Effect of magnetohydrodynamics on heat transfer intensification and entropy generation of nanofluid flow inside two interacting open rectangular cavities

MHD mixed convection heat transfer and entropy generation analysis for Cu–water nanofluid inside two interacting open cavities are numerically investigated. The right and the left walls of each cavity are heated or cooled at uniform but different heat flux densities. The nanofluid flow is described by the Buongiorno model in order to take into account the thermophoresis effect and the Brownian motion. The governing equations are solved using the finite volume method with the SIMPLE algorithm. The effects of relevant parameters including the Hartmann number (Ha), the Richardson number (Ri), the opening ratio (R), the heat flux ratio (R_q) and the nanoparticles volume fraction (ϕ_i) are analyzed. The results show that the flow pattern resulting from the simultaneous action of the magnetic field and the buoyancy force is heightened by the decrease in Ha and R and the increase in Ri and R_q. The heat transfer, which evolves in a non-monotonous way with the Hartmann number, is enhanced by the rise of the Richardson number, the heat flux ratio and the nanoparticles volume fraction, as well as by the reduction in the opening ratio. It is also observed that, overall, the thermodynamic disorder is dominated by the thermal irreversibility which decreases at high Ha with the augmentations of Ri and ϕ_i and the reductions in R and R_q.