Hall Parameter Research Articles

Transport coefficients for magnetic-field evolution in inviscid magnetohydrodynamics

The magnetized resistivity and electrothermal tensors when substituted into the induction equation lead to electrothermal magnetic field generation, resistive magnetic diffusion, and magnetic field advection due to resistivity gradients, temperature gradients, and currents. The advection terms driven by the temperature gradient and current have cross field components (perpendicular to both the magnetic field and the driving term) that depend on significantly modified versions of Braginskii's transport coefficients [S. I. Braginskii, in Reviews of Plasma Physics, edited by M. A. Leontovich (Consultants Bureau, New York, 1965), Vol. 1, p. 205]. The improved fits to Braginskii's coefficients given by Epperlein and Haines [Phys. Fluids 29, 1029 (1986)] and Ji and Held [Phys. Plasmas 13, 042114 (2013)] give physically incorrect results for cross field advection at small Hall parameters (product of cyclotron frequency and collision time). The errors in Epperlein and Haines' fits are particularly severe, giving increasing advection velocities below a Hall parameter of one when they should decrease linearly to zero. Epperlein and Haines' fits can also give erroneous advection terms due to variations in the effective atomic number. The only serious error in Braginskii's fits is an overestimate in advection due to perpendicular resistivity. New fits for the cross field advection terms are obtained from a direct numerical solution of the Fokker–Planck equation and Ji and Held's higher order expansion approach that are continuous functions of the effective atomic number.

Effectiveness of Hall current and ion slip on hydromagnetic biologically inspired flow of Cu − Fe 3 O 4/H 2 O hybrid nanomaterial

Heat transfer augmentation is a significant concern in numerous engineering and industrial cooling/heating appliances nowadays. The usage of hybrid nanoliquids has been drawing attention of scientists in order to reduce the limitations of nanofluids and merge the chemical and physical characteristics of nanoparticles in an effective manner. Keeping such effectiveness in mind, present article aims to investigate the peristaltic flow of hybrid nanofluid with heat transfer and irreversibility analysis. Hybrid nanofluid is formed by mixing copper (Cu) and iron oxide (Fe 3 O 4) nanoparticles in water (H 2 O). The Cu − Fe 3 O 4 hybrid nanofluid with nanoparticles volume concentration 2% is used in this study. Impacts of Hall current, ion-slip, mixed convection and viscous dissipation are taken into consideration. Mathematical modeling for entropy generation is formulated via second law of thermodynamics. Governing equations of given problem are first converted into ordinary differential equations by employing lubrication approach. Obtained dimensionless equations are then tackled analytically with the aid of regular perturbation technique. Results reveal that temperature of hybrid nanofluid decreases by improving concentration of nanoparticles. Heat transfer rate at wall increases by improving Hartman number. Entropy generation reduces by improving Hall and ion-slip parameters. Bejan number increases by increasing Hartman number. Velocity of hybrid nanofluid increases by enhancing Grashof number. Pressure gradient of hybrid nanofluid increases by increasing Hall parameter. Pressure rise per wavelength decreases by enhancing ion-slip parameter. A comparison of temperature for base fluid, nanofluid and hybrid nanofluid is also furnished in tabular form. Additionally, comparison of numerical and analytical outcomes of velocity is also provided graphically. It is anticipated that the present study provides a theoretical data for the selection and design of hybrid nanofluid based heat exchanger.

