Effects Of Magnetic Field Parameters Research Articles

Aligned Magnetohydrodynamics and Thermal Radiation Effects on Ternary Hybrid Nanofluids Over Vertical Plate with Nanoparticles Shape Containing Gyrotactic Microorganisms

Nowadays, challenges in development of heat transfer for various engineering fields including heat exchangers, electronics, chemical and bio-industry and others are crucial. Ternary hybrid nanofluids (THNF) as a new heat transfer liquids can be considered as effective medium for increment of heat and energy transport. In the case of THNF when three nanoparticles are added in the based fluid to enhance the transport processes. Dissimilar to the nanofluids (NF) and hybrid nanofluids (HNF) model that considers two types of nanoparticles, this studied consider the three types of nanoparticles in this work which are Aluminium Oxide (AI2O3), Copper (Cu), and Carbon Nanotube (CNT) with different shapes containing gyrotactic microorganisms. The objective is to find the effect of magnetohydrodynamics (MHD) and radiation to the steady of THNF flow past the vertical plate. The mathematical model has been formulated based on a combination Tiwari-Das and Buongiorno nanofluids model. The governing flow and heat transfer equations are simplified to the ordinary differential equations (ODEs) with the adaptation of conventional similarity transformations which are then evaluated by the bvp4c solver (MATLAB) to generate the numerical solutions. The solutions are visually represented through graphs and table to be easily observed. The results indicated that the effect of magnetic field parameter decrease the velocity and contrary in concentration, and microorganism profile while the temperature is increased in magnetic but contrary in radiation parameter . The concentration and density microorganism of THNF is increase with higher value in and but decrease in velocity and temperature. The spherical nanoparticle shape has a higher density, causing the skin friction of THNF to be lower compared to NF and HNF.

The effect of magnetic field parameters on fibre orientation in high-performance fibre-reinforced concrete

We aim at determining the value of minimal magnetic induction for magnetic orientation of fibres in cementitious composite in a given mixture and establish the effect of the magnetic field shape on the final mechanical properties. The magnetic orientation is a suitable method to ensure the required direction of steel ferromagnetic fibres in the composite. The strength of the magnetic field (magnetic induction) and rheology of the fresh mixture play a crucial role in the magnetic orientation. A special device generating alternating and direct magnetic fields with different magnetic inductions was built to determine the minimal magnetic induction for the given mixture. Moreover, the effects of using alternating magnetic field are explored. The used magnetic inductions are 60 mT, 80 mT, 100 mT and 120 mT. The nondestructive inductive measuring method is applied to confirm the orientation of fibres in the hardened composite. The effect of the shape of the magnetic field and magnetic induction on flexural strength is presented. Moreover, the effects of using the alternating or direct magnetic field on the microstructure are explored using a scanning electron microscope.

Spline collocation for magnetohydrodynamic stagnation-point flow towards a stretching sheet

Steady two-dimensional stagnation-point flow of an incompressible viscous electrically con– ducting fluid over a flat deformable sheet is investigated when the sheet is stretched in its own plane with a velocity proportional to the distance from the stagnation-point. Using similarity variables, the governing partial differential equations are transformed into a set of non-dimensional ordinary differential equations. These equations are then solved numerically using Spline collocation method. It is shown that the velocity at a point decreases/increases with increase in the magnetic field when the free stream velocity is less/greater than the stretching velocity. Temperature distribution in the flow is obtained when the surface is held at a constant temperature. In the present reported work the effect of magnetic field parameter and Prandtl number on flow have been discussed.

S-waves propagation in a magneto-elastic half-space of non-homogeneous anisotropic material under couple stress and rotation

The effect of magnetic field parameter H ¯ , rotation parameter Ω ¯ and couple stress parameter R on propagation of shear waves in an anisotropic, thinly layered laminated medium is explored. The frequency equation for the problem has been derived to determine the velocity of the shear waves using linear inhomogeneties. The numerical computation for different values of rigidity parameter A, density parameter C, anisotropic factor N ¯ , initial stress parameter P ¯ , magnetic field parameter H ¯ couple stress parameter R and wave number has been made and the results are shown graphically using MATLAB. The results indicate that the effects of initial stress, magnetic field, anisotropy, couple stress and rotation are very pronounced.

