Magnetic Field Parameters Research Articles

MHD Flow and Heat Transfer of Water-Based Nanofluid Passing a Permeable Exponentially Shrinking Sheet with Thermal Radiation

The key objective of the present study is to elaborate the concept of boundary layer flow and heat transfer of magnetohydrodynamics namely Cu-water nanofluid flow towards an exponentially shrinking sheet with aid of mathematical modeling and computation. The present mathematical model is investigated under the influence of thermal radiation and suction. Using exponential form of similarity variables, the system of partial differential equations (PDEs) are converted in to a set of ordinary differential equations (ODEs). The resulting nonlinear ODEs are computationally solved by using a two-point boundary value problem numerical technique, which constitutes with common finite difference method. The influence of physical parameters such as magnetic field parameter, Eckert number, suction parameter, radiation parameter are described in details with the help of graphical demonstration of velocity and temperature distributions, coefficient of skin fiction and rate of heat transfer. Computational results reveal that after suspension of nanoparticles into base fluid as water fluid temperature raised significantly compare to that of pure fluid. It is also observed that for rising values of magnetic field parameter, thermal radiation, particles volume fraction fluid temperature distribution significantly improved; whereas opposite phenomena is true for suction parameter and Prandtl number. The rate of heat transfer accelerated with Eckert number, Prandtl number, while coefficient of skin friction boost with thermal radiation parameter. For verifying purposes, a comparison has been shown between present results and the computational results of previous studies and found a very close agreement.

SORET AND DUFOUR EFFECTS IN A THREE-DIMENSIONAL MHD FLOW PAST A SEMI-INFINITE UNIFORMLY MOVING VERTICAL PLATE WITH CONSTANT HEAT FLUX

In this paper, we have considered the three-dimensional MHD flow past a semi-infinite uniformly moving porous plate with Soret and Dufour effects. The plate is subjected to a sinu-soidal suction velocity and constant heat flux. It is assumed that a uniform magnetic field is applied normal to the plate and directed into the fluid region. But the induced magnetic field is neglected in the study on the assumption that the magnetic Reynolds number is very small. The analytic solutions are obtained by adopting the method of perturbation technique. The influence of magnetic field parameter, thermal diffusion and diffusion-thermo effects on the flow, heat and mass transfer characteristics are mainly focused on the study. It is found from our study that fluid velocity increases under the influence of Soret and Dufour effects.

Entropy analysis along thermophoretic particle deposition on nanofluid flow through different geometries with thermal radiation

The current study analyses the entropy of nanofluid flow over three different geometries with thermophoretic particle deposition and thermal radiation. It is essential while considering heat exchangers, transpiration, fiber coating, and other similar processes, to have a solid understanding of the transfer of both heat and mass that occurs during MHD flows across three dissimilar shapes. A mathematical model will be utilized to explore magnetohydrodynamic flows including energy transfer with heat and mass variations. In this model, some of the innovative concepts include thermophoresis, Brownian motion, the Cattaneo–Christov dual flux with the application of an external magnetic field, and the entropy generation effect are considered. By the appropriate similarity transformations, fundamental PDE’s converted into ODE’s. To solve these ODE's, the Runge–Kutta fourth order is used along with the shooting technique. The results are displayed in graphs and tables. It is observed that the velocity gets decreases with the increase of the porous parameter and magnetic field and gets stronger with the increase of the Grashof number. The temperature increases with an increase in the magnetic field, radiation parameter, Brownian motion parameter, and thermophoresis parameter. Concentration increases with the increase in a magnetic field and Brownian motion parameter but reduces with the increase of other parameters. Entropy generation gets enhanced with an increase in the magnetic field, temperature difference, concentration difference and diffusion parameters. When a flow is directed through geometries the heat and mass transfer rates are both affected by a parameter known as the thermal relaxation parameter. The influence of skin friction, Nusselt number and Sherwood number were analyzed and results were discussed.

