Abstract: An analysis of the impact of the magnetic field on the flow of the Al₂O₃-water nanofluid which results from the natural convection that occurs inside a cavity having a non-regular shape was investigated. For this study the monophasic model is applied. Analytical solution of the transport equations is difficult; therefore, the use of Ansys-Fluent software appears essential. An analysis of the impacts of Rayleigh numbers (7.68.10⁴, 1.5.10⁵ and 3.072.10⁵) and Hartmann (0 to 75) as well as the concentration of nanoparticles expressed as a percentage (0 to 5%) on heat transmission and entropy production was exposed. Numerical results are expressed in form of streamlines, isotherms and Nusselt number. Mean Nusselt number and entropy production vary proportionally with the Rayleigh number and the volume fractions of the particles and they are inversely proportional to the Hartmann number. For volume fractions of the chosen Al₂O₃ nanoparticles, heat transfer is improved. After analysis of obtained results, correlations for Nusselt number expressed as an expression of two variables which are Hartmann and volumes fractions of nanoparticles have been proposed to predict the rate of heat transmission inside the enclosure. These laws are rarely presented in this kind of study.

Keywords: Magneto-hydrodynamic, free convection, nanofluid, enclosure, entropy production.