Effect Of Uniform Magnetic Field Research Articles

Analysis of effects of moving wall direction in a one sided semi-circular porous cavity on mixed magneto-bioconvection in the presence of hybrid nanofluid with oxytactic bacteria

A computational analysis on the effects of direction of wall movement in a one sided semi-circular porous cavity on mixed magneto-bioconvection of hybrid nanofluid in the presence of oxytactic bacteria has been performed. The working fluid is the hybrid nanofluid. The enclosure is cooled from semi-circle side and heated from moving lid under the effect of uniform magnetic field in the horizontal direction. The numerical solution of governing equations is obtained by using the higher order finite element method (FEM). The reliability of designed solver is tested through the experimental and numerical data available in the literature. Two cases of the boundary conditions are considered related to the tendency of right vertical lid of the cavity. Other parameters are Richardson number, Darcy number, Hartmann number, Peclet number and porosity. It is found that moving lid direction is the most effective parameter for the flow field, isotherms, oxygen and microorganism distributions. Moreover, higher heat transfer rate is obtained in Case-I for different values of Darcy number. Around 10% increment is occurred on mass transfer with different Pe number in case of downward moving lid due to increment of convection mode of heat transfer inside the cavity.

Effect of magnetic field locations on thermo-magnetic convection performance of Fe3O4/H2O ferrofluid flowing in a novel dimpled tube: An experimental study

The aim of this study is to examine the hydrothermal behavior of Fe3O4 Ferrofluid flowing under the effect of uniform magnetic field (0 T ≤ B ≤ 0.3 T). In addition, magnetic field locations were changed for each experiment to observe effect of the magnetic field locations (x/D = 20, 40, 60) on the hydrothermal behavior of the proposed system. Fe3O4 Ferrofluid was prepared in φ = 1.0% volume concentration in water and flows under the laminar regime (1131 ≤ Re ≤ 2102). Comparisons of the hydrothermal behavior of the novel proposed parameters were performed according to combinations of the different magnetic field locations and magnitudes. It is concluded that the highest Nusselt number was obtained using B = 0.3 T for the magnetic field location of x/D = 20 for both in smooth and dimpled tubes. Compared to B = 0 T, the Nusselt number enhancement was detected by 64.03% for smooth tube for the magnetic field location of x/D = 20 for B = 0.3 T whereas Nusselt number wasaugmented by 45.40% for dimpled tube for the same input parameters. Furthermore, no considerable changes in friction factor was determined under magnetic field effect when the application of magnetic field locations was changed. As a result of these findings, the highest increase in Performance Evaluation Criteria belonging dimpled tube was calculated by 33.54% at Re = 2102 for B = 0.16 T for the magnetic field location of x/D = 20. As a general conclusion, this study can shed light on investigating ferrofluids behavior under magnetic field applied in variable magnetic field locations.

Heatfunction Analytics of Conjugate Natural Convection Heat Transfer in Partitioned Enclosure Filled with Hybrid Nanofluid Under Magnetic Fields

The need for suitable control of fluid flow and heat transfer for an enhanced performance has led to the use of magnetic field, appropriate design and sizing of the device and the right choice of the flow governing parameters for many industrial processes. This study investigates the effects of uniform magnetic field on the heat flow induced by buoyancy in a square enclosure partitioned into two cavities with a conducting solid body. The cavities are filled with the hybrid nanofluid composed from water and equal proportion of Cu and Al2O3 nanoparticles. The problem is analysed numerically by solving the momentum, energy and heatfunction equation with the finite difference method. The governing parameters including the Rayleigh, Ra, and Hartmann, Ha, numbers, solid concentration of the hybrid nanoparticles, , and the ratio of the thermal conductivity of the hybrid nanofluid to that of the solid conducting partition wall, k* are altered in the range of and respectively. The results show that the average heat function in the left cavity reduces with Ra and Ha while the overall fluid and heat flow are enhanced with the increase in the Ra and k* and retarded by increasing the Ha. The results of this work can be used as baseline data for the design and appropriate sizing of the heat transfer devices.

