Operational and structural modifications were numerically investigated in an effort to improve the performance of a liquidcooled heatsink. The water/silver nanofluid was utilized as coolant, where the effects of nanoparticle concentration and Reynolds number were the operational variables considered, while the effect of rifling the inlet tube of coolant was a structural parameter investigated. The considered range for nanoparticle concentration and Reynolds number was 0–1% and 5000– 20,000, respectively. The overall hydrothermal performance of the heatsink with rifled inlet was found to be 1.073–1.541 times higher than that of heatsink with plain inlet. In addition, it was revealed that rifling the inlet tube of heatsink entails a 4.26–21.79% decrement in the thermal entropy and a 9.90–110.97% increase in the frictional entropy. Moreover, it was demonstrated that friction is the main source of entropy generation in the flow, and the second-law performance of the heatsink with plain inlet is better than that of heatsink with rifled inlet.