Hall and ion slip effects on magnetohydrodynamic convective rotating flow of Jeffreys fluid over an impulsively moving vertical plate embedded in a saturated porous medium with Ramped wall temperature

AbstractIn the present study, it is explored theoretically Hall and ion slip effects on the unsteady magnetohydrodynamic (MHD) rotating flow of a viscous, incompressible electrically conducting, and optically thick radiating Jeffreys fluid over an impulsively, moving vertical plate embedded in a saturated porous medium, when the temperature of the plate has a provisionally ramped profile. The exact solutions of the governing equations for the flow domain are attained by making use of the Laplace transform method. The specified analytical solutions are also acquired for some limiting cases. The research phrases of engineering curiosity for skin friction and Nusselt number are originated for both ramped wall temperature and the isothermal plate. Sherwood number is also obtained. The numerical results of velocity, temperature, and concentration distributions are exhibited graphically whereas skin friction, Nusselt number, and also Sherwood number are mentioned in a table form. It is observed that on either cases of ramped wall temperature and isothermal plate, the resultant velocity enhances with an increase in Hall and ion slip parameters. Reversal behavior is observed with an increase in magnetic field parameter, Jeffreys fluid parameter and Prandtl number. Thermal and concentration buoyancy forces and thermal radiation tend to accelerate the resultant velocity throughout the boundary layer region. The temperature reduces with an increase in Prandtl number and reverse effect is observed with an increase in thermal radiation parameter. Mass diffusion tends to enhance to species concentration. The rotation and Jeffreys fluid parameters tend to enhance both stress components. Nusselt number enables to lessen with growing in thermal radiation parameter and is magnified on escalating in time. The Sherwood number is improved with increasing in Schmidt number at the plate and it is refused on increasing in time.

Effect of the Hall currents and thermal radiation on the flow of a nanofluid through a vertical rotating channel

The present article is intended to focus on the combined influence of Hall currents and thermal radiation on the magnetohydrodynamic flow of a nanofluid through a vertical rotating channel. The nanofluid is prepared by choosing the copper nanoparticles and water as a base fluid. The impact of mixed convection is also considered. The solution to the formulated problem is computed through a mathematical software Matlab. The physical interpretation of the problem is performed by preparing the graphical results. Consequences manifest that a decline in both primary and secondary velocity is produced via a rise in the strength of Lorentz forces. However, the disparate impact of the Hall parameter on primary and secondary velocity is noticed. Increasing the angular velocity of the vertical channel raises both velocity profiles. The tangent phase of the rate of heat transfer at the left vertical wall significantly decays for increment in the radiation parameter; however, it is directly related to the Prandtl number and the frequency parameter. Further, the temperature is intensified for a rise in the Prandtl number and the frequency parameter, and it decays for an increase in radiation parameters.

Unsteady magnetohydrodynamic flow of generalized second grade fluid through porous medium with Hall effects on heat and mass transfer

This work investigates the unsteady magnetohydrodynamic flow of generalized second grade fluid through a porous medium with Hall effects on heat and mass transfer. The second grade fluid with a fractional derivative is used for the constitutive equation. A second-order fractional backward difference formula in the temporal direction and a spectral collocation method in the spatial direction are proposed to solve the model numerically. In the numerical implementation, a fast method is applied to decrease the memory requirement and computational cost. The velocity, temperature, and concentration profiles are discussed through graphs. The effects of various parameters on the velocity profiles, temperature field, and concentration field are shown. Results indicate that as the fractional derivative γ increases and the Hall parameter m decreases, the amplitudes of the velocity components decrease.

Significance of Hall effect and Ion slip in a three-dimensional bioconvective Tangent hyperbolic nanofluid flow subject to Arrhenius activation energy

The dynamics of partially ionized fluid flow subjected to the magnetic field are altogether distinct in comparison to the flow of natural fluids. Fewer studies are available in the literature discussing the alluring characteristics of the Hall effect and the Ion slip in nanofluid flows. Nevertheless, the flow of nanofluid flow with Hall and Ion slip effect integrated with activation energy, gyrotactic microorganisms, and Cattaneo–Christov heat flux is still scarce. To fill in this gap, our aim here is to examine the three dimensional electrically conducting Tangent hyperbolic bioconvective nanofluid flow with Hall and Ion slip under the influence of magnetic field and heat transmission phenomenon past a stretching sheet. Impacts of Cattaneo–Christov heat flux, Arrhenius activation energy, and chemical reaction are also considered here. For the conversion of a non-linear system to an ordinary one, pertinent transformations procedure is implemented. By using the bvp4c MATLAB function, these equations with the boundary conditions are worked out numerically. The significant impacts of prominent parameters on velocity, temperature, and concentration profiles are investigated through graphical illustrations. The results show that the velocity of the fluid is enhanced once the Ion slip and Hall parameters values are improved. Furthermore, the concentration is improved when the values of the activation energy parameter are enhanced.