Two-phase MHD Flow through Porous Medium with Heat Transfer in a Horizontal Channel

The present study deals with two layered MHD immiscible fluid flow through porous medium in presence of heat transfer through parallel plate channel. The fluids are incompressible, and flow is fully developed. The fluids are of different viscosities and thermal conductivities so flowing without mixing each other. Two different phases are accounted for study and are electrically conducting. Temperature of the walls of parallel plate channel is constant. Rheological properties of the immiscible fluids are constant in nature. The flow is governed by coupled partial differential equations which are converted to ordinary differential equations and exact solutions are obtained. The velocity profile and temperature distribution are evaluated and solved numerically for different heights and viscosity ratios for the two immiscible fluids. The effect of magnetic field parameter M and porosity parameter K is discussed for velocity profile and temperature distribution. Combined effects of porous medium and magnetic fields are accelerating the flow which, can be helpful in draining oil from oil wells.

Hybrid ferrofluid along with MWCNT for augmentation of thermal behavior of fluid during natural convection in a cavity

Current pagination concerns with exploration regarding thermal characteristics induced by hybridization of Fe3O4 with MWCNT in a permeable tank filled with viscous fluid with magnetization. Roseland approximation is obliged to configure radiative heat flux aspects. Modeling and structuring of considered problem is established in partial differential setup. CVFEM is implemented to seek out solution of constructed differential layout. Data establishing properties of Fe3O4 with MWCNTs is disclosed in tabular format. Impression of sundry variables in view of isotherm and stream pattern is divulged. Local convective thermal rate against involved variables in 3D snapshots is captured. Test about grid independence and comparison with conducted work to get assurance of present finding is explicated. It is deduced that heat transfer along walls enhances verses Rayleigh and Darcy parameters whereas delineates against mounting effect of magnetic field parameter.

Study of Second Order(Rivlin-Ericksen) MHD Fluid Flow Due to an Impulsively Started Flat Plate Through Porous Medium

present note is the study of second order Rivlin-Ericksen MHD fluid flow due to impulsively started flat plate through porous medium. The unsteady laminar flow of an elastico-viscous fluid suspended with a uniform distribution of non-conducting dust particles in presence of uniform transverse magnetic field fixed relative to the plate which is applied normal to the flow. Laplace transform is used and analytical results for the velocity of fluid, mixed particles and the skin friction at the plate are obtained. The effect of magnetic field parameter (M), porosity parameter (K) and the mass concentration (l) of the mixed particle on the velocity of both the fluid, the particle and on the skin friction are discussed numerically and displayed graphically

Magnetohydrodynamic convective-radiative oscillatory flow of a chemically reactive micropolar fluid in a porous medium

This paper deals with the investigation of double-diffusive heat and mass transfer characteristics of an oscillatory viscous electrically conducting micropolar fluid over a moving plate with convective boundary condition and chemical reaction. The non-linear partial differential equations are first converted into nonlinear ordinary differential equations by means of perturbation analysis and the governing equations are solved analytically. The effects of magnetic field, chemical reaction, permeability parameter, Prandtl number, Schmidt number, thermal radiation and viscosity parameter are analyzed on skin friction, Nusselt number, velocity, and temperature & concentration distributions. It is observed that the concentration profiles decrease with increase in the dimensionless time and increase with increase in the chemical reaction parameter. It is also observed that the velocity profile increases with increase in time but reverse effects are found by increasing the value of the viscosity ratio parameter. Further, it is seen that the effect of magnetic field parameter is to increase the micro-rotational velocity profiles but reverse effect is observed by increasing time.

