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Ali J. Chamkha - One of the best experts on this subject based on the ideXlab platform.
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conjugate natural convection flow of ag mgo water hybrid nanofluid in a Square Cavity
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Mohammad Ghalambaz, Ali Doostani, Ehsan Izadpanahi, Ali J. ChamkhaAbstract:The conjugate natural convection of a new type of hybrid nanofluid (Ag–MgO/water hybrid nanofluid) inside a Square Cavity is addressed. A thick layer of conductive solid is considered over the hot wall. The governing partial differential equations (PDEs) representing the physical model of the natural convection of the hybrid nanofluid along with the boundary conditions are reported. The thermophysical properties of the nanofluid are directly calculated using experimental data. The governing PDEs are transformed into a dimensionless form and solved by the finite element method. The effect of the variation of key parameters, such as the volume fraction of nanoparticles, Rayleigh number, and the ratio between the thermal conductivity of the wall and the thermal conductivity of the hybrid nanofluid (Rk), is studied. Furthermore, the effects of the key parameters are investigated on the temperature distribution, local Nusselt number, and average Nusselt number. The results of this study show that the heat transfer rate increases by adding hybrid nanoparticles for a conduction-dominant regime (low Rayleigh number). The heat transfer rate is an increasing function of both the Rayleigh number and the thermal conductivity ratio (Rk). In the case of a convective-dominant flow (high Rayleigh number flow) and an excellent thermally conductive wall, the local Nusselt number at the surface of the conjugate wall decreases substantially by moving from the bottom of the Cavity toward the top.
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entropy generation analysis during mhd natural convection flow of hybrid nanofluid in a Square Cavity containing a corrugated conducting block
International Journal of Numerical Methods for Heat & Fluid Flow, 2019Co-Authors: Tahar Tayebi, Ali J. ChamkhaAbstract:The purpose of this paper is to study the influence of magnetic field on entropy generation and natural convection inside an enclosure filled with a hybrid nanofluid and having a conducting wavy solid block. Also, the effect of fluid–solid thermal conductivity ratio is investigated.,The governing equations that are formulated in the dimensionless form are discretized via finite volume method. The velocity–pressure coupling is assured by the SIMPLE algorithm. Heat transfer balance is used to verify the convergence. The validation of the numerical results was performed by comparing qualitatively and quantitatively the results with previously published investigations.,The results indicate that the magnetic field and the conductivity ratio of the wavy solid block can significantly affect the dynamic and thermal field and, consequently, the heat transfer rate and entropy generation because of heat transfer, fluid friction and magnetic force.,To the best of the authors’ knowledge, the present numerical study is the first attempt to use hybrid nanofluid for studying the entropy generation because of magnetohydrodynamic natural convective flow in a Square Cavity with the presence of a wavy circular conductive cylinder. Irreversibilities due to magnetic effect are taken into account. The effect of fluid–solid thermal conductivity ratio is considered.
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Impacts of heated rotating inner cylinder and two-phase nanofluid model on entropy generation and mixed convection in a Square Cavity
Heat and Mass Transfer, 2019Co-Authors: Ammar I. Alsabery, Engin Gedik, Ali J. Chamkha, Ishak HashimAbstract:A numerical study is carried out on mixed convection and entropy generation of Al2O3/water nanofluid due to a rotating cylinder inside a Square Cavity. The numerical computations are performed taking the non-homogenous model of Buongiorno into consideration. The inner moving rotating circular cylinder is maintained at a constant hot temperature T _ h and the other left and right vertical walls of the Cavity are maintained at a constant cold temperature T _ c . The bottom and top horizontal walls are maintained as adiabatic. The Galerkin weighted residual method is implemented to numerically solve the governing equations. The Rayleigh number (10^4 ≤ R a ≤ 10^7), angular rotational velocity (0 ≤Ω≤ 600) nanoparticles loading (0 ≤ ϕ ≤ 0.04) and the dimensionless radius of rotating cylinder (0.1 ≤ R ≤ 0.4) are the governing parameters of this study. Numerical results for the streamlines, isotherms, isentropic lines, nanoparticle loading, local and average Nusselt number and Bejan number are obtained and presented graphically. A detailed discussion of the results is performed to highlight the physics of the problem.
