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Unsteady flow of variable viscosity Cu-water and Al2O3-water nanofluids in a porous pipe with buoyancy force

Sara Khamis, Daniel Oluwole Makinde, Yaw Nkansah-Gyekye

International Journal of Numerical Methods for Heat & Fluid Flow

ISSN: 0961-5539

Article publication date: 7 September 2015

240

Abstract

Purpose

The purpose of this paper is to investigate the combined effects of buoyancy force and variable viscosity on unsteady flow and heat transfer of water-based nanofluid containing copper and alumina as nanoparticles through a porous pipe.

Design/methodology/approach

Using the Boussinesq and boundary-layer approximations with Buongiorno nanofluid model. The governing nonlinear partial differential equations for the continuity, momentum and energy balance are formulated. The equations obtained are solved numerically using a semi-discretization finite difference method (know) as method of line coupled with Runge-Kutta-Fehlberg integration scheme.

Findings

Numerical results for the skin-friction, heat transfer and for the velocity and temperature profiles are obtained. The results show that with suction, Cu-water produces higher skin friction and heat transfer rate than Al2O3-water. Both nanofluids velocity and temperature increase with a decrease in viscosity and an increase in buoyancy force intensity.

Practical implications

Buoyancy-driven flow and heat transfer in porous geometries has many significant applications in industrial and engineering such as, electrical and microelectronic equipments, solar-collectors, geothermal engineering, petroleum reservoirs, thermal buildings insulation. This work provides very important information for researchers on this subject.

Originality/value

This paper illustrates the effects of buoyancy force and temperature dependent on heat transfer and fluid flow problem using Cu-water and Al2O3-water nanofluids in a porous pipe.

Keywords

Citation

Khamis, S., Makinde, D.O. and Nkansah-Gyekye, Y. (2015), "Unsteady flow of variable viscosity Cu-water and Al2O3-water nanofluids in a porous pipe with buoyancy force", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 25 No. 7, pp. 1638-1657. https://doi.org/10.1108/HFF-09-2014-0286

Publisher

:

Emerald Group Publishing Limited

Copyright © 2015, Emerald Group Publishing Limited

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