Hall Parameter Research Articles

Influence of Dufour and thermal radiation on unsteady MHD Walter’s liquid model-B flow past an impulsively started infinite vertical plate embedded in a porous medium with chemical reaction, Hall and ion slip current

The current examination is concerned with the influence of Dufour and thermal radiation on unsteady MHD Walter’s liquid model-B flow past an impulsively started infinite vertical plate embedded in a porous medium with chemical reaction, Hall and ion-slip current. Perturbation scheme was utilized for solving non-dimensional governing equations. Computations are performed graphically to analyze the behaviour of velocity, temperature and concentration along with Skin friction, Nusselt number and Sherwood number are presented in tabular form on the vertical plate with the difference of emerging physical parameters. Finally, it is concluded that primary and secondary velocities are steeply accelerated with the incremental values of Hall and ion-slip parameter, and the same effect occurred in the case of axial and transverse components of the shearing stress. Primary and secondary velocities are enhanced with the ascending values of Dufour number. But contrast repercussions were demonstrated in the case of temperature. However, primary and secondary velocities and concentration decline with the increasing values of chemical reaction parameter but the contradicted outcome is taken place in the case of temperature. Meanwhile, primary velocity, secondary velocity and temperature are fallen with the amplified values of radiation absorption, but the inverse effect occurs in the case of Nusselt number.

Impact of Hall Current on the Entropy Generation of Radiative MHD Mixed Convection Casson Fluid

One of the fundamental problems in engineering processes is the efficient utilization of energy during convection in fluid flow. Studies show that entropy generation exists for all fluid transfer processes and entropy generation destroys useful energy. Furthermore, it has been discovered that some pertinent flow parameters might be chosen in order to minimize entropy generation inside the system. In view of this, the fully developed electrically conducting free convection Casson fluid flow formed by two infinite vertical parallel plates with thermal radiation, Hall current and rotation effects is investigated. The governing equations have been obtained and transformed by suitable transformation variables. Semi-analytical solutions via differential transform technique are obtained using relevant boundary conditions. The results are utilized to calculate fluid irreversibility and Bejan number. The impacts of Hall parameter, rotation parameter, thermal radiation, Casson parameter, Hartman number, Schmidt number and chemical reaction together with skin friction, Nusselt number and Sherwood number are discussed and presented via plots and tables. Generally, entropy generation is discouraged at the upper walls of the channel with higher values of Casson parameter, Schimdt number and chemical reaction parameter while Hall current parameter boost entropy generation in the entire flow channel. Furthermore, Heat transfer irreversibility dominates entropy generation due to a rise in the values of chemical reaction parameter and Schmidt number.

Computation of Non-isothermal Thermo-convective Micropolar Fluid Dynamics in a Hall MHD Generator System with Non-linear Distending Wall

A theoretical model for steady non-isothermal convective heat transfer in non-Newtonian magnetized micropolar gas flow from a non-linear stretching/contracting wall in the presence of strong magnetic field is presented, as a simulation of an MHD (magnetohydrodynamic) Hall energy generator. Subsonic flow is considered, and compressibility effects neglected. The strength of the magnetic field which is applied in the general case obliquely to the wall is sufficient to invoke the collective effects of Hall current and Ohmic heating (Joule dissipation). Viscous heating is also included in the energy balance. Deploying similarity transformations, the governing equations are normalized into nonlinear ordinary differential equations with associated boundary conditions. The non-linear boundary value problem thus posed is then solved computationally with Nachtsheim–Swigert iteration technique along with the fourth-fifth order Runge–Kutta integration method. Verification of solutions is obtained with the semi-analytical Homotopy analysis method. Further validation is conducted with the semi-numerical Adomian decomposition method. In both cases excellent agreement is obtained with the Runge–Kutta shooting quadrature solutions. Additional validation is conducted with earlier Newtonian studies in the absence of micropolar, Hall current and dissipation effects. The influence of local Grashof number, local Hartmann number, Eringen microrotational parameter, Eringen coupling vortex parameter, Prandtl number and Eckert number on non-dimensional velocity components (primary, secondary and angular) and temperature within the boundary layer are graphically illustrated and interpreted at length. Furthermore, the effects of the thermophysical (e.g. non-isothermal power law index), electromagnetic parameters (e.g. Hall parameter) and geometric parameter (wall extension/contraction parameter) on the skin-friction coefficient (i.e. primary and secondary shear stress and wall couple stress) and surface heat transfer rate (Nusselt number) are evaluated. The study is relevant to near wall transport phenomena in novel MHD Hall power generators.