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mixed convection flow caused by an oscillating cylinder in a Square Cavity filled with cu al2o3 water hybrid nanofluid
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: S A M Mehryan, Ali J. Chamkha, Mohammad Ghalambaz, Ehsan IzadpanahiAbstract:The aim of this paper is to examine the effects of Cu–Al2O3/water hybrid nanofluid and Al2O3/water nanofluid on the mixed convection inside a Square Cavity caused by a hot oscillating cylinder. The governing equations are first transformed into dimensionless form and then discretized over a non-uniform unstructured moving grid with triangular elements. The effects of several parameters, such as the nanoparticle volume fraction, the Rayleigh number, the amplitude of the oscillation, and the period of the oscillation of the cylinder are investigated numerically. The results indicate that the motion of the oscillating cylinder toward the top and bottom walls increases the average Nusselt number when the Rayleigh number is low. Furthermore, the presence of Al2O3 and Cu–Al2O3 nanoparticles leads to an increase in the values of the average Nusselt number Nuavg for cases of low values of the Rayleigh number. It is found that the natural convection heat transfer rate of a simple Al2O3/water nanofluid is better than that of Cu–Al2O3/water hybrid nanofluid.
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conjugate heat transfer of al2o3 water nanofluid in a Square Cavity heated by a triangular thick wall using buongiorno s two phase model
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, T Armaghani, Ishak HashimAbstract:The present study investigates the conjugate heat transfer in a Square Cavity heated by a triangular solid and saturated with $$\text{Al}_2\text{O}_3$$ –water nanofluid. Two-phase Buongiorno’s model is used for modeling the nanofluid heat transfer. The finite element method is used for numerical solution of the dimensionless governing equations subject to the boundary conditions. Comparisons of the proposed method with previously published experimental and numerical works show a good agreement. The effects of some parameters such as the Rayleigh number, thermal conductivity ratio, dimensionless triangular wall thickness and nanofluid volume fraction on heat transfer and nanoparticle distributions are completely studied and discussed. The results show clockwise rotations for streamlines and nanoparticle migration. Also the Nusselt number increases with the nanofluid volume fraction. A continuous reduction is seen for the mean Nusselt number by increasing the dimensionless triangular wall thickness for all the considered values of the Rayleigh number.
Mikhail A Sheremet - One of the best experts on this subject based on the ideXlab platform.
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mhd convective heat transfer in a discretely heated Square Cavity with conductive inner block using two phase nanofluid model
Scientific Reports, 2018Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, Mikhail A Sheremet, Ishak HashimAbstract:The problem of steady, laminar natural convection in a discretely heated and cooled Square Cavity filled by an alumina/water nanofluid with a centered heat-conducting solid block under the effects of inclined uniform magnetic field, Brownian diffusion and thermophoresis is studied numerically by using the finite difference method. Isothermal heaters and coolers are placed along the vertical walls and the bottom horizontal wall, while the upper horizontal wall is kept adiabatic. Water-based nanofluids with alumina nanoparticles are chosen for investigation. The governing parameters of this study are the Rayleigh number (103 ≤ Ra ≤ 106), the Hartmann number (0 ≤ Ha ≤ 50), thermal conductivity ratio (0.28 ≤ k w ≤ 16), centered solid block size (0.1 ≤ D ≤ 0.7) and the nanoparticles volume fraction (0 ≤ ϕ ≤ 0.04). The developed computational code is validated comprehensively using the grid independency test and numerical and experimental data of other authors. The obtained results reveal that the effects of the thermal conductivity ratio, centered solid block size and the nanoparticles volume fraction are non-linear for the heat transfer rate. Therefore, it is possible to find optimal parameters for the heat transfer enhancement in dependence on the considered system. Moreover, high values of the Rayleigh number and nanoparticles volume fraction characterize homogeneous distributions of nanoparticles inside the Cavity. High concentration of nanoparticles can be found near the centered solid block where thermal plumes from the local heaters interact.