Improvement of the cyclone separation efficiency with a magnetic field

In this paper, an attempt is made to improve the gas-solid cyclone collection efficiency by applying a low strength magnetic field. At first, Eulerian-Lagrangian approach is utilized to model the fluid flow and track a large number of solid particles inside a high efficiency Stairmand cyclone with body diameter of 0.3m. Then, response surface methodology (RSM) is used to design a series of experiments with magnetic number, horizontal and vertical distance of the magnetic field source from the origin as the effective parameters. Finally, desirability function is used to calculate the values of the effective parameters at which the efficiency has its highest value. Furthermore, a comprehensive study on the effect of magnetic field parameters on separation efficiency is done by means of sensitivity analysis. The results show that a low strength magnetic field can increase the separation efficiency for 2 and 4µm particles from 82.96% and 97.78% to 91.11% and 100%, respectively. Analysis of response surface methodology declare that there is a strong interaction between the magnetic number and the position of the magnetic source. Sensitivity analysis shows that separation efficiency is highly sensitive to the vertical distance of the magnetic source from the origin, rather than horizontal distance and magnetic number. Moreover, the total separation efficiency is increased by 1.1% at its optimum value. Increase in separation efficiency without a change in pressure drop and cyclone geometry configuration are the main advantages of this method.

Nonlinear vibration of a rotating cantilever beam in a surrounding magnetic field

The nonlinear vibrations of a rotating cantilever beam made of magnetoelastic materials surrounded by a uniform magnetic field are investigated. The kinetic energy, potential energy and work done by the electromagnetic force are obtained. A nonlinear dynamic model, based on the Hamilton principle, which includes the stretching vibration and bending vibration is presented. The Galerkin method is adopted to discretize the dynamic equations. The proposed method is validated by comparison with the literature. The nonlinear behaviors of the responses are studied. Then simulations for different kinds of magnetic field are conducted. The effects of magnetic field parameters, including the amplitude, plane angle, spatial angle and time-varying frequency, on the dynamic behaviors of the stretching motion and bending motion are investigated in detail. The results illustrate that the interaction effects between the rotating cantilever beam and the magnetic field will increase the vibration amplitude and fluctuation of the beam. In particular, we found that: collinear magnetic fields with equal amplitude lead to the same dynamic responses; the amplitude of magnetic field intensity increases the dynamic responses remarkably; the response amplitude changes nonlinearly with the plane angle and spatial angle of the magnetic field; and the increase of time-varying frequency enhances dynamic responses of the rotating cantilever beam.

Micropolar nanofluid flow with MHD and viscous dissipation effects towards a stretching sheet with multimedia feature

An applied thermal system for heat and mass transfer and energy management problem of hydromagnetic flow with magnetic and viscous dissipation effects micropolar nanofluids towards a stretching sheet has been studied. A system of partial differential equations for micropolar and nanofluid has been analyzed by a combination of the similarity transformation and accurate finite-difference method. Those solutions are used to obtain distributions of the local convective heat transfer coefficient and the stretching sheet temperature. The related importance dimensionless parameters are Prandtl number Pr, magnetic parameter M, material parameter K, Eckert number Ec, Brownian motion number Nb, thermophoresis parameter Nt and the Schmidt number Sc, respectively. The numerical results are indicated that an increasing in the magnetic parameter is given a decreasing in the values of the velocities and Nusselt number, or an increasing in the values of the shear stress, couple stress at the surface, temperature and concentration. The material parameter K has the opposite effect of magnetic field parameter on the values of the velocities, temperature, concentration, shear stress, Nusselt number and Schmidt number. The temperature is decreased as the Prandtl number increasing, or is increased as the Eckert number increasing. The concentration is decreased as Schmidt number increasing. At last, the study has been presented one multimedia video to show its main contain, it will be appeared at Elsevier AudioSlides website.