Rotational nanofluids for oxytactic microorganisms with convective boundary conditions using bivariate spectral quasi-linearization method

In this study, we considered the three-dimensional flow of a rotating viscous, incompressible electrically conducting nanofluid with oxytactic microorganisms and an insulated plate floating in the fluid. Three scenarios were considered in this study. The first case is when the fluid drags the plate, the second is when the plate drags the fluid and the third is when the plate floats on the fluid at the same velocity. The denser microorganisms create the bioconvection as they swim to the top following an oxygen gradient within the fluid. The velocity ratio parameter plays a key role in the dynamics for this flow. Varying the parameter below and above a critical value alters the dynamics of the flow. The Hartmann number, buoyancy ratio and radiation parameter have a reverse effect on the secondary velocity for values of the velocity ratio above and below the critical value. The Hall parameter on the other hand has a reverse effect on the primary velocity for values of velocity ratio above and below the critical value. The bioconvection Rayleigh number decreases the primary velocity. The secondary velocity increases with increasing values of the bioconvection Rayleigh number and is positive for velocity ratio values below 0.5. For values of the velocity ratio parameter above 0.5, the secondary velocity is negative for small values of bioconvection Rayleigh number and as the values increase, the flow is reversed and becomes positive.

Analysis of a magnetic field and Hall effects in nanoliquid flow under insertion of dust particles

AbstractIn this study, the two‐phase hydromagnetic flow of a viscous liquid through a suspension of dust and nanoparticles is considered. The influence of the Hall current is also taken into account. The similarity variables are utilized to transform the problem into one independent variable. The obtained expressions in one independent variable are solved through the Runge–Kutta–Fehlberg scheme connected with the shooting procedure. The computed results are sketched for employing multiple values of physical constraints on the temperature and velocity of the nanofluid and dust phase. The characterization of various nanoparticles like Cu, Al2O3, TiO2, and Ag on velocities and temperatures of both phases is made through plots. A comparative analysis in the limiting approach is presented to justify the present solution methodology. The range of emerging parameters is taken as 0 ≤ l ≤ 3, 0.1 ≤ βt ≤ 3, 0 ≤ m ≤ 2.5, 0 ≤ M2 ≤ 2, 0.1 ≤ βv ≤ 3, 0 ≤ ϕ ≤ 0.4, and −0.8 ≤ λ ≤ 0.8. From the study, it is revealed that βt has the opposite effect on the temperature of dust and nanofluid phases. The Hall parameter m raises the profiles of velocities in the nanoliquid and dust phases. Also, it is found that the transverse velocities h(η) and H((η) and temperatures θ(η) and θp(η) rise for larger ϕ.

Steady MHD Casson Ohmic heating and viscous dissipative fluid flow past an infinite vertical porous plate in the presence of Soret, Hall, and ion‐slip current

AbstractIn the present study, the influence of Hall and ion‐slip current on steady magnetohydrodynamics mixed convective, Ohmic heating, and viscous dissipative Casson fluid flow over an infinite vertical porous plate in the presence of Soret effect and chemical reaction are investigated. The modeling equations are transformed into dimensionless equations and then solved analytically through the multiple regular perturbation law. Computations are performed graphically to analyze the behavior of fluid velocity, temperature, concentration, skin friction, Nusselt number, and Sherwood number on the vertical plate with the difference of emerging physical parameters. This study reflects that the incremental values of Casson fluid parameter and Schmidt number lead to reduction in velocity. However, fluid velocity rises due to enhancement of ion‐slip parameter but an opposite effect is observed in case of Hall parameter. In addition, the Sherwood number declines with enhancing dissimilar estimators of the chemical reaction, Schmidt number, as well as Soret number.

