Magnetohydrodynamic Mixed Convection Heat Research Articles

Irreversibility analysis of Magnetohydrodynamic (MHD) mixed convection flow of viscoelastic hybrid nanofluid flow in a channel

This manuscript delves into the analysis of irreversibility in Magnetohydrodynamic (MHD) mixed convection flow of a viscoelastic hybrid nanofluid within a vertical channel. The study adopts a parallel plate configuration and employs Aluminum oxide (Al2O3) and Titanium oxide (TiO2) nanoparticles dispersed in a Carboxymethyl cellulose (CMC)-water base fluid. Utilizing similarity transformations, the governing partial differential equations (PDEs) are converted into a set of ordinary differential equations (ODEs), streamlining the mathematical model. These ODEs are then solved using the homotopy analysis method via Mathematica software for various governing parameter values. Key parameters including the Brinkman number, volume fractions of nanoparticles, magnetic effects, and wall temperature parameter are systematically investigated. Noteworthy insights include that volume fraction and magnetic parameter augments velocity at the left wall and slows down it toward the right wall; Brinkman number and wall temperature parameters significant in elevating temperature; Entropy and Bejan number respond differently to variations in the Brinkman number. Entropy escalates with increasing magnetic parameter, while the Bejan number declines. Illustrated through graphs, these findings enrich the comprehension of MHD mixed convection flow and heat transfer in viscoelastic hybrid nanofluids, elucidating irreversibility aspects tied to such systems.

Entropy analysis and MHD mixed convection heat transfer of the magnetic nanofluid in an asymmetric T-shaped cavity using the lattice Boltzmann method

The magneto hydrodynamic (MHD) mixed convection of titanium oxide/water nanofluids (NFs) in a T-shaped two-dimensional cavity is studied numerically in this article. The upper wall of the cavity has a low temperature and the lower walls of the cavity have a high temperature. The cavity has an inclination angle of 45⁰ under the influence of a horizontal magnetic field (MFD) with Ha = 20. On the upper wall, the slip parameter is changed from 0 to 0.1. The values ​​of entropy generation (ETG), Bejan number (Be), and Nusselt number (Nu), as well as velocity and temperature contours, are presented for different slip parameters when Richardson number (Ri) changes in the range of 0.1 to 100. Lattice Boltzmann method (LBM) is used for simulations. The results demonstrate that an enhancement of the slip parameter causes a decrease in the ETG and a reduction in Nu slightly. ETG and Nu have a decreasing trend by changing Ri from 0.1 to 10; but, they are increased with a further increase of Ri to 100. With an increase in Ri, the local Nusselt number on the left side of the cold wall decreases.

Magnetohydrodynamic Mixed Convection Heat and Mass Transfer of Nanofluid Flow Over a Stretching Wedge-Shaped Surface with the Effect of Thermophoresis and Brownian Motion

The present study has been investigated to the consequence of the magnetic parameter, Grashof number, modified Grashof number, Prandtl number, thermal radiation parameter, Brownian motion parameter, thermophoresis parameter, heat generation parameter, Schmidt number, Biot number, stretching parameter, Lewis number, and chemical reaction parameter, respectively, over a stretching wedge of the magnetohydrodynamic (MHD) BL nanofluid flow. The main goal of this paper is to numerically investigate the nature of the MHD BL nanofluid flow along a stretching wedge-shaped surface with radiation, heat source, and chemical reaction parameters. The fundamental equations has been transformed into ordinary differential equations (ODEs) by the usual transformation. The numerical solutions are found by employing Runge-Kutta fourth-order method by exploiting symbolic software MATLAB via the shooting method. The novelty of the current study is implicated in the area of fluid dynamics to solve nonlinear differential equations numerically and is an important contribution to the field of nanofluids flow. Numerical solutions reveal that the concerned physical parameters lead to progress in the skin friction factor, rate of change of heat transfer as well as the rate of change of concentration. Brownian motion and thermophoresis parameters play a crucial role in the variation of temperature and concentration profiles and also in the development of thermal and concentration boundary layers.