Impact of an inclined magnetic field on couple stress fluid flow over a stretching surface with effect of Stefan blowing, radiation and chemical reaction

The present work focuses on the investigation of the couple stress nanofluid flow with the inclined magnetic field, heat, and mass transform effect. The impact of parameters such as the Schmidt number, the Prandtl number, the Stefan Boltzmann constant, and the magnetic field parameter is evaluated. The regular partial differential equations (PDEs) are mapped into ordinary differential equations (ODEs) and solved analytically, while the exact solution of heat and mass transfer is given in terms of confluent hypergeometric function. It is shown that the impact of the couple blowing effect has primitive impact on velocity, temperature and concentration profiles. The magnetic parameter, by posing a magnetic field normal to the stretching sheet, reduces the flow velocity, the couple stress fluid parameter increases the amplitude of oscillations in velocity and skin friction coefficient, the heat source/sink parameter increases the temperature of the fluid, the volume fraction of the nanoparticles increases the thermal efficiency of the fluid, the chemical reaction parameter decreases the temperature of the fluid, and, finally, the thermal radiation increases the nanofluid temperature.

A generalized More-Gibson-Thomson heat transfer model for the study of thermomagnetic responses in a solid half-space

In this article, thermomagnetic interactions in a two-dimensional (2D), isotropic, homogeneous, and thermoelastic infinite half-space are discussed. It was proposed to use an improved version of the Moore-Gibson-Thompson (MGT) model of thermoelasticity. Since the relaxation time was taken into account in the Green-Naghdi formulation, this model was established. In addition, Maxwell's equations of magnetic and electric fields were taken into account during the formulation of the governing equations. The surface of the solid is considered to be free of traction, under the influence of a varying temperature, and immersed in a constant external magnetic field. In order to solve the non-dimensional coupled magnetic-thermal equations, the normal mode analysis approach and the deletion method were employed. The effects of the magnetic field, thermal factors, and other parameters on the investigated field variables are illustrated graphically and analyzed. There was also a comparison made between the outcomes of the suggested system and those of other thermal frameworks that can be derived as special cases. The results show that the MGT model reduced the magnitudes of the analyzed variables, which may have significant ramifications for various real-world scenarios.

Homotopy Perturbation Method for MHD Heat and Mass Transfer Flow of Convective Fluid through a Vertical Porous Plate in the Presence of Chemical Reaction and Inclined Magnetic Field

The present work is devoted to study a viscous, incompressible, and electrically conducting fluid on an MHD fluid flowing past a semi-infinite porous plate in the presence of chemical reaction and inclined magnetic parameter. The governing equations are expressed in non-dimensional form and the resulting nonlinear equations are solved employing the Homotopy perturbation method for the nondimensional velocity, temperature, and concentration profiles. The effects of various controlling parameters such as Casson parameter, Hartmann number, inclined magnetic parameter, porosity parameter, Grashof number, angle of inclination, Prandtl number, Eckert number, radiation parameter, Schmidt number and thermal radiation parameters are presented graphically and discussed in detail. It was found that, velocity profile is enhanced in the presence of Casson, magnetic field and inclined angle parameters whereas it declined with positive increase in the porosity, Grashof and inclined angle numbers. Similarly, increase in Prandtl, Eckert, radiation and inclined angle numbers lead to increase in the temperature distribution of the fluid, while it deceased as the magnetic field parameter increased. The effect of increased thermal radiation parameter is proportional to the concentration profile, whereas it declines for increase in values of Schmidt number.

Homotopy Perturbation Method for MHD Heat and Mass Transfer Flow of Convective Fluid through a Vertical Porous Plate in the Presence of Chemical Reaction and Inclined Magnetic Field