Couple Stresses and Thermophoresis Influences on Free Convective Heat and Mass Transfer of Viscoelastic Fluid with Hall and Ion-Slip Effects.

An analysis is presented to investigate the Hall and Ion-slip effects on non-Newtonian couple stress fluid flow between vertical channel in the presence of thermophoresis phenomena. The considered fluid obeys to the viscoelastic second-grade model. The problem is modulated mathematically to describe continuity, momentum, temperature, and concentration equations. The influences of physical parameters of dimensionless equations of velocity components () and (), temperature () and concentration () have been shown in some of figuthe res, as well as skin friction (), Nusselt number() and Sherwood number() have been computed. It is found that the velocity decreases with increasing in Hall parameter and Ion slip parameters.

Hall and ion slip effects on MHD rotating flow of ciliary propulsion of microscopic organism through porous media

In this paper, the combined effects of Hall and ion slip on MHD rotating flow of ciliary propulsion of microscopic organism through porous medium have been studied. We consider a symplectic metachronal wave of extensible envelope over the organism. The partial differential equations of creeping flow are transformed into ordinary differential equations through stream function. The series solutions of velocity and pressure distributions are obtained. Also the trapping phenomena have been discussed with the help of stream lines. The effects of Hartmann number, permeability parameter, Hall and ion slip parameters on the velocity field, pressure, working rate per unit volume, and the stream function are observed by computational results.

Entropy generation for peristaltic motion of Carreau’s fluid with mixture of ethylene glycol and boron-nitride nanoparticles

Present work addresses the mixed convective peristaltic transport of electrically conducting ethylene glycol and boron-nitride nanofluids through inclination of asymmetric channel. This investigation also includes the effects of Hall and Ohmic heating. The factor of thermal conductivity is considered to change with temperature. Computations have been done for entropy, temperature, velocity, pressure gradient and concentration by considering the lubrication theory. Analytical solutions of nonlinear system have been computed through homotopy perturbation method. Entropy generation is analyzed graphically under Brownian movement, variable conductivity and thermophoresis aspects. Numeric benchmark of heat mass transport rates is presented. Stresses at the boundaries are examined using bar charts. This research shows that the studied nanofluid presents rise in entropy generation for increase in Hall parameter while reduction is noted when thermal and concentration Grashoff numbers increases. Entropy generation can be controlled at the upper wall when inclination of channel increases but at the same time it rises at the lower wall. Also, the results are found to be in good agreement with the numerical and outcomes reported previously.

Hall-magnetohydrodynamic waves in flowing ideal incompressible solar-wind plasmas: reconsidered

It is well established that the magnetically structured solar atmosphere supports the propagation of MHD waves along various kind of jets including also the solar wind. It is well-known as well that under some conditions, namely high enough jet speeds, the propagating MHD modes can become unstable against to the most common Kelvin--Helmholtz instability (KHI). In this article, we explore how the propagation and instability characteristics of running along a slow solar wind MHD modes are affected when they are investigated in the framework of the ideal Hall-magnetohydrodynamics. Hall-MHD is applicable if the jet width is shorter than or comparable to the so called Hall parameter $l_\mathrm{Hall} = c/\omega_\mathrm{pi}$ (where $c$ is the speed of light and $\omega_\mathrm{pi}$ is the ion plasma frequency). We model the solar wind as a moving with velocity $\vec{v}_0$ cylindrical flux tube of radius $a$, containing incompressible plasma with density $\rho_\mathrm{i}$ permeated by a constant magnetic field $\vec{B}_\mathrm{i}$. The surrounding plasma is characterized with its density $\rho_\mathrm{e}$ and magnetic field $\vec{B}_\mathrm{e}$. The dispersion relation of MHD waves is derived in the framework of both standard and Hall-MHD and is numerically solved with input parameters: the density contrast $\eta = \rho_\mathrm{e}/\rho_\mathrm{i}$, the magnetic fields ratio $b = {B}_\mathrm{e}/{B}_\mathrm{i}$, and the Hall scale parameter $l_\mathrm{Hall}/a$. It is found that the Hall current, at moderate values of $l_\mathrm{Hall}/a$, stimulates the emerging of KHI of the kink ($m = 1)$ and high-mode ($m \geqslant 2$) MHD waves, while for the sausage wave ($m = 0$) the trend is just the opposite---the KHI is suppressed.

