio (N), magnetic field orientation angle (φ) and enclosure inclination angle (Φ). In addition, the entropy generation due to fluid friction, thermal gradients, diffusion, and magnetic field beside the total entropy generation are studied and discussed. It is found that the flow circulation decreases strongly when the magnetic field applied horizontally and the enclosure is considered vertical. Heatline visualization concept is successfully applied to the considered problem. The average Nusselt number decreases when the Lewis number increases, while the average Sherwood number increases when the Lewis number increases. Also, both average Nusselt and Sherwood numbers increase when the Darcy number and buoyancy ratio increase. Moreover, the results show that the entropy generations due to magnetic field when the enclosure is subjected to the horizontal magnetic field are higher than the corresponding values when it subjected to the vertical magnetic field.

Experimental measurement of characteristic I(c) (ε, θ, B) response in GdBa2Cu3Oδ coated conductor tapes under low magnetic field at 77 K.

The continued development in the design technology of practical superconducting devices adopting high temperature superconductors tapes has led to a deeper understanding of their electromechanical behaviors. Rare-earth-barium-copper-oxide coated conductor (CC) tapes exhibit anisotropy of transport property (Ic) under magnetic field and its intrinsic strain effect is much significant depending on the orientation to the tape surface and the magnetic field intensity applied. Different experimental systems have already been developed to measure the relation of Ic with mechanical strain ε, magnetic field intensity B, and its angle of orientation, θ. However, few systems and instruments can measure these relationships simultaneously; either Ic-B-θ or Ic-ε-B is usually measured. In this study, a device which can measure these influences simultaneously based on a pair of permanent magnet systems was constructed and the characteristic responses of critical current Ic with strain, magnetic field, and its orientation with respect to the CC tape surface were investigated. The angular dependence of Ic with strain at 77 K in reactive co-evaporation by deposition and reaction GdBCO CC tapes has been measured using the permanent magnet system. The orientation angle of magnetic field with respect to the tape's surface was varied by rotating the rig fixture that holds a pair of permanent magnets. The strain sensitivity of Ic at different angles under low magnetic field was evaluated. As a result, a characteristic surface Ic (ε, θ, B) has been constructed as the characteristic response of Ic with strain and varying orientation under magnetic field.

On the Exchange of Kinetic and Magnetic Energy between Clouds and the Interstellar Medium

We investigate, through 2D MHD numerical simulations, the interaction of a uniform magnetic field oblique to a moving interstellar cloud. In particular we explore the transformation of cloud kinetic energy into magnetic energy as a result of field line stretching. Some previous simulations have emphasized the possible dynamical importance of a ``magnetic shield'' formed around clouds when the magnetic field is perpendicular to the cloud motion (Jones et al. 1996, Miniati et al. 1998). It was not clear, however, how dependent those findings were to the assumed field configuration and cloud properties. To expand our understanding of this effect, we examine several new cases by varing the magnetic field orientation angle with respect to the cloud motion (\theta), the cloud-background density contrast, and the cloud Mach number. We show that in 2D and with \theta large enough, the magnetic field tension can become dominant in the dynamics of the motion of high density contrast, low Mach number clouds. In such cases a significant fraction of cloud kinetic energy can be transformed into magnetic energy with the magnetic pressure at the cloud nose exceeding the ram pressure of the impinging flow. We derive a characteristic timescale for this process of energy ``conversion''. We find also that unless the cloud motion is highly aligned to the magnetic field, reconnection through tearing mode instabilities in the cloud wake limit the formation of a strong flux rope feature following the cloud. Finally we attempt to interpret some observational properties of the magnetic field in view of our results.

Josephson vortex lattice melting in Bi2Sr2CaCu2O8

The Josephson vortex lattice state of the highly anisotropic high-Tc superconductor Bi2Sr2CaCu2O8 has been probed by measurements of the out-of-plane (c-axis) resistivity as a function of temperature, current density, magnetic field strength H, and magnetic field orientation angle θ. Anomalous dissipation is observed below a critical temperature identified as the melting transition of the Josephson vortex lattice. The critical T-H and T-θ phase boundaries are determined. The melting transition is interpreted as a Kosterlitz-Thouless depairing of interlayer vortex/anti-vortex pairs.

Observation of Josephson vortex lattice melting in a highly anisotropic superconductor

The Josephson vortex lattice state of the highly anisotropic high- T c superconductor Bi 2Sr 2CaCu 2O 8 has been probed by measurements of the out-of-plane ( c-axis) resistivity as a function of temperature, current density, magnetic field strength H and magnetic field orientation angle θ. Anomalous dissipation is observed below a critical temperature identified as the melting transition of the Josephson vortex lattice. The critical T- H and T- θ phase boundaries are determined. The melting transition is interpreted as a Kosterlitz-Thouless depairing of interlayer vortex/anti-vortex pairs. The same model accounts well for unusual in-plane dissipation observed previously in Bi 2Sr 2CaCu 2O 8.

Determination of anisotropy parameters in magnetically uniaxial specimens by torque derivatives

Formulae are given for determination, from torque curve slopes, of the first- and second-order anisotropy parameters in magnetically uniaxial specimens. The customary situation in which torque is plotted versus applied magnetic field orientation angle is examined. Corrections to measured torque slope arise from the off-set of the magnetization vector <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\overrightarrow{M}_{s}</tex> , from the applied magnetic field <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\overrightarrow{H}</tex> direction.