Semi-analytical investigation of heat transfer characteristics in suction-assisted Cu–Ag/water hybrid nanofluid flow through a coupled stretching–rotating coaxial disk system with convective heat source/sink

Abstract This study presents a semi-analytical examination of hybrid nanofluid flow through a coupled disk system, which is stretching and rotating coaxially. The hybrid Nanofluid (HNF) consists of copper and silver nanoparticles incorporated into the base fluid, water. The impacts of the heat source/sink, magnetic field, Darcy–Forchheimer, suction, and convective conditions at the lower disk are all integrated into the mathematical model. The governing partial differential equations are transformed using similarity variables into a coupled system of ordinary differential equations and solved using the Homotopy Analysis Method (HAM). The results show that the temperature profile declines monotonically, and the radial, axial, and tangential velocity profiles increase with the rotation parameter. Increasing the magnetic parameter produces an effect opposite to that of the rotation parameter on the velocity and temperature profiles. The temperature profile decreases with the heat sink, porosity, and suction factors and increases with the Biot number. The Nusselt number and skin friction results for the lower and upper disks are separately presented in tables for comparison between the HNF and the nanofluid (NF). Furthermore, a nanoparticle volume fraction of $$\\phi_{1} + \\phi_{2} = 0.06$$ enhances the HNF lower and upper disk Nusselt numbers by 48.6% and 51.2%, respectively, compared with the base fluid, and exceeds the corresponding values for the Cu/water NF by 5.8% and 9.8%, respectively. The results demonstrate the potential of Cu–Ag/water hybrid nanofluid for thermal management in rotating disk systems.