Magnetohydrodynamic mixed convection and entropy generation analysis of Al2O3-water nanofluid past a confined circular cylinder

Numerical simulations are carried out for transient magnetohydrodynamic mixed convective heat transfer of alumina–water nanofluid flow past an isothermal circular cylinder confined in an electrically insulated rectangular duct in the presence of a uniform transverse magnetic field. A control volume method is used to solve the governing equations on a nonuniform Cartesian grid, and the cylinder is imposed using the immersed boundary method. Numerical experiments are performed for a Reynolds number based on the cylinder diameter of ReD=200, blockage ratio of BR=0.2, Richardson numbers of (Ri=−1;0;2), nanoparticle volume fractions of (φ=0.0;0.1;0.2), and Hartmann numbers in the range 0≤Ha≤13. In this work, mean and instantaneous flow and thermal distributions are analyzed graphically, and their corresponding sensitivity to the nanoparticle volume fraction has been determined. Numerical predictions demonstrate the impact of buoyancy and magnetic parameters regarding the spatial development and shedding characteristics of the near wake, and we explore their potential use to selectively excite or suppress vortex shedding, augmentation of heat transfer, and entropy generation minimization in nanofluid flow. The results reported herein indicate that depending on the parametric set, linear and nonlinear flow response to magnetic excitation is observed with bifurcations between different states. The outcome of the study shows that vortex shedding is completely suppressed when a critical value of the Hartmann number is reached, and that the threshold value of the Hartmann number strongly depends on the value of the buoyancy parameter and nanoparticle volume fraction. Based on the entropy distributions, we show that for all values of the nanoparticle volume fraction and in the range of buoyancy and magnetic parameters considered in this work, the entropy generation is dominated by irreversibilities due to heat transfer and the relative contributions of entropy generation due to fluid friction and magnetic effect are not preponderate.

Assessment of thermal behavior of nanofluid flow in a wavy walled cavity in presence of sliding motion and magnetic field

In this study, magnetohydrodynamic mixed convective heat transport phenomena of CuO-water nanofluid in a double lid-driven cavity having a heated wavy bottom wall is investigated numerically. The cavity in consideration has moving vertical walls, assumed adiabatic. The wavy bottom wall is kept at a high temperature and the top wall is exposed with ambient temperature, respectively. The dimensionless governing equations are discretized and solved using the finite element approach. The impacts of various governing parameters such as the Rayleigh number (Ra = 103–106), Hartmann number (Ha = 0–70), Reynolds number (Re = 10–500), and nanoparticle concentration (φ = 0–3%) are examined and visualized by illustrations of local distributions of streamlines and isotherms. A correlation representing the relationship of the average Nusselt number, Nu in terms of all the examined parameters has been presented. The numerical simulations reveal that the convective heat transfer rate within the wavy enclosure is maximum for higher values of Reynold’s number and nanoparticle concentration and lower values of Hartmann number. Comparisons with other similar published numerical investigations show good agreement with the current outcomes.

Magneto-hydrodynamic mixed convective heat transfer in a nanofluid filled wavy conduit having rotating cylinders

Flow and thermal characteristics of mixed convection in a nanofluid filled wavy conduit was numerically investigated in this study. The conduit was considered to contain a pair of rotating cylinders. It was heated and cooled from its lower and upper wavy surface, respectively. The rotating cylinders were placed along the centerline of the wavy conduit. It was also permeated by an external magnetic field. Finite element method was implemented to simulate the conservation equations. Based on the current investigation, a new model was developed for improving thermal conductivity of nanofluids inside a wavy conduit. In addition, a detailed parametric study was presented to visualize the effects of governing parameters on the flow structure and temperature field in the conduit. The numerical results indicated that the physical parameters noticeably influenced both fluid flow in terms of streamlines, velocity profiles and temperature distributions in terms of isotherms, average Nusselt number. The rotating cylinders, wavy surfaces and the inclined magnetic field were found to have the most significant effect on the heat transfer mechanism. Maximum heat transfer occurred as the magnetic field was placed at an angle of 90o.

Heat Transfer Augmentation

This article presents a brief review of various methodologies applied for heat transfer enhancement in laminar flow convection regime. Experimental setup for laminar flow convection heat transfer enhancement using insertions has been explained along with the associated results. Nusselt’s number is found to be a key parameter for investigatigation in order to perceive the enhancement in heat transfer. Similarly, the magnetohydrodynamic mixed convection heat transfer enhancement technique has also been explored. The results of isotherms and fluid flow parameters are discussed which directly affect the heat transfer coefficient. This review article complements the literature in related field and thus will be helpful in order to carry out further experiments in heat transfer enhancement in future.