The present work is devoted to study a viscous, incompressible, and electrically conducting fluid on an MHD fluid flowing past a semi-infinite porous plate in the presence of chemical reaction and inclined magnetic parameter. The governing equations are expressed in non-dimensional form and the resulting nonlinear equations are solved employing the Homotopy perturbation method for the nondimensional velocity, temperature, and concentration profiles. The effects of various controlling parameters such as Casson parameter, Hartmann number, inclined magnetic parameter, porosity parameter, Grashof number, angle of inclination, Prandtl number, Eckert number, radiation parameter, Schmidt number and thermal radiation parameters are presented graphically and discussed in detail. It was found that, velocity profile is enhanced in the presence of Casson, magnetic field and inclined angle parameters whereas it declined with positive increase in the porosity, Grashof and inclined angle numbers. Similarly, increase in Prandtl, Eckert, radiation and inclined angle numbers lead to increase in the temperature distribution of the fluid, while it deceased as the magnetic field parameter increased. The effect of increased thermal radiation parameter is proportional to the concentration profile, whereas it declines for increase in values of Schmidt number.

Unsteady flow of micropolar fluid on a magnetized sheet: Effects of magnetic and microrotation parameters on wall couple stress and skin friction

AbstractIn this study, we investigate the unsteady flow of a micropolar fluid past a magnetized stretchable/shrinkable sheet. Our research aims to analyze the effects of magnetic field, moving slit, and various parameters on the velocity, magnetic, and microrotation profiles of the fluid. By applying the Blasius–Rayleigh–Stokes variable, we derive ordinary differential equations from the partial differential equations that define the problem. We solve the transformed set of equations using the shooting method and obtain dual solutions. Our findings indicate that skin friction decreases with increasing values of the microrotation parameter and magnetic interaction parameter. We also observe that the magnetic interaction parameter enhances the microrotation of molecules. Overall, our study provides valuable insights into the behavior of unsteady flows in micropolar fluids and sheds light on the impact of various parameters on dual solutions.

In Silico Experiments to Explore the Heating Efficiency of Magnetic Nanoparticles in Hyperthermia Preclinical Tests

AbstractPreclinical tests on murine models are typically performed to evaluate the therapeutic efficacy of novel magnetic nanoparticles (MNPs) in cancer treatment with magnetic hyperthermia. Here, through in silico experiments, in vivo tests are mimicked on a 30 g mouse and a 500 g rat, with the aim of determining the optimal treatment conditions allowing to reach the therapeutic temperature range (40−45 °C) within tumor regions. Various types of MNPs are considered with very different heating properties in terms of specific loss power, varying their administered dose, as well as the frequency and peak amplitude of the magnetic field. The analysis is performed by means of finite element models that solve the low‐frequency electromagnetic (EM) field problem and the Pennes’ bioheat transfer equation, to calculate the temperature increase in biological tissues due to the combined effects of EM field exposure and MNP activation. The methodology, which can be generalized to any type of MNPs, has permitted to identify the proper doses of MNPs to be administered to the tumor region, as a function of their heating properties and magnetic field parameters, highlighting the conditions that can lead to possible overheating, generation of hot spots or magnetic hyperthermia inefficacy.

A Terahertz Radiation Linear Polarizer Based on Using a Magnetic Fluid in an External Magnetic Field

A model of a magnetically controlled linear polarizer of terahertz (THz) waves based on a cell filled with a magnetic fluid and controlled by an external magnetic field was proposed. The magnetic fluid consisted of a synthetic oil with high transparency in the THz range and ferromagnetic alloy microparticles. Selection of the ferromagnetic particles size and concentration, and also parameters of the external magnetic field was conducted. It was shown that when using ferromagnetic particles of 10–35 μm size, a concentration of 10 wt.%, and a magnetic field with induction of 6.7–57.2 mT, the created construction works as a linear polarizer of the THz wave in the ranged from 0.3 to 1.5 THz, with the degree of polarization of the initially non-polarized THz wave transmitted through the cell being at least of 80%.

Radially Polarized Laser-Induced Electron Acceleration in Vacuum

Enhanced electron acceleration due to tightly focused (TF) short-intense radially polarized (RP) Gaussian laser pulse in vacuum has been investigated. An axicon optical lens is utilized to accomplish a TF laser beam. The TF-RP laser fields are truncated to fifth order in diffraction angle. The innate and attractive symmetry of the tightly focused RP laser pulse imposes the trapping of electrons in the route of the laser propagation throughout laser–electron interaction. The applied axial magnetic field further ensures the enhancement in ponderomotive strength, pushing the electron in the expediting phase up to longer distances. Utilizing the optimum parameters of RP laser and magnetic field, noteworthy augmentation in the electron acceleration up to GeV range is obtained. The electron energy gain variations are plotted and analyzed for initial laser intensity, initial phase, electron initial energy and applied magnetic field parameters.

