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Article
Publication date: 17 July 2019

Hanieh Nazarafkan, Babak Mehmandoust, Davood Toghraie and Arash Karimipour

This study aims to apply the lattice Boltzmann method to investigate the natural convection flows utilizing nanofluids in a semicircular cavity. The fluid in the cavity is a…

146

Abstract

Purpose

This study aims to apply the lattice Boltzmann method to investigate the natural convection flows utilizing nanofluids in a semicircular cavity. The fluid in the cavity is a water-based nanofluid containing Al2O3 or Cu nanoparticles.

Design/methodology/approach

The study has been carried out for the Rayleigh numbers from 104 to 106 and the solid volume fraction from 0 to 0.05. The effective thermal conductivity and viscosity of nanofluid are calculated by the models of Chon and Brinkman, respectively. The effects of solid volume fraction on hydrodynamic and thermal characteristics are investigated and discussed. The averaged and local Nusselt numbers, streamlines, temperature contours for different values of solid volume fraction and Rayleigh number are illustrated.

Findings

The results indicate that more solid volume fraction corresponds to more averaged Nusselt number for both types of nanofluids. It is also found that the effects of solid volume fraction of Cu are stronger than those of Al2O3.

Originality/value

Numerical study of natural convection of nanofluid in a semi-circular cavity with lattice Boltzmann method in the presence of water-based nanofluid containing Al2O3 or Cu nanoparticles.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 5
Type: Research Article
ISSN: 0961-5539

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Article
Publication date: 17 October 2018

Mohammad Sadegh Dehghani, Davood Toghraie and Babak Mehmandoust

The purpose of this study is numerical simulation of magnetohydrodynamics (MHD) water–Al2O3 nanofluid mixed convection in a grooved channel with internal heat generation in solid…

183

Abstract

Purpose

The purpose of this study is numerical simulation of magnetohydrodynamics (MHD) water–Al2O3 nanofluid mixed convection in a grooved channel with internal heat generation in solid cylinders. Simulations were carried out at Reynolds numbers 50 ≤ Re ≤ 100, Hartmann numbers 0 ≤ Ha ≤ 15, Grashof numbers 5,000 ≤ Gr ≤ 10−4 and volume fraction 0 ≤ φ ≤ 0.04. The effect of Reynolds number and the influence of magnetic field and pressure drop on convective heat transfer coefficient were studied in different volume fractions of nanoparticles at different Reynolds numbers.

Design/methodology/approach

The results show that average Nusselt number increases by increasing Reynolds and Hartman numbers. Also, when Hartman number increases, velocity profile becomes asymmetric. Pressure distribution shows that magnetic field applies Lorentz force at opposite direction of the flow, which causes asymmetric distribution of pressure. As a result, pressure in the upper half of the cylinder is higher than the lower half. Finally, velocity and temperature contours along the channel for different Hartmann numbers, volume fraction 3 per cent, Re = 50 and 100 and Gr = 10,000, are presented.

Findings

The effect of Reynolds number and the influence of magnetic field and pressure drop on convective heat transfer coefficient were studied in different volume fractions of nanoparticles at different Reynolds numbers.

Originality/value

Effect of MHD on the flow and heat transfer characteristics of Water–Al2O3 nanofluid in a grooved channel with internal heat generation in solid cylinders.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 29 no. 4
Type: Research Article
ISSN: 0961-5539

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