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natural convection combined with thermal radiation in a Square Cavity filled with a viscoelastic fluid
International Journal of Numerical Methods for Heat & Fluid Flow, 2018Co-Authors: Mikhail A SheremetAbstract:The purpose of this paper is to study natural convective heat transfer and viscoelastic fluid flow in a differentially heated Square Cavity under the effect of thermal radiation.,The Cavity filled with a viscoelastic fluid is heated uniformly from the left wall and cooled from the right side while insulated from horizontal walls. Governing partial differential equations formulated in non-dimensional stream function, vorticity and temperature with corresponding boundary conditions have been solved by finite difference method of second order accuracy. The effects of Rayleigh number (Ra = 1e+3−1e+5), radiation parameter (Rd = 0 − 10), Prandtl number (Pr = 1 − 30) and elastic number (E = 0.0001 − 0.001) on flow patterns, temperature fields, average Nusselt number at hot vertical wall and rate of fluid flow have been studied.,It has been found that a growth of elastic number leads to the heat transfer reduction and convective flow attenuation. The heat conduction is a dominating heat transfer mechanism for high values of radiation parameter.,The originality of this work is to analyze heat transfer and fluid flow of a viscoelastic fluid inside a differentially heated Cavity. The results would benefit scientists and engineers to become familiar with the flow and heat behavior of non-Newtonian fluids, and the way to predict the properties of this flow for possibility of using viscoelastic fluids in compact heat exchangers, electronic cooling systems, polymer engineering, etc.
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conjugate natural convection of al2o3 water nanofluid in a Square Cavity with a concentric solid insert using buongiorno s two phase model
International Journal of Mechanical Sciences, 2018Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, Mikhail A Sheremet, Ishak HashimAbstract:Abstract The problem of conjugate natural convection of Al2O3–water nanofluid in a Square Cavity with concentric solid insert and isothermal corner boundaries using non-homogenous Buongiorno’s two-phase model is studied numerically by the finite difference method. An isothermal heater is placed on the left bottom corner of the Square Cavity while the right top corner is maintained at a constant cold temperature. The remainder parts of the walls are kept adiabatic. Water-based nanofluids with Al2O3 nanoparticles are chosen for the investigation. The governing parameters of this study are the nanoparticle volume fraction (0 ≤ ϕ ≤ 0.04), the Rayleigh number (102 ≤ Ra ≤ 106), thermal conductivity of the solid block ( k w = 0.28 , 0.76, 1.95, 7 and 16) (epoxy: 0.28, brickwork: 0.76, granite: 1.95, solid rock: 7, stainless steel: 16) and dimensionless solid block thickness (0.1 ≤ D ≤ 0.7). Comparisons with previously experimental and numerical published works verify good agreement with the proposed method. Numerical results are presented graphically in the form of streamlines, isotherms and nanoparticles volume fraction as well as the average Nusselt number and fluid flow rate. The results show that the thermal conductivity ratio and solid block size are very good control parameters for an optimization of heat transfer inside the partially heated and cooled Cavity.
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flow and heat transfer evolution of pcm due to natural convection melting in a Square Cavity with a local heater
International Journal of Mechanical Sciences, 2017Co-Authors: Nadezhda S Bondareva, Mikhail A SheremetAbstract:Abstract Growth of computing efficiency of electronic equipment closely related to design heat sinks and heat storage devices for temperature controlling inside the system. To remove of heat from the electronic devices and achieve a suitable temperature, the phase change materials are used. The present study is devoted to the problem of complex interaction of natural convection and melting of phase change material inside a Square Cavity with a local heater of volumetric heat generation. Thermal properties of the Square heat source match the silicone characteristics at the working temperature about 330 K. Conservation equations of mass and momentum have been formulated using the dimensionless stream function and vorticity. To solve the governing equations of fluid flow, heat and mass transfer the finite difference method has been used. The effects of heat generation intensity and buoyancy force have been analyzed by varying the Rayleigh number, the Stefan number and the Ostrogradsky number. Evolution of temperature field and streamlines has been examined.
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flow and heat transfer evolution of pcm due to natural convection melting in a Square Cavity with a local heater
International Journal of Mechanical Sciences, 2017Co-Authors: Nadezhda S Bondareva, Mikhail A SheremetAbstract:Abstract Growth of computing efficiency of electronic equipment closely related to design heat sinks and heat storage devices for temperature controlling inside the system. To remove of heat from the electronic devices and achieve a suitable temperature, the phase change materials are used. The present study is devoted to the problem of complex interaction of natural convection and melting of phase change material inside a Square Cavity with a local heater of volumetric heat generation. Thermal properties of the Square heat source match the silicone characteristics at the working temperature about 330 K. Conservation equations of mass and momentum have been formulated using the dimensionless stream function and vorticity. To solve the governing equations of fluid flow, heat and mass transfer the finite difference method has been used. The effects of heat generation intensity and buoyancy force have been analyzed by varying the Rayleigh number, the Stefan number and the Ostrogradsky number. Evolution of temperature field and streamlines has been examined.