Influence of Hall current on hydromagnetic natural convective flow between two vertical concentric cylinders in presence of heat source/sink

AbstractThe fully developed laminar magnetohydrodynamic free convection between two concentric vertical cylinders with Hall currents and heat source/sink, in the presence of the radial magnetic field, are studied. The governing thermal energy and momentum equations are changed into ordinary differential equations whose solutions are determined in closed‐form expressions of the Bessel and modified Bessel functions of order zero. A parametric investigation illustrating the impacts of the Hall current, magnetic field, heat source, and radii ratio has been accomplished graphically to examine the changes in temperature as well as velocity while the Nusselt number, mass flux, and skin friction values have been presented in tabular forms. The results ensure that the Hall current has a strong and direct impact on the flow character, such that the influence of the Hall parameter enhances the velocity fields in the appearance of heat source and sink. The velocity remains almost constant as the Hall parameter value is greater than four. Moreover, the velocity and temperature fields have an increasing tendency due to the heat source and inversely for the heat sink.

Hall and ion slip effects on Unsteady MHD Convective Rotating flow of Nanofluids\u2014Application in Biomedical Engineering

There is an intense worldwide activity in the development of instrumentation for medical diagnosis and bioscreening based on biological labeling and detection of nanoparticles. Based on this profound observation, Hall and ion slip effects on magnetohydrodynamic (MHD) free convective rotating flow of nanofluids in a porous medium past a moving vertical semi-infinite flat plate are investigated. The equations for governing flow are solved analytically by perturbation approximation. The effects of various parameters on the flow are discussed through graphs and tables. The velocity increases with Hall and ion slip parameters. An increase in the convective parameter led to amplify the thermal boundary layer thickness, but when the heat generation parameter is taken into consideration, an opposite effect occurs. The skin friction coefficient increases with an increase in nanoparticle volume fraction and it reduces with increase in Hall and ion slip parameters. Outcomes disclose that the impact of thermal convection of nanoparticles has increased the temperature distribution, which helps in destroying the cancer cells during the drug delivery process.

Double Diffusion Non-Isothermal Thermo-Convective Flow of Couple Stress Micropolar Nanofluid Flow in a Hall MHD Generator System

Nanofluids are potential liquids that enhance the thermophysical characteristics and the ability to transport heat rather than base liquids. This article discusses the non-isothermal heat transfer of the convective steady flow of magnetohydrodynamic micropolar nanofluid over a non-linear extended wall, considering the effects of Brownian motion and thermophoresis, coupled stress, hall current and viscous dissipation effects. Fluid flow is controlled by a high magnetic field. The system of equations is resolved using the Homotopy Analysis Method (HAM) technique and the results are visualized graphically. The effects of different fluid parameters summarizing the problem behavior on primary, secondary and angular velocity, temperature, volume fraction and nanoparticle concentration profiles are measured using graphs. The primary velocity component decreased throughout the entire flow study with magnetic, couple stress and Hall parameters. The large magnetic field parameter and the smaller couple stress parameter lower the secondary velocity, while the increase of the local Grashof number increases the secondary velocity. The strong magnetic parameter, the local Grashof number and the couple stress parameter reduce the angular velocity as observed. The large magnetic parameter, Grashof number, Hall parameter and radiation parameter reduces temperature, while the temperature increases with the increase in Brinkman number and Prandtl number. Brownian motion and thermophoresis encourage the transfer of heat. Tables are used to highlight the impact of dimensionless parameters on the skin friction coefficient, Nusselt and Sherwood numbers.

