Effect of the magnetic field on the heat transfer enhancement of nanofluids in rectangular enclosures

¹ Rabat National School of Mines (ENSMR), BP: 753 Agdal-Rabat, Morocco
² Research team in Smart Electrical, Mechanical and Energy Systems (SEMES), Polydisciplinary Faculty, University of Sultan Moulay Slimane, Beni Mellal, Morrocco
³ Multidisciplinary Research Laboratory in Physics (M.R.L.P), Polydisciplinary Faculty, Sultan Moulay Slimane University, Beni Mellal, Morocco
⁴ Laboratory of Intelligent Systems, Advanced Mechanics and Renewable Energy, Faculty of Sciences and Technologies, Sultan Moulay Slimane University, Beni-Mellal, Morocco

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 22 May 2026

Abstract

The application of a magnetic field tends to reduce the convective flows in enclosures, thereby decreasing convective heat transfer. However, adding nanoparticles to the fluid improves both thermal conductivity and viscosity, thus improving the conductive heat transfer. The enhanced total heat transfer is desirable in engineering problems like cooling systems for electronic devices. Therefore, the research for the best control of the pertinent parameters is a must. In this study, nanofluid convective heat transfer is investigated, seeking the best control of the governing parameters, namely, the Hartmann number 0≤Ha≤80, aspect ratio 0.25≤A≤4, and Al₂O₃ nanoparticle volume fraction 0≤φ≤0.05. Results show that the relationship between the heat transfer and nanoparticle volume fraction is different depending on A and Ha. In the absence of a magnetic field, there exists a critical value of A beyond which this relationship changes from enhancing to deteriorating heat transfer, whereas the application of a magnetic field leads to enhanced heat transfer with the use of nanofluids in horizontal enclosures which is due to the weakening effect on the flow that the magnetic field plays and leads to a strengthening effect of the nanofluid thermal conductivity over viscosity.