▎ 摘　　要

The goal of this article is to assess the merit of utilizing an innovative water-based nanofluid containing the reduced graphene oxide-cobalt oxide hybrid nanocomposite in a microchannel heat sink equipped with rectangular ribs and sinusoidal cavities. For this end, the two-phase mixture numerical model based on the finite volume technique and Coupled approach is used. The simulation is conducted at amounts of Reynolds number ranged from 100 to 500 with the nanofluid concentrations of 0.05%, 0.1%, and 0.2%. The thermophysical properties are temperature-dependent. The results indicate that though the created vortices decline by utilizing the nanofluid, the thermal features significantly improve due to enhanced thermal conductivity. The convective heat transfer coefficient, solid temperature, temperature uniformity, and thermal resistance promote by maximum amounts of 14%, 2.3%, 27%, and 25%, respectively. Also, considering the imposed pressure drop due to the use of the nanofluid, it was found that in all the cases, the nanofluid increases the heat transfer coefficient more than the pressure drop, which is an excellent outcome. Finally, it is unmasked that deploying the 0.2% nanofluid at Reynolds number of 500 improves the thermal features with the least pressure drop increment, and therefore, this case is recommended for practical applications.