Application of Successive Linearization Method on Steady Radial Flow of Nanofluids Between Inclined Plane Walls

The present work purveys the heat transfer enhancement in the steady two-dimensional viscous incompressible radial flow of Au-Water and Ag-Water nanofluids in the presence of MHD effect between the stationary convergent/divergent channel walls which are permitted to stretch or shrink. A uniform magnetic field is applied. The governing partial differential equations of the present physics and their appropriate boundary conditions are initially cast into dimensionless forms to reduce into the ordinary differential equations. The resulting equations thus formed are then solved by adopting the Successive Linearization Method (SLM) to get the accurate numerical solution. Solution errors and residual norms are analyzed to elaborate the convergence and accuracy of the numerical solution. The behavior of thermal conductivity of both types of nanofluids is examined for converging channel and diverging channel cases under the uniform magnetic field effect. The present results are validated with favorable comparisons with previously published results as the current investigations’ unique cases. A parametric study of the governing parameters, namely the magnetic field strength parameter, Reynolds number, angle of inclination, and the stretching parameter on the non-dimensional velocity and temperature, is conducted. Analysis discloses that the profiles of the flow are largely impacted by the physical parameters. It is noticed that the magnetic parameter deploys an enhancing influence on fluid velocity profile as well as heat transfer rate, and the effect of the magnetic field is less pronounced on Au-water nanofluid than that of the Ag-water nanofluid. The fluid velocity increases as the values of Re increase for both the nanofluids in the convergent channel and decreases in the case of the divergent channel. Fluid temperature increases as Re increases for the divergent channel. The velocity of both the nanofluids increases as the angle of inclination of the plates increases.

Magnetohydrodynamic (MHD) Convective Nanofluid Flow, Heat Transfer and Irreversibility Analysis in a Horizontal Micro Tall Cavity with Heat Sources in the Slip Regime

The contemporary study aims to numerically analyze the MHD convective heat transfer and entropy generation analysis for the case of a micro open tall cavity filled with Al2O3/water under the effect of uniform magnetic field in the slip flow regime using the LBM for resolving the governing equations. The slip velocity and the temperature jump conditions are used to incorporate the micro aspect. The Brownian motion effects are considered in the thermal conductivity. The flow pattern and heat transfer characteristics and the irreversibility are studied dependently on various dimensionless independent variables such as: nanoparticles volume fractionΦ(0–4%), Rayleigh number (Ra) (102–104), Knudsen number (Kn) (0–10−1) and Hartmann number (Ha) (0–75). It is found that the change of aspect ratio, Ra,Φand the magnetic field strength affect the hydrodynamic and thermal behaviors inside the micro medium. Concerning the Kn, which presents the most influential parameter on the heat transfer, flow pattern, thermal field and entropy generation, it was concluded it decreases the heat transfer, entropy generation and Bejan number inside the micro tall open cavity. Moreover, it deteriorates the formed rolling cells and the plumes in the micro domain. The nanoparticles size effect is also studied, and found to reduce the heat transfer.

Galerkin finite element analysis of thermal aspects of Fe3O4-MWCNT/water hybrid nanofluid filled in wavy enclosure with uniform magnetic field effect

In this contribution, a numerical investigation was made for heat transfer and steady magneto-hydrodynamic natural convection in a fined cold wavy-walled porous enclosure with a hot elliptic inner cylinder occupied by hybrid Fe3O4-MWCNT /water nanofluid. The enclosure is also placed in a uniform magnetic field. The governing equations are verified by using the Galerkin Finite Element Method (GFEM). Our numerical conclusions are expressed in terms of distributions of isotherms, Nusselt number, and streamlines, which are important, control parameters for the heat convection, and flow in the enclosure. The findings elucidate that the Nuavg rises with the growth of Ra, porosity ratio, and Da ratio increase, though it reduces with the growth of Hartmann number.

