Investigation of micropolar hybrid ferrofluid flow over a vertical plate by considering various base fluid and nanoparticle shape factor

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Kh. Hosseinzadeh ◽  
So Roghani ◽  
A. Asadi ◽  
Amirreza Mogharrebi ◽  
D.D. Ganji
Keyword(s):  
Magnetic Field ◽  
Shape Factor ◽  
Vertical Plate ◽  
Magnetic Parameter ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Nanoparticle Volume Fraction ◽  
Convection Heat ◽  
Content Type

Purpose The purpose of this paper is to investigate micropolar magnetohydrodynamics (MHD) fluid flow passing over a vertical plate. Three different base fluids have been used that include water, ethylene glycol and ethylene glycol/water (50%–50%). Also, a nanoparticle was used in all of the base fluids. The effects of natural convection heat transfer and magnetic field have been taken into account. Design/methodology/approach The main purpose of solving the governing equations is to scrutinize the effects of the magnetic parameter, the nanoparticle volume fraction, micropolar parameter and nanoparticles shape factor on velocity, temperature and microrotation profiles, the skin friction coefficient and the Nusselt number. These surveys have been considered for three base fluids simultaneously. Findings The results indicate that for water-based fluids, the temperature profile of lamina-shaped nanoparticles is 38.09% higher than brick-shaped nanoparticles. Originality/value This paper provides micropolar MHD fluid flow analysis considering natural convection heat transfer and magnetic field in three different base fluids. The aim of assessments is the diagnosis of some parameter effects, such as magnetic parameter and nanoparticle volume fraction, on velocity, temperature and microrotation profiles and components. Also, the use of mixed base fluids presented as a novelty in this paper.

Free convection and thermal radiation of nanofluid inside nonagon inclined cavity containing a porous medium influenced by magnetic field with variable direction in the presence of uniform heat generation/absorption

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Mohamed Dhia Massoudi ◽  
Mohamed Bechir Ben Hamida ◽  
Mohammed A. Almeshaal
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Heat Generation ◽  
Shape Factor ◽  
Convection Heat Transfer ◽  
Nano Particles ◽  
Convection Heat ◽  
Content Type ◽  
Uniform Heat ◽  
Heated Source

Purpose The purpose of this paper is to study the natural convection and radiation heat transfer inside Nonagon inclined cavity with variable heated source length, which contains a porous medium saturated with nanofluid in the presence of uniform heat generation or absorption under the effect of uniform magnetic field with variable direction. The shape factor of nano particles is taking account for the model of nanofluid. Design/methodology/approach This study is established in two-dimensional space. The 2D numerical study is effectuated with Comsol Multiphysics based on the on the finite element method. The 2D equation system is exposed on dimensionless form taking into account the boundary conditions. Findings Results obtained show that the convection heat transfer is ameliorated with the augmentation of heated source length. The convection heat transfer is enhanced by increasing Rayleigh, Darcy numbers and the heated source length; however, it is reduced by rising Hartmann number. The presence of radiation parameter lead to improve the convection heat transfer in the presence of both uniform heat generation/absorption. The average Nusselt number reaches a maximum for an inclination of cavity γ = 45° and a minimum for γ = 60°. Both the increase of the shape factor of nano particles and the solid fraction of nano particles improve the convection heat transfer. Originality/value Different studies have been realized to study the heat transfer inside cavity contains porous medium saturated with nanofluid under magnetic field effect. In this work, the Nonagon geometric of cavity studied has never been studied. In addition, the effect of radiation parameter with relation of the shape factor of nanoparticles in the presence of uniform heat generation/absorption on the heat transfer performance have never been investigated. Also, the effect of magnetic field direction with relation of the inclination cavity on heat transfer performance.

scholarly journals Numerical Study of Natural Convection Heat Transfer in a Porous Annulus Filled with a Cu-Nanofluid

