The present study deals with numerical simulation of fully developed flow and heat transfer through a wavy surface described by the function y = 2asin(2)(pi x/L). Finite volume method on collocated grid is used to solve incompressible, time-dependent Navier-Stokes and energy equation in primitive variable form. Effect of geometry, generated by varying H-min/H-max ratio from 0.1 to 0.5 and keeping L/a ratio fixed to 8, on fluid flow and heat transfer characteristics has been elaborated at a Reynolds number of 600. The critical Reynolds number of unsteadiness is found to depend on the geometrical parameters. At Re = 600, one model shows the flow with multiple frequencies while the others reveal single frequency. It is established that geometry with H-min/H-max ratio 0.2 produces the highest Nusselt number and spawns the best thermal performance factor (TPF). With increase in Reynolds number, the steady flow shows a decrease in TPF while an increase in TPF is noticed when the flow is unsteady. (C) 2012 Elsevier Ltd. All rights reserved.