Unsteady nonlinear magnetohydrodynamic micropolar transport phenomena with Hall and Ion-slip current effects: Numerical study

Unsteady viscous two-dimensional magnetohydrodynamic micropolar flow, heat and mass transfer from an infinite vertical surface with Hall and Ion-slip currents is investigated theoretically and numerically. The simulation presented is motivated by electro-conductive polymer (ECP) materials processing in which multiple electromagnetic effects arise. The primitive boundary layer conservation equations are transformed into a non-similar system of coupled non-dimensional momentum, angular momentum, energy and concentration equations, with appropriate boundary conditions. The resulting two-point boundary value problem is solved numerically by an exceptionally stable and well-tested implicit finite difference technique. A stability analysis is included for restrictions of the implicit finite difference method (FDM) employed. Validation with a Galerkin finite element method (FEM) technique is included. The influence of various parameters is presented graphically on primary and secondary shear stress, Nusselt number, Sherwood number and wall couple stress. Secondary (cross flow) shear stress is strongly enhanced with greater magnetic parameter (Hartmann number) and micropolar wall couple stress is also weakly enhanced for small time values with Hartmann number. Increasing thermo-diffusive Soret number suppresses both Nusselt and Sherwood numbers whereas it elevates both primary and secondary shear stress and at larger time values also increases the couple stress. Secondary shear stress is strongly boosted with Hall parameter. Ion slip effect induces a weak modification in primary and secondary shear stress distributions. The present study is relevant to electroconductive non-Newtonian (magnetic polymer) materials processing systems.

Magnetized peristaltic particle–fluid propulsion with Hall and ion slip effects through a permeable channel

In this article, combine impacts of the Hall and ion slip with heat exchange on the peristaltic movement of MHD particle–fluid suspension through a permeable channel have been examined. The representing flow issue for the liquid stage and dusty stage have been displayed with the assistance of long wavelength and disregarding the inertial forces. Correct arrangements are gotten for velocity and temperature profile. The effect of all the applicable parameters, for example, particle volume fraction, Hartmann number, ion slip parameter, Hall parameter, Darcy number, Prandtl number, Eckert number, are portrayed for velocity and temperature profile. It is observed that the velocity profile appears inverse close to the qualities for bigger estimations of the Darcy parameter, however, it diminishes because of Hartmann number and particle volume fraction. Moreover, the behavior of velocity profile stays comparative for hall and ion slip parameter. The Darcy parameter also shows significant resistance to the temperature profile.

Numerical study of heat transfer and Hall current impact on peristaltic propulsion of particle-fluid suspension with compliant wall properties

In this paper, the effects of heat transfer and Hall current on the sinusoidal motion of solid particles through a planar channel has been discussed. The walls of the channel are considered as compliant under the effects of magnetohydrodynamics. The mathematical formulation has been performed using energy equation, momentum equation, and Ohm’s law. The modeled equations are further modified by taking the assumption of a zero Reynolds number and long wavelength. Numerical shooting technique has been employed to solve the nonlinear differential equations. The impact of all the emerging parameters such as wall rigidity, wall tension, mass characterization, Hall parameter, Hartmann number, Weissenberg number, particle volume fraction, Prandtl number, and Eckert number, respectively. Particularly, we discussed their effects on velocity and temperature profile.