Hall and ion slip impacts on unsteady MHD convective rotating flow of heat generating/absorbing second grade fluid

We have explored theoretically the Hall and ion slip impacts on an unsteady laminar MHD convective rotating flow of heat generating or absorbing second grade fluid over a semi-infinite vertical moving permeable surface. The non-dimensional equations for the governing flow are solved to the most excellent possible investigative solution using perturbation methodology. The effects of parameters on velocity, temperature and concentration are demonstrated graphically and described in detail. For engineering curiosity, the shear stresses, Nusselt number and Sherwood number are obtained analytically, represented computationally in a tabular format as well as explained with respect to foremost parameters. It is concluded that, the resultant velocity is increased with an increasing in Hall and ion slip parameters throughout fluid region. The thermal and solutal buoyancy forces contribute to the resultant velocity ever-increasing to high. The temperature distribution is trim downs through an increasing in heat source parameter. The concentration is reduced with an increase in the chemical reaction parameter in the entire fluid region. Rotation parameter is to diminish the skin friction, whereas it is augmented through an increase of the Hall and ion slip effects. The rate of mass transfer is increased with increasing chemical reaction parameter.

Effect of Hall Currents on Convective Heat and Mass Transfer Flow of a Viscous Electrically Conducting Fluid in A Nonuniformly Heated Vertical Channel with Radiation

In the present document we inspect the deportation study of heat and mass transfer flow of a viscous electrically conducting fluid in a vertical wavy channel under the influence of an inclined magnetic fluid with heat generating sources. The walls of the channels are perpetuated at constant temperature and concentration. The equations reign over the flow heat and concentration are solved by employing perturbation technique with a slope d of the wavy wall. The velocity, temperature and concentration distributions are investigated for a different value of Grashof number Hartmann number, Buoyancy ratio etc. The rate of heat and mass transfer are numerically estimated for a different variation of the governing parameters. It is found that higher the Lorentz force lesser the axial velocity in the flow region. An increase in the Hall parameter (m) enhances the axial velocity.

Modeling and analysis of peristalsis of hybrid nanofluid with entropy generation

This investigation intends to explore the peristaltic transport of rotating fluid in a channel. The channel is considered symmetric with flexible walls, and porous medium fills the saturated space. In this analysis, hybrid nanofluid consisting of titanium oxides and copper particles is taken. Water is used as the base fluid. MHD and Hall effects are employed in this problem. Formulation of energy equation is based on radiation and non-uniform heat source or sink parameter. Convection conditions are utilized for the boundary. Thermodynamics second relation is employed for entropy generation. Maxwell–Garnetts model of thermal conductivity is employed. Numerical analysis is carried out using NDSolve of Mathematica. The effect of nanoparticle volume fraction, Taylor number, Hartman number, porosity and Hall parameters is analyzed for axial and secondary velocities, temperature, entropy generation and heat transfer rate. This study divulges that an enhancement in rotation parameter caused an increase in secondary velocity. Moreover, as volume fraction of nanoparticles enhances from 0.01 to 0.04, decay is noticed in fluid’s axial and secondary velocities. In this case, entropy also decreases. This study further disclosed that heat transfer rate gradually increases as we exceed the volume fraction of nanoparticles from 0.02 to 0.08. More pores also lead to an enhancement in fluid velocity, temperature and entropy.