Numerical approach for temperature dependent properties of sutterby fluid flow with induced magnetic field past a stretching cylinder

In this analysis, Sutterby fluid flow of induced magnetic hydrodynamic at a stretchable cylinder is deliberated. The viscous dissipation impacts with temperature-dependent properties are applied on the fluid flow. The governing equations are developed using boundary layer approximation in terms of differential equations. The differential equations are dimensionless by means of suitable transformation. The dimensionless system is elucidated by the numerical procedure. Governing physical parameters influences are offered through graphs as well as tabular form. The curves of the velocity function show to enhance due to an increment in the decay-resistant parameter. The curves of the velocity function increased due to higher values of the magnetic field parameter. The sponginess parameter and velocity have inverse relation presented in graph. Temperature augmented due to increasing values of ε. The variable thermal conductivity and temperature have direct relation. Due to this relation, temperature boosted up by boosting the thermal conductivity.

Flow Analysis of a Micropolar Nanofluid Between Two Parallel Disks in the Presence of a Magnetic Field

The present article addresses the steady and laminar magnetohydrodynamics (MHD) flow of a micropolar nanofluid between two porous disks. The fluid is flowing uniformly in the inward and upward directions from both disks. The microrotation of the nanoparticles acts an important role in the flow regime. To show its significance, a comparative study of the analytical results and numerical results is presented. Titanium dioxide is chosen as nanoparticles in the water-based fluid. An appropriate transformation is used for transforming PDEs into ODEs. These nonlinear ODEs are computed by the differential transform method (DTM). The consequences of the Reynolds number, material parameter, and magnetic parameter on the radial velocity, axial velocity, and microrotation profile are graphically presented and discussed. The results calculated by DTM and the results calculated numerically are compared and tabulated. This comparison shows the accuracy and validity of DTM. The coefficient of skin friction is also tabulated and compared with the numerical result. At the end of this study, it is concluded that the behavior of the radial and the axial velocities and the microrotation profile are almost the same in the case of the Reynolds number and the magnetic field parameters.

Steady 3-D Magneto Hydrodynamics-Casson Moving Fluid Across a Porous Sheet as it is Being Linearly Stretched Out Thermal Radiation and Prandtl Number: FEM Approach

In this research paper, the study focuses on results of heat radiation on Casson fluid flowing in three dimensions toward a linearly stretched sheet packed with porous media when a magnetic field is present, as well as when Prandtl number effects when there is a porous medium involved. The Roseland approximation, which integrates a heat radiation’s impact into the energy equation, is used to incorporate thermal radiation into this research endeavour. To be used in this fluid flow the basic governing partial equations for this fluid flow were changed from linear ordinary differential equations by converting non-linear partial equations with similarity variables are utilised. The numerical solutions to the resultant linear ordinary duality equations are obtained by the use of the finite element approach. Graphical representations of the effectiveness and accuracy of this finite element approach are provided for a variety of characteristics as the permeability (K), Casson fluid (β), and magnetic field (M) parameters Stretching sheet parameter (C), Prandtl number (Pr) and Thermal radiation component (R). and conditions. A comparison of our numerical findings with previously published data (S. Nadeem, R. U. Haq, N. S. Akbar, and Z. H. Khan, Alexandria Eng. J. 52, 577 (2013)) reveals a a high level of consistency among the two sets of data.