Differential transform solution for Hall and ion‐slip effects on radiative‐convective Casson flow from a stretching sheet with convective heating

AbstractMagnetohydrodynamic (MHD) materials processing is becoming increasingly popular in the 21st century as it offers significant advantages over conventional systems, including improved manipulation of working fluids, reduction in wear, and enhanced sustainability. Motivated by these developments, the present work develops a mathematical model for Hall and ion‐slip effects on non‐Newtonian Casson fluid dynamics and heat transfer toward a stretching sheet with a convective heating boundary condition under a transverse magnetic field. The governing conservation equations for mass, linear momentum, and thermal (energy) are simplified with the aid of similarity variables and Ohm's law. The emerging nonlinear‐coupled ordinary differential equations are solved with an analytical technique known as the differential transform method. The impact of different emerging parameters is presented and discussed with the help of graphs and tables. Generally, aqueous electroconductive polymers are considered, for which a Prandtl number of 6.2 is employed. With increasing Hall parameter and ion‐slip parameter, the flow is accelerated, whereas it is decelerated with greater magnetic parameter and rheological (Casson) fluid parameter. Skin friction is also decreased with greater magnetic field effect, whereas it is increased with stronger Hall parameter and ion‐slip parameter values.

Mixed convection flow of nanofluid with Hall and ion-slip effects using spectral relaxation method

In this article, the Hall and ion-slip effects on a mixed convection flow of an electrically conducting nanofluid over a stretching sheet in a permeable medium have been discussed. Using the similarity transformations, the partial differential equations corresponding to the momentum, energy, and concentration equations are transformed to a system of nonlinear ordinary differential equations which are solved numerically using a spectral relaxation method (SRM). The effects of significant parameters on the velocities, temperature, and concentration profiles are analyzed graphically. Moreover, the results of the skin friction coefficients, local Nusselt number, and Sherwood number are determined numerically. The results of the analysis showed that the velocity profile in the flow direction increases with an increase in mixed convection parameter λ, Hall parameter βh, and ion-slip parameter βi, and it decreases with an increase in the magnetic parameter M. Furthermore, temperature and concentration profiles decrease as the mixed convection parameter λ and buoyancy ratio Nr increase. It is also observed that the skin friction coefficients, local Nusselt number, and Sherwood number increase with an increase in the Hall parameter βh, mixed convection parameter λ, and buoyancy ratio Nr.

Study of the Couple Stress Convective Micropolar Fluid Flow in a Hall MHD Generator System

The steady non-isothermal convective heat transfer in magnetohydrodynamic micropolar fluid flow over a non-linear extending wall is examined. The fluid flow is treated with strong magnetic field. The influence of magnetic field, Hall current, viscous dissipation, and couple stress are mainly focused in this work. The fluid flow problem is solved by analytical method. The impact of developing dimensionless parameters on primary, secondary, and angular velocity components and temperature profile are determined through graphs. The greater magnetic parameter, local Grashof number, Hall parameter, power-law index, Prandtl number, nonlinear wall geometric parameter, and couples stress parameter reduce the primary velocity component while the material parameter, and Eckert number escalates the primary velocity component. The greater local Grashof number, material parameter, power-law index, Prandtl number, and wall geometric parameter reduces the secondary velocity component while the greater magnetic parameter, Hall parameter, Eckert number, and couple stress parameter escalates the secondary velocity component.

Electrical Transport Properties of Gallium Phosphide under High Pressure

The electrical transport properties of gallium phosphide (GaP) under high pressure (up to 50 GPa) are investigated using in situ impedance‐spectrum and Hall‐effect measurements. A discontinuous resistance is observed at 9.9 GPa because of the pressure‐induced grain boundary effect, whereas the pressure‐induced metallization of GaP occurred at ≈24.6 GPa. The metallization transition is determined by measuring the temperature‐dependent resistance and resistivity, and the transition is observed to be reversible. The main cause of the sharp decrease in the resistance and resistivity is a pressure‐induced structural phase transition at 39.3 GPa, as reflected by the measured Hall parameters.