Numerical investigation of ferrofluid jet flow and convective heat transfer under the influence of magnetic sources

Highlights: • Ferrofluid jet flow and heat transfer characteristics are numerically studied. • Effects of magnetic sources intensity Mn and jet inlet height R are considered. • Heat transfer is improved with the increase of Mn, and the reduction of R and X_i. • Pressure drops intensify with the augmentation of Mn and the diminution of R. • The most efficient system is obtained for Mn = 50 and R = 1/4. -- Abstract: This work presents a numerical investigation of convective heat transfer and confined ferrofluid jet flow through a channel under the influence of six magnetic sources placed outside the system and arranged in a staggered manner. The upper and the lower walls are maintained at a constant heat flux density, while the side walls at the inlet are thermally insulated. For the ferrofluid flow, the ferrohydrodynamics (FHD) and thermophoresis effects, as well as the Brownian motion are taken into account. The governing equations are solved numerically using the finite volume method with the SIMPLE algorithm. The influence of the magnetic number (Mn), the sources position (X_i), and the jet inlet height (R) on the flow as well as on the heat transfer characteristics is analyzed. The results show that the flow structure and the thermal boundary layers development are strongly disturbed by the presence of the magnetic sources as well as the narrowing at the channel inlet. The heat transfer is enhanced with the increase of the magnetic number Mn and the reduction of the opening ratio R. It is also found that the closer the sources from the channel inlet, the higher the heat exchange, with an optimal position depending on Mn and R. Finally, the comparison between the gain in heat transfer rate and the pressure drop indicates that the case R = 1/4 and Mn = 50 leads to the most efficient system.