Mohammad Ghalambaz - One of the best experts on this subject based on the ideXlab platform.
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conjugate natural convection flow of ag mgo water hybrid nanofluid in a Square Cavity
Journal of Thermal Analysis and Calorimetry, 2020Co-Authors: Mohammad Ghalambaz, Ali Doostani, Ehsan Izadpanahi, Ali J. ChamkhaAbstract:The conjugate natural convection of a new type of hybrid nanofluid (Ag–MgO/water hybrid nanofluid) inside a Square Cavity is addressed. A thick layer of conductive solid is considered over the hot wall. The governing partial differential equations (PDEs) representing the physical model of the natural convection of the hybrid nanofluid along with the boundary conditions are reported. The thermophysical properties of the nanofluid are directly calculated using experimental data. The governing PDEs are transformed into a dimensionless form and solved by the finite element method. The effect of the variation of key parameters, such as the volume fraction of nanoparticles, Rayleigh number, and the ratio between the thermal conductivity of the wall and the thermal conductivity of the hybrid nanofluid (Rk), is studied. Furthermore, the effects of the key parameters are investigated on the temperature distribution, local Nusselt number, and average Nusselt number. The results of this study show that the heat transfer rate increases by adding hybrid nanoparticles for a conduction-dominant regime (low Rayleigh number). The heat transfer rate is an increasing function of both the Rayleigh number and the thermal conductivity ratio (Rk). In the case of a convective-dominant flow (high Rayleigh number flow) and an excellent thermally conductive wall, the local Nusselt number at the surface of the conjugate wall decreases substantially by moving from the bottom of the Cavity toward the top.
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mixed convection flow caused by an oscillating cylinder in a Square Cavity filled with cu al2o3 water hybrid nanofluid
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: S A M Mehryan, Ali J. Chamkha, Mohammad Ghalambaz, Ehsan IzadpanahiAbstract:The aim of this paper is to examine the effects of Cu–Al2O3/water hybrid nanofluid and Al2O3/water nanofluid on the mixed convection inside a Square Cavity caused by a hot oscillating cylinder. The governing equations are first transformed into dimensionless form and then discretized over a non-uniform unstructured moving grid with triangular elements. The effects of several parameters, such as the nanoparticle volume fraction, the Rayleigh number, the amplitude of the oscillation, and the period of the oscillation of the cylinder are investigated numerically. The results indicate that the motion of the oscillating cylinder toward the top and bottom walls increases the average Nusselt number when the Rayleigh number is low. Furthermore, the presence of Al2O3 and Cu–Al2O3 nanoparticles leads to an increase in the values of the average Nusselt number Nuavg for cases of low values of the Rayleigh number. It is found that the natural convection heat transfer rate of a simple Al2O3/water nanofluid is better than that of Cu–Al2O3/water hybrid nanofluid.
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analysis of fluid solid interaction in mhd natural convection in a Square Cavity equally partitioned by a vertical flexible membrane
Journal of Magnetism and Magnetic Materials, 2017Co-Authors: S A M Mehryan, Mohammad Ghalambaz, Muneer A Ismael, Ali J. ChamkhaAbstract:Abstract This paper investigates numerically the problem of unsteady natural convection inside a Square Cavity partitioned by a flexible impermeable membrane. The finite element method with the arbitrary Lagrangian-Eulerian (ALE) technique has been used to model the interaction of the fluid and the membrane. The horizontal walls of the Cavity are kept adiabatic while the vertical walls are kept isothermal at different temperatures. A uniform magnetic field is applied onto the Cavity with different orientations. The Cavity has been provided by two eyelets to compensate volume changes due the movement of the flexible membrane. A parametric study is carried out for the pertinent parameters, which are the Rayleigh number (10 5 – 10 8 ), Hartmann number (0–200) and the orientation of the magnetic field (0–180°). The change in the Hartmann number affects the shape of the membrane and the heat transfer in the Cavity. The angle of the magnetic field orientation also significantly affects the shape of the membrane and the heat transfer in the Cavity.
