Transient Mixed Convection Flow of A Second-Grade Visco-Elastic Fluid over a Vertical Surface

The viscoelastic boundary layer flow and mixed convection heat transfer near a vertical isothermal surface have been examined in this paper. The governing equations are formulated and solved numerically using an explicit finite difference technique. The velocity and temperature profiles, boundary layer thicknesses, Nusselt numbers and the local skin friction coefficients are shown graphically for different values of the viscoelsatic parameter. In general, it is found that the velocity decreases inside the boundary layer as the viscoelsatic parameter is increased and consequently, the local Nusselt number decreases. This is due to higher tensile stresses between viscoelsatic fluid layers which has a retardation effects on the motion of these layers and consequently, on the heat transfer rates for the mixed convection heat transfer problem under investigation. A Comparison with available published results on special cases of the problem shows excellent agreement

Transient Free Convection Flow of a Micropolar Fluid Over a Vertical Surface

In recent years, the dynamics of micropolar fluids, originated from the theory of Eringen, has been a popular area of research. As the fluids con-sist of randomly oriented molecules, and as each volume element of the fluid has translational as well as rotational motions, the analysis of physical prob-lems in these fluids has revealed several interesting phenomena, which are not found in Newtonian fluids. The present study presents a numerical study for transient natural convection heat transfer of a micropolar boundary layer flow near a vertical isothermal surface. The governing equations are formulated and solved numerically using the MackCormak’s technique. A comparison with previously published results on special cases of the problem shows ex-cellent agreement. Representative results for the velocity, micro-rotation and temperature profiles are shown graphically for different values of material pa-rameters. In general, it is found that the temperature increases inside the boundary layer for the micropolar flows as compared to the Newtonian flows. Nomenclature B dimensionless material parameter; Cf local coefficient of friction; Cp specific heat of the fluid at constant pressure; g magnitude of acceleration due to gravity