Numerical Heat and Mass Transfer of a Micropolar Fluids Flow with Magnetic Effect to Past a Stretching Sheet

A heat and mass transfer and energy management problem of for hydromagnetic flow with magnetic effect micropolar fluids past through a stretching sheet has been studied. Governing equations are included continuity equation, momentum equation, angular momentum equation, energy equation and the concentration equation of a micropolar fluid have been analyzed by a combination of the similarity transformation and a accurate finite-difference method. These solutions are used to obtain distributions of the local convective heat transfer coefficient and the stretching sheet temperature. The ranges of these dimensionless parameters, the Prandtl number Pr, the magnetic parameter M, the material parameter K, the Eckert number Ec and the Schmidt number Sc are from 0.3 to 0.71, 0 to 20, 0 to 2, 0 to 0.8 and 0.5 to 10, respectively. The numerical results indicate that, an increase in the magnetic parameter gives a decrease in the values of the velocities and Nusselt number, or an increase in the values of the shear stress, couple stress at the surface, temperature and concentration. The material parameter has the opposite effect of magnetic field parameter on the values of the velocities, temperature, concentration, shear stress, Nusselt number and Schmidt number. The temperature decreases as the Prandtl number increases, or increases as the Eckert number increases. The concentration decreases as Schmidt number increases.

Effects of heat source/sink on magnetohydrodynamic flow and heat transfer of a non-Newtonian power-law fluid on a stretching surface

Non-Newtonian boundary layer flow and heat transfer characteristics over a stretching surface with thermal radiation and slip condition at the surface is analyzed. The flow is subject to a uniform transverse magnetic field. The suitable local similarity transformations are used to transform the non-linear partial differential equations into system of ordinary differential equations. The non-linear ordinary differential equations are linearized by using Quasi-linearization technique. The implicit finite difference scheme has been adopted to solve the obtained coupled ordinary differential equations. The important finding in this communication is the combined effects of Magnetic field parameter M, power law index n, slip parameter l, radiation parameter R, surface temperature parameter g , heat source/sink parameter S, local Eckert number Ec, temperature difference parameter r, generalized local Prandtl number Pr on velocity and temperature profiles and also the skin-friction coefficient -f''(0)and heat transfer coefficient -?'(0) results are discussed. The results pertaining to the present study indicate that as the increase of magnetic field parameter, slip parameter decreases the velocity profiles, where as the temperature profiles increases for both Newtonian and non-Newtonian fluids. The power law index n and heat source/sink parameter decreases the dimensionless velocity and temperature profiles. The effect of radiation parameter, Eckert number leads to increase the dimensionless temperature. It is found that increasing the slip parameter has the effect of decreasing the skin-friction coefficient-f''(0)and heat transfer coefficient-?'(0).With the increase of power law index n is to reduce the skin-friction coefficient and increase the heat transfer coefficient.

Impact of magnetic field parameters and iron oxide nanoparticle properties on heat generation for use in magnetic hyperthermia

Heating of nanoparticles (NPs) using an AC magnetic field depends on several factors, and optimization of these parameters can improve the efficiency of heat generation for effective cancer therapy while administering a low NP treatment dose. This study investigated magnetic field strength and frequency, NP size, NP concentration, and solution viscosity as important parameters that impact the heating efficiency of iron oxide NPs with magnetite (Fe3O4) and maghemite (γ-Fe2O3) crystal structures. Heating efficiencies were determined for each experimental setting, with specific absorption rates (SARs) ranging from 3.7 to 325.9W/g Fe. Magnetic heating was conducted on iron oxide NPs synthesized in our laboratories (with average core sizes of 8, 11, 13, and 18nm), as well as commercially-available iron oxides (with average core sizes of 8, 9, and 16nm). The experimental magnetic coil system made it possible to isolate the effect of magnetic field parameters and independently study the effect on heat generation. The highest SAR values were found for the 18nm synthesized particles and the maghemite nanopowder. Magnetic field strengths were applied in the range of 15.1–47.7kA/m, with field frequencies ranging from 123 to 430kHz. The best heating was observed for the highest field strengths and frequencies tested, with results following trends predicted by the Rosensweig equation. An increase in solution viscosity led to lower heating rates in nanoparticle solutions, which can have significant implications for the application of magnetic fluid hyperthermia in vivo.