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phase change heat transfer of single hybrid nanoparticles enhanced phase change materials over a heated horizontal cylinder confined in a Square Cavity
Advanced Powder Technology, 2017Co-Authors: Ali J. Chamkha, Ehsan Izadpanahi, A Doostanidezfuli, Mohammad GhalambazAbstract:Abstract The melting process of a nano-enhanced phase-change material is investigated in a Square Cavity with a hot cylinder located in the middle of the Cavity in the presence of both single and hybrid nanoparticles. The dimensionless partial differential equations are solved numerically using the Galerkin finite element method using a grid with 6000 quadrilateral elements. The effects of the volume fraction of nanoparticles, the Fourier number, the thermal conductivity parameter, and the viscosity parameters are studied. The results show that the solid-liquid interface and the liquid fraction are significantly affected by the volume fraction of nanoparticles and the thermal conductivity parameter. Additionally, it is found that the melting rate is much larger when the Fourier number changes between 0 and 0.5 and a further increase in the Fourier number causes a reduction in the rate of the melting.
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fluid structure interaction study of natural convection heat transfer over a flexible oscillating fin in a Square Cavity
International Journal of Thermal Sciences, 2017Co-Authors: Mohammad Ghalambaz, Muneer A Ismael, Esmail Jamesahar, Ali J. ChamkhaAbstract:Abstract The material of this study is a numerical formulation of a fluid-structure interaction represented by an oscillating elastic fin attached to a hot vertical wall of a Square Cavity. The Cavity is filled with air, Pr = 0.7, and differentially heated while the horizontal walls are kept adiabatic. The finite element Galerkin method with the aid of the Arbitrary Lagrangian-Eulerian (ALE) procedure is used in the numerical analysis. The elastic fin undergoing an excitation and is subjected to buoyancy forces. The ranges of the studied parameters are the Rayleigh number Ra = 10 4 –10 7 , fin length L = 0.1–0.4, oscillating amplitude A = 0.001–0.1, oscillating period τ = 0.01–1, thermal conductivity ratio (fin to fluid) k r = 1–1000, and the non-dimensional Young's modulus E = 10 8 -10 13 . The results show that increasing the non-dimensional amplitude the oscillating fin can significantly enhance the Nusselt number. The non-dimensional periods about τ ≈ 0.1 and higher shows better enhancement compared to lower periods. A fin length of 0.2 can be considered as the best length for heat transfer enhancement and compatible with various oscillating amplitudes.
Ammar I. Alsabery - One of the best experts on this subject based on the ideXlab platform.
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Impacts of heated rotating inner cylinder and two-phase nanofluid model on entropy generation and mixed convection in a Square Cavity
Heat and Mass Transfer, 2019Co-Authors: Ammar I. Alsabery, Engin Gedik, Ali J. Chamkha, Ishak HashimAbstract:A numerical study is carried out on mixed convection and entropy generation of Al2O3/water nanofluid due to a rotating cylinder inside a Square Cavity. The numerical computations are performed taking the non-homogenous model of Buongiorno into consideration. The inner moving rotating circular cylinder is maintained at a constant hot temperature T _ h and the other left and right vertical walls of the Cavity are maintained at a constant cold temperature T _ c . The bottom and top horizontal walls are maintained as adiabatic. The Galerkin weighted residual method is implemented to numerically solve the governing equations. The Rayleigh number (10^4 ≤ R a ≤ 10^7), angular rotational velocity (0 ≤Ω≤ 600) nanoparticles loading (0 ≤ ϕ ≤ 0.04) and the dimensionless radius of rotating cylinder (0.1 ≤ R ≤ 0.4) are the governing parameters of this study. Numerical results for the streamlines, isotherms, isentropic lines, nanoparticle loading, local and average Nusselt number and Bejan number are obtained and presented graphically. A detailed discussion of the results is performed to highlight the physics of the problem.
