RESEARCH ARTICLE Copyright © 2016 American Scientific Publishers All rights reserved Printed in the United States of America Journal of Computational and Theoretical Nanoscience Vol. 13, 1670–1684, 2016 Thermo-Diffusion Effects on Unsteady Mixed Convection in a Magneto-Nanofluid Flow Along an Inclined Cylinder with a Heat Source, Ohmic and Viscous Dissipation S. M. S. Ahamed, S. Mondal ∗ , and P. Sibanda School of Mathematics, Statistics and Computer Science, University of KwaZulu-Natal, Private Bag X01 Scottsville 3209, Pietermaritzburg, South Africa We present a numerical solution of the unsteady nanofluid boundary-layer flow on an inclined cylin- der. We investigate heat and mass transfer in the presence of a chemical reaction, viscous and Ohmic dissipation due to applied transverse magnetic and electric fields. In this study two dif- ferent nanoparticles; namely copper and silver are considered with water as the base fluid. The model equations are solved using the spectral local linearization method. Results for the skin fric- tion coefficient, the wall temperature and mass gradients as well as the velocity, temperature and concentration profiles have been obtained for various physical parameters values. The results have been benchmarked with previously published results. Keywords: Ohmic Heating, Viscous Dissipation, Electromagnetic Flow, Thermo-Diffusion, Nanofluid, Chemical Reaction. 1. INTRODUCTION The steady and unsteady boundary layer flow, and heat and mass transfer over a stretching or shrinking cylin- der has several applications in engineering processes that involve both metal and polymer sheets. Important relevant engineering applications can be found in polymer process- ing, melt-spinning, hot rolling, paper production, wire and glass-fiber production, etc. In these processes, the quality of the final product depends on the rate of cooling and the rate of stretching or shrinking. 1 The flow due to a shrinking plane was first studied by Miklavˇ ciˇ c and Wang. 14 Researchers who have studied flow owing to a stretch- ing cylinder include, among others, Wang, 2 Ishak et al. 3 Wang and Ng, 4 Wang, 5 Ishak et al., 6 and Fang et al. 7 The problem of the unsteady sticky influx as a consequence of an expanding, stretching cylinder provided an exact similarity solution to the Navier-Stokes equations. Fang et al. 8 obtained numerical solutions of unsteady flow over a stretching cylinder. The numerical solutions for a steady state stagnation point flow of an inviscid and incompress- ible fluid along a shrinking cylinder were presented by Lok and Pop. 9 Zaimia et al. 10 investigated the behaviour of the unsteady viscous flow over a shrinking cylinder with suction. Choi 27 proposed the concept of a “nanofluid” by sus- pending solid nanoparticles in a base fluid in order ∗ Author to whom correspondence should be addressed. to address challenges in thermal engineering. Currently nanofluids are made by dispersing nanometer-sized solid particles, rods or tubes in traditional heat transfer fluids such as water or oil. Investigations in the past decade have shown that nanofluids exhibit significantly enhanced ther- mophysical properties compared to base fluids. The full impact of nanofluid technology is still to be fully realized but is nonetheless expected to be significant in the coming years, Sudhan et al. 37 Abu-Nada and Chamkha 23 studied mixed convection flow in an inclined square enclosure filled with an alumina-water nanofluid. Oztop and Abu-Nada 24 stud- ied natural convection in a rectangular enclosure filled with a nanofluid containing copper, alumina, and titanium nanoparticles. They concluded that the highest value of heat transfer is obtained using copper nanoparticles. The study of magnetic field effects has important appli- cations in physics, chemistry and engineering. Many types of industrial equipment, such as magnetohydrodynamic (MHD) generators, pumps and bearings are affected by the interaction between the electrically conducting fluid and a magnetic field. Many studies in the literature have been made in relation to these applications. One of the basic and important problems in this area is the hydro-magnetic behaviour of boundary layers along fixed or moving sur- faces. MHD boundary layers are found in various techni- cal systems employing liquid metals and plasma flow with transverse magnetic fields. 29 1670 J. Comput. Theor. Nanosci. 2016, Vol. 13, No. 3 1546-1955/2016/13/1670/015 doi:10.1166/jctn.2016.5097