In this study, laminar and steady flow of hybrid Al2O3–Cu/water nanofluid is done for volume fraction of solid nanoparticles 0–2% in a double-layered microchannel with sinusoidal walls. The results of this study show that the sinusoidal shape of the microchannel walls has a strong effect on increasing heat transfer, and increasing solid nanoparticle volume fraction in base fluid can have a significant difference for increasing Nusselt number, so that the value of Nusselt number for solid nanoparticles volume fraction of 2% for Re = 50, 300, 700 and 1200 experiences 23%, 22% 19% and 13% increase compared with the base fluid. By increasing fluid viscosity, the shear stress especially in the areas close to wall and in fluid layers is increased and this factor can increase pressure drop in higher solid nanoparticles volume fractions. The static temperature profiles are affected by hot surfaces and their sinusoidal shapes in lower Reynolds numbers, and the curve for temperature of flow centerline for Re = 700 and 1200 is straight lines. Therefore, the usage of it for Reynolds numbers above 700 is not recommended.
