Natural convection of a magnetizable hybrid nanofluid inside a porous enclosure subjected to two variable magnetic fields

Abstract

This problem deals with natural convective heat transfer of a magnetic nanofluid in a porous medium subjected to two variable magnetic sources. In many industrial processes, heat transfer is affected by magnetic sources. The equations governing the problem were solved, using the finite element method. The study results were compared to literature ones and a very good consistency was found. The effects of different parameters, namely the magnetic number (Mnf = 100–5000), the strength ratio of the two magnetic sources (γr = 0.2–5), Hartmann number (Ha = 0–50), and porosity coefficient (ε = 0.1–09), on natural convective heat transfer inside a porous cavity have been examined. At low Rayleigh numbers, the average Nusselt number was independent of the strength ratio of the two magnetic sources. At high Rayleigh numbers, the Nusselt number decreases first with increasing the strength ratio of the two magnetic sources and then remains constant. Results also showed that at Ra = 1e4, the Nusselt number increases with increasing the magnetic number; whereas, at Ra = 1e6, the magnetic number has an increasing impact on the Nusselt number only at high γr values.