Magnetic Field Inclination Angle Research Articles

Unsteady Hydromagnetic Flow Of A Nanofluid In The Presence Of Inclined Magnetic Field In A Porous Media

The unsteady hydromagnetic flow of a nanofluid in the presence of an angled magnetic field in porous media is investigated, with consideration given to the effect of the nanofluid’s viscosity variation parameter. The governing partial differential equations are obtained and transformed into dimensionless form by employing dimensionless quantities. Because of its stability, consistency, and high convergence rate, the finite difference approach is used to derive the numerical schemes of transformed partial differential equations, in line with the Crank-Nicolson method. The study subsequently examined at how dimensionless numbers, a viscosity variation parameter, and the magnetic field’s inclination angle affected velocity and temperature profiles. The results show that raising the Reynolds number and magnetic parameter increases the velocity profiles of the nanofluid, whereas increasing the permeability parameter reduces the velocity of the nanofluid. Higher Reynolds, Eckert, and Prandtl numbers lead to larger temperature profiles of the fluid flow. Moreover, study found that increasing the viscosity parameter and magnetic field inclination angle can accelerate fluid flow velocity profiles. In addition, the temperature profiles of the fluid flow grow with the viscosity parameter and the angle of inclination of the magnetic field. The current findings are consistent with previous research, indicating their correctness and validity.

Instability in Supernova Fallback Disks and Its Effect on the Formation of Ultralong Period Pulsars

Several pulsars with unusually long periods were discovered recently, comprising a potential population of ultralong period pulsars (ULPPs). The origin of their long periodicity is not well understood, but may be related to magnetars spun down by surrounding fallback disks. While there are few systematic investigations on the fallback-disk-assisted evolution of magnetars, instability in the disk has received little attention, which determines the lifetime of the disk. In this work we simulate the evolution of the magnetic field, spin period, and magnetic inclination angle of magnetars with a supernova fallback disk. We find that a thermal viscous instability in the disk could significantly affect the formation of ULPPs. Our simulation results also reveal that a large fraction of ULPPs seem to be nearly aligned and orthogonal rotators. This might help place ULPPs above the death line in the pulse period–period derivative plane. However, some extra mechanisms seem to be required to account for the radio emission of ULPPs.

Convection flow of NE-phase change material-water mixture in evacuated tube solar collector manifold: Numerical analysis of MHD double-diffusive convection and exothermic reaction

This study investigates the convection flow of nano-encapsulated phase change material (NEPCM)-water mixture in an evacuated tube solar collector manifold, focusing on the effects of magnetohydrodynamic (MHD) double-diffusive convection and exothermic reaction. Computational fluid dynamics simulations using the Galerkin finite element method were employed to analyze temperature and concentration distributions, fluid flow, melting zone of PCM nanocapsules, Nusselt number, Sherwood number, entropy generation, and thermal performance. The numerical analysis considers a range of dimensionless parameters, including Rayleigh number (Ra=103−105), Lewis number (Le=0.1−10), buoyancy ratio (Nz=1−5), nanoparticle concentration (ϕ=0.01−0.035), fusion temperature (ϴf=0.1−0.9), Stefan number (Ste=0.1−0.9), Hartmann number (Ha=0−50), magnetic field inclination angle (γ=0°−90°), and Frank-Kamenetskii number (FK=0−2.5). Results show that increasing Ra enhances the average Nusselt number (Nuav) by up to 156.1 % and the average Sherwood number (Shav) by up to 104.5 %, while increasing the total entropy generation by up to 13,155 %. Increasing FK reduces Nuav by up to 42.2 % but increases Shav by up to 13.1 %. The Lewis number and buoyancy ratio significantly influence the hydrothermal performance, with Nuav exhibiting non-monotonic behavior and Shav increasing by up to 240.9 % as Le increases. The nanoparticle concentration enhances Nuav by up to 49.7 %. Interestingly, the magnetic field effects are less pronounced than in previous studies, with Ha having a minor impact on Nuav and Shav. These findings have significant implications for the design and optimization of evacuated tube solar collectors and other thermal energy storage systems, potentially leading to improved efficiency and performance in real-world applications.

Magnetic field effects on double-diffusive mixed convection and entropy generation in a cam-shaped enclosure

This study investigates double-diffusive mixed convection and entropy generation under magnetic influence within a novel cam-shaped enclosure, with applications in automotive engineering. The unique geometry creates distinct flow patterns that enhance heat and mass transport. Using the Galerkin finite element method, we analyzed the effects of key parameters, including buoyancy ratio, Reynolds number, Hartmann number, magnetic field inclination angle on average Nusselt and Sherwood numbers, and total entropy generation. Results show that increasing the buoyancy ratio and Reynolds number enhances heat transfer, while the Hartmann number significantly impacts flow characteristics and entropy generation. The magnetic field inclination angle exhibits a non-linear effect on heat transfer and entropy production. These findings provide valuable insights for optimizing heat transfer systems in complex automotive geometries.

Statistical and numerical analysis of magnetic field effects on laminar natural convection heat transfer of nanofluid in a hexagonal cavity

This paper presents a statistical and numerical investigation that examines the optimization and sensitivity analysis of the unsteady laminar natural convective heat transfer flow of Fe3O4-water nanofluid in a hexagonal cavity considering the impacts of a sloping magnetic field in one-component nanofluid model. The inclined walls of the cavity are maintained at a constantly low temperature, while the bottom wall is uniformly heated. The upper wall, however, is regarded as adiabatic. The nanofluid thermal conductivity model incorporates the impact of Brownian motion. The Galerkin weighted residual finite element method has been employed to solve the governing dimensionless equations. The results are provided regarding the average Nu, streamlines, and isotherms. The study uses response surface methodology to analyze the sensitivity of parameters such as the Ha, Ra, and nanoparticle volume percentage. Using a response surface policy allows for optimizing the process and identifying the most favorable circumstances to achieve the maximum thermal transfer rate. The flow pattern of the nanofluid is significantly affected by the magnetic field and its alignment. The numerical results indicate a significant rise in the average Nu as the nanoparticle volume percentage, magnetic field inclination angle, nanoparticle type factor, and Ra increase. Conversely, the Hartmann number and the nanoparticle's diameter have contrasting effects. When considering Brownian motion, the average Nu grows by 225.89 % for Ra = 106 with ϕ = 0.03 and 25.28 % for the other case. The optimal condition for heat transfer occurs when Ra = 106, Ha = 4, and ϕ =0.03 while keeping the other parameters constant.

Magnetic field effects on double diffusion of four sloshing fins in a nanofluid-occupied cavity

ABSTRACT This article offers a novel study on the impacts of magnetic field and Soret-Dufour numbers on the thermosolutal convection of sloshing four fins on the wall sides of a square cavity occupied by a nanofluid. The incompressible condition of smoothed particle hydrodynamics (SPH) entitled ISPH method simulated sloshing four fins inside a nanofluid flow contained by a square cavity. The scales of pertinent parameters are fin length 0.05 ≤ L Fin ≤ 0.3 , Dufour number 0 ≤ Du ≤ 1 , a magnetic field inclination angle 30 ∘ ≤ γ ≤ 90 ∘ , Soret number 0 ≤ Sr ≤ 2 , Hartmann number 10 ≤ Ha ≤ 50 , Rayleigh number 10 4 ≤ Ra ≤ 10 7 , and nanoparticle parameter 0 ≤ ϕ ≤ 0.2 . The simulations of the ISPH method indicated the significant role of the fin’s length in enhancing the nanofluid alterations and transmission of thermal/solutal convection inside a cavity. Besides, the Rayleigh number has a great influence on improving nanofluid velocity and power of temperature/concentration. The Soret/Dufour numbers are successful in boosting the nanofluid speed as well as heat and mass transport, while the Hartmann number and nanoparticles parameter are effective in reducing the nanofluid movements.

Plasma dynamics and collisional magnetic presheath structure in unmagnetized divertor plasma in fusion devices

A model of strongly ionized plasma dynamics in a slightly inclined magnetic field with ions, unmagnetized with respect to ion–ion collisions, typical for detached regimes, is presented. It is demonstrated that far from the material surface, the parallel dynamics remains almost the same as in the magnetized plasma. In the wall vicinity, parallel plasma motion is transformed into perpendicular classical diffusion originating from electron–ion collisions, forming a diffusive layer. At a distance of few ion gyroradii from the material surface, a collisional magnetic presheath is formed, where ions move toward the surface with the velocity of the order of the sound speed, in spite of the fact that an ion exhibits many collisions before reaching the surface. For typical inclination angles of magnetic field of the order of few degrees, the electrostatic potential in the diffusive layer and in the presheath deviates considerably from the Boltzmann potential for electrons, which is typical for collisionless magnetic presheath. Moreover, the normal electric field in some regions is directed away from the surface, which is important for impurities to interact with the surface.

Laminar convective heat transfer combining buoyancy and thermal radiation of Carreau fluid within a concentric and eccentric annulus

The present study concerns a steady-state laminar combined thermal radiation and buoyancy-driven conjugate magnetohydrodynamic (MHD) natural convective flow and heat transfer inside a fully porous medium eccentric circular annulus bounded by two infinite horizontal cylinders occupied by a Carreau fluid permeated by a uniform transverse magnetic field (B0 ) and inclined by an angle (α). The convective and thermal radiation are approximated by the Boussinesq and Roseland models, respectively. The numerical integration was performed using the implicit finite volume method. The convective terms in the momentum and energy equations were Discretized using the second-order upwind method. On the other hand, the diffusive terms were Discretized using the central difference scheme. The pressure-velocity coupling was solved using the SIMPLE approach. The findings suggest a clear trend of enhancement in the heat transfer rate when the aspect ratio and annulus eccentricity increase. This pattern is more pronounced in the negative vertical eccentricities. It is worth noting that the eccentric annulus, which has an annulus aspect ratio of 1.6 and a vertical eccentricity of −0.8, offers the best performance regarding the heat transfer mechanism inside the annulus gap. The heat transfer mechanism turns out to be strongly affected by thermal radiation, Hartmann number, and magnetic field inclination angle. The increased thermal radiation parameter and the decreased flow behavior index improve the heat transfer mechanism between the Carreau fluid and the inner cylinder in the annular gap. Furthermore, the average Nusselt number increases considerably as the induced magnetic field inclines.

Effect of magnetic field on viscous flow through porous wavy channel using boundary element method

AbstractThe study aims to investigate the effect of uniform inclined magnetic field on two‐dimensional flow of a steady, viscous incompressible fluid at low Reynolds number through a porous wavy channel. We consider a channel having sinusoidal walls filled with a fully saturated porous medium. The porous regime is assumed to be homogenous and isotropic. The viscous flow through a porous regime is governed by Brinkman equation, where the viscous forces are dominant. This allows us to assume the no‐slip boundary conditions at the walls of the wavy channel. Boundary element method (BEM) based on non‐primitive variables namely, stream function‐vorticity variables is used to solve the Brinkman equation. Further, we consider a very small magnetic Reynolds number to eliminate the magnetic‐induced equation. We analyzed that an increase in Hartman number, porosity, and reduction in inclination angle of magnetic field, wave amplitude, and Darcy number led to a reduction in horizontal velocity, whereas an increase in Hartman number, porosity, wave amplitude, and decrease in Darcy number and angle of inclination of magnetic field led to an increase in vertical velocity. Moreover, the flow reversal phenomena occur in the vicinity of the crest regime of the porous wavy channel for high wave amplitude and low Hartman number. The proposed investigation has widespread applications, such as drug delivery systems to target the drug precisely, magneto‐hydrodynamic pumps to regulate the blood flow in artificial hearts to reduce the risk of blood clotting, and so forth.

Effects of heater positions on magneto-hydrodynamic convection of CuO-water nanofluid flow in a grooved channel

PurposeThis study aims to delve into the coupled mixed convective heat transport process within a grooved channel cavity using CuO-water nanofluid and an inclined magnetic field. The cavity undergoes isothermal heating from the bottom, with variations in the positions of heated walls across the grooved channel. The aim is to assess the impact of heater positions on thermal performance and identify the most effective configuration.Design/methodology/approachNumerical solutions to the evolved transport equations are obtained using a finite volume method-based indigenous solver. The dimensionless parameters of Reynolds number (1 ≤ Re ≤ 500), Richardson number (0.1 ≤ Ri ≤ 100), Hartmann number (0 ≤ Ha ≤ 70) and magnetic field inclination angle (0° ≤ γ ≤ 180°) are considered. The solved variables generate both local and global variables after discretization using the semi-implicit method for pressure linked equations algorithm on nonuniform grids.FindingsThe study reveals that optimal heat transfer occurs when the heater is positioned at the right corner of the grooved cavity. Heat transfer augmentation ranges from 0.5% to 168.53% for Re = 50 to 300 compared to the bottom-heated case. The magnetic field’s orientation significantly influences the average heat transfer, initially rising and then declining with increasing inclination angle. Overall, this analysis underscores the effectiveness of heater positions in achieving superior thermal performance in a grooved channel cavity.Research limitations/implicationsThis concept can be extended to explore enhanced thermal performance under various thermal boundary conditions, considering wall curvature effects, different geometry orientations and the presence of porous structures, either numerically or experimentally.Practical implicationsThe findings are applicable across diverse fields, including biomedical systems, heat exchanging devices, electronic cooling systems, food processing, drying processes, crystallization, mixing processes and beyond.Originality/valueThis work provides a novel exploration of CuO-water nanofluid flow in mixed convection within a grooved channel cavity under the influence of an inclined magnetic field. The influence of different heater positions on thermomagnetic convection in such a cavity has not been extensively investigated before, contributing to the originality and value of this research.

Analytical and Numerical Solutions for Heat, Mass and Entropy Generation of Fourth Grade Nanofluid Flow Over A Vertical Plate

The focus of this research is to investigate magnetohydrodynamic flow, entropy generation, heat and mass transfer analysis for fourth grade nanofluid over a vertical plate in a porous medium subject to slip and convective boundary conditions. Lie group invariant similarity variable is used to transform the partial differential equations (PDEs) governing the problem to system of coupled nonlinear ordinary differential equations (ODEs). The resulting dimensionless ODEs are solved using Homotopy Perturbation Method (HPM). HPM results are validated with the numerical solutions via shooting method alongside the six order Runge-Kutta integration technique. The results revealed effects of new embedded governing flow parameters on velocity, temperature, entropy generation and concentration profiles.Furthermore, the impact of new embedded flow parameters on skin friction coefficient, Nusselt number and Sherwood number at the plate surface are investigated and the results are shown in tabular forms. The results indicate that suction on the plate can be used to control momentum, thermal and solutal boundary layer thickness. This research discovered that magnetic parameter, Eckert number, Biotsolutal number and Hartmann number can be respectively used to adjust fluid flow’s velocity, temperature, concentration and entropy generation. This research also detected that the force driving the fourth grade nanofluid flow called buoyancy driven force can be accelerated or decelerated by adjusting angle of magnetic field inclination. The present investigation has applications in industries and engineering, such as petroleum industries, chemical industries and metallurgy sciences

The Decay of Two Adjacent Sunspots Associated with Moving Magnetic Features

The relationship between the decay of sunspots and moving magnetic features (MMFs) plays an important role in understanding the evolution of active regions. We present observations of two adjacent sunspots, the gap between them, and a lot of MMFs propagating from the gap and the sunspots' outer edges in NOAA Active Region 13023. The MMFs are divided into two types based on their magnetic field inclination angle: vertical (0° < γ < 45°) and horizontal (45° ≤ γ < 90°) MMFs (V-MMFs and H-MMFs, respectively). The main results are as follows: (1) the mean magnetic flux decay rates of the two sunspots are −1.7 × 1020 and −1.4 × 1020 Mx day−1; (2) the magnetic flux generation rate of all MMFs is calculated to be −1.9 × 1021 Mx day−1, which is on average 5.6 times higher than the total magnetic flux loss rate of the sunspots; (3) the magnetic flux of V-MMFs (including a pore separated from the sunspots) is 1.4 times larger than the total lost magnetic flux of the two sunspots, and in a later stage when the pore has passed through the reference ellipse, the magnetic flux generation rate of the V-MMFs is almost the same as the magnetic flux loss rate of the sunspots; and (4) within the gap, the magnetic flux of V-MMFs is one-third of the total magnetic flux. Few V-MMFs stream out from the sunspots at the nongap region. All observations suggest that MMFs with vertical magnetic fields are closely related to the disintegration of the sunspot, and most of the MMFs from the gap may originate directly from the sunspot umbra.

MHD Mixed Convection Flow and Heat Transfer due to an Inclined Stretching/Shrinking Sheet

This study focuses on the numerical analysis of magnetohydrodynamic (MHD) mixed convection flow of a viscous fluid over an inclined stretching sheet. The sheet’s temperature and stretching velocity are assumed to follow a power law distribution. To simplify the governing partial differential equations (PDEs), we apply similarity transformations, which transform them into ordinary differential equations (ODEs). We employ the bvp4c solver in Matlab for numerical computations. Specifically, when the buoyancy force is present and the parameternis related tomasn= 2m− 1, we obtain similarity solutions. For a particular variant of the shrinking strength, non-unique solutions are found. It is evident from the temporal stability analysis that only one of them remains stable throughout time. The study investigates the effects of various parameters, such as velocity and temperature exponents, magnetic field strength, inclination angle, and buoyancy, on the flow and heat transfer properties, which are illustrated through graphical representations. Notable findings include that the local Nusselt numbers and skin friction coefficients decrease when the inclination angle of the stretching sheet increases, while they increase when the inclination angle of the shrinking sheet increases.

Convective heat transport and entropy generation in butterfly-shaped magneto-nanofluidic systems with bottom heating and top cooling

PurposeThe purpose of this study is to carry out a comprehensive analysis of magneto-hydrodynamics (MHD), nanofluidic flow dynamics and heat transfer as well as thermodynamic irreversibility, within a novel butterfly-shaped cavity. Gaining a thorough understanding of these phenomena will help to facilitate the design and optimization of thermal systems with complex geometries under magnetic fields in diverse applications.Design/methodology/approachTo achieve the objective, the finite element method is used to solve the governing equations of the problem. The effects of various controlling parameters such as butterfly-shaped triangle vertex angle (T), Rayleigh number (Ra), Hartmann number (Ha) and magnetic field inclination angle (γ ) on the hydrothermal performance are analyzed meticulously. By investigating the effects of these parameters, the authors contribute to the existing knowledge by shedding light on their influence on heat and fluid transport within butterfly-shaped cavities.FindingsThe major findings of this study reveal that the geometrical shape significantly alters fluid motion, heat transfer and irreversibility production. Maximum heat transfer, as well as entropy generation, occurs when the Rayleigh number reaches its maximum, the Hartmann number is minimized and the angle of the magnetic field is set to 30° or 150°, while the butterfly wings angle or vertex angle is kept at a maximum of 120°. The intensity of the magnetic field significantly controls the heat flow dynamics, with higher magnetic field strength causing a reduction in the flow strength as well as heat transfer. This configuration optimizes the heat transfer characteristics in the system.Research limitations/implicationsFurther research can be expanded on this study by examining thermal performance under different curvature effects, orientations, boundary conditions and additional factors. This can be accomplished through numerical simulations or experimental investigations under various multiphysical scenarios.Practical implicationsThe geometric configurations explored in this research have practical applications in various engineering fields, including heat exchangers, crystallization processes, microelectronic devices, energy storage systems, mixing processes, food processing, air-conditioning, filtration and more.Originality/valueThis study brings value by exploring a novel geometric configuration comprising the nanofluidic flow, and MHD effect, providing insights and potential innovations in the field of thermal fluid dynamics. The findings contribute a lot toward maximizing thermal performance in diverse fields of applications. The comparison of different hydrothermal behavior and thermodynamic entropy production under the varying geometric configuration adds novelty to this study.

Thermal performance investigation of transient natural convective nanofluid flow in a square cavity with inclined periodic magnetic field

The goal of this paper is to analyze the thermal exhibition of transient free convective nanofluid flow in a square cavity with inclined periodic magnetic field using one-component thermally equilibrium homogeneous model. Distinct thermal settings (constant, parabolic, and sinusoidal) for the left heated wall are deliberated when the right wall of the cavity is cold and the horizontal walls are insulated. For numerical simulations, eight types of nanofluids consisting Cu, Co, Zn, and Al2O3 nanoparticles along with H2O and kerosene as base fluids have been employed. During numerical computation, the impacts of different factors (Hartmann number, Rayleigh number, nanoparticles volume fraction, period, and inclination angle) on the fluid flow and heat transfer are examined. The numerical results show that cobalt-kerosene nanofluid distributes the maximum heat transfer rate compared to other 7 types of nanofluids. The results also indicate that sinusoidal thermal scenery at the left heated wall delivers the uppermost average Nusselt number compared to the other types of thermal approaches. The optimum thermal performance is achieved at magnetic field's inclination angle δ=π3 and period number λ = 1 for the case of sinusoidal scenery.

MRT-LB simulation and response surface analysis of natural convection of non-Newtonian ferrofluid in an enclosure with non-uniformly heated radiator through GPU computing

The multiple-relaxation-time (MRT) lattice Boltzmann method (LBM) has been applied to numerically analyze the natural convection of non-Newtonian ferrofluid in an enclosure with a horizontal plate or radiator that is not uniformly heated. The left and right walls of the enclosure are cold (Tc), while the bottom and upper walls are assumed to be adiabatic. Simulations using numerical models are run for a variety of dimensionless variables, including Rayleigh numbers (Ra=104,105,106), Hartmann numbers (Ha=0,20,40,60,80), power-law index (n=0.6,0.8,1.0,1.2,1.4), magnetic field inclination angles (γ=0,π/4,π/2,3π/4), and the maximum ferroparticle volume fractions is 6% (ϕ=0.06). The numerical results are reported in the form of isotherms, streamlines, velocity, temperature, mean Nusselt number, and entropy production. The study found that the Nu¯ rises with the increment of the Rayleigh number but decreases with the enhancement of the Ha, n, and ϕ. The temperature declines rapidly when the magnetic field inclination angle values increase to γ=90°, then gains temperature. The velocity and temperature both increase as the ϕ increases. For increasing the power-law index, the Nu¯ grows by 1.6% in the case of Ra=104 but falls by 14.56% and 54.87% when Ra=105 and Ra=106, respectively. The entropy profile is discussed in detail. The Be number is more significant than 0.5 for various n at Ra=104 and 105, suggesting that entropy formation is primarily due to heat gradients. Response surface methodology (RSM) also describes the numerical results with variable Ra numbers (104, 105, 106), n=0.6,1.0,1.4), angles (γ=0,π/2,3π/4), Ha=40 and ϕ=0.06. Finally, the residual plots, 2D and 3D plots are described. All the simulations are conducted by the GPU (Graphics Processing Unit) computing with the NVIDIA CUDA C/C++ platform.

Lattice Boltzmann simulation of natural convection of ethylene glycol-alumina nanofluid in a C-shaped enclosure with MFD viscosity through a parallel computing platform and quantitative parametric assessment

There has been a strong interest to design and optimise thermally efficient heating and cooling equipment. The conventional fluids such as oil and water have limited thermal efficiency. Therefore, researchers have been seeking alternatives to the conventional fluids to improve the efficacy of heat exchanging and electronic cooling devices and nanofluid has been identified as a great option in this regard. Although nanofluid is a great alternative, certain specifications, geometries, and pertinent parameters need to be thoroughly investigated for a comprehensive understanding with the aid of robust computational technique. The aim of this study was to investigate the multiple-relaxation-time (MRT) lattice Boltzmann method (LBM) to numerically analyse the effects of magnetic field dependent (MFD) viscosity on the natural convection of ethylene glycol (C2H6O2)-alumina (Al2O3) nanofluid in a side heated two-dimensional C-shaped enclosure using graphics processing unit (GPU) by a computing unified device architecture (CUDA) C parallel computing platform. Numerical simulations were performed at multifarious Rayleigh numbers, Hartmann numbers, and the different magnetic field inclination angles to study the heat transfer and various flow patterns under magnetic field-dependent (MFD) viscosity, solutions were presented by varying volume fraction of nanoparticles, Rayleigh numbers, viscous parameters, magnetic inclination angles, and Hartman numbers on streamlines, isotherms, local and average Nusselt number and temperature. Further correlation developments were conducted through Levenberg-Marquardt data-driven algorithm to investigate the influence of all the parameters on average Nusselt numbers, entropy generation, and fluid irreversibility parameter. The findings demonstrated that as the Rayleigh numbers augmented, the average Nusselt number increased significantly due to the influence of buoyancy, whereas under the influence of Hartmann numbers, average Nusselt numbers decreased due to the dominance of magnetic field strength and Lorentz force. However, the heat transfer continued to improve if the concentration of the nanoparticles increased, thus showcasing the importance of hybrid nanofluid. In addition, the entropy generation impact across the cavity for the ethylene glycol-alumina nanofluid was greatly enhanced by a stronger buoyancy influence.

AI predicts MHD double-diffusive mixed convection and entropy generation in hybrid-nanofluids for different magnetic field inclination angles by ANN

The goal of the current numerical study is to determine how different magnetic field inclination angles along with Reynolds numbers affect mixed convective heat and mass transfer as well as entropy generation in a lid-driven trapezoidal enclosure with two rotating cylinders inside. As governing fluids, several water-based nanofluids and hybrid nanofluids with fixed solid volume fractions (5%) are employed. The impacts of three different types of SWCNT-Cu-Al2O3-water hybrid nanofluids, each made up of different ratios of SWCNT, Cu, and Al2O3 nanoparticles in water, are seen in this work, along with the effects of SWCNT-water, Cu-water, and Al2O3-water nanofluids separately. To obtain the results in the form of average Nusselt number, average Sherwood number, average temperature, and Bejan number as output parameters inside the enclosure for different magnetic field inclination angles (0° ≤ λ ≤ 90°) and other governing parameter values, the governing Navier-Stokes, thermal energy, and mass conservation equations are solved using the Galerkin weighted residual finite element method through numerical simulation. Then the simulation data is used to develop a novel artificial neural network model for efficient prediction. To achieve the best outcomes for the output parameters, the optimal values of each of these input parameters are determined by both FEM and ANN and a comparative study between these two is conducted. Cu-Al2O3-water hybrid nanofluid is used to test the performance of the developed ANN model for new cases. For each type of fluid in the present framework, maximum heat and mass transfer often take place when the magnetic field is applied at an inclined angle with respect to the horizontal axis. A satisfactory accuracy is obtained for the developed novel ANN model while predicting respective results. For training and validation data, it predicts convective heat and mass transfer with 96.81% accuracy and average dimensionless temperature and Bejan number with 98.74% accuracy. For test data, it predicts convective heat and mass transfer with 97.03% accuracy and average dimensionless temperature and Bejan number with 99.17% accuracy.

Natural convection and entropy generation in a trapezoidal region with hybrid nanoliquid under magnetic field

PurposeThis paper aims to study numerically the steady natural convective heat transfer of a hybrid nanosuspension (Ag-MgO/H2O) within a partially heated/cooled trapezoidal region with linear temperature profiles at inclined walls under an effect of uniform Lorentz force. This investigation is useful for researchers studying in the area of cavity flows to know features of the flow structures and nature of hybrid nanofluid characteristics. In addition, a detailed entropy generation analysis has been performed to highlight possible regimes with minimal entropy generation rates.Design/methodology/approachThe governing equations formulated using the Oberbeck–Boussinesq approach and single-phase nanoliquid model are transformed to a non-dimensional form by using non-dimensional variables. The obtained equations with appropriate boundary conditions are resolved by the finite difference technique. The developed code has been validated comprehensively. Analysis has been performed for a wide range of governing parameters, including Rayleigh number (Ra = 105), Prandtl number (Pr = 6.82), Hartmann number (Ha = 0–100), magnetic field inclination angle (φ = 0–?/2) and nanoparticles volume fraction (φhnf = 0 and 2%).FindingsIt has been shown that inclined magnetic field can be used to manage the energy transport performance. An inclusion of nanoparticles without Lorentz force influence allows forming more stable convective regime with descending heat plume in the central zone, while such a regime was performed for clear fluid only for moderate and high Hartmann numbers. Moreover, the average overall entropy generation can be decreased with a growth of the Hartmann number, while an addition of hybrid nanoparticles allows reducing this parameter for Ha = 30 and 50. The average Nusselt number can be increased with a growth of the nanoparticles concentration for low values of the magnetic field intensity.Originality/valueGoverning equations written using the conservation laws and dimensionless non-primitive variables have been resolved by the finite difference approach. The created numerical code has been verified by applying the grid independence test and computational outcomes of other researchers. The comprehensive analysis for various key parameters has been performed.

Influence of magnetic field inclination angles on hybrid nanofluids: Enhanced MHD double-diffusive mixed convection and entropy generation in a trapezoidal enclosure

This current numerical investigation is focused on analyzing the influences of various magnetic field inclination angles on mixed convective heat and mass transfer along with entropy generation in a lid-driven trapezoidal enclosure with double rotating cylinders inside by highlighting significant correlations between system’s input & output parameters. In this study, the effects of three types of SWCNT-Cu-–water hybrid-nanofluids composed of various ratios of nanoparticles in water are observed along with the individual impacts of SWCNT-water, Cu-water, and –water nanofluids. Galerkin weighted residual finite element method is used to solve the governing Navier-Stokes, thermal energy, and mass conservation equations numerically to get the results in forms of average Nusselt number, average Sherwood number, average entropy generation, and average temperature. The optimum conditions are identified to get the best results and these results are also represented in the forms of streamlines, isotherm, and isoconcentration contours for several parameters to get a better insight into heat and mass transfer. In most cases, maximum heat, and mass transfer along with maximum average total entropy generation occur if the magnetic field is assigned at an inclined angle with respect to the horizontal axis for each type of fluid in this current framework.