Akademik Veri Yönetim Sistemi
INTERNATIONAL JOURNAL OF HEAT AND FLUID FLOW, cilt.121, sa.110467, ss.1-17, 2026 (SCI-Expanded, Scopus)
In this study, forced convective heat transfer of ferrofluids flowing through a circular tube under constant magnetic fields with varying field directions is investigated experimentally. For heat transfer enhancement, a multidirectional magnet arrangement incorporating stepwise angular rotations along the tube axis is proposed and implemented. To provide a comprehensive assessment, several magnet configurations with distinct axial and angular variations are examined. Experiments are performed using water-based ferrofluids with nanoparticle volume fractions of 0.5% and 1% over a Reynolds number range of 400–1000. Local and average Nusselt numbers, together with pressure drop characteristics are evaluated to assess the coupled thermal and hydraulic behavior of the system.
The results demonstrate that stepwise variations in the direction of a constant magnetic field can be an effective strategy for enhancing heat transfer rates. Among the tested magnetic field configurations, the arrangement incorporating 45 ◦ stepwise rotation exhibited the highest performance, yielded increases of up to 140% in local and 43% in average Nusselt numbers. The observed enhancements are interpreted in terms of magnetically induced flow reorganization and localized boundary layer disruption, supported by supplementary visual observations of particles. Notably, these improvements are achieved without any noticeable increase in pressure drop compared with conventional configurations, confirming the superior thermohydraulic efficiency of the proposed magnet arrangement.