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Mathematical Problems in Engineering
Volume 2015, Article ID 391786, 13 pages
http://dx.doi.org/10.1155/2015/391786
Research Article

Effect of Variable Fluid Properties on Natural Convection of Nanofluids in a Cavity with Linearly Varying Wall Temperature

1Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50601 Kuala Lumpur, Malaysia
2Institute of Mathematical Sciences, Faculty of Science, University of Malaya, 50601 Kuala Lumpur, Malaysia
3UTM Centre for Industrial and Applied Mathematics, Department of Mathematical Sciences, Universiti Teknologi Malaysia, 81310 Johor Bahru, Johor, Malaysia

Received 16 October 2014; Revised 24 January 2015; Accepted 25 January 2015

Academic Editor: Quanxin Zhu

Copyright © 2015 M. Bhuvaneswari et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The present study analyzed convective heat transfer and fluid flow characteristics of nanofluid in a two-dimensional square cavity under different combinations of thermophysical models of nanofluids. The right vertical wall temperature is varying linearly with height and the left wall is maintained at low temperature whereas the horizontal walls are adiabatic. Finite volume method is used to solve the governing equations. Two models are considered to calculate the effective thermal conductivity of the nanofluid and four models are considered to calculate the effective viscosity of the nanofluid. Numerical solutions are carried out for different combinations of effective viscosity and effective thermal conductivity models with different volume fractions of nanoparticles and Rayleigh numbers. It is found that the heat transfer rate increases for Models M1 and M3 on increasing the volume fraction of the nanofluid, whereas heat transfer rate decreases for Model M4 on increasing the volume fraction of the nanoparticle. The difference among the effective dynamic viscosity models of nanofluid plays an important role here such that the average Nusselt number demonstrates an increasing or decreasing trend with the concentration of nanoparticle.