## THERMAL SCIENCE

International Scientific Journal

### HOMOTOPY ANALYSIS METHOD FOR MIXED CONVECTIVE BOUNDARY LAYER FLOW OF A NANOFLUID OVER A VERTICAL CIRCULAR CYLINDER

**ABSTRACT**

This article deals with the study of the steady axisymmetric mixed convective boundary layer flow of a nanofluid over a vertical circular cylinder with prescribed external flow and surface temperature. By means of similarity transformation, the governing partial differential equations are reduced into highly non-linear ordinary differential equations. The resulting non-linear system has been solved analytically using an efficient technique namely homotopy analysis method (HAM). Expressions for velocity and temperature fields are developed in series form. In this study, three different types of nanoparticles are considered, namely alumina (), titania (), and copper () with water as the base fluid. For copper-water nanofluid, graphical results are presented to describe the influence of the nanoparticle volume fraction on the velocity and temperature fields for the forced and mixed convection flows. Moreover, the features of the flow and heat transfer characteristics are analyzed and discussed for foregoing nanofluids. It is found that the skin friction coefficient and the heat transfer rate at the surface are highest for copper-water nanofluid compared to the alumina-water and titania-water nanofluids.

**KEYWORDS**

PAPER SUBMITTED: 2012-02-25

PAPER REVISED: 2012-09-02

PAPER ACCEPTED: 2012-09-12

**THERMAL SCIENCE** YEAR

**2015**, VOLUME

**19**, ISSUE

**Issue 2**, PAGES [549 - 561]

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