The prediction of heat transfer characteristics numerically depends on several factors such as the numerical method, the boundary and operating conditions, etc. The present paper investigated the influence of using the uniform and non-uniform inlet velocity profiles on the heat transfer coefficient (h), pumping power (W˙ p), temperature uniformity (θ), and thermal and frictional entropy generation rates (S˙th and S˙fr) in a pin-fin heatsink with silver/water nanofluid (NF) coolant. The numerical study is conducted utilizing the two-phase mixture scheme. The results proved that h is almost the same for two inlet profiles with the maximum deviation of 0.2%. θ and W˙ p, however, for uniform profile is nearly 2.52–1.86% and 15–26% higher than those for the other case at Reynolds numbers of 500–2000, respectively, indicating a lower temperature uniformity and higher power consumption for uniform velocity profile. The figure of merit was obtained as 1.19–1.36 at Re numbers of 500–2000; indicating the better hydrothermal performance of the non-uniform inlet velocity profile over the other case. In addition, S˙th was almost the same for both cases due to same mean temperature and temperature gradients. However, S˙fr for non-uniform profiles was 4.41–8.84% lower than that for other profile at Reynolds numbers of 500–2000.
