Structures of flow in a corrugated duct were experimentally examined employing the technique of Particle Image Velocimetry (PIV). The aspect ratio of the corrugated channel was selected as 0.3. Understanding the influences of phase shift, phi on the flow behavior and augmentation of heat transfer is one of the main objectives of this experimental work. Therefore, two different phase shifts such as phi = 0 degrees and 90 degrees and two different Reynolds Numbers, Re of 2 x 10(3) and 6 x 10(3) have been investigated for the available corrugated channel. In order to obtain the physics of the flow characteristics of the corrugated channel, the Turbulence Kinetic Energy, TKE, vorticity, and time-average velocity contours were calculated for both Reynold numbers, Re and phase shifts, phi. The experimental results revealed that transporting energy and increasing of momentum transfer by corrugated channel caused a better augmentation of the heat transfer rate for both phase shift angles than the smooth channel. It appears that the turbulence generated by the sharp corner of the corrugated channels is the most influential factor in increasing the entrainment between wake and core flows.