Mechanism of dislocation kinetics under magnetoplastic effect

The plasticity of material is associated closely with the movement and proliferation of dislocation. Therefore, in the deformation and plasticity theory the dislocation kinetics is an important topic. In the case of no magnetic field, the conventional dislocation kinetics normally focuses on the dislocation microstructure, nucleation and mobility, and the inherent relationship between electron spin and plasticity is seldom concerned. As a matter of fact, the electron rotation is directionless and unordered in the absence of magnetic field, so the electron behavior will not take an apparent effect on the microstructure and properties of material. Nevertheless, in the presence of magnetic field the case is different. The magnetic field will influence the electron spin and, therefore, atomic rearrangement. The dislocation behavior and plasticity will also be affected by the magnetic field, which is called the magnetoplastic effect. In this paper, on the basis of magnetoplastic effect the dislocation kinetics involving dislocation stress, mobility and others is discussed both qualitatively and quantitatively. It has rarely reported currently in the literature. The pulsed magnetic field is first utilized to process solid nanometer alumina particulates reinforced aluminum matrix composites. The experimental results demonstrate that the dislocation density increases with magnetic induction intensity increasing from zero to 3 T. The phenomenon reveals the characteristic of plastic deformation in a processed sample. The further theoretical analysis displays that the generated magnetic force is not large enough to activate the dislocation movement. The fundamental reason lies in the magnetoplastic effect, that is, the magnetic field brings about the transition of electron spin in the radical pairs between paramagnetic dislocation cores and obstacles. The radical pairs tend to be conversed from the singlet state with high bonding energy to the triplet state with low bonding energy, therefore, the prerequisite energy for dislocation to surmount the obstacles will be lowed and the depinning tendency will be apparent. In a period of dislocation movement, the rate limiting consists in the dislocation stopping at the obstacle; on the contrary, the electron excitation and atomic arrangement governed by the magnetic field take negligible time. Hence, it can be seen that the performance of magnetic field is highly efficient. The critical magnetic induction intensity is calculated to be 3 T. That is, when the intensity is lower than 3 T, the magnetoplastic effect becomes strong with the increase of magnetic induction intensity and action time; when the intensity is higher than 3 T, the effect changes gently. Under this critical magnetic induction intensity, the dislocation velocity is deduced to be on the order of 10-3 m/s. Moreover, the dislocation length will be increased by two orders of magnitude. The displacement of dislocation is proportional to the square of magnetic induction intensity and action time of magnetic field. To sum up, the magnetic field treatment has been proved to be an efficient approach to improve the plasticity of material. The prospective research will focus on the mechanical properties of alloys or composites subjected to magnetic field, together with tensile stress so as to acquire the effect of magnetic field parameters of macro plasticity of materials.

Effect of thermal radiation and Hall current on heat and mass transfer of unsteady MHD flow of a viscoelastic micropolar fluid through a porous medium

Heat and mass transfer effects on unsteady flow of a viscoelastic micropolar fluid over an infinite moving permeable plate in a saturated porous medium in the presence of a transverse magnetic field with Hall effect and thermal radiation are studied. The governing system of partial differential equations is transformed to dimensionless equations using dimensionless variables. The dimensionless equations are then solved analytically using perturbation technique to obtain the expressions for velocity, microrotation, temperature and concentration. With the help of graphs, the effects of magnetic field parameter M, thermal radiation parameter Nr, Hall current parameter m, K, viscoelastic parameter a, and slip parameter h on the velocity, microrotation, temperature and concentration fields within the boundary layer are discussed. The result showed that increase in Nr and m increases translational velocity across the boundary layer while (a) decreases translational velocity in the vicinity of the plate but the reverse happens when away from the plate. As h increases the translational velocity across the boundary layer increases. The higher the values of Nr, the higher the micro-rotational velocity effect while m lowers it. Also the effects n, a, m, Nr, Pr and Sc on the skin friction coefficient, Nusselt number and Sherwood numbers are presented numerically in tabular form. The result also revealed that increase in n reduces the skin friction coefficient. Pr enhances the rate of heat transfer while Sc enhances the rate of mass transfer.