Heat Transfer Augmentation

This article presents a brief review of various methodologies applied for heat transfer enhancement in laminar flow convection regime. Experimental setup for laminar flow convection heat transfer enhancement using insertions has been explained along with the associated results. Nusselt’s number is found to be a key parameter for investigatigation in order to perceive the enhancement in heat transfer. Similarly, the magnetohydrodynamic mixed convection heat transfer enhancement technique has also been explored. The results of isotherms and fluid flow parameters are discussed which directly affect the heat transfer coefficient. This review article complements the literature in related field and thus will be helpful in order to carry out further experiments in heat transfer enhancement in future.

A Theoretical Study of Steady MHD mixed convection heat transfer flow for a horizontal circular cylinder embedded in a micropolar Casson fluid with thermal radiation

In this study, an investigation is carried out for laminar steady mixed 2D magnetohydrodynamic (MHD) flow of micropolar Casson fluid with thermal radiation over a horizontal circular cylinder with constant surface temperature. In the present study, an investigation is carried out on the effects of physical parameters on Casson fluid non dimensional numbers. The governing nonlinear partial differential equations and the controlling boundary conditions are derived for this case study. Furthermore, these equations are solved numerically using finite difference technique known as Keller Box Method (KBM). The effects of non-dimensional governing parameters, namely Casson parameter, mixed convection parameter, magnetic parameter, radiation parameter on the Nusselt number and local friction coefficient, as well as temperature, velocity and angular velocity are discussed and shown graphically. It is noticed that the local skin friction and the local Nasselt number has decrement behaviors when increasing the values the Casson parameter. But the opposite happens when the mixed convection parameter λ increase. It is found that the results in this study are in good agreement with previous studies. This proves that calculations using KBM method and the chosen step size are accurate enough for this type of problems.

Hall current and thermophoresis effects on magnetohydrodynamic mixed convective heat and mass transfer thin film flow

The combined influences of Hall current and thermophoresis on a magnetohydrodynamic mixed convective heat and mass transfer flow of a thin film second-grade fluid with viscous dissipation and thermal radiation past a stretching sheet are analyzed. An external strong and uniform magnetic field is applied transversely to the stretching sheet. The surface of the stretching sheet is taken to move with a linear velocity and subject to the constant reference temperature and concentration. Entropy generation is introduced to investigate the irreversibility associated with flow, heat and mass transfer. The basic governing equations for the velocities, temperature and concentration of the fluid motion have been modeled by employing appropriate similarity transformations which result in high nonlinear coupled differential equations with physical conditions. The solution of the transformed systems of equations has been achieved by employing Homotopy Analysis Method (HAM) which lead to detailed expressions for the velocities, temperature and concentration components. The obtained results are compared with the published results in the tables 3–5 demonstrating an excellent agreement and correlation. Graphs are discussed to elucidate the effects of various parameters.

Study of two-dimensional boundary layer thin film fluid flow with variable thermo-physical properties in three dimensions space

The conversion of study in two dimensional (x, y) medium into three dimensions space (x, y, z) of a magnetohydrodynamic mixed convective heat and mass transfer boundary layer flow of a thin film second-grade fluid with temperature dependent viscosity and thermal conductivity in the presence of thermal radiation and viscous dissipation past a stretching sheet is analyzed. The occurrence of Hall current in two dimensional (x, y) medium produces a force in z-direction which generates a cross flow in that direction and so the motion is made in three dimensions space (x, y, z). Similarity transformations are used and the transformed system of equations of the problem has been solved by utilizing homotopy analysis method. The salient impacts of the emerging parameters on velocities, temperature and concentration fields have been displayed graphically and illustrated.

