Role of localized magnetic field in vortex generation in tri-hybrid nanofluid flow: A numerical approach

Abstract Tri-hybrid nanofluid (THNF) can achieve a higher heat transfer rate than conventional hybrid nanofluid by combining three different nanoparticles with synergistic effects. It can have more diverse physical and thermal properties by choosing different combinations of nanoparticles. That is why it has more potential applications in various fields such as solar thermal, biomedical, and industrial processes. On the other hand, vortices are circular motions of liquid or gas that occur when there is a velocity difference. They are important for understanding how fluids mix and transport mass. They can be found in nature, such as in tornadoes and hurricanes. The aim of the current study is to mainly investigate the complex interaction of Lorentz force with the tri-hybrid nanoparticles inside a lid-driven square cavity. It can be seen that the magnetic field has caused the evolution of new vortices (which are very important while analyzing any flow model due to their importance in interpreting fluid mixing and mass transport phenomena) in the flow field, thus adding much more significance to our work. Most of the scientific literature is enriched with investigations dealing with the problems assuming a uniform magnetic field occupying the flow field, but in this research, a vertical strip of magnetism within the flow field will be introduced. It may be the first effort to interpret the role of the applied magnetic field in the formation of the new vortices in the flow field. A single-phase model is utilized to describe THNF whereas a numerical solution to the governing differential equations has been obtained by employing an algorithm based on the central difference discretization and the alternating direction implicit method. The analysis reveals that the magnetic field intensity may result in up to 13 and 119% increase in the skin friction and Nusselt number, respectively. Similarly, a remarkable change in the Nusselt number and the skin friction is also observed by raising the Reynolds number Re. Moreover, the localization or confinement of the magnetic field does not always increase or decrease the Nusselt number. Thus, it is concluded that there will be a certain width of the magnetic corridor for which the Nusselt number would be optimal. Further, the THNF containing Al2O3, Ag, and TiO2 outperforms in terms of enhancing the average Nusselt number, compared to the simple nanofluid containing the abovementioned particles.