ORIGINAL Mixed convection boundary layer flow over a horizontal circular cylinder with Newtonian heating Mohd Zuki Salleh • Roslinda Nazar • Ioan Pop Received: 11 December 2008 / Accepted: 9 August 2010 Ó Springer-Verlag 2010 Abstract The steady mixed convection boundary layer flow over a horizontal circular cylinder, generated by Newtonian heating in which the heat transfer from the surface is proportional to the local surface temperature, is considered in this study. The governing boundary layer equations are first transformed into a system of non- dimensional equations via the non-dimensional variables, and then into non-similar equations before they are solved numerically using a numerical scheme known as the Kel- ler-box method. Numerical solutions are obtained for the skin friction coefficient Re 1/2 C f and the local wall tem- perature h w (x) as well as the velocity and temperature profiles with two parameters, namely the mixed convection parameter k and the Prandtl number Pr. List of symbols a Radius of the cylinder C f Skin friction coefficient f Dimensionless stream function g Acceleration due to gravity Gr Grashof number h s Heat transfer parameter for Newtonian heating’ Pr Prandtl number Re Reynolds number T Fluid temperature T ? Ambient temperature u, v Velocity components along the x and y directions, respectively U ? Free stream velocity u e (x) Velocity outside boundary layer x, y Cartesian coordinates along the surface and normal to it, respectively Greek symbols a Thermal diffusivity b Thermal expansion coefficient c Conjugate parameter for Newtonian heating d i2 , d i4 Kronecker delta operator g Similarity variable h Dimensionless temperature k Mixed convection parameter l Dynamic viscosity m Kinematic viscosity w Stream function Subscripts w Condition at the surface ? Condition at infinity Superscript 0 Differentiation with respect to y and g 1 Introduction Boundary layer flow over a circular cylinder was the sub- ject of intense studies since the early work of Prandtl in 1904 (Schlichting [1]). It is well known that the first M. Z. Salleh Faculty of Industrial Science and Technology, Universiti Malaysia Pahang, 26300 UMP Kuantan, Pahang, Malaysia R. Nazar (&) School of Mathematical Sciences, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia e-mail: rmn72my@yahoo.com I. Pop Faculty of Mathematics, University of Cluj, CP 253, 3400 Cluj, Romania 123 Heat Mass Transfer DOI 10.1007/s00231-010-0662-y