Chemical Reaction and Thermal Radiation Effects on MHD Mixed Convection over a Vertical Plate with Variable Fluid Properties

This article investigates the magnetohydrodynamic mixed convective heat, and mass transfer flow of an incompressible, viscous, Boussinesq, electrically conducting fluid from a vertical plate in a sparsely packed porous medium in the presence of thermal radiation and an nth order homogeneous chemical reaction between the fluid and the diffusing species numerically. In this investigation, the fluid and porous properties like thermal and solutal diffusivity, permeability and porosity are all considered to be vary. The governing non-linear PDE's for the fluid flow are derived and transformed into a system of ODE's using an appropriate similarity transformation. The resultant equations are solved numerically using shooting technique and Runge-Kutta integral scheme with the help of Newton-Raphson algorithm in order to know the characteristics of the fluid for various non-dimensional parameters which are controlling the physical system graphically. The results of the numerical scheme are validated and a numerical comparison has been made with the available literature in the absence of some parameters and found that in good agreement. Nomenclature

Influence of Soret-Dufour and thermophoresis on hydromagnetic mixed convection heat and mass transfer over an inclined flat plate with non-uniform heat source/sink and chemical reaction

ABSTRACTThe paper is devoted to the study of thermophoresis and Soret-Dufour effects on magnetohydrodynamic mixed convective heat and mass transfer over an inclined flat plate with non-uniform heat source/sink. Governing non-linear coupled ordinary differential equations are solved numerically using Runge-Kutta Fehlberg technique with shooting scheme. The effects of various physical parameters on the velocity, temperature, and concentration profiles are depicted graphically. The values of skin-friction coefficient, Nusselt number and Sherwood number are presented in a tabular form. It is found that increase in thermophoretic and chemical reaction parameters retard the velocity and concentration distributions in the boundary layer.

Nanoparticle transport effect on magnetohydrodynamic mixed convection of electrically conductive nanofluids in micro-annuli with temperature-dependent thermophysical properties

This is a numerical investigation of nanoparticle transport effect on magnetohydrodynamic mixed convective heat transfer of electrically conductive nanofluids in micro-annuli with temperature-dependent thermophysical properties. The modified Buongiorno's non-homogeneous model is applied for the nanoparticle-fluid suspension to simulate the migration of nanoparticles into the base fluid, originating from the thermophoresis (nanoparticle migration because of temperature gradient) and Brownian motion (nanoparticle slip velocity because of concentration gradient). Due to surface roughness at the solid–fluid interface in micro-annuli, the wall surfaces are subjected to a linear slip condition to assess the non-equilibrium region near the interface. The fluid flow has been assumed to be fully developed, and the governing equations including continuity, momentum, energy, and nanoparticle transport equation are reduced to a system of ordinary differential equations, before they have been solved numerically. The results are presented with and without considering the dependency of thermophysical properties upon the temperature. It is indicated that ignoring the temperature dependency of thermophysical properties does not significantly affect the flow fields and heat transfer behavior of nanofluids, but it changes the relative magnitudes. Furthermore, in the presence of magnetic field, smaller nanoparticles are more appropriate than larger ones.

Nanoparticles migration effects on magnetohydrodynamic (MHD) laminar mixed convection of alumina/water nanofluid inside microchannels

This is a theoretical study on effects of nanoparticles migration on magnetohydrodynamic mixed convective heat transfer of alumina/water nanofluid inside a vertical microchannel. Walls are subjected to different heat fluxes; q''lw for the left wall and q''rw for the right wall, and nanoparticles are assumed to have a slip velocity relative to the base fluid, induced by Brownian diffusion and thermophoresis. Scale analysis of the governing equations indicates that buoyancy effects due to the temperature distribution is insignificant, however, the buoyancy effects due to concentration distribution of nanoparticles have vast effects on flow and heat transfer characteristics. Further, it is shown that nanoparticles eject themselves from the heated walls and accumulate in the core region, but they are more likely to accumulate near the wall with lower heat flux. Also, the non-uniform nanoparticle distribution causes velocities to move toward the wall with higher heat flux and enhances heat transfer rate there. Moreover, while the nanoparticle volume fraction is smaller than 0.1, the maximum increase in the values of heat transfer rate is 37% for small nanoparticles which drops to 14% for larger nanoparticles. Applying a magnetic field leads to 42% and 30% increase in the values of heat transfer rate for small and large nanoparticles respectively. Additionally, one-sided heating serves as another causing factor for increasing the heat transfer rate which boosts it up to 80% for large nanoparticles.