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conjugate heat transfer of al2o3 water nanofluid in a Square Cavity heated by a triangular thick wall using buongiorno s two phase model
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, T Armaghani, Ishak HashimAbstract:The present study investigates the conjugate heat transfer in a Square Cavity heated by a triangular solid and saturated with $$\text{Al}_2\text{O}_3$$ –water nanofluid. Two-phase Buongiorno’s model is used for modeling the nanofluid heat transfer. The finite element method is used for numerical solution of the dimensionless governing equations subject to the boundary conditions. Comparisons of the proposed method with previously published experimental and numerical works show a good agreement. The effects of some parameters such as the Rayleigh number, thermal conductivity ratio, dimensionless triangular wall thickness and nanofluid volume fraction on heat transfer and nanoparticle distributions are completely studied and discussed. The results show clockwise rotations for streamlines and nanoparticle migration. Also the Nusselt number increases with the nanofluid volume fraction. A continuous reduction is seen for the mean Nusselt number by increasing the dimensionless triangular wall thickness for all the considered values of the Rayleigh number.
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mhd convective heat transfer in a discretely heated Square Cavity with conductive inner block using two phase nanofluid model
Scientific Reports, 2018Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, Mikhail A Sheremet, Ishak HashimAbstract:The problem of steady, laminar natural convection in a discretely heated and cooled Square Cavity filled by an alumina/water nanofluid with a centered heat-conducting solid block under the effects of inclined uniform magnetic field, Brownian diffusion and thermophoresis is studied numerically by using the finite difference method. Isothermal heaters and coolers are placed along the vertical walls and the bottom horizontal wall, while the upper horizontal wall is kept adiabatic. Water-based nanofluids with alumina nanoparticles are chosen for investigation. The governing parameters of this study are the Rayleigh number (103 ≤ Ra ≤ 106), the Hartmann number (0 ≤ Ha ≤ 50), thermal conductivity ratio (0.28 ≤ k w ≤ 16), centered solid block size (0.1 ≤ D ≤ 0.7) and the nanoparticles volume fraction (0 ≤ ϕ ≤ 0.04). The developed computational code is validated comprehensively using the grid independency test and numerical and experimental data of other authors. The obtained results reveal that the effects of the thermal conductivity ratio, centered solid block size and the nanoparticles volume fraction are non-linear for the heat transfer rate. Therefore, it is possible to find optimal parameters for the heat transfer enhancement in dependence on the considered system. Moreover, high values of the Rayleigh number and nanoparticles volume fraction characterize homogeneous distributions of nanoparticles inside the Cavity. High concentration of nanoparticles can be found near the centered solid block where thermal plumes from the local heaters interact.
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conjugate natural convection of al2o3 water nanofluid in a Square Cavity with a concentric solid insert using buongiorno s two phase model
International Journal of Mechanical Sciences, 2018Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, Mikhail A Sheremet, Ishak HashimAbstract:Abstract The problem of conjugate natural convection of Al2O3–water nanofluid in a Square Cavity with concentric solid insert and isothermal corner boundaries using non-homogenous Buongiorno’s two-phase model is studied numerically by the finite difference method. An isothermal heater is placed on the left bottom corner of the Square Cavity while the right top corner is maintained at a constant cold temperature. The remainder parts of the walls are kept adiabatic. Water-based nanofluids with Al2O3 nanoparticles are chosen for the investigation. The governing parameters of this study are the nanoparticle volume fraction (0 ≤ ϕ ≤ 0.04), the Rayleigh number (102 ≤ Ra ≤ 106), thermal conductivity of the solid block ( k w = 0.28 , 0.76, 1.95, 7 and 16) (epoxy: 0.28, brickwork: 0.76, granite: 1.95, solid rock: 7, stainless steel: 16) and dimensionless solid block thickness (0.1 ≤ D ≤ 0.7). Comparisons with previously experimental and numerical published works verify good agreement with the proposed method. Numerical results are presented graphically in the form of streamlines, isotherms and nanoparticles volume fraction as well as the average Nusselt number and fluid flow rate. The results show that the thermal conductivity ratio and solid block size are very good control parameters for an optimization of heat transfer inside the partially heated and cooled Cavity.