Hall and ion slip impact on magneto-titanium alloy nanoliquid with diffusion thermo and radiation absorption

The radiation-absorption, diffusion-thermo and Hall and ion slip effects, on MHD-free convective rotating flow of nanofluid (Ti6Al4V-H2O) past a semi-infinite permeable moving plate with a constant heat source, are discussed. Making use of the Perturbation technique, we found that velocity, temperature and concentration are discussed through graphs. We evaluated the skin friction, Nusselt number and Sherwood number analytically and then discussed computationally. The resultant velocity reduces with increasing rotation parameter, magnetic parameter, suction parameter and enhances with increasing Hall and ion slip parameters and Dufour parameter. Nusselt number decreases with Dufour parameter and Sherwood number increases with chemical reaction parameter.

Lorentz Forces Effects on the Interactions of Nanoparticles in Emerging Mechanisms with Innovative Approach

This paper focuses on advances in the understanding of both the fundamental and applied aspects of nanomaterials. Nanoparticles (titania and graphene oxide) in water-based fluid lying on a surface incorporating the leading edge accretion (or ablation) are analyzed. Entropy generation rate is also considered. The Hall current effect is induced in the flow of hybrid nanofluid, due to which the two-dimensional study converts into three-dimensional space. Similarity transformations convert the equations of momentum, heat transfer, nanoparticles volume fraction and boundary conditions into non-dimensional form. Mathematica software is used to obtain the computation through homotopy analysis method. Analysis is provided through the effects of different parameters on different profiles by sketching the graphs. Flow, heat transfer and nanoparticles concentration in TiO2/H2O, as well as GO-TiO2/H2O, are decreased with increasing the Stefan blowing effect, while entropy generation rate elevates upon increasing each parameter. Both of the velocity components are reduced with increasing the Hall parameter. Streamlines demonstrate that trapping is increased at the left side of the surface. The obtained results are compared with the published work which show the authentication of the present work.

Dissipative Power-law fluid flow using spectral quasi linearization method over an exponentially stretchable surface with Hall current and power-law slip velocity

The present article aims to reports laminar, incompressible, electrically conducting two-dimensional non-Newtonian (power-law) liquid flow via exponentially stretching sheet with power-law slip velocity conditions. Transverse magnetic field, Hall current, viscous dissipation and radiative flux effects are incorporated in the formulation. Rosseland's diffusion model is defined for the radiation heat transfer. The non-linear partial derivation formulations satisfying the flow are transformed to the non-linear derivative equations by employing the local similarity quantities and then solved analytically through spectral quasi-linearization method (SQLM). The resultant solution is computed for different parameters in tables and graphical representation for clear understanding of the thermo-physical terms. Extensive visualization of primary and secondary velocities, temperature distributions for various emerging parameters presented for n = 0.7 (pseudo-plastic fluid) and n = 1,3 (dilatant fluid). The results are verified for limiting cases by comparing with various investigations and found excellent accuracy for Newtonian case. It is interesting to note that secondary flow rate is more dominant for both the cases of pseudo plastic and dilatant fluids for Hall parameter and Eckert number. Increasing Hall current leads suppress the fluid temperature but as Eckert number grows it leads grow the fluid temperature. Further, it is observed that as Hall parameter increases local Nusselt number strongly elevates.

Effect of Heat and Mass Transfer on Casson Fluid Flow Between Two Co-Axial Tubes with Peristalsis

The effects of both Hall currents and radiation on unsteady flow of an incompressible non-Newtonian fluid obeying Casson model through a porous medium have been discussed. The thermal-diffusion and diffusion thermo effects are taken into our consideration. The non-linear partial differential equations which govern this problem are simplified by making the assumption of long wave length and small Reynolds number. These equations are solved numerically by using explicit finite difference method. In addition, the axial velocity, temperature and concentration are illustrated graphically for various parameters of the problem such as magnetic parameter (Hartman number), the upper limit apparent viscosity coefficient, Hall parameter, the pressure gradient, Prandtl number, Eckert number, Darcy number, Dufour number, the radiation parameter, Schmidt number, Soret number, the chemical reaction parameter and heat source/sink parameter. Furthermore, it is noticed that the behavior of the pressure gradient and Hartman number parameters is to increase or decrease the temperature distributions and is quite reverse

Magnetic field generation from composition gradients in inertial confinement fusion fuel.

