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

Abstract

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.