Researches and Applications in Mechanical Engineering Vol. 2 Iss. 3, September 2013 www.seipub.org/rame 57 MHD Natural Convection Flow of Fluid with Variable Viscosityfrom a Porous Vertical Plate Amena Ferdousi *1 , M. Mostafizur Rahman 2 , Mohammad Salek Parvez 3 , M. A. Alim 4 1 Faculty of Electronics and Electrical Engineering, Eastern University, Dhaka, Bangladesh. 2 Department of Computer Science and Engineering, Daffodil International University, Dhaka, Bangladesh. 3 Department of Natural Sciences, Daffodil International University, Dhaka, Bangladesh. 4 Department of Mathematics, Bangladesh University of Engineering and Technology, Dhaka, Bangladesh. *1 amena@easternuni.edu.bd; 2 mostafiz.math@daffodilvarsity.edu.bd; 3 sparvez@daffodilvarsity.edu.bd; 4 maalim@math.buet.ac.bd Abstract The behaviour of magnetohydrodynamic (MHD) natural convection flow from a porous vertical plate is studied with respect to variable viscosity. To model the flow, the governing boundary layer equations are first transformed into a non dimensional form. The resulting non linear system of partial differential equations is then solved numerically using finite difference method together with Keller-Box scheme. The study shows that the variation of viscosity influences the surface shear stress (skin friction coefficient) and the rate of heat transfer (local Nusselt number). It has an effect on velocity as well as temperature profiles. Studied has been performed with a selection of parameters set consisting of magnetohydrodynamic parameter M, viscosity variation parameter γ, Prandtl number Pr. Results are shown graphically and tabular form and the comparison agrees well with a published paper. Keywords Porous Plate; Magnetohydrodynamic; Natural Convection; Variable Viscosity Nomenclature ar Rossel and mean absorption co-efficient Cf Local skin friction coefficient Cp Specific heat at constant pressure f Dimensionless stream function g Acceleration due to gravity k Thermal conductivity Nux Local Nusselt number Pr Prandtl number Q Heat generation parameter qw Heat flux at the surface c q Conduction heat flux r q Radiation heat flux Rd Radiation parameter T Temperature of the fluid in the boundary layer T ∞ Temperature of the ambient fluid Tw Temperature at the surface (,) uv Dimensionless velocity components along the (x, y)axes V Wall suction velocity T T w − ∞ (x, y) Axis in the direction along and normal to the surface respectively Greek symbols α Equal to 4 3 R d β Coefficient of thermal expansion ∆ Equal to 1 w θ − T ∆ Equal to η Similarity variable θ Dimensionless temperature function w θ Surface temperature parameter µ Viscosity of the fluid ν Kinematic viscosity ξ Similarity variable ρ Density of the fluid σ Stephman-Boltzman constant s σ Scattering co-efficient µf Absolute Viscosity at the film temperature τ Coefficient of skin friction τw Shearing stress ψ Non-dimensional stream function Subscripts w wall conditions ∞ Ambient temperature Introduction From technical point of view, the electrically conducting fluid flow in presence of magnetic field is