Experimental asymmetries in fusion implosions can lead to magnetic field generation in the hot plasma core. For typical parameters, previous studies found that the magnetization Hall parameter, given by the product of the electron gyro-frequency and Coulomb collision time, can exceed one. This will affect the hydrodynamics through inhibition and deflection of the electron heat flux. The magnetic field source is the collisionless Biermann term, which arises from the Debye shielding potential in electron pressure gradients. We show that there is an additional source term due to the Z dependence of the Coulomb collision operator. If there are ion composition gradients, such as jets of carbon ablator mix entering the hot-spot, this source term can rapidly exceed the Biermann fields. In addition, the Biermann fields are enhanced due to the increased temperature gradients from carbon radiative cooling. With even stronger self-generated fields, heat loss to the carbon regions will be reduced, potentially reducing the negative effect of carbon mix. This article is part of a discussion meeting issue 'Prospects for high gain inertial fusion energy (part 1)'.

Peristaltic radiative flow of Sisko nanomaterial with entropy generation and modified Darcy’s law

Nanomaterials are quite significant in the physiological and engineering processes. Such materials have motivated the recent scientists in view of their enhanced thermophysical characteristics than conventional liquids. With this in mind, the intention here is to address the peristaltic activity of Sisko nano-liquid subject to Hall and Ohmic heating effects. Fluid-saturated porous space is modeled using the modified Darcy’s law. Thermal radiation is also accounted. In addition, the analysis carried out is subject to thermal jump, velocity slip and zero mass flux condition. Numerical solution to the resulting nonlinear problem through the lubrication approach is developed. Solution analysis is made by pointing out the impacts of sundry variables. The temperature profile increases by increasing the Hartman number due to the Joule heating effect. However, temperature decreases by increasing the Hall parameter.

MoS2-SiO2/EG hybrid nanofluid transport in a rotating channel under the influence of a strong magnetic dipole (Hall effect)

PurposeThe article focuses on the magnetohydrodynamic (MHD) convective flow of MoS2-SiO2 /ethylene glycol (EG) hybrid nanofluid. The effectiveness of Hall current, periodically heating wall and shape factor of nanoparticles on the magnetized flow of hybrid nanocomposite molybdenum disulfide- silicon dioxide (MoS2-SiO2) suspended in ethylene glycol (EG) in a vertical rotating channel under the influence of strong magnetic dipole (Hall effect) and thermal radiation is assessed. One of the channel walls has an oscillatory temperature gradient. Four different shapes (i.e. brick, cylinder, platelet and blade) of nanoparticles disseminated in base fluid (EG) are considered for simulation of the flow.Design/methodology/approachThe analytical solution of governing equations has been presented. Influences of emerging physical parameters on the velocity and temperature profiles, the shear stresses and the rate of heat transfer are pointed out and discussed via graphs and tables.FindingsThe analysis revealed that Hall parameter has suppressing behavior on the velocity profiles within the rotating channel. The impact of nanoparticle shape factor advances the temperature characteristics significantly in the rotating channel. Brick-shape nanoparticles put up relatively low-temperature distribution in the rotating channel. The Hall parameter reduces the amplitudes of the shear stresses at the channel wall. However, the radiation parameter enhances the amplitude of the rate of heat transfer at the channel wall.Social implicationsThe important technical advantage of hybrid composition of nanoparticles as a drug carrier is its stability, high thermal conductivity, high load carrying capacity, etc. The proposed model may be beneficial in biomedical engineering, automobile parts, mineral and cleaning oils manufacturing, rubber and plastic industries.Originality/valueTo the best of our knowledge, there is little or no report on the aspects of assessment of the effectiveness of Hall current and nanoparticle shape factor on an MHD flow and heat transfer of an electrically conducting MoS2-SiO2/EG ethylene glycol-based hybrid nanofluid confined in a vertical channel with periodically varying wall temperature subject to a rotating frame. The present work furnishes a robust benchmark for the dynamics of nanofluids.

