Multi-mechanism entropy generation analysis in electromagnetic controlled mixed convection of liquid sodium systems

Liquid sodium is a promising working fluid for electromagnetically (EM) controlled thermal-hydraulic systems due to its high electrical conductivity and thermal diffusivity. However, quantitative understanding of mixed convection under coupled EM effects remains limited. This study numerically investigates Lorentz-force-driven mixed convection in a rectangular channel under DC electric fields (0.047–0.234 V/m) and magnetic fields (0.05–1.07 mT, Ha = 1–20) at Ra = 5 × 10⁶ and 1 × 10⁷. Using a non-equilibrium thermodynamic framework, we analyze EM field effects on flow structure, heat transfer, and multi-source entropy generation. Results reveal that buoyancy-Lorentz force interaction leads to distinct flow regimes and non-monotonic heat transfer. Notably, EM forcing modifies the thermal boundary layer and induces partial decoupling between flow intensity and Nusselt number: increased flow strength does not always enhance Nu . Entropy analysis shows thermal irreversibility dominates overall dissipation, with its distribution strongly influenced by temperature field restructuring. These findings demonstrate EM fields as effective tools for regulating convective heat transfer and controlling irreversibility, providing a theoretical basis for active optimization of liquid metal thermal-hydraulic systems in advanced nuclear applications.