Laminar periodic flow and heat transfer characteristics in a square channel fitted with 90 transverse and 45 inclined baffle elements in tandem, inline and staggered arrangements on two opposite walls have been investigated numerically. The P-vortex flows created by using the 45 baffles help to induce impingement flows on the BLE sidewall and wall in the baffle cavity leading to drastic increase in heat transfer in the square channel. The order of enhancement is about 150e850% for using both the 45 baffles with BR ¼ 0.05e0.3. However, the heat transfer augmentation is associated with enlarged pressure loss ranging from 2 to 70 times above the smooth channel. Thermal enhancement factors for both the 45 baffle arrays are found to be almost the same and much higher than unity and theirs maximum values are about 2.6 indicating higher thermal performance over the smooth channel. For the 45 baffles, the heat transfer enhancement is around 100e200% higher than that for the 90 baffle whereas the friction loss can be reduced at about 10e150%.