Analytical study of Al2O3-Cu/water micropolar hybrid nanofluid in a porous channel with expanding/contracting walls in the presence of magnetic field

Forced convection fluid flow and heat transfer is investigated in a porous channel with expanding or contracting walls with which is filled Al2O3-Cu/water micropolar hybrid nanofluid in the presence of magnetic field. In order to solve the governing equations analytically, the least square method is employed. The hot bottom wall is cooled by the coolant fluid which is injected into the channel from the top wall. The range of nanoparticles volume fraction (90% Al2O3 and 10% Cu by volume) is between 0% and 2%. The effects of consequential parameters such as Reynolds number, Hartmann number, micro rotation factor and nanoparticles volume fraction on velocity and temperature profiles are examined. The results show that with increasing Reynolds number, the values of temperature and micro rotation profiles decrease. Furthermore, when the hybrid nanofluid is used compared to common nanofluid, the heat transfer coefficient will increase significantly. It is also observed that when the Hartmann number increases, Nusselt number increases, too.