Double diffusion from a vertical wavy surface in a porous medium saturated with a non-Newtonian fluid

This paper reports a study on the phenomenon of double diffusion near a vertical sinusoidal wavy surface in a porous medium saturated with a non-Newtonian power-law fluid with constant wall temperature and concentration. A coordinate transformation is employed to transform the complex wavy surface to a smooth surface, and the obtained boundary layer equations are then solved by the cubic spline collocation method. Effects of Lewis number, buoyancy ratio, power-law index, and wavy geometry on the Nusselt and Sherwood numbers are studied. The mean Nusselt and Sherwood numbers for a wavy surface are found to be smaller than those for the corresponding smooth surface. An increase in the power-law index leads to a smaller fluctuation of the local Nusselt and Sherwood numbers. Moreover, increasing the power-law index tends to increase both the thermal boundary layer thickness and the concentration boundary layer thickness, thus decreasing the mean Nusselt and Sherwood numbers. (c) 2006 Elsevier Ltd. All rights reserved.