The effects of uniform magnetic field on the mechanical and microstructural properties of concrete incorporating steel fibers

This study investigated the effects of applying a uniform magnetic field (UMF) of flux density 500 mili Tesla (mT) to fresh and hardened concrete specimens with steel fibers at volume ratios of 1 and 1.5% on mechanical and microstructural properties. To attain these objectives, compressive and splitting tensile strengths tests were carried out on the specimens with steel fiber-reinforced concrete (SFRC) at 28 days. Furthermore, the microstructure of SFRC, subjected to the UMF, was assessed via scanning electron microscopy (SEM) images. An electromagnetic instrument, capable of generating a density of 500 mT, was used to produce UMF. Finally, a model equation was proposed to predict the splitting tensile strength of SFRC subjected to the UMF as a function of its compressive strength. The application of UMF to SFRC specimens incorporating 1.5% steel fibers revealed an increase in both compressive and splitting tensile strengths up to about 18.2% and 9.5%, respectively. The SEM analysis indicated that the UMF enhanced the cement hydration process, which is responsible for the higher mechanical strength development of SFRC compared to the control specimen.

Natural convection of nanoliquid from elliptic cylinder in wavy enclosure under the effect of uniform magnetic field: numerical investigation

In the current article, a three-dimensional numerical simulation is conducted to scrutinize the steady laminar natural convective flow and transfer of heat between a cold wavy porous enclosure and a hot elliptic cylinder. Alumina nanoparticles are dispersed in the water to enhance the heat exchange process. The nanofluid flow is taken as laminar and incompressible, while the advection inertia effect in the porous layer is taken into account by adopting the Darcy–Forchheimer model. The problem is explained in the dimensionless form of the governing equations and solved by the finite element method. The influences of different governing parameters such as nanoparticles volume fraction (ϕ), angle of rotation (α), Darcy number (Da), Hartmann number (Ha), and Rayleigh number (Ra) on the fluid flow, temperature (T) filed and average Nusselt number are presented. The results exhibit that the heat transfer is enhanced when either of Ra, Da and ϕ is raised. The permeability increment achieved a 12.73% enhancement in the heat transfer rate. Also, when $$\mathrm{Ha}$$ is altered from 0 to 100, a reduction in values of the Nusselt number is given up to 22.22%. Furthermore, the optimal inclination angle for the convective process is α = 45°.

Effect of magnetic field exposure time on mechanical and microstructure properties of steel fiber-reinforced concrete (SFRC)

The present experimental study is an effort to investigate the effect of uniform magnetic field (UMF) exposure time on mechanical and microstructural behaviors of steel fiber-reinforced concrete (SFRC) with fiber volume fractions of 0.4, 0.7 and 1% by employing compressive and flexural strengths tests, and scanning electron microscopy (SEM) imaging. Following this, the brittleness index of SFRC specimens due to different exposure times was assessed. In addition, the ultrasonic test was employed to assess nondestructively the compressive strength of SFRC affected by the UMF for different times. For this purpose, ready-mixed SFRC specimens were exposed to the UMF of density 5000 Gauss, during the casting process, for three different time periods: 1, 2 and 3 min. The study also investigated the effect of UMF exposure direction on the compressive strength of SFRC specimens. Finally, an equation has been proposed to estimate flexural strength of SFRC exposed to the UMF based on compressive strength results. The obtained results demonstrated that the mechanical strength of SFRC increased as the UMF exposure time increased which is more obvious for specimens containing 0.7% steel fibers by volume of the concrete. Concerning this, compressive and flexural strengths of the specimens, exposed to the UMF for 3 min increased by about 21 and 27%, respectively. Furthermore, based on the SEM analysis, chemical reactions of cement hydration increased with increasing the UMF exposure time, leading to increasing bond between cement paste and steel fibers.

