Series solution for heat transfer of continuous stretching sheet immersed in a micropolar fluid in the existence of radiation M.S. Shadloo Center of Excellence in Energy Conversion, School of Mechanical Engineering, Sharif University of Technology, Tehran, Iran A. Kimiaeifar Department of Mechanical Engineering, Aalborg University, Aalborg, Denmark, and D. Bagheri Polymer Engineering Department, Amirkabir University of Technology, Tehran, Iran Abstract Purpose – The purpose of this paper is to study a two-dimensional steady convective flow of a micropolar fluid over a stretching sheet in the presence of radiation with constant temperature. Design/methodology/approach – The corresponding momentum, microrotation and energy equations are analytically solved using homotopy analysis method (HAM). Findings – To validate the method, investigate the accuracy and convergence of the results, a comparison with existing numerical and experimental results is done for several cases. Finally, by using the obtained analytical solution, for the skin-friction coefficient and the local Nusselt number as well as the temperature, velocity and angular velocity, profiles are obtained for different values of the constant parameters, such as Prandtl number, material, boundary and radiation parameter. Originality/value – In this paper, a series solution is presented for the first time. Keywords Flow, Convection, Heat transfer, Micropolar fluid, Stretching sheet, Radiation, Homotopy analysis method Paper type Research paper 1. Introduction Micropolar fluids are characterized by microstructures belonging to a class of fluids with nonsymmetrical stress tensor referred to as polar fluids (Lukaszewicz, 1999). The theory of micropolar fluids, which was initially introduced and investigated by Eringen (1966), takes into account fluids consisting of randomly oriented particles suspended in a viscous medium. Since this theory may be applied to explain a wide variety of industrial and engineering fluid flows such as polymeric fluids, liquid crystals, paints, human and animal blood, colloidal fluids, etc. the dynamics of micropolar fluids has become a popular area of research. Extensive reviews of the theory and its applications can be found in the review article by Ariman et al. (1973) and more recently in Eringen’s (2001) book. The current issue and full text archive of this journal is available at www.emeraldinsight.com/0961-5539.htm Received 1 January 2011 Revised 26 May 2011 Accepted 11 June 2011 International Journal of Numerical Methods for Heat & Fluid Flow Vol. 23 No. 2, 2013 pp. 289-304 q Emerald Group Publishing Limited 0961-5539 DOI 10.1108/09615531311293470 Series solution for heat transfer 289