The effect of variable viscosity on mixed convection heat transfer along a vertical moving surface

The effect of temperature dependent viscosity on laminar mixed convection boundary layer flow and heat transfer on a continuously moving vertical surface is studied. The fluid viscosity is assumed to vary as an inverse linear function of temperature. Local similarity solutions are obtained for the boundary layer equations subject to isothermally moving vertical surface with uniform speed. The effect of various governing parameters, such as Prandtl number Pr, the mixed convection parameter lambda = S Gr(x)/Re-x(2) and the viscosity/temperature parameter theta(r) which determine the velocity and temperature distributions, the local heat transfer coefficient, and the local shear stress coefficient at the surface are studied. Significant changes are obtained in dimensionless local heat transfer and shear stress coefficient at the surface when the magnitude of theta(r) has small values for each lambda. Critical values of lambda are obtained for predominate natural convection and buoyancy shear stress for assisting and opposing flow for various Or. (c) 2005 Elsevier SAS. All rights reserved.