The impact of uniform magnetic field on the pulsatile non-Newtonian blood flow in an elastic stenosed artery

Since the effect of magnetic fields on blood flow is not fully understood or studied comprehensively, this paper, for the first time, addresses the effect of uniform magnetic fields with different intensities on the pulsatile non-Newtonian blood flow in an elastic artery with axially symmetrical single and double stenoses using the commercial software COMSOL Multiphysics 5.1. The results are suggestive that an increase in the percent stenosis increases the pressure drop, which is more dramatic in double stenosis. Moreover, for a given percent stenosis, increasing the Hartmann (Ha) number, in addition to increasing the pressure drop, increases the amount by which the pressure drop is raised. The shear stress results revealed that increasing the magnetic field intensity results in the reduction of the vortex region formed in the back of the stenosis, reducing the area prone to disease, which can resolve pathological issues. The impact of the magnetic field was found to be decreased by increasing the percent stenosis. It was also observed that the percentage difference between the maximum wall shear stresses for various percent stenoses is reduced by increasing the Ha number for both single and double stenoses.

Role of magnetic field and cavity inclination on double diffusive mixed convection in rectangular enclosed domain

Effect of uniform magnetic field on double-diffusive mixed convection in a rectangular inclined domain of aspect ratio (A) as 2.0 is analyzed using finite volume technique. The computation conditions selected for this study are Hartmann number (0 ≤ Ha ≤ 50), cavity inclination angle (0° ≤ γ ≤ 90°), Buoyancy ratio (N = 1.0 and − 1.0), and Richardson number (0.1 ≤ Ri ≤ 10). The Prandtl number (Pr = 0.7), Lewis number (Le = 5.0) and Reynolds number (Re = 1000) are constant. The obtained temperature, concentration, and streamline contours by studying the above parameters are discussed in detail. The heat and mass transfer rates are analyzed using local and average Nusselt numbers (Nu), and Sherwood number (Sh) on the top wall. Results show that the heat and mass transfer rates are increased with an inclination angle and decreased with an increase in Ha. For non-zero Ha, the optimum cavity angle is observed to be 60° for N = 1.0 to achieve better convection rate, whereas, for N = −1.0, the optimum cavity angle is found to be 30°.

Free convection and thermal radiation of nanofluid inside nonagon inclined cavity containing a porous medium influenced by magnetic field with variable direction in the presence of uniform heat generation/absorption

Purpose The purpose of this paper is to study the natural convection and radiation heat transfer inside Nonagon inclined cavity with variable heated source length, which contains a porous medium saturated with nanofluid in the presence of uniform heat generation or absorption under the effect of uniform magnetic field with variable direction. The shape factor of nano particles is taking account for the model of nanofluid. Design/methodology/approach This study is established in two-dimensional space. The 2D numerical study is effectuated with Comsol Multiphysics based on the on the finite element method. The 2D equation system is exposed on dimensionless form taking into account the boundary conditions. Findings Results obtained show that the convection heat transfer is ameliorated with the augmentation of heated source length. The convection heat transfer is enhanced by increasing Rayleigh, Darcy numbers and the heated source length; however, it is reduced by rising Hartmann number. The presence of radiation parameter lead to improve the convection heat transfer in the presence of both uniform heat generation/absorption. The average Nusselt number reaches a maximum for an inclination of cavity γ = 45° and a minimum for γ = 60°. Both the increase of the shape factor of nano particles and the solid fraction of nano particles improve the convection heat transfer. Originality/value Different studies have been realized to study the heat transfer inside cavity contains porous medium saturated with nanofluid under magnetic field effect. In this work, the Nonagon geometric of cavity studied has never been studied. In addition, the effect of radiation parameter with relation of the shape factor of nanoparticles in the presence of uniform heat generation/absorption on the heat transfer performance have never been investigated. Also, the effect of magnetic field direction with relation of the inclination cavity on heat transfer performance.