Homotopy analysis method for thermophoretic particle deposition effect on magnetohydrodynamic mixed convective heat and mass transfer past a porous wedge in the presence of suction

Homotopy analysis method is used to analyze the effect of thermophoretic particle deposition on magnetohydrodynamic mixed convection flow with heat and mass transfer over a porous wedge. An explicit analytical solution is obtained which is valid throughout the solution domain and is consistent with numerical results.

VARIABLE VISCOSITY AND CHEMICAL REACTION EFFECTS ON NON-DARCY MAGNETOHYDRODYNAMIC MIXED CONVECTIVE HEAT AND MASS TRANSFER PAST A POROUS WEDGE IN THE PRESENCE OF SUCTION OR INJECTION

An analysis is presented to investigate the effects of variable viscosity on non-Darcy magnetohydrodynamic mixed convective heat and mass transfer of a viscous, incompressible, and electrically conducting fluid past a porous wedge in the presence of a chemical reaction. The wall of the wedge is embedded in a uniform non-Darcian porous medium to allow for possible fluid wall suction or injection. The governing partial differential equations of the problem, subjected to their boundary conditions, are solved numerically by applying an efficient solution scheme for local nonsimilarity boundary layer analysis. Numerical calculations, up to a third-order level of truncation, are carried out for different values of dimensionless parameters in the problem, and an analysis of the results obtained shows that the flow field is influenced appreciably by the applied magnetic field. The results are compared with those known from the literature, and excellent agreement between the results is obtained.

Numerical study of free convection magnetohydrodynamic heat and mass transfer from a stretching surface to a saturated porous medium with Soret and Dufour effects

We examine the combined effects of Soret and Dufour diffusion and porous impedance on laminar magnetohydrodynamic mixed convection heat and mass transfer of an electrically-conducting, Newtonian, Boussinesq fluid from a vertical stretching surface in a Darcian porous medium under uniform transverse magnetic field. By applying two equal and opposing forces along the x-axis, the sheet is stretched with a speed proportional to the distance from the fixed origin x = 0. The steady-state boundary layer equations are non-dimensionalized into non-similar form and then solved numerically by the local non-similarity method with shooting quadrature. The effects of the Darcian linear porous drag parameter (Da), Soret number (Sr), Dufour number (Du), Prandtl number (Pr), Schmidt number (Sc), magnetohydrodynamic parameter (M) and concentration-to-thermal-buoyancy ratio parameter (N), on the fluid velocity, temperature, concentration, local skin friction, Nusselt number function and Sherwood number function distributions in the regime are depicted graphically and analyzed in detail. Applications of the study include magnetic materials processing and chemical engineering systems.

Nonsimilar solutions of magnetohydrodynamic and thermophoresis particle deposition on mixed convection problem in porous media along a vertical surface with variable wall temperature

Steady-state Magnetohydrodynamic mixed convection heat and mass transfer in the presence of thermophoretic and transverse magnetic field over a vertical flat plate embedded in a conductive fluid-saturated porous medium is investigated. Variations of the wall temperature and concentration are taken into account. The non-linear governing equations of the boundary layer in non-dimensional form are discretised by the finite difference method. An excellent agreement of the results with the previously published work is observed. Representative results are displayed graphically, which show the influence of the magnetic force and boundary conditions on the governing parameters of the problem.

Effects of chemical reaction and thermophoresis on magneto-hydrodynamic mixed convective heat and mass transfer flow along an inclined plate in the presence of heat generation and (or) absorption with viscous dissipation and Joule heating

The present paper deals with the effects of thermophoresis and the homogeneous chemical reactions of first order on magneto-hydrodynamic mixed convective flow past a heated inclined permeable flat plate in the presence of heat generation or absorption considering the viscous dissipation and Joule heating. The resulting governing partial differential equations are transformed into non-dimensional ordinary differential equations using the usual similarity transformations and then solved numerically by applying the Nachtsheim–Swigert shooting iteration technique together with the sixth-order Runge–Kutta integration scheme. Comparison with previously published work is performed and very good agreement is obtained. A parametric study of the governing parameters is carried out and the results are displayed graphically. The results show that viscous drag, rate of heat transfer, and wall deposition flux decreases as the angle of inclination increases. It is also observed that due to the presence of the first-order homogeneous chemical reaction, the concentration decreases with increasing values of the chemical reaction parameter.PACS Nos.: 44.20.+b, 47.65.–d, 47.70.Fw