English

This paper is an investigation of the effects of chemical reaction on two dimensional steady stagnation point flow of an electrically conducting, incompressible, and viscous fluid with radiation towards a heated shrinking porous surface. A chemically reactive species is emitted from the vertical surface into the flow field. The governing partial differential equations are solved using the Newton-Raphson shooting method along with the fourth-order Runge-Kutta integration. Velocity, temperature and concentration profiles are presented graphically. Numerical results for the skin friction coefficient, the rate of heat transfer represented by the local Nusselt number and the rate of mass transfer represented by the local Sherwood number are presented in tables and discussed quantitatively. The effects of magnetic field parameter, the velocity ratio parameter, the radiation parameter, the suction parameter, Schmidt number, Eckert number, Prandtl number and reaction rate parameter on the flow field are discussed.   Key words: Porous medium, stagnation point, magnetohydrodynamics (MHD), shrinking surface, radiation.

Entropy effects in hydromagnetic free convection flow past a vertical plate embedded in a porous medium in the presence of thermal radiation

This article investigates the irreversibility effects in hydromagnetic free convective flow past an infinite vertical plate embedded in a porous medium. Thermal radiation effects are also assumed to be present and the Rosseland approximation is used to describe the heat flux in the energy equation. The governing equations are non-dimensionalised by suitable transformations and the Laplace transformation technique is used to obtain exact solutions. The expressions for velocity and temperature are utilized to compute the local entropy generation number and the Bejan number. The effects of magnetic field parameter, permeability parameter, Grashof number and radiation parameter on velocity, temperature, entropy generation rate and Bejan number are analyzed and presented through graphs.

Radiation Effects on MHD Free Convection Flow along Vertical Flat Plate in Presence of Joule Heating and Heat Generation

Abstract In this paper, the effect of radiation on magnetohydrodynamic (MHD) free convection flow along a vertical flat plate in presence of Joule heating and heat generation have been investigated. The governing equations associated with the conduction based boundary conditions are transformed into dimensionless form employing the appropriate transformations and then solved numerically using the implicit finite difference method with Keller box scheme. The numerical solutions are obtained in terms of velocity profiles, temperature distributions, skin friction coefficient and heat transfer rate and then presented graphically and discussed. A complete parametric analysis is done on these numerical results to show the effects of the magnetic parameter, radiation parameter, Joule heating parameter and heat generation parameter. It is found that radiation, Joule heating and heat generation play significant role on MHD natural convection flow during heat transfer. To illustrate the accuracy of the results, the present results for the local skin friction and surface temperature distribution excluding the effects of magnetic field parameter, radiation parameter, Joule heating parameter and heat generation parameter are compared with the results of Merkin and Pop designed for the fixed value of Prandtl number and an excellent agreement were found.

Second Law Analysis for Variable Viscosity Hydromagnetic Boundary Layer Flow with Thermal Radiation and Newtonian Heating

The present paper is concerned with the analysis of inherent irreversibility in hydromagnetic boundary layer flow of variable viscosity fluid over a semi-infinite flat plate under the influence of thermal radiation and Newtonian heating. Using local similarity solution technique and shooting quadrature, the velocity and temperature profiles are obtained numerically and utilized to compute the entropy generation number. The effects of magnetic field parameter, Brinkmann number, the Prandtl number, variable viscosity parameter, radiation parameter and local Biot number on the fluid velocity profiles, temperature profiles, local skin friction and local Nusselt number are presented. The influences of the same parameters and the dimensionless group parameter on the entropy generation rate in the flow regime and Bejan number are calculated, depicted graphically and discussed quantitatively. It is observed that the peak of entropy generation rate is attained within the boundary layer region and plate surface act as a strong source of entropy generation and heat transfer irreversibility.