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 990
Author(s):  
Lingyun Zhang ◽  
Yupeng Hu ◽  
Minghai Li
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Darcy Number ◽  
Radius Ratio ◽  
Natural Convection Heat Transfer ◽  
Nanoparticle Volume Fraction ◽  
Convection Heat

Natural convection heat transfer in a porous annulus filled with a Cu nanofluid has been investigated numerically. The Darcy–Brinkman and the energy transport equations are employed to describe the nanofluid motion and the heat transfer in the porous medium. Numerical results including the isotherms, streamlines, and heat transfer rate are obtained under the following parameters: Brownian motion, Rayleigh number (103–105), Darcy number (10−4–10−2), nanoparticle volume fraction (0.01–0.09), nanoparticle diameter (10–90 nm), porosity (0.1–0.9), and radius ratio (1.1–10). Results show that Brownian motion should be considered. The nanoparticle volume fraction has a positive effect on the heat transfer rate, especially with high Rayleigh number and Darcy number, while the nanoparticle diameter has an inverse influence. The heat transfer rate is enhanced with the increase of porosity. The radius ratio has a significant influence on the isotherms, streamlines, and heat transfer rate, and the rate is greatly enhanced with the increase of radius ratio.

Natural convection of a hybrid nanofluid subjected to non-uniform magnetic field within porous medium including circular heater

2019 ◽  
Vol 29 (4) ◽  
pp. 1211-1231 ◽  
Author(s):  
Mohsen Izadi ◽  
Nemat M. Maleki ◽  
Ioan Pop ◽  
S.A.M. Mehryan
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Hybrid Nanofluid ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Content Type ◽  
Porosity Coefficient

PurposeThis paper aims to numerically investigate the natural convection heat transfer of a hybrid nanofluid into a porous cavity exposed to a variable magnetic field.Design/methodology/approachThe non-linear elliptical governing equations have been solved numerically using control volume based finite element method. The effects of different governing parameters including Rayleigh number (Ra= 103− 106), Hartman number (Ha= 0 − 50), volume fraction of nanoparticles (φ= 0 − 0.02), curvature of horizontal isolated wall (a= 0.85 − 1.15), porosity coefficient (ε= 0.1 − 0.9) and Darcy number (Da= 10−5− 10−1) have been studied.FindingsThe results indicate that at low Darcy numbers close to 0, the average Nusselt numberNuaenhances as porosity coefficient increases. Fora= 1 anda= 1.15 in comparison witha= 0.85, the stretching of the isothermal lines is maintained from the left side to the right side and vice versa, which indicates increased natural convection heat transfer for this configuration of the top and bottom walls. In addition, at higher Rayleigh numbers, by increasing the Hartmann number, a significant decrease is observed in the Nusselt number, which can be attributed to the decreased power of the flow.Originality/valueThe authors believe that all the results, both numerical and asymptotic, are original and have not been published elsewhere.

Benchmark results for natural and mixed convection heat transfer in a cavity

2015 ◽  
Vol 25 (5) ◽  
pp. 998-1029 ◽  
Author(s):  
Kerim Yapici ◽  
Salih Obut
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Two Dimensional ◽  
Nanoparticle Volume Fraction ◽  
Convection Heat ◽  
Content Type ◽  
Mixed Convection Heat Transfer ◽  
Volume Method

Purpose – The purpose of this paper is to numerically investigate steady, laminar natural and mixed convection heat transfer in a two-dimensional cavity by using a finite volume method with a fourth-order approximation of convective terms, with and without the presence of nanoparticles. Highly accurate benchmark results are also provided. Design/methodology/approach – A finite volume method on a non-uniform staggered grid is used for the solution of two-dimensional momentum and energy conservation equations. Diffusion terms, in the momentum and energy equations, are approximated using second-order central differences, whereas a non-uniform four-point fourth-order interpolation (FPFOI) scheme is developed for the convective terms. Coupled mass and momentum conservation equations are solved iteratively using a semi-implicit method for pressure-linked equation method. Findings – For the case of natural convection problem at high-Rayleigh numbers, grid density must be sufficiently high in order to obtain grid-independent results and capture reality of the physics. Heat transfer enhancement for natural convection is observed up to a certain value of the nanoparticle volume fraction. After that value, heat transfer deterioration is found with increasing nanoparticle volume fraction. Originality/value – Developed a non-uniform FPFOI scheme. Highly accurate benchmark results for the heat transfer of Al2O3-water nanofluid in a cavity are provided.