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heatline visualization of conjugate natural convection in a Square Cavity filled with nanofluid with sinusoidal temperature variations on both horizontal walls
International Journal of Heat and Mass Transfer, 2016Co-Authors: Ammar I. Alsabery, Ishak Hashim, Ali J. Chamkha, Habibis SalehAbstract:Abstract The problem of conjugate natural convection in a Square Cavity filled with a nanofluid with sinusoidal temperature variations on both horizontal walls is visualized by heatlines. Water-based nanofluids with Ag, Cu, Al2O3, or TiO2 nanoparticles are chosen for investigation. The governing equations together with the specified boundary conditions are solved numerically using the finite difference method over a wide range of Rayleigh number ( 10 5 ⩽ Ra ⩽ 10 8 ) , nanoparticle volume fractions ( 0 ⩽ ϕ ⩽ 0.2 ), phase deviations ( 0 ⩽ γ ⩽ π ), amplitude ratios ( 0 ⩽ e ⩽ 1 ), wall to nanofluid thermal conductivity ratios ( 0.44 ⩽ K r ⩽ 23.8 ) and wall thickness to height ratios ( 0 ⩽ S ⩽ 0.7 ). Comparisons with previously published work verify good agreement with the proposed method. Detailed computational results for the influence of the various parameters on streamlines, heatlines, isotherms, and the overall heat transfer are shown graphically. It is found that the heat transfer rate is significantly enhanced by incrementing the solid wall thickness. Different values of the thermal conductivity ratio are shown to depict a variety of enhancements for the heat transfer rate.
Ishak Hashim - One of the best experts on this subject based on the ideXlab platform.
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Impacts of heated rotating inner cylinder and two-phase nanofluid model on entropy generation and mixed convection in a Square Cavity
Heat and Mass Transfer, 2019Co-Authors: Ammar I. Alsabery, Engin Gedik, Ali J. Chamkha, Ishak HashimAbstract:A numerical study is carried out on mixed convection and entropy generation of Al2O3/water nanofluid due to a rotating cylinder inside a Square Cavity. The numerical computations are performed taking the non-homogenous model of Buongiorno into consideration. The inner moving rotating circular cylinder is maintained at a constant hot temperature T _ h and the other left and right vertical walls of the Cavity are maintained at a constant cold temperature T _ c . The bottom and top horizontal walls are maintained as adiabatic. The Galerkin weighted residual method is implemented to numerically solve the governing equations. The Rayleigh number (10^4 ≤ R a ≤ 10^7), angular rotational velocity (0 ≤Ω≤ 600) nanoparticles loading (0 ≤ ϕ ≤ 0.04) and the dimensionless radius of rotating cylinder (0.1 ≤ R ≤ 0.4) are the governing parameters of this study. Numerical results for the streamlines, isotherms, isentropic lines, nanoparticle loading, local and average Nusselt number and Bejan number are obtained and presented graphically. A detailed discussion of the results is performed to highlight the physics of the problem.
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conjugate heat transfer of al2o3 water nanofluid in a Square Cavity heated by a triangular thick wall using buongiorno s two phase model
Journal of Thermal Analysis and Calorimetry, 2019Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, T Armaghani, Ishak HashimAbstract:The present study investigates the conjugate heat transfer in a Square Cavity heated by a triangular solid and saturated with $$\text{Al}_2\text{O}_3$$ –water nanofluid. Two-phase Buongiorno’s model is used for modeling the nanofluid heat transfer. The finite element method is used for numerical solution of the dimensionless governing equations subject to the boundary conditions. Comparisons of the proposed method with previously published experimental and numerical works show a good agreement. The effects of some parameters such as the Rayleigh number, thermal conductivity ratio, dimensionless triangular wall thickness and nanofluid volume fraction on heat transfer and nanoparticle distributions are completely studied and discussed. The results show clockwise rotations for streamlines and nanoparticle migration. Also the Nusselt number increases with the nanofluid volume fraction. A continuous reduction is seen for the mean Nusselt number by increasing the dimensionless triangular wall thickness for all the considered values of the Rayleigh number.