Effect of point/line heat source and Hall current on free convective flow between two vertical walls

The influence of a point heat source and Hall current on the laminar hydromagnetic free convective flow of an incompressible and electrically conducting viscous liquid between two vertical walls has been studied. A wavelet function is utilised to mathematically formulate the point or line heat source. The incidental equations on the flow have been processed subject to the Boussinesq approximation. A unified analytical solution of basic equations like thermal energy and momentum has been derived by employing Laplace transform technique. The impacts of the pertinent physical parameters, such as Hall parameter, magnetic field and point heat source, on the velocity field are explained graphically. The valuable result from the investigation is that an increase in the length of the point heat source leads to the enhancement of the velocity profiles. Moreover, it is noticeable that an enhancement of Hall current has a direct connection with the primary factor of the volumetric flow rate and skin friction.

Characteristics of Output Power as a Function of Hall Parameter in Capacitive-coupled MHD Generator using Microwave Discharge Plasma

Characteristics of Output Power as a Function of Hall Parameter in Capacitive-coupled MHD Generator using Microwave Discharge Plasma

High mobility and size dependent carrier concentration in CdTe nanoparticles synthesized by single injection hydrothermal method for device applications

Single Injection Hydrothermal (SIH) method is employed to synthesize high mobility CdTe nanoparticles (NPs). The hexagonal CdTe NPs are typified for different durations of synthesis and found to have linear dependence on size as a function of time, as revealed by the Powder-X ray Diffractometer (P-XRD) studies. Transmission Electron Microscopic (TEM) image clearly depicts regular fringe like pattern for the CdTe NPs except at few free space grain boundary defects. From the van der Pauw measurements of Hall parameters, it is found that there is a linear dependence between particle size and the carrier concentration; however the linear variation of p-type carrier concentration is found to impede mobility and conductivity. Smaller sized CdTe NPs are found to possess higher mobility. Interestingly, p-type conductivity has been found to get transformed in to n-type with the increase in electrons as majority carriers, in phase with increasing duration of synthesis. Synthesis of such high mobility CdTe NPs tuneable to the desired type of conductivity can be promising for the device fabrication such as photovoltaic cells.

Spectral local linearisation method for MHD Casson fluid on stratified bioconvective porous medium flow due to gyrotactic microorganisms

AbstractIn this paper, the effect of hall parameter on the flow of Casson nanofluid containing gyrotactic microorganisms over a stretching boundary in a porous medium is studied. The stratification, porosity, and Casson fluid parameters are also examined. Using suitable similarity transformations, the basic equations describing the flow are converted to nonlinear differential equations, which are then solved computationally using the spectral local linearisation method. The effects of key parameters such as the Hall parameter, the thermophoresis parameter, the porosity parameter, and Casson fluid parameters are analyzed. The results obtained suggest that the Hall parameter has the effect of decreasing the secondary flow, the heat and mass transfer rate, and density of the motile microorganisms. A decrease in the the Hall parameter is found to cause an increase in the transfer rate, the mass transfer rate, and the density of the motile microorganisms. An increase in the porosity parameter leads to a decline in the skin friction, heat transfer rate, mass transfer rate, and density of the motile microorganisms. The applications of this study arise in industrial areas, including Hall current accelerators, planetary dynamics, Hall current sensors, and magnetohydrodynamic power generators.