The effect of uniform magnetic field on spatial-temporal evolution of thermocapillary convection with the silicon oil based ferrofluid

A uniform axial or transverse magnetic field is applied on the silicon oil based ferrofluid of high Prandtl number fluid (Pr ? 111.67), and the effect of magnetic field on the thermocapillary convection is investigated. It is shown that the location of vortex core of thermocapillary convection is mainly near the free surface of liquid bridge due to the inhibition of the axial magnetic field. A velocity stagnation region is formed inside the liquid bridge under the axial magnetic field (B = 0.3-0.5 T). The disturbance of bulk reflux and surface flow is suppressed by the increasing axial magnetic field. There is a dynamic response of free surface deformation to the axial magnetic field, and then the contact angle variation of the free surface at the hot corner is as following, ?hot, B = 0.5 T = 83.34? > ?hot, B = 0.3 T = 72.16? > > ?hot,B = 0.1 T = 54.21? > ?hot, B = 0 T = 43.33?. The results show that temperature distribution near the free surface is less and less affected by thermocapillary convection with the increasing magnetic field, and it presents a characteristic of heat-conduction. In addition, the transverse magnetic field does not realize the fundamental inhibition for thermocapillary convection, but it transfers the influence of thermocapillary convection to the free surface.

The Effect of Uniform Magnetic Field on Pressurized FG Cylindirical and Spherical Vessels

The stress analysis of functionally graded thick hollow cylindrical and spherical pressure vessels under the effect of uniform magnetic field are examined. These pressure vessels are designed in such a way that the material properties and magnetic permeability are exponentially graded in radial direction, provided that the inner surface is pure metal and the outer surface is pure ceramic. The differential equations with variable coefficients obtained under these conditions are handled by both Complementary Functions Method and Pseudospectral Chebyshev Method. Benchmark solutions available in the literature for some special cases are used to confirm the results. The effects of different mixture and uniform magnetic field on stresses and displacement distribution are shown in graphical form.

Finite Difference Analysis of Time-Dependent Viscous Nanofluid Flow Between Parallel Plates

This article computes effect of uniform magnetic field on nanofluid flow filling porous medium inside parallel sheets. Darcy’s law is used to characterize porous medium. Flow is caused by stretching of the lower sheet. The governing systems are computed using Finite difference technique. This scheme is used due to its more general and powerful nature to solve nonlinear problems. Results are obtained and discussed graphically. Nusselt number, skin friction, streamlines, velocity and temperature are emphasized.

Theoretical and mathematical analysis of entropy generation in fluid flow subject to aluminum and ethylene glycol nanoparticles

BackgroundHere we have conducted a magnetohydrodynamic (MHD) flow of viscous material with alumina water and ethylene glycol over a stretched surface. The flow is discussed with and without effective Prandtl number. MHD liquid is considered. Electric field is absent. Effect of uniform magnetic field is taken in the vertical direction to the surface. Influence of thermal radiation as well as Joule heating are taken into account for both aluminum oxide-water and aluminum oxide-Ethylene glycol nanofluids. Velocity slip and melting heat effects are considered. MethodsThe nonlinear flow expressions are numerically solved via ND-solve technique (built-in-Shooting). ResultsThe physical impacts of flow variables like mixed convection parameter, magnetic parameter, Reynold number, Eckert number, melting parameter and heat source/sink parameter are graphically discussed. Moreover, entropy generation (irreversibility) and Bejan number are discussed graphically through various flow variables. Physical quantities like skin friction coefficient and Sherwood and Nusselt numbers are numerically calculated and discussed through Tables. ConclusionsImpact of magnetic and slip parameters on the velocity field show decreasing behavior for both effective and without effective Prandtl number. Temperature field increases for both effective and without effective Prandtl number for higher values of magnetic and radiative parameters. Entropy number is an increasing function of Reynolds number while Bejan number shows opposite impact against Reynolds number. Moreover, heat transfer rate upsurges versus larger melting and radiative parameter.