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mhd convective heat transfer in a discretely heated Square Cavity with conductive inner block using two phase nanofluid model
Scientific Reports, 2018Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, Mikhail A Sheremet, Ishak HashimAbstract:The problem of steady, laminar natural convection in a discretely heated and cooled Square Cavity filled by an alumina/water nanofluid with a centered heat-conducting solid block under the effects of inclined uniform magnetic field, Brownian diffusion and thermophoresis is studied numerically by using the finite difference method. Isothermal heaters and coolers are placed along the vertical walls and the bottom horizontal wall, while the upper horizontal wall is kept adiabatic. Water-based nanofluids with alumina nanoparticles are chosen for investigation. The governing parameters of this study are the Rayleigh number (103 ≤ Ra ≤ 106), the Hartmann number (0 ≤ Ha ≤ 50), thermal conductivity ratio (0.28 ≤ k w ≤ 16), centered solid block size (0.1 ≤ D ≤ 0.7) and the nanoparticles volume fraction (0 ≤ ϕ ≤ 0.04). The developed computational code is validated comprehensively using the grid independency test and numerical and experimental data of other authors. The obtained results reveal that the effects of the thermal conductivity ratio, centered solid block size and the nanoparticles volume fraction are non-linear for the heat transfer rate. Therefore, it is possible to find optimal parameters for the heat transfer enhancement in dependence on the considered system. Moreover, high values of the Rayleigh number and nanoparticles volume fraction characterize homogeneous distributions of nanoparticles inside the Cavity. High concentration of nanoparticles can be found near the centered solid block where thermal plumes from the local heaters interact.
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conjugate natural convection of al2o3 water nanofluid in a Square Cavity with a concentric solid insert using buongiorno s two phase model
International Journal of Mechanical Sciences, 2018Co-Authors: Ammar I. Alsabery, Ali J. Chamkha, Mikhail A Sheremet, Ishak HashimAbstract:Abstract The problem of conjugate natural convection of Al2O3–water nanofluid in a Square Cavity with concentric solid insert and isothermal corner boundaries using non-homogenous Buongiorno’s two-phase model is studied numerically by the finite difference method. An isothermal heater is placed on the left bottom corner of the Square Cavity while the right top corner is maintained at a constant cold temperature. The remainder parts of the walls are kept adiabatic. Water-based nanofluids with Al2O3 nanoparticles are chosen for the investigation. The governing parameters of this study are the nanoparticle volume fraction (0 ≤ ϕ ≤ 0.04), the Rayleigh number (102 ≤ Ra ≤ 106), thermal conductivity of the solid block ( k w = 0.28 , 0.76, 1.95, 7 and 16) (epoxy: 0.28, brickwork: 0.76, granite: 1.95, solid rock: 7, stainless steel: 16) and dimensionless solid block thickness (0.1 ≤ D ≤ 0.7). Comparisons with previously experimental and numerical published works verify good agreement with the proposed method. Numerical results are presented graphically in the form of streamlines, isotherms and nanoparticles volume fraction as well as the average Nusselt number and fluid flow rate. The results show that the thermal conductivity ratio and solid block size are very good control parameters for an optimization of heat transfer inside the partially heated and cooled Cavity.
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heatline visualization of conjugate natural convection in a Square Cavity filled with nanofluid with sinusoidal temperature variations on both horizontal walls
International Journal of Heat and Mass Transfer, 2016Co-Authors: Ammar I. Alsabery, Ishak Hashim, Ali J. Chamkha, Habibis SalehAbstract:Abstract The problem of conjugate natural convection in a Square Cavity filled with a nanofluid with sinusoidal temperature variations on both horizontal walls is visualized by heatlines. Water-based nanofluids with Ag, Cu, Al2O3, or TiO2 nanoparticles are chosen for investigation. The governing equations together with the specified boundary conditions are solved numerically using the finite difference method over a wide range of Rayleigh number ( 10 5 ⩽ Ra ⩽ 10 8 ) , nanoparticle volume fractions ( 0 ⩽ ϕ ⩽ 0.2 ), phase deviations ( 0 ⩽ γ ⩽ π ), amplitude ratios ( 0 ⩽ e ⩽ 1 ), wall to nanofluid thermal conductivity ratios ( 0.44 ⩽ K r ⩽ 23.8 ) and wall thickness to height ratios ( 0 ⩽ S ⩽ 0.7 ). Comparisons with previously published work verify good agreement with the proposed method. Detailed computational results for the influence of the various parameters on streamlines, heatlines, isotherms, and the overall heat transfer are shown graphically. It is found that the heat transfer rate is significantly enhanced by incrementing the solid wall thickness. Different values of the thermal conductivity ratio are shown to depict a variety of enhancements for the heat transfer rate.
