Magnetic field effect on natural convection in a nanofluid-filled square enclosure

This paper examines the natural convection in an enclosure that is filled with a water-Al2O3 nanofluid and is influenced by a magnetic field. The enclosure is bounded by two isothermal vertical walls at temperatures Th and Tc and by two horizontal adiabatic walls. Based upon numerical predictions, the effects of pertinent parameters such as the Rayleigh number (103 ≤ Ra ≤ 107), the solid volume fraction (0 ≤ ϕ ≤ 0.06) and the Hartmann number (0 ≤ Ha ≤ 60) on the flow and temperature fields and the heat transfer performance of the enclosure are examined. Prandtl number is considered to be Pr = 6.2. The results show that the heat transfer rate increases with an increase of the Rayleigh number but it decreases with an increase of the Hartmann number. An increase of the solid volume fraction may result in enhancement or deterioration of the heat transfer performance depending on the value of Hartmann and Rayleigh numbers.