scholarly journals Hydromagnetic natural convection from a horizontal porous annulus with heat generation or absorption

2020 ◽  
Vol 307 ◽  
pp. 01005
Author(s):  
Jabrane Belabid ◽  
Soufiane Belhouideg
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Heat Generation ◽  
Inclination Angle ◽  
Hartmann Number ◽  
Saturated Porous Medium ◽  
Darcy Law ◽  
Cylindrical Annulus ◽  
Field Inclination

The problem of unsteady laminar, two-dimensional hydromagnetic natural convection heat transfer in a concentric horizontal cylindrical annulus filled with a fluid-saturated porous medium in the presence of a transverse magnetic field and fluid heal generation effects is studied numerically. It is assumed that the inner and outer walls of the cylindrical annulus are maintained at uniform and constant temperatures Ti and To respectively. The model consists of the heat equation and the equations of motion under the Darcy law. The derived problem with the stream function-temperature formulation is solved numerically using the alternating direction implicit method. This investigation concerns the effect of magnetic field inclination angle, Hartmann number and heat generation on the heat transfer and the flow pattern. The obtained numerical results are presented graphically in terms of streamlines and isotherms. It was found that the heat transfer mechanisms and the flow characteristics depend strongly on the magnetic field inclination angle, Hartmann number and heat generation..

Numerical simulation of natural convection within wavy square enclosure filled with nanofluid under magnetic field using EFGM with parallel algorithm

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Surabhi Nishad ◽  
Sapna Jain ◽  
Rama Bhargava
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Content Type ◽  
The Magnetic Field ◽  
Field Inclination

Purpose This paper aims to study the flow and heat transfer inside a wavy enclosure filled with Cu-water nanofluid under magnetic field effect by parallel implemented meshfree approach. Design/methodology/approach The simulation has been carried out for a two-dimensional model with steady, laminar and incompressible flow of the nanofluid filled inside wavy enclosure in which one of the walls is sinusoidal such that the amplitude (A = 0.15) and number of undulations (n = 2) are fixed. A uniform magnetic field B0 has been applied at an inclination angle γ. The governing equations for the transport phenomena have been solved numerically by implementing element-free Galerkin method (EFGM) with the sequential as well as parallel approach. The effect of various parameters, namely, nanoparticle volume fraction (φ), Rayleigh number (Ra), Hartmann number (Ha) and magnetic field inclination angle (γ) has been studied on the natural convection flow of nanofluid. Findings The results are obtained in terms of average Nusselt number calculated at the cold wavy wall, streamlines and isotherms. It has been observed that the increasing value of Rayleigh number results in increased heat transfer rate while the Hartmann number retards the fluid motion. On the other hand, the magnetic field inclination angle gives rise to the heat transfer rate up to its critical value. Above this value, the heat transfer rate starts to decrease. Originality/value The implementation of the magnetic field and its inclination has provided very interesting results on heat and fluid flow which can be used in the drug delivery where nanofluids are used in many physiological problems. Another important novelty of the paper is that meshfree method (EFGM) has been used here because the domain is irregular. The results have been found to be very satisfactory. In addition, parallelization of the scheme (which has not been implemented earlier in such problems) improves the computational efficiency.

A Differential Quadrature Solution of MHD Natural Convection in an Inclined Enclosure With a Partition

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Kamil Kahveci ◽  
Semiha Öztuna
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Inclination Angle ◽  
Hartmann Number ◽  
Differential Quadrature ◽  
Flow And Heat Transfer ◽  
Inclined Enclosure ◽  
Vorticity Generation

Magnetohydrodynamics natural convection in an inclined enclosure with a partition is studied numerically using a differential quadrature method. Governing equations for the fluid flow and heat transfer are solved for the Rayleigh number varying from 104 to 106, the Prandtl numbers (0.1, 1, and 10), four different Hartmann numbers (0, 25, 50, and 100), the inclination angle ranging from 0degto90deg, and the magnetic field with the x and y directions. The results show that the convective flow weakens considerably with increasing magnetic field strength, and the x-directional magnetic field is more effective in reducing the convection intensity. As the inclination angle increases, multicellular flows begin to develop on both sides of the enclosure for higher values of the Hartmann number if the enclosure is under the x-directional magnetic field. The vorticity generation intensity increases with increase of Rayleigh number. On the other hand, increasing Hartmann number has a negative effect on vorticity generation. With an increase in the inclination angle, the intensity of vorticity generation is observed to shift to top left corners and bottom right corners. Vorticity generation loops in each region of enclosure form due to multicelluar flow for an x-directional magnetic field when the inclination angle is increased further. In addition, depending on the boundary layer developed, the vorticity value on the hot wall increases first sharply with increasing y and then begins to decrease gradually. For the high Rayleigh numbers, the average Nusselt number shows an increasing trend as the inclination angle increases and a peak value is detected. Beyond the peak point, the foregoing trend reverses to decrease with the further increase of the inclination angle. The results also show that the Prandtl number has only a marginal effect on the flow and heat transfer.

scholarly journals CuO–Water Nanofluid Magnetohydrodynamic Natural Convection inside a Sinusoidal Annulus in Presence of Melting Heat Transfer

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
M. Sheikholeslami ◽  
R. Ellahi ◽  
C. Fetecau
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Melting Heat ◽  
Melting Heat Transfer ◽  
Limiting Case ◽  
Good Agreement ◽  
Melting Parameter

Impact of nanofluid natural convection due to magnetic field in existence of melting heat transfer is simulated using CVFEM in this research. KKL model is taken into account to obtain properties of CuO–H2O nanofluid. Roles of melting parameter (δ), CuO–H2O volume fraction (ϕ), Hartmann number (Ha), and Rayleigh (Ra) number are depicted in outputs. Results depict that temperature gradient improves with rise of Rayleigh number and melting parameter. Nusselt number detracts with rise of Ha. At the end, a comparison as a limiting case of the considered problem with the existing studies is made and found in good agreement.

scholarly journals Heat transfer augmentation of magnetohydrodynamics natural convection in L-shaped cavities utilizing nanofluids

2012 ◽  
Vol 16 (2) ◽  
pp. 489-501 ◽  
Author(s):  
Ehsan Sourtiji ◽  
Seyed Hosseinizadeh
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Aspect Ratio ◽  
Flow Field ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
The Magnetic Field

A numerical study of natural convection heat transfer through an alumina-water nanofluid inside L-shaped cavities in the presence of an external magnetic field is performed. The study has been carried out for a wide range of important parame?ters such as Rayleigh number, Hartmann number, aspect ratio of the cavity and solid volume fraction of the nanofluid. The influence of the nanoparticle, buoyancy force and the magnetic field on the flow and temperature fields have been plotted and discussed. The results show that after a critical Rayleigh number depending on the aspect ratio, the heat transfer in the cavity rises abruptly due to some significant changes in flow field. It is also found that the heat transfer enhances in the presence of the nanoparticles and increases with solid volume fraction of the nanofluid. In addition, the performance of the nanofluid utilization is more effective at high Ray?leigh numbers. The influence of the magnetic field has been also studied and de?duced that it has a remarkable effect on the heat transfer and flow field in the cavity that as the Hartmann number increases the overall Nusselt number is significantly decreased specially at high Rayleigh numbers.

Double Diffusive Magnetohydrodynamic (MHD) Natural Convection and Entropy Generation in a Discretely Heated Inclined Dome-Shaped Enclosure Filled with Cu-Water Nanofluid

2021 ◽  
Vol 10 (4) ◽  
pp. 564-579
Author(s):  
Rujda Parveen ◽  
Priyajit Mondal ◽  
Tapas Ray Mahapatra
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Convective Heat ◽  
Entropy Generation ◽  
Inclination Angle ◽  
Hartmann Number ◽  
Substantial Impact ◽  
Double Diffusive

This research presents an investigation of laminar two-dimensional double-diffusive free convection and entropy formation in an inclined enclosure under the influence of an inclined magnetic field. The performance of natural convective heat transfer can be improved by doing modifications in enclosure geometry that impact the flow structure. We have considered a dome-shaped enclosure to examine the heat and mass transfer performance. The enclosure is saturated with Cu-water nanofluid and the two sidewalls of the enclosure are maintained at constant temperature Tc(<Th) and concentration cc(<ch). The top-curved wall is adiabatic, and the lower wall is discretely heated and concentrated. The governing equations are first non-dimensionalized and then written in stream function-velocity formulation that is solved numerically using the Bi-CGStab method. A comparison with previously published work in literature is presented and found to be in excellent agreement. Numerical simulations are performed for various values of considered parameters such as Rayleigh number (Ra), Hartmann number (Ha), the orientation of magnetic field (γ), volume fraction of nanoparticles (Φ), and inclination angle of the enclosure (δ). The mentioned parameters have a substantial impact on the cavity flow characteristics. The obtained results demonstrate that the average Sherwood number and Nusselt number are decreasing functions of both the Hartmann number and inclination angle of the enclosure. The minimum heat and mass transfer took place at δ = 135° as the angle of inclination of the enclosure restrains the fluid velocity and reduces the heat transfer rate. Also, entropy generation analysis is conducted for all the considered parameters. The results show that the dome-shaped enclosure has a substantial impact on the fluid flow that enables a smoother and more effective flow inside the cavity, which improves the natural convective heat and mass transmission.

Numerical investigation of magnetic field inclination angle on transient natural convection in an enclosure filled with nanofluid

2014 ◽  
Vol 31 (7) ◽  
pp. 1342-1360 ◽  
Author(s):  
Masoud Kharati Koopaee ◽  
Iman Jelodari
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Rayleigh Number ◽  
Thermal Behavior ◽  
Inclination Angle ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Field Orientation ◽  
Content Type ◽  
Maximum Value

Purpose – The objective of present research is to characterize the unsteady thermal behavior of a square enclosure filled with water-Al2O3 nanofluids in the presence of oriented magnetic fields. The purpose this paper is to study the effect of pertinent parameters on the transient natural convection in the enclosure. Design/methodology/approach – In this research, an in-house implicit finite volume code based on the SIMPLE algorithm is utilized for numerical calculations. To ensure the accuracy of results, comparisons are also made with previous works in literature. In this study, a constant strength magnetic field is concerned and for Rayleigh numbers of Ra=103, 104 and 105 the effect of magnetic field orientation with respect to the case of zero inclination on the thermal performance of cavity is investigated at Hartmann number range of Ha=15-90. In the present work, the nano-particle volume fractions range from φ=0-0.06. Findings – Results show that when Rayleigh number is Ra=103, the inclination angle, solid particles and Hartmann number has no effect on the transient behavior. It is shown that during the time advancement to steady condition, the heat transfer rate relative to zero inclination angle, may reach to a maximum value. This relative maximum heat transfer increases as the inclination angle increases and decreases as the solid volume fraction increases. The effect of increase in Hartmann number is to decrease this maximum value at Rayleigh number of Ra=104 and at Rayleigh number of Ra=105, depending on the Hartmann number, this value may increase or decrease. It is also found that an increase in Hartmann number leads to delay the appearance of the relative maximum value of heat transfer. Results show that this maximum value is of more significance at zero solid volume fraction when inclination angle is 90 degrees and Hartmann number is Ha=60. Originality/value – Limited works could be found in the literature regarding the idea of using nanofluids as the working fluid in an enclosure in the presence of magnetic field. In these works, the steady state thermal behavior of enclosures subjected to fixed magnetic fields is concerned. In the present work, the unsteady thermal behavior is concerned and the effect of magnetic field orientation angles on transient heat transfer performance of the enclosure at different Rayleigh and Hartmann numbers and solid volume fractions is explored.

Uniform Magnetic field (UMF) Effect on the Heat Transfer of a Porous Half-Annulus Enclosure Filled by Cu-Water Nanofluid Considering Heat Generation

2018 ◽  
Vol 14 (3) ◽  
pp. 187-198 ◽  
Author(s):  
Mohammad Hatami ◽  
Jingyu Jin ◽  
Hamid Reza Ashorynejad ◽  
Dengwei Jing
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Finite Element Method ◽  
Finite Element ◽  
Nusselt Number ◽  
Heat Generation ◽  
Uniform Magnetic Field ◽  
Hartmann Number ◽  
Outer Wall ◽  
Element Method

Background: In this work, the effect of a uniform magnetic field (UMF) on the natural convection heat transfer of Cu-water nanofluid in a porous half-annulus cavity is studied by finite element method, considering heat generation. The effects of four parameters (magnetic field angle (γ), Hartmann number (Ha), nanoparticles volume fraction (φ) and Rayleigh number (Ra)) on the local and average Nusselt numbers of outer wall have been investigated. Methods: Numerical Finite Element Method (FEM) based on FlexPDE commercial code was used to solve the described problems and the validation was also performed by Finite Difference Method (FDM) in previous studies. Results: It was found that by applying external magnetic field with a certain angle with respect to the geometry, the maximum local heat Nusselt number could shift to one side of outer wall and the shift is dependent on the angle of the imposed magnetic field. Conclusion: Our results also confirm that increasing the Hartmann number decreases the Nusselt number due to Lorentz force resulting from the presence of stronger magnetic field which slows down the fluid motion and in turn leads to a decreased heat transfer.

Numerical study on the steady-state heat transfer rate of nanofluid filled within square cavity in the presence of oriented magnetic field

2013 ◽  
Vol 228 (8) ◽  
pp. 1348-1362 ◽  
Author(s):  
Masoud K Koopaee ◽  
Amir Omidvar ◽  
Iman Jelodari
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Solid Particles ◽  
Square Cavity ◽  
Inclination Angles ◽  
Rayleigh Numbers ◽  
Field Inclination

In this paper, the steady-state natural convection in a square cavity filled with water–Al2O3 nanofluid in the presence of magnetic fields with variable inclination angles is investigated numerically. The enclosure is subjected to different side-wall temperatures while the top and bottom walls are assumed to be adiabatic. The thermal behavior of enclosure is assessed using a finite volume-based computer program. In order to ensure the accuracy of results, comparisons are also made with a previous published work. In this research, at constant magnetic field strengths, the effect of magnetic field inclination angle on the rate of heat transfer in the square cavity is investigated at the Rayleigh numbers of Ra = 103, 104, 105 and 106. In this work, the Hartmann number ranges from Ha = 0 to 120 and the solid volume fraction varies from φ = 0 to 0.06. Numerical results show that depending on the Rayleigh and Hartmann numbers, the maximum heat transfer rate may occur at magnetic field inclination angles of 45°, 60° or 90° and the effect of magnetic field inclination angle is significant at high values of Rayleigh and Hartmann numbers. It is found that addition of nano-sized solid particles causes higher heat transfer rate when Ra = 103, whereas at Rayleigh number of Ra = 106, a reverse behavior is observed. Results show that at Rayleigh numbers of Ra = 104 and 105, the effect of solid particles addition on the thermal performance of the enclosure depends on the Hartmann number. It is also shown that an increase in the inclination angle causes higher velocity within the enclosure and addition of solid particles leads to suppression of flow field.

scholarly journals Turbulent natural convection heat transfer in a square cavity with nanofluids in presence of inclined magnetic field

2021 ◽  
pp. 326-326
Author(s):  
Mohamed El Hattab ◽  
Zakaria Lafdaili
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Orientation Angle ◽  
Inclined Magnetic Field ◽  
Square Cavity ◽  
Turbulent Natural Convection

In this paper, we present a numerical study of turbulent natural convection in a square cavity differentially heated and filled with nanofluid and subjected to an inclined magnetic field. The standard k-? model was used as the turbulence model. The transport equations were discretized by the finite volume method using the SIMPLE algorithm. The influence of the Rayleigh number, the Hartmann number, the orientation angle of the applied magnetic field, the type of nanoparticles as well as the volume fraction of nanoparticles, on the hydrodynamic and thermal characteristics of the nanofluid was illustrated and discussed in terms of streamlines, isotherms and mean Nusselt number. The results obtained show that the heat transfer rate increases with increasing Rayleigh number and orientation angle of the magnetic field but it decreases with increasing Hartmann number. In addition, heat transfer improves with increasing volume fraction and with the use of Al2O3 nanoparticles.

Numerical Investigation of Magneto-Natural Heat Transfer in Nanofluid Filled Inclined Enclosure

2020 ◽  
Vol 9 (2) ◽  
pp. 98-105
Author(s):  
L. Eljamali ◽  
R. Sehaqui
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Hartmann Number ◽  
Temperature Profiles ◽  
Governing Equations ◽  
Alternating Direction Implicit ◽  
Alternating Direction ◽  
Inclined Enclosure ◽  
Vertical Walls

This paper examines the natural convection in an inclined enclosure that is filled with a water-copper nanofluid and influenced by a magnetic field applied normal to the plane of the cavity. The horizontal walls are assumed to be insulated while the side vertical walls of the cavity are heated differentially. The governing equations are re-formulated in functions of stream function and vorticity. The resulting boundary value problem is solved numerically using an ADI method (alternating direction implicit). A variety of plots showing the velocity and temperature profiles and the influence of Hartmann number as well as Rayleigh number on the streamlines and isotherms are shown.

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