A study of natural convection heat transfer in a nanofluid filled enclosure with elliptic inner cylinder

2014 ◽  
Vol 24 (8) ◽  
pp. 1906-1927 ◽  
Author(s):  
M. Sheikholeslami ◽  
R. Ellahi ◽  
Mohsan Hassan ◽  
Soheil Soleimani
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Volume Fraction ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Enhancement ◽  
Content Type ◽  
Inclined Angle

Purpose – The purpose of this paper is to study the effects of natural convection heat transfer in a cold outer circular enclosure containing a hot inner elliptic circular cylinder. The fluid in the enclosure is Cu-water nanofluid. The main emphasis is to find the numerical treatment for the said mathematical model. The effects of Rayleigh number, inclined angle of elliptic inner cylinder, effective of thermal conductivity and viscosity of nanofluid, volume fraction of nanoparticles on the flow and heat transfer characteristics have been examined. Design/methodology/approach – A very effective and higher order numerical scheme Control Volume-based Finite Element Method (CVFEM) is used to solve the resulting coupled equations. The numerical investigation is carried out for different governing parameters namely; the Rayleigh number, nanoparticle volume fraction and inclined angle of elliptic inner cylinder. The effective thermal conductivity and viscosity of nanofluid are calculated using the Maxwell-Garnetts (MG) and Brinkman models, respectively. Findings – The results reveal that Nusselt number increases with an increase of nanoparticle volume fraction, Rayleigh numbers and inclination angle. Also it can be found that increasing Rayleigh number leads to a decrease in heat transfer enhancement. For high Rayleigh number the minimum heat transfer enhancement ratio occurs at. Originality/value – To the best of the authors’ knowledge, no such analysis is available in the literature which can describe the natural convection heat transfer in a nanofluid filled enclosure with elliptic inner cylinder by means of CVFEM.

MHD natural convection of Cu/H2O nanofluid in a horizontal semi-cylinder with a local triangular heater

2018 ◽  
Vol 28 (12) ◽  
pp. 2979-2996 ◽  
Author(s):  
A.S. Dogonchi ◽  
Mikhail A. Sheremet ◽  
Ioan Pop ◽  
D.D. Ganji
Keyword(s):  
Magnetic Field ◽  
Rayleigh Number ◽  
Free Convection ◽  
Shape Factor ◽  
Uniform Magnetic Field ◽  
Hartmann Number ◽  
Volume Fraction ◽  
Horizontal Cylinder ◽  
Content Type ◽  
Nanoparticles Volume Fraction

Purpose The purpose of this study is to investigate free convection of copper-water nanofluid in an upper half of circular horizontal cylinder with a local triangular heater under the effects of uniform magnetic field and cold cylinder shell using control volume finite element method (CVFEM). Design/methodology/approach Governing equations formulated in dimensionless stream function, vorticity and temperature variables using the single-phase nanofluid model with Brinkman correlation for the effective dynamic viscosity and Hamilton and Crosser model for the effective thermal conductivity have been solved numerically by CVFEM. Findings The impacts of control parameters such as the Rayleigh number, Hartmann number, nanoparticles volume fraction, local triangular heater size, shape factor on streamlines and isotherms as well as local and average Nusselt numbers have been examined. The outcomes indicate that the average Nusselt number is an increasing function of the Rayleigh number, shape factor and nanoparticles volume fraction, while it is a decreasing function of the Hartmann number. Originality/value A complete study of the free convection of copper-water nanofluid in an upper half of circular horizontal cylinder with a local triangular heater under the effects of uniform magnetic field and cold cylinder shell using CVFEM is addressed.

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