FREE-CONVECTION BOUNDARY-LAYER FLOW OF A NON-NEWTONIAN FLUID ALONG A VERTICAL WAVY SURFACE

A theoretical analysis of laminar free-convection flow over a vertical isothermal wavy surface in a non-Newtonian power-law fluid is conside red. The governing equations are first cast into a nondimensional form by using suitable boundary-layer variables that substract out the eff ect of the wavy surface from the boundary conditions. The boundary-lay er equations are then solved numerically by a very efficient implicit finite-difference method known as the Kelter-Box method. A sinusoidal surface is used to elucidate the effects of the power-law index, ampli tude wavelength, and Prandtl number on the velocity and temperature fi elds, as well as on the local Nusselt number. It is shown that the loc al Nusselt number varies periodically along the wavy surface. The wave length of the local Nusselt number variation is half that of the wavy surface, irrespective of whether the fluid is a Newtonian fluid or a n on-Newtonian fluid. Comparisons with earlier works are also made, and the agreement is found to be very good. (C) 1997 by Elsevier Science I nc.