Free Convection in Rectangular Enclosures Containing Nanofluid With Nanoparticles of Various Diameters

Jani, Saeid; Mahmoodi, Mostafa; Amini, Meysam; Akbari, Mohammad

doi:10.1615/heattransres.2013004029

Cited by 5 publications

(8 citation statements)

References 29 publications

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“…For large Rayleigh numbers, the decrease in the heat transfer was caused by the elevated viscosity of the nanofluid, which reduces the fluid flow and the heat convection The decrease in the heat transfer with the addition of nanoparticles under elevated flow conditions was not an anticipated result, given the intended purpose of nanofluids to increase the efficiency of thermal processes. However, similar behavior has been observed and reported in previous experimental [36] and numerical [21] investigations of the thermal behavior of buoyancy-driven nanofluids in rectangular enclosures. In [36], the Nusselt number of the base fluid in a porous medium was found to be higher than that of the nanofluid for elevated Rayleigh numbers.…”

Section: Discussionsupporting

confidence: 89%

“…The decrease in the heat transfer with the addition of nanoparticles under elevated flow conditions was not an anticipated result, given the intended purpose of nanofluids to increase the efficiency of thermal processes. However, similar behavior has been observed and reported in previous experimental [36] and numerical [21] investigations of the thermal behavior of buoyancy-…”

Section: Effect Of the Volume Fraction (φ)supporting

confidence: 90%

“…For large Rayleigh numbers, the decrease in the heat transfer was caused by the elevated viscosity of the nanofluid, which reduces the fluid flow and the heat convection mechanisms. This decrease in the heat transfer of the nanofluids under elevated flow conditions was not an anticipated result, given the intended purpose of nanofluids to increase the efficiency of thermal processes; however, it was corroborated by previous experimental [36] and numerical [21] observations. Furthermore, the very presence of the porous medium affected the heat transfer noticeably, as an increase in the effective viscosity of the fluid further impeded the nanofluid motion through the pores.…”

Section: Discussionsupporting

confidence: 66%

“…In [36], the Nusselt number of the base fluid in a porous medium was found to be higher than that of the nanofluid for elevated Rayleigh numbers. In [21], the Nusselt number decreased (~10-30%) with the addition of nanoparticles for high Rayleigh numbers. In the present case, the phenomenon was more intense (~50%) due to the additional presence of the porous medium.…”

Section: Discussionmentioning

confidence: 99%

“…However, intensification of viscous dissipation has a negative effect in the heat-transfer rate. Jani [21] studied the free convection heat transfer in rectangular enclosure. The obtained results showed that the rate of heat transfer increased only at low Rayleigh numbers.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the Natural Convection Flow in a Square Porous Enclosure Filled with a Micropolar Nanofluid under Magnetohydrodynamic Conditions

et al. 2020

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The laminar, natural convective flow of a micropolar nanofluid in the presence of a magnetic field in a square porous enclosure was studied. The micropolar nanofluid is considered to be an electrically conductive fluid. The governing equations of the flow problem are the conservation of mass, energy, and linear momentum, as well as the angular momentum and the induction equations. In the proposed model, the Darcy–Brinkman momentum equations with buoyancy and advective inertia are used. Experimentally obtained forms of the dynamic viscosity, the thermal conductivity, and the electric conductivity are employed. A meshless point collocation method has been applied to numerically solve the flow and transport equations in their vorticity-stream function formulation. The effects of characteristic dimensionless parameters, such as the Rayleigh and Hartmann numbers, for a range of porosity and solid volume fraction of Al2O3 particles in a water-based micropolar nanofluid on the flow and heat transfer in the cavity are investigated. The results indicate that the intensity of the magnetic field significantly affects both the flow and the temperature distributions. Moreover, the addition of nanoparticles deteriorates the heat-transfer efficiency under specific conditions.

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Section: Discussionsupporting

confidence: 89%

Section: Effect Of the Volume Fraction (φ)supporting

confidence: 90%

Section: Discussionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling the Natural Convection Flow in a Square Porous Enclosure Filled with a Micropolar Nanofluid under Magnetohydrodynamic Conditions

et al. 2020

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Finite element analysis of mixed convection flow in a trapezoidal cavity with non-uniform temperature

Ibrahim

Hirpho

2021

Heliyon

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MHD flow and heat transfer of a magnetite–water nanofluid in porous medium under the effects of chemical reaction

Amini¹,

GhasemiKafrudi²,

Habibi³

et al. 2017

WJE

Self Cite

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Purpose Due to the extensive industrial applications of stagnation flow problems, the present work aims to investigate the magnetohydrodynamics (MHD) flow and heat transfer of a magnetite nanofluid (here Fe3O4–water nanofluid) impinging a flat porous plate under the effects of a non-uniform magnetic field and chemical reaction with variable reaction rate. Design/methodology/approach Similarity transformations are applied to reduce the governing partial differential equations with boundary conditions into a system of ordinary differential equations over a semi-infinite domain. The modified fourth-order Runge–Kutta method with the shooting technique which is developed for unbounded domains is conducted to give approximate solutions of the problem, which are then verified by results of other researchers, showing very good agreements. Findings The effects of the volume fraction of nanoparticles, permeability, magnetic field, chemical reaction and Schmidt number on velocity, temperature and concentration fields are examined and graphically illustrated. It was found that fluid velocity and temperature fields are affected strongly by the types of nanoparticles. Moreover, magnetic field and radiation have strong effects on velocity and temperature fields, fluid velocity increases and thickness of the velocity boundary layer decreases as magnetic parameter M increases. The results also showed that the thickness of the concentration boundary layer decreases with an increase in the Schmidt number, as well as an increase in the chemical reaction coefficient. Research limitations/implications The thermophysical properties of the magnetite nanofluid (Fe3O4–water nanofluid) in different conditions should be checked. Practical implications Stagnation flow of viscous fluid is important due to its vast industrial applications, such as the flows over the tips of rockets, aircrafts, submarines and oil ships. Moreover, nanofluid, a liquid containing a dispersion of sub-micronic solid particles (nanoparticles) with typical length of the order of 1-50 nm, showed abnormal convective heat transfer enhancement, which is remarkable. Originality/value The major novelty of the present work corresponds to utilization of a magnetite nanofluid (Fe3O4–water nanofluid) in a stagnation flow influenced by chemical reaction and magnetic field. It should be noted that in addition to a variable chemical reaction, the permeability is non-uniform, while the imposed magnetic field also varies along the sheet. These, all, make the present work rather original.

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Free Convection in Rectangular Enclosures Containing Nanofluid With Nanoparticles of Various Diameters

Cited by 5 publications

References 29 publications

Modeling the Natural Convection Flow in a Square Porous Enclosure Filled with a Micropolar Nanofluid under Magnetohydrodynamic Conditions

Modeling the Natural Convection Flow in a Square Porous Enclosure Filled with a Micropolar Nanofluid under Magnetohydrodynamic Conditions

Finite element analysis of mixed convection flow in a trapezoidal cavity with non-uniform temperature

MHD flow and heat transfer of a magnetite–water nanofluid in porous medium under the effects of chemical reaction

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