Analysis of general unified MHD boundary-layer flow of a viscous fluid - a novel numerical approach through wavelets

The common boundary-layer equations are derived in which the boundary-layer forms either due to the flow of a viscous fluid over a moving wedge or due to the stretching of the surface with a non-uniform velocity using the concept of the velocity ratio (free stream velocity to the stretching surface velocity). The extreme values of the velocity ratio parameter then characterize both former and latter boundary-layer flows. The model also considers the effect of uniform magnetic field which is applied normal to the flow. Once the mainstream flow is approximated either in the form of the power of distance along the wedge surface or as zero, the self-similar solutions exist. Using suitable transformations, the boundary-layer equations have been converted into the Falkner–Skan-type equation over the unbounded domain that accounts the velocity ratio parameter. The governing problem over an unbounded domain is solved using a novel numerical scheme which makes use of the power of Haar wavelets coupled with collocation method and quasilinearization technique. The wavelet solutions have been verified to be very accurate when compared with numerous previously observed results. Several interesting physical aspects of the considered problem are focused and justified through both theoretical as well as numerical approach. The results show that there are over- and under-shoots in the solutions. Also, the flow divides into near-field (the solutions are confined to a viscous region) and far-field region (inviscid region). It is noticed that the boundary-layer thickness decreases for increasing pressure gradient and magnetic field parameters. Further, interestingly, our study leads to dual solutions for some range of physical parameters, which is explored for the first time through wavelet method in the literature. The physical hydrodynamics is explored and discussed.

Effect of Uniform Magnetic Field on Melting at Various Rayleigh Numbers

Melting phenomena occurs in various industrial applications, such as metal castings of turbine blades, environmental engineering, PCM-based thermal storage devices, etc. During the design of these devices, they are designed for efficient heat transfer rate. To improve the heat transfer rate, understanding of the important flow processes during the melting (and solidification) is necessary. An objective of the present work is to study the effect of natural convection and magnetic field on interface morphology and thereby on melting rate. In this work, therefore, an effect of uniform transverse magnetic field on the melting inside a cavity, filled initially with solid gallium, at various Rayleigh numbers (Ra=3×105, 6×105, and 9×105) is presented. A 2D unsteady numerical simulation, with the enthalpy-porosity formulation, is performed using ANSYS-Fluent. The magnetic field is characterized by the Hartmann number (Ha) and the results are shown for the Ha = 0, 30 and 50. The horizontal walls of the cavity are considered insulated and vertical walls are respectively considered hot and cold. It is observed that the role of natural convection during the melting is significant on the temperature distribution and solid-liquid interface. The increased magnetic field (Ha = 30 and 50) found to have a suppressing effect on the dominance of natural convection at all Rayleigh numbers (Ra=3×105, 6×105, and 9×105).

MHD Buoyancy Flow of Nanofluids over an Inclined Plate Immersed in Uniform Porous Medium in the Presence of Solar Radiation

ABSTRACTFree convective flow and heat transfer of nanofluid close to the inclined plate immersed in the porous medium under the effects of uniform magnetic field and solar radiation has been studied. Boundary-layer approach, Boussinesq approximation and two-phase nanofluid model have been used for a formulation of the governing equations taking into account convective-radiative heat exchange with an environment. The local similarity method has been adopted for the analysis of the considered phenomenon. The obtained equations have been solved numerically using MATLAB software. The effects of control characteristics on profiles of velocity, temperature and nanoparticles volume fraction as well as Nusselt number have been studied in detail.

Natural convection heat transfer in a cavity filled with electrically conducting nano-particle suspension in the presence of magnetic field

This work reports the effect of uniform magnetic field on the heat transfer behavior in the natural convection of electrically conducting but non-magnetic nano-particle suspensions. The experiments are carried out in a differentially heated cubical cavity with two opposite vertical faces at a different uniform temperature kept in a uniform magnetic field. The Rayleigh number range for the present experiment is between 1 × 106 and 1 × 107. To investigate the effect of volume fraction and the type of nanofluid, three different volume fractions of multi-wall carbon nanotubes, graphene, copper, and silica nanofluid are tested at different strengths and directions of the magnetic field. The presence of magnetic field deteriorates the heat transfer which depends upon the direction, strength of the magnetic field and type, and volume fraction of the nanofluid used. The role of magnetic field in the suppression of heat transfer in the presence of magnetic field is explained by a theory involving the interaction of moving electrically conducting particles with the uniform magnetic field.