Title: On inherent irreversibility in Sakiadis flow of nanofluids

Authors: O.D. Makinde; W.A. Khan; A. Aziz

Addresses: Institute for Advanced Research in Mathematical Modelling and Computations, Cape Peninsula University of Technology, P.O. Box 1906, Bellville 7535, South Africa ' Department of Engineering Sciences, National University of Sciences and Technology, Karachi 75350, Pakistan ' Department of Mechanical Engineering, School of Engineering and Applied Science, Gonzaga University, Spokane, WA 99258, USA

Abstract: The problem of entropy generation and inherent irreversibility in the steady boundary layer shear flow of nanofluids over a moving flat plate is studied numerically. The governing partial differential equations are transformed into ordinary differential equations using a similarity transformation and then solved numerically by a Runge-Kutta-Fehlberg method with the shooting technique. Two types of nanofluids, namely, Cu-water and TiO₂-water, are used. The effects of nanoparticle volume fraction, the type of nanoparticles, group parameter, and the local Reynolds number on the entropy generation rate, irreversibility ratio and the Bejan number are discussed. It is found that the entropy generation rate at the plate surface decreases with increasing nanoparticle volume fraction and the group parameter. Moreover, the heat transfer irreversibility at the plate surface with TiO₂-water nanofluid is slightly higher than that at the plate surface with Cu-water nanofluid.

Keywords: Sakiadis flow; nanofluids; copper; titania; water; heat transfer; entropy generation rate; irreversibility ratio; Bejan number; nanotechnology; boundary layer; shear flow; nanoparticles.

DOI: 10.1504/IJEX.2013.056131

International Journal of Exergy, 2013 Vol.13 No.2, pp.159 - 174

Received: 26 Mar 2012
Accepted: 11 Sep 2012
Published online: 31 Aug 2013 *

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