Effect of Diagonal Magnetic Field on Natural Convection of Nano-Fluid Inside a Square Enclosure with Two Variable Heat Sources

In this research, the natural convection heat transfer for a square enclosure containing two Nano-fluids, water-alumina and water-copper, which is affected by a diagonal magnetic field, is simulated numerically and the effects of some parameters such as Rayleigh number ( ), Hartmann number ( ), magnetic field angle ( ), nanoparticle volume fraction ( ), type of heat source (linear or sine), length of the heat source ( ) and the non-uniformity parameter of the source ( ) have been studied on the flow and temperature fields. The results show that with increasing Rayleigh  number and Hartmann number, the amount of heat transfer increases and decreases, respectively. Also, the thermal performance of the enclosure is improved by increasing the angle of the magnetic field (from 0 to 90 degrees) and by adding solid nanoparticles to the base fluid, it means a relative increment in enclosure heat transfer is observed. In both high and low Rayleigh numbers, the maximum heat transfer is related to the constant temperature source. After that, for high Rayleigh numbers a sinusoidal source (λ = 1) and for low Rayleigh numbers a linear source (λ =0.5), where the conduction heat transfer dominates on enclosure, have the highest average Nusselt number, respectively. The results also indicate that when the length of heat sources increases, the rate of heat transfer increases too.