A two-dimensional steady and laminar incompressible flow in a corrugated enclosure is analyzed numerically. Two types of corrugation (vee and sinusoidal) on vertical walls of the enclosure are considered. In this analysis, two vertical corrugated walls are maintained at a constant low temperature, a constant heat flux source whose length is 40% of the total length of the enclosure is discretely embedded at the bottom wall, the non-heated part of the bottom wall and the top wall are considered adiabatic. The pressure velocity form of the Navier-Stokes equations and energy equation are used to represent the mass, momentum and energy conservations of the fluid medium in the enclosure. The Galerkin finite element method has been used to see the effect of corrugation geometry on heat transfer for different Grashof numbers. The average Nusselt number at the heat source surface for different corrugated enclosures are compared with each other. Results are presented in the form of streamline and isotherm plots.

 Keywords: Natural convection, corrugation amplitude, penalty finite element, Nusselt number.