Dynamics of Williamson Hybrid Nanofluid Over an Extending Surface with Non-Linear Convection and Shape Factors

Combined effects of the magnetic field, heat source/sink, and homogeneous–heterogeneous chemical reaction on the three-dimensional fluid flow over a stretching sheet have been examined in this paper. For originality and practicality, the influence of non-linear convection on hybridised nanoparticles of titanium dioxide (TiO2) and silver (Ag) in the non-Newtonian engine oil (EO) are introduced into the governing equations, which are then dimension-free by utilizing appropriate transformations. Williamson fluid model has been employed to determine the rheological features of the considered fluid mixture. MATLAB inbuilt bvp4c solver and Keller box method are proposed for the numerical solution of current fluid theories. Physical elaboration of the graphs is given to recognize the influence on fluid flow and heat transport mechanism in different rising conditions. Based on results, the implication of magnetic field and Williamson parameters restrict the fluid flow for both nanofluid (TiO2/EO) and hybrid nanofluid (TiO2 + Ag/EO). Special case studies of the shape factor effect show more enhancement in heat transfer rate for cylindrically shaped nanoparticles 25.8162% followed by brick-shaped 20.3286% and spherical-shaped 17.0583%. This study will provide better insight into applications including aircraft refrigeration, lubrication, plastic processing, engine and generator cooling, and so forth.

Entropy analysis of a Sisko nanofluid on a stretching sheet under the Hall effect

The novelty of this paper is examining the impacts of Hall currents on Sisko nanofluid slip flow generated by an exponentially stretching sheet in the existence of entropy generation. Entropy generation assessment, Brownian, thermophoresis and Bejan numbers during convection flow are explored in the presence of the Hall effect. The pertinent parameters are Hall parameter m, a magnetic field parameter M, Brownian motion parameter [Formula: see text], thermophoresis parameter [Formula: see text], generalized thermal Biot number [Formula: see text], generalized velocity slip parameter [Formula: see text] and material parameter of Sisko fluid A. The changes in pertinent parameters on principal and secondary velocities, entropy generation and temperature are discussed. The coefficients of local skin friction, Brownian, thermophoresis and Nusselt/Sherwood numbers are expressed in a tabular structure. Two different kinds of power-law nanofluid, Pseudoplastic [Formula: see text] and dilatant fluid [Formula: see text] are considered. The current results exposed that growth in magnetic field parameter diminishes the nanofluid axial velocity and boosts the profiles of temperature, secondary nanofluid velocity and nanoparticle volume fraction. The coefficients of local skin friction are enhanced according to a growth in the magnetic field factor. The Pseudoplastic fluid supports the velocity, temperature and nanoparticle volume fraction profiles compared to the dilatant fluid. The local entropy generation number, Bejan number, local skin friction coefficients and local Nusselt/Sherwood numbers are influenced by the pertinent parameters.

Cosmological magnetic fields from primordial Kerr-Newman black holes

The origin of our universe's cosmological magnetic fields remains a mystery. In this study, we consider whether these magnetic fields could have been generated in the early universe by a population of charged, spinning primordial black holes. To this end, we calculate the strength and correlation length of the magnetic fields generated by this population, and describe their evolution up to the current epoch. We find that near-extremal black holes in the mass range $ M \sim 10^{28} -10^{36} \, {\rm g}$ could potentially generate magnetic fields with present day values as large as $B \sim 10^{-20} - 10^{-15} \, {\rm G}$; those with $M \gtrsim10^{38} \, \rm{g}$ could have produced even larger fields $B \gtrsim 10^{-14} \, {\rm G}$. To motivate this scenario, we briefly discuss how new physics may have induced a chemical potential which could have briefly maintained the black holes in an electrically charged state in the early universe. Finally, we comment on a correlation between the parameters of the cosmological magnetic field and the stochastic gravitational wave background coming from the merger of primordial black hole binaries as the primary observable signature of this scenario.

Optimization of heat transfer nanofluid blood flow through a stenosed artery in the presence of Hall effect and hematocrit dependent viscosity

The heat transfer rate of the MHD nanofluid blood flow through a stenosed composite artery with hematocrit-dependent viscosity and Hall effect is optimized by using the response surface methodology (RSM). An experimental design and sensitivity analysis based on RSM are employed to examine the impact of different physical parameters and how changes to these parameters affect the response factors of interest. RSM is utilized in the process of constructing the model dependencies between the output response variables, such as the skin friction coefficient and the local Nusselt number, and the independent input parameters, such as the magnetic field parameter, the Hall parameter, and the Brinkman number. These model dependencies are used to determine the relationship between the output response variables and the independent input parameters. For medical applications, the effects of the aforementioned parameters on the velocity and temperature along the radial axis have been examined and physically interpreted. Shear stress and Nusselt number are analyzed using graphs for several physical factors in addition to stenosis height. The increases in the hematocrit parameter are accompanied with a decrease in velocity profile, as it enhances the fluid viscosity that reduces the fluid motion. The sensitivity of Nux (Nusselt number) and τ (shear stress profile) are positive for Br, while negative for M and Be. In addition, current research may be helpful in biomedical by detecting the abnormalities in the artery with the help of the artery image, also known as magnetic resonance angiography (MRA).

Computational assessment of thermally stratified magnetohydrodynamics Maxwell nanofluid with Joule heating and melting heat transfer

Researchers have reported an excellent desire for power storage devices that are more reliable and long-lasting. Battery storage devices are used in waste-to-energy recovery, wind power, mixed energy generation, and heating reactor designs. There are three more helpful methods for storing heat energy: Latent heat storage, like sensible heat storage and chemical heat storage, is a type of energy storage. In these processes, latent thermal energy storage is quite expensive and productive. Melting is a technique for storing heat energy in a material. The substance is frozen to release the stored heat energy. Melting phenomena include freezing a ground-based pump’s heat exchanger coils, tundra melting, magma solidification, and semiconducting processes. Because of the importance mentioned above, the current study investigates the behavior of a two-dimensional Maxwell nanofluid with heat radiation influence across a stretchable surface. The melting process, quadratic thermal and solutal stratification viscous dissipations, and Joule heating effects will also be examined. The impacts of Brownian motion and thermophoresis diffusion will also be assessed. Moreover, the binary chemical reaction will be included when evaluating the MHD mixed convective flow. The governing nonlinear equations of velocity, temperature, and concentration of nanoparticles will also be used to form the constructed fluid model. Under the boundary layer approximation, the equations governing the problem are reduced into non-linear and dimensionless ordinary differential equations using appropriate transformations. The dimensionless governing equations are solved using the convergent approach. The Maxwell fluid parameter enhances while the magnetic field parameter decreases the velocity of the nanofluid, which is one of the most noteworthy findings of the study. However, when the Brownian motion and thermophoresis parameters increase, the fluid temperature increases. The decrease occurs in the concentration profile with improving solutal stratification estimations while growing with enhancing chemical reaction parameters. With the increase in nanoparticle volume fraction, the nanofluid’s temperature decrease, but the nanofluid’s velocity improves.

Simulation study on 300mm monocrystalline silicon celerity single crystal

Since entering the 21st century, the survival and development of mankind are faced with great challenges and great opportunities. With the decrease of petroleum, coal, natural gas and other resources, a large number of harmful products generated in the combustion process of fossil fuels have caused incalculable adverse effects on human living environment. Thermal stress in crystals is one of the key factors affecting the properties of solar level monocrystalline silicon. In this paper, the relationship between the heat loss mode and the stress in crystal is studied. If carbon is introduced into the crystal growth process, it will promote the formation of oxygen precipitation and SiC precipitated phase, resulting in increased stress in the crystal, thus affecting the quality of monocrystalline silicon. The distribution of carbon impurities in the melt is closely related to the convection behavior of the melt. The carbon atoms in the atmosphere diffused into the melt mainly through the free surface area near the crucible wall. By adjusting the structural parameters of symmetric magnetic field and asymmetric magnetic field, the convection intensity in the carbon atom doped region can be suppressed, the thickness of carbon atom diffusion layer can be increased, and the oxygen content and distribution uniformity in the crystal can be controlled by magnetic pull technology to improve the crystal quality.