Hindawi Publishing Corporation Journal of Applied Mathematics Volume 2012, Article ID 372623, 10 pages doi:10.1155/2012/372623 Research Article Boundary Layer Flow and Heat Transfer with Variable Fluid Properties on a Moving Flat Plate in a Parallel Free Stream Norfifah Bachok, 1 Anuar Ishak, 2 and Ioan Pop 3 1 Department of Mathematics and Institute for Mathematical Research, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia 2 School of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia 3 Faculty of Mathematics, University of Cluj, CP 253, Romania Correspondence should be addressed to Anuar Ishak, anuarishak@yahoo.com Received 23 March 2012; Accepted 26 April 2012 Academic Editor: Srinivasan Natesan Copyright q 2012 Norfifah Bachok 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. The steady boundary layer flow and heat transfer of a viscous fluid on a moving flat plate in a parallel free stream with variable fluid properties are studied. Two special cases, namely, constant fluid properties and variable fluid viscosity, are considered. The transformed boundary layer equations are solved numerically by a finite-difference scheme known as Keller-box method. Numerical results for the flow and the thermal fields for both cases are obtained for various values of the free stream parameter and the Prandtl number. It is found that dual solutions exist for both cases when the fluid and the plate move in the opposite directions. Moreover, fluid with constant properties shows drag reduction characteristics compared to fluid with variable viscosity. 1. Introduction The problem of forced convection flow and heat transfer past a continuously moving flat plate is a classical problem of fluid mechanics and has attracted considerable interest of many researchers not only because of its many practical applications in various extrusion processes but also because of its fundamental role as a basic flow problem in the boundary layer theory of Newtonian and non-Newtonian fluid mechanics. It has been solved for the first time in 1961 by Sakiadis 1. Thereafter, many solutions have been obtained for different situations of this class of boundary layer problems. The solutions for the cases when the mass transfer effect is included fluid injection and fluid suction, chemical effects are considered, constant or variable surface temperatures, and other situations have been reported by Klemp and Acrivos 2, Abdelhafez 3, Hussaini et al. 4, Afzal et al. 5, Bianchi and Viskanta 6,