Thermogravitational convection in hybrid ferrofluids under magnetic field-dependent viscosity in a split-baffle enclosure

Purpose This study aims to investigate the influence of magnetic-field-responsive nanofluids on convective heat transfer within a wavy energy storage enclosure, considering the combined effects of thermal radiation, surface waviness, cold baffles and magnetic-field-dependent viscosity to enhance thermal performance under realistic conditions. Design/methodology/approach The left wall of the cavity is maintained at a high temperature, while the right wall is kept at a low temperature. The remaining boundaries are assumed to be adiabatic. The cold split baffles are vertically located at the center of the enclosure. The governing momentum and energy transport equations are solved using the finite difference method. The effects of key dimensionless parameters, namely the Rayleigh number, Darcy number, radiation parameter, heat source/sink parameter, Hartmann number, magnetic number, magnetic field inclination angle and nanoparticle volume fraction are systematically investigated. Findings The results demonstrate that increasing enclosure waviness and optimal positioning of cold baffles significantly enhance fluid circulation and disrupt thermