Effects of two-phase nanofluid model on natural convection in a square cavity in the presence of an adiabatic inner block and magnetic field

2018 ◽  
Vol 28 (7) ◽  
pp. 1613-1647 ◽  
Author(s):  
Ammar I. Alsabery ◽  
Tahar Tayebi ◽  
Ali J. Chamkha ◽  
Ishak Hashim
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Boussinesq Approximation ◽  
Phase Model ◽  
Square Cavity ◽  
Two Phase ◽  
Left Wall ◽  
Content Type ◽  
Conjugate Natural Convection ◽  
The Right

Purpose The purpose of this paper is to study problem of conjugate MHD natural convection of Al2O3-water nanofluid in a square cavity with conductive inner block using Buongiorno’s two-phase model numerically. Design/methodology/approach An isothermal heater is placed on the left wall of the square cavity, while the right wall is maintained at a constant cold temperature. The horizontal top and bottom walls are kept adiabatic. The boundaries of the annulus are assumed to be impermeable, the fluid within the cavity is a water-based nanofluid having Al2O3 nanoparticles. The Boussinesq approximation is applicable. The governing equations subject to the boundary conditions are solved using the finite difference method. Findings Numerical results are presented graphically in the form of streamlines, isotherms and nanoparticles distributions as well as the local and average Nusselt numbers. The results show that the effect of the nanoparticles addition on the average Nusselt number is essential for low Rayleigh, high Hartmann and high values of length ratio when attenuated the convective flow. Originality/value According to exist studies and to the authors’ best knowledge, so far, there have been no studies of conjugate natural convection of Al2O3-water nanofluid in a square cavity with a conductive inner block using Buongiorno’s two-phase model with the effect of the magnetic field. Thus, the authors believe that this work is new and valuable. The aim of this study is to investigate the MHD natural convection of Al2O3-water nanofluid in a square cavity with conductive inner block using Buongiorno’s two-phase model.

Lattice Boltzmann simulation of transient natural convection of air in square cavity under a magnetic quadrupole field

2016 ◽  
Vol 26 (8) ◽  
pp. 2441-2461 ◽  
Author(s):  
Nan Xie ◽  
Yihai He ◽  
Ming Yao ◽  
Changwei Jiang
Keyword(s):  
Magnetic Field ◽  
Steady State ◽  
Natural Convection ◽  
Lattice Boltzmann ◽  
Distribution Functions ◽  
Square Cavity ◽  
Quadrupole Field ◽  
Content Type ◽  
Magnetic Quadrupole ◽  
Magnetic Quadrupole Field

Purpose The purpose of this paper is to apply the lattice Boltzmann method (LBM) with multiple distribution functions model, to simulate transient natural convection of air in a two-dimensional square cavity in the presence of a magnetic quadrupole field, under non-gravitational as well as gravitational conditions. Design/methodology/approach The density-temperature double distribution functions and D2Q9 model of LBM for the momentum and temperature equations are currently employed. Detailed transient structures of the flow and isotherms at unsteady state are obtained and compared for a range of magnetic force numbers from 1 to 100. Characteristics of the natural convection at initial moment, quasi-steady state and steady state are presented in present work. Findings At initial time, effects of the magnetic field and gravity are both relatively limited, but the effects become efficient as time evolves. Bi-cellular flow structures are obtained under non-gravitational condition, while the flow presents a single vortex structure at first under gravitational condition, and then emerges a bi-cellular structure with the increase of magnetic field force number. The average Nusselt number generally increases with the augment of magnetic field intensity. Practical implications This paper will be useful in the researches on crystal material and protein growth, oxygen concentration sensor, enhancement or suppression of the heat transfer in micro-electronics and micro-processing technology, etc. Originality/value The current study extended the application of LBM on the transient natural convective problem of paramagnetic fluids in the presence of an inhomogeneous magnetic field.

The influence of thermal radiation on unsteady free convection in inclined enclosures filled by a nanofluid with sinusoidal boundary conditions

2018 ◽  
Vol 28 (8) ◽  
pp. 1738-1753 ◽  
Author(s):  
Mikhail A. Sheremet ◽  
Ioan Pop ◽  
Alin V. Rosca
Keyword(s):  
Natural Convection ◽  
Temperature Distribution ◽  
Thermal Radiation ◽  
Convective Flow ◽  
Vertical Wall ◽  
Radiation Parameter ◽  
Square Cavity ◽  
Left Wall ◽  
Content Type ◽  
Sinusoidal Temperature

Purpose The purpose of this study is a numerical analysis of transient natural convection in an inclined square cavity filled with an alumina-water nanofluid under the effects of sinusoidal wall temperature and thermal radiation by using a single-phase nanofluid model with empirical correlations for effective viscosity and thermal conductivity. Design/methodology/approach The domain of interest includes the nanofluid-filled cavity with a sinusoidal temperature distribution along the left vertical wall. Horizontal walls are supposed to be adiabatic, while right vertical wall is kept at constant low temperature. Temperature of left wall varies sinusoidally along y-coordinate. It is assumed in the analysis that the thermophysical properties of the fluid are independent of temperature and the flow is laminar. The governing equations have been discretized using the finite difference method with the uniform grid. Simulations have been carried out for different values of the Rayleigh number, cavity inclination angle, nanoparticles volume fraction and radiation parameter. Findings It has been found that a growth of radiation parameter leads to the heat transfer enhancement and convective flow intensification. At the same time, an inclusion of nanoparticles illustrates a reduction in the average Nusselt number and fluid flow rate. Originality/value The originality of this work is to analyze unsteady natural convection in a square cavity filled with a water-based nanofluid in the presence of a sinusoidal temperature distribution along one wall. The results would benefit scientists and engineers to become familiar with the analysis of convective heat and mass transfer in nanofluids and the way to predict the properties of nanofluid convective flow in advanced technical systems, in industrial sectors including transportation, power generation, chemical sectors, electronics, etc.

scholarly journals Natural Convection in an Inclined Porous Cavity with Spatial Sidewall Temperature Variations

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
M. S. Selamat ◽  
R. Roslan ◽  
I. Hashim
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Mean Value ◽  
Wave Number ◽  
Governing Equations ◽  
Square Cavity ◽  
Left Wall ◽  
Temperature Variations ◽  
The Right ◽  
Sinusoidal Temperature

The natural convection in an inclined porous square cavity is investigated numerically. The left wall is assumed to have spatial sinusoidal temperature variations about a constant mean value, while the right wall is cooled. The horizontal walls are considered adiabatic. A finite difference method is used to solve numerically the nondimensional governing equations. The effects of the inclination angle of the cavity, the amplitude and wave numbers of the heated sidewall temperature variation on the natural convection in the cavity are studied. The maximum average Nusselt number occurs at different wave number. It also found that the inclination could influence the Nusselt number.

The effect of viscous dissipation on natural convection in a square cavity

2019 ◽  
Vol 5 (3) ◽  
pp. 118-130 ◽  
Author(s):  
Pavel T. Zubkov ◽  
Eduard I. Narygin
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Viscous Dissipation ◽  
Convection Heat Transfer ◽  
Dissipation Function ◽  
Initial Condition ◽  
Square Cavity ◽  
Conservation Of Energy ◽  
Left Wall ◽  
The Right

This article studies the natural convection of a viscous, incompressible fluid in a square cavity in a gravitational field. The temperature of vertical walls is constant. The temperature of the left wall is higher than temperature of the right wall; the horizontal walls are considered thermally insulated. The initial condition for the temperature of a fluid in a square caviry is the constant and equals the temperature of the right wall. The initial condition for the velocity is zero. We consider only those cases where the obtained flow in the cavity is laminar. All thermophysical characteristics are assumed constant, except for one when the motion equation accounts for the gravity. Mathematical model is the Boussinesq approximation but the equation of conservation of energy contains Rayleigh dissipation function.<br> In this article, the authors have researched the effect of viscous dissipation on natural convection heat transfer in square field. The results show that viscous dissipation significantly affects the heat transfer through the cavity. This problem was solved with the finite volume method by algorithm SIMPLER for Pr=1, Gr=10<sup>4</sup>, and 10<sup>−5</sup>≤Ec≤10<sup>−3</sup>.

Effect of finite wall thickness on entropy generation and natural convection in a nanofluid-filled partially heated square cavity

2019 ◽  
Vol 30 (3) ◽  
pp. 1518-1546 ◽  
Author(s):  
Muhamad Safwan Ishak ◽  
Ammar I. Alsabery ◽  
A. Chamkha ◽  
Ishak Hashim
Keyword(s):  
Natural Convection ◽  
Entropy Generation ◽  
Wall Thickness ◽  
Solid Wall ◽  
Past Research ◽  
Boussinesq Approximation ◽  
Bejan Number ◽  
Square Cavity ◽  
Content Type ◽  
Horizontal Wall

Purpose The purpose of this paper is to study the effects of finite wall thickness on the natural convection and entropy generation in a square cavity filled with Al2O3–water nanofluid in the presence of bottom heat source. Design/methodology/approach The moving isothermal heater was placed on the bottom solid wall. The vertical walls (left and right walls) were fully maintained at low temperatures. The rest of the bottom solid wall along with the top horizontal wall was kept adiabatic. The boundaries of the domain are assumed to be impermeable; the fluid within the cavity is a water-based nanofluid having Al2O3 nanoparticles. The Boussinesq approximation is applicable. The dimensionless governing equations subject to the selected boundary conditions are solved using the finite difference method. The current proposed numerical method is proven excellent through comparisons with the existing experimental and numerical published studies. Findings Numerical results were demonstrated graphically in several forms including streamlines, isotherms and local entropy generation, as well as the local and average Nusselt numbers. The results reveal that the thermal conductivity and thickness of the solid wall are important control parameters for optimization of heat transfer and Bejan number within the partially heated square cavity. Originality/value According to the past research studies mentioned above and to the best of the authors’ knowledge, the gap regarding the problem with entropy generation analysis and natural convection in partially heated square cavity has yet to be filled. Because of this, this study aims to investigate the entropy generation analysis as well as the natural convection in nanofluid-filled square cavity which was heated partially. A square cavity with an isothermal heater located on the bottom solid horizontal wall of the cavity and partly cold sidewalls are essential problems in thermal processing applications. Hence, the authors believe that this present work will be a valuable contribution in improving the thermal performance.

Thermal performance analysis of hybrid nanofluid natural convection in a square cavity containing an elliptical obstacle under variable magnetic field

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Soufien Belhaj ◽  
Brahim Ben-Beya
Keyword(s):  
Magnetic Field ◽  
Natural Convection ◽  
Boundary Conditions ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Field Variable ◽  
Variable Magnetic Field ◽  
Hybrid Nanofluid ◽  
Square Cavity ◽  
Content Type

Purpose This study aims to analyze entropy generation and magnetohydrodynamic (MHD) natural convection of hybrid nanofluid in a square cavity, with a heated elliptical block placed at the center, in presence of a periodic-variable magnetic field. Design/methodology/approach In this paper, simulations were performed with a FORTRAN home code. The numerical methodology used to solve Navier–Stokes, energy and entropy generation equations with corresponding boundary conditions, is essentially based on the finite volume method and full multigrid acceleration. Findings The cavity is filled with Ag–Tio2/Water hybrid nanofluid. The main objective of this investigation is to predict the effects of body’s size (6 cases), type of applied magnetic field (variable or uniform), the non-dimensional period number of the variable magnetic field (VMF) (0.2 ≤ Λ ≤ 0.8), the inclination angle of the VMF (0 ≤ χ ≤ 90), Rayleigh number (5 × 103 ≤ Ra ≥ 105) and Hartmann number (5 ≤ Ha ≥ 100) on thermal performance, heat transfer rate, entropy generation and flow patterns. Originality/value To the authors’ best knowledge, this paper is the first numerical investigation deals with the entropy generation and natural convection of hybrid nanofluid in a two-dimensional cavity, with specific thermal boundary conditions, containing an elliptical block under periodic-variable magnetic field. Different combinations between flow-governing parameters were made to find optimal thermal performance.

Effects of two-phase nanofluid model on convection in a double lid-driven cavity in the presence of a magnetic field

2019 ◽  
Vol 29 (4) ◽  
pp. 1272-1299 ◽  
Author(s):  
Ammar I. Alsabery ◽  
Taher Armaghani ◽  
Ali J. Chamkha ◽  
Muhammad Adil Sadiq ◽  
Ishak Hashim
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Mixed Convection ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Square Cavity ◽  
Two Phase ◽  
Content Type ◽  
Driven Cavity ◽  
Horizontal Wall

Purpose The aim of this study is to investigate the effects of two-phase nanofluid model on mixed convection in a double lid-driven square cavity in the presence of a magnetic field. The authors believe that this work is a good contribution for improving the thermal performance and the heat transfer enhancement in some engineering instruments. Design/methodology/approach The current work investigates the problem of mixed convection heat transfer in a double lid-driven square cavity in the presence of magnetic field. The used cavity is filled with water-Al2O3 nanofluid based on Buongiorno’s two-phase model. The bottom horizontal wall is maintained at a constant high temperature and moves to the left/right, while the top horizontal wall is maintained at a constant low temperature and moves to the right/left. The left and right vertical walls are thermally insulated. The dimensionless governing equations are solved numerically using the Galerkin weighted residual finite element method. Findings The obtained results show that the heat transfer rate enhances with an increment of Reynolds number or a reduction of Hartmann number. In addition, effects of thermophoresis and Brownian motion play a significant role in the growth of convection heat transfer. Originality/value According to above-mentioned studies and to the authors’ best knowledge, there has no study reported the MHD mixed convection heat transfer in a double lid-driven cavity using the two-phase nanofluid model. Thus, the authors of the present study believe that this work is valuable. Therefore, the aim of this comprehensive numerical study is to investigate the effects of two-phase nanofluid model on mixed convection in a double lid-driven square cavity in the presence of a magnetic field. The authors believe that this work is a good contribution for improving the thermal performance and the heat transfer enhancement in some engineering instruments.

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