Effects of uniform or non-uniform heating at bottom wall on MHD mixed convection in a porous cavity saturated by nanofluid

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Subramanian Muthukumar ◽  
Selvaraj Sureshkumar ◽  
Arthanari Malleswaran ◽  
Murugan Muthtamilselvan ◽  
Eswari Prem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Bottom Wall ◽  
Uniform Heating ◽  
The Magnetic Field

Abstract A numerical investigation on the effects of uniform and non-uniform heating of bottom wall on mixed convective heat transfer in a square porous chamber filled with nanofluid in the appearance of magnetic field is carried out. Uniform or sinusoidal heat source is fixed at the bottom wall. The top wall moves in either positive or negative direction with a constant cold temperature. The vertical sidewalls are thermally insulated. The finite volume approach based on SIMPLE algorithm is followed for solving the governing equations. The different parameters connected with this study are Richardson number (0.01 ≤ Ri ≤ 100), Darcy number (10−4 ≤ Da ≤ 10−1), Hartmann number (0 ≤ Ha ≤ 70), and the solid volume fraction (0.00 ≤ χ ≤ 0.06). The results are presented graphically in the form of isotherms, streamlines, mid-plane velocities, and Nusselt numbers for the various combinations of the considered parameters. It is observed that the overall heat transfer rate is low at Ri = 100 in the positive direction of lid movement, whereas it is low at Ri = 1 in the negative direction. The average Nusselt number is lowered on growing Hartmann number for all considered moving directions of top wall with non-uniform heating. The low permeability, Da = 10−4 keeps the flow pattern same dominating the magnetic field, whereas magnetic field strongly affects the flow pattern dominating the high Darcy number Da = 10−1. The heat transfer rate increases on enhancing the solid volume fraction regardless of the magnetic field.

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.

Natural Convection in a Square Cavity Utilizing Different Nanofluids in Presence of Constant Magnetic Field With Brownian Motion Effect

2018 ◽  
Author(s):  
Misarah Abdelaziz ◽  
Wael El-Maghlany ◽  
Ashraf S. Ismail
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Brownian Motion ◽  
Rayleigh Number ◽  
Transfer Rate ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Heat Sources ◽  
Square Cavity

Natural convection in a square cavity filled with water-Al2 O3 nanofluid is studied numerically. Upper, lower, and left surfaces are insulated. Right wall is at low temperature, while two heat sources are kept at high temperature. The sources are vertically attached to the horizontal walls of a cavity . A uniform magnetic field is applied in a horizontal direction. Effective thermal conductivity and viscosity of nanofluids are obtained using Koo-Kleinstreuer model which implements the Brownian motion of nanoparticles effect. Steady state laminar regime is assumed. The conservation of mass, momentum, and energy equations are solved using finite volume method. The numerical results are reported for the effect of Rayleigh number, solid volume fraction, and Hartmann number on the streamlines as well as the isotherms. In addition, the results for average Nusselt number are presented for various parametric conditions. This study is presented in the following ranges, Rayleigh number from 103 to 105, Hartmann number from 0 to 60, and solid volume fraction from 0 to 0.06, while the Prandtl number which represents water is kept constant at 6.2. The results showed that heat transfer rate decreases with the rise of Hartmann number and increases with the rise of Rayleigh number, and volume fraction. Moreover, results showed that heat sources positions, lengths and intensities have crucial effect on heat transfer rate. Additionally, the effect of nanofluids type was studied, it was found that water-Cu nanofluid enhances the heat transfer better than water-Al2O3, water-CuO and water-TiO2 nanofluids.

scholarly journals A Tilted Lorentz Force Effect on Porous Media Filled with Nanofluid

2018 ◽  
Vol 48 (2) ◽  
pp. 50-71
Author(s):  
M. Muthtamilselvan ◽  
S. Sureshkumar
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Staggered Grid ◽  
Convection Flow ◽  
The Magnetic Field

Abstract This paper is intended to investigate the effects of an inclined magnetic field on the mixed convection flow in a lid-driven porous enclosure filled with nanofluid. Both the left and right vertical walls of the cavity are thermally insulated while the bottom and top horizontal walls are maintained at constant but different temperatures. The governing equations are solved numerically by using finite volume method on a uniformly staggered grid system. The computational results are obtained for various combinations of Richardson number, Darcy number, Hartmann number, inclination angle of magnetic field, and solid volume fraction. It is found that the presence of magnetic field deteriorates the fluid flow, which leads to a significant reduction in the overall heat transfer rate. The inclination angle of magnetic field plays a major role in controlling the magnetic field strength and the overall heat transfer rate is enhanced with the increase of inclination angle of magnetic field. Adding the nanoparticles in the base fluid significantly increases the overall heat transfer rate in the porous medium whether the magnetic field is considered or not.

scholarly journals 3D Magneto-Buoyancy-Thermocapillary Convection of CNT-Water Nanofluid in the Presence of a Magnetic Field

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 258 ◽  
Author(s):  
Lioua Kolsi ◽  
Salem Algarni ◽  
Hussein A. Mohammed ◽  
Walid Hassen ◽  
Emtinene Lajnef ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Flow Structure ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Stabilization ◽  
Magnetic Field Magnitude ◽  
The Magnetic Field

A numerical study is performed to investigate the effects of adding Carbon Nano Tube (CNT) and applying a magnetic field in two directions (vertical and horizontal) on the 3D-thermo-capillary natural convection. The cavity is differentially heated with a free upper surface. Governing equations are solved using the finite volume method. Results are presented in term of flow structure, temperature field and rate of heat transfer. In fact, results revealed that the flow structure and heat transfer rate are considerably affected by the magnitude and the direction of the magnetic field, the presence of thermocapillary forces and by increasing nanoparticles volume fraction. In opposition, the increase of the magnetic field magnitude leads to the control the flow causing flow stabilization by merging vortexes and reducing heat transfer rate.

scholarly journals Hydrothermal and Entropy Investigation of Ag/MgO/H2O Hybrid Nanofluid Natural Convection in a Novel Shape of Porous Cavity

2021 ◽  
Vol 11 (4) ◽  
pp. 1722
Author(s):  
Nidal Abu-Libdeh ◽  
Fares Redouane ◽  
Abderrahmane Aissa ◽  
Fateh Mebarek-Oudina ◽  
Ahmad Almuhtady ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Natural Convection ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Hybrid Nanofluid ◽  
The Finite Element Method ◽  
Governing Equations ◽  
Nanofluid Flow ◽  
The Magnetic Field

In this study, a new cavity form filled under a constant magnetic field by Ag/MgO/H2O nanofluids and porous media consistent with natural convection and total entropy is examined. The nanofluid flow is considered to be 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 results of the values of Darcy (Da), Hartmann (Ha) and Rayleigh (Ra) numbers, porosity (εp), and the properties of solid volume fraction (ϕ) and flow fields were studied. The findings show that with each improvement in the Ha number, the heat transfer rate becomes more limited, and thus the magnetic field can be used as an outstanding heat transfer controller.

scholarly journals Numerical study of natural convection nanofluids flow in tilted cavities with a partially thermally heat source

2021 ◽  
Vol 13 (11) ◽  
pp. 168781402110606
Author(s):  
Djamila Benyoucef ◽  
Samira Noui ◽  
Afaf Djaraoui
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Source ◽  
Heat Transfer Rate ◽  
Tilt Angle ◽  
Transfer Rate ◽  
Base Fluid ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Bottom Wall

Numerically, natural convection heat transfer of nanofluids in a two-dimensional tilt square enclosure was investigated, with a partial heat source embedded on the bottom wall subject to a fixed heat flux. The remaining portions of the horizontal bottom wall are assumed to be adiabatic, while the upper horizontal wall and the vertical ones are supposed to be at a relatively low temperature. Using the finite volume method and the SIMPLER algorithm, the governing equations have been discretized and solved. Simulations have been carried out for more than one nanoparticle and base fluid, a range of Rayleigh numbers ([Formula: see text] Ra [Formula: see text]), various values of heat source length and location (0.2 [Formula: see text]  B [Formula: see text] 0.8 and 0.2 [Formula: see text]  D [Formula: see text] 0.5, respectively), solid volume fraction ([Formula: see text]) as well as tilt angle ([Formula: see text]). The results indicate that the heat transfer performance increases by adding nanoparticles into the base fluid. An optimum solid volume fraction raises and reduces the heat transfer rate and maximum temperature of the surface heat source. respectively. Moreover, the results show a significant impact of the tilt angle on the flow, temperature patterns, and the heat transfer rate with a specific tilt angle depending to the pertinent parameters.

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.

Coupled Free and Forced Convection Heat Transfer in a Porous Enclosure Saturated by Nanofluid with Irregular Temperature Distributions on Sidewalls

2017 ◽  
Vol 15 (6) ◽  
Author(s):  
M. Muthtamilselvan ◽  
S. Sureshkumar ◽  
Deog Hee Doh
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Amplitude Ratio ◽  
Solid Volume Fraction ◽  
Side Wall ◽  
Darcy Number ◽  
Total Heat Transfer ◽  
Phase Deviation

Abstract A two dimensional steady and laminar mixed convection flow in lid-driven porous cavity filled with Cu-water nanofluid is presented in this numerical investigation. The vertical side walls are considered with two spatially varying sinusoidal temperature distributions of different amplitude ratios and phase deviations while the horizontal walls are thermally insulated. The transport equations are solved using finite volume method on a uniformly staggered grid system. The variations of fluid flow, heat transfer, mid-plane velocity, and Nusselt number were discussed over a wide range of Richardson number $(Ri)$ , Darcy number $(Da)$ , porosity $(\epsilon)$ , amplitude ratio $(\epsilon_a)$ , phase deviation $(\phi)$ , and solid volume fraction $(\chi)$ . The results show that the total heat transfer rate increases on increasing Darcy number, amplitude ratio, and solid volume fraction with fixed $Ri$ . For $\phi=\frac{3\pi}{4}$ , the average Nusselt number gets its maximum value when the natural convection dominates. It is found that for $Ri =0.01$ and $1$ , the total heat transfer rate decreases on increasing porosity whereas for $Ri=100$ it is contradictory. It is also observed that the heat transfer is affected mainly on the right side wall where the phase deviation varies from $0$ to $\pi$ . But the effect of $\phi$ is not significant on the left side wall. The sinusoidal temperature distribution along the sidewalls gives better heat transfer rate than the uniform temperature.

scholarly journals MHD Free Convection and Entropy Generation in a Corrugated Cavity Filled with a Porous Medium Saturated with Nanofluids

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 846 ◽  
Author(s):  
Ali Chamkha ◽  
Fatih Selimefendigil
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Entropy Generation ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Darcy Number ◽  
Grashof Number ◽  
Triangular Wave ◽  
Flow Features

MHD free convection inside a triangular-wave-shaped corrugated porous cavity with Cu-water nanofluid is numerically studied with the finite element method. The influences of the Grashof number ( 10 4 ≤ Gr ≤ 10 6 ), Hartmann number ( 0 ≤ Ha ≤ 50 ), Darcy number ( 10 − 4 ≤ Da ≤ 10 − 1 ) and solid volume fraction of the nanoparticle ( 0 ≤ ϕ ≤ 0.05 ) on the convective flow features are examined. It is observed that increasing the Grashof number and Darcy number enhances the heat transfer, while the effect is opposite for the Hartmann number. As the corrugation frequency of the triangular wave increases, the local and averaged heat transfer rates decrease, which is more effective for higher values of Grashof and Darcy numbers. Normalized total entropy generation increases as the Darcy number and solid volume fraction of the nanoparticles increase and decreases as the Hartmann number increases both for flat and corrugated wall configurations.

Natural convection analysis flow of Al2O3-Cu/water hybrid nanofluid in a porous conical enclosure subjected to the magnetic field

2020 ◽  
Vol 92 (1) ◽  
pp. 10904 ◽  
Author(s):  
Rabeh Slimani ◽  
Abderrahmane Aissa ◽  
Fateh Mebarek-Oudina ◽  
Umair Khan ◽  
M. Sahnoun ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Darcy Number ◽  
Hybrid Nanofluid ◽  
Porosity Ratio ◽  
The Magnetic Field

The current study investigates MHD natural convection heat transfer of a hybrid nanofluid in a truncated cone along with transparent domains having the stimulus of an inherent constant magnetic field. The governing equations subject to the physical boundary conditions are solved numerically by using the Galerkin finite element method. The effects of the various parameters involved in the problem such as the Rayleigh number Ra (ranging between 103 and 106), the Hartmann number Ha (ranging between 0 and 60), and the porosity ratio ε (0.1–0.9) are examined. Moreover, the effects of Da which represents the Darcy number (between 10‑3 and 10‑1) and the volume fraction of nanoparticles ϕ for the dissipated nanoparticles of Al2O3-Cu are reported in terms of the streamlines and isotherms distributions as well as the Nusselt number. Such parameters are critical control parameters for both the fluid flow and the rate of heat transfer of the natural convection in the annular space. The solution outcomes proof that the average Nusselt number varies directly with the dynamic field flowing through a porous media, whereas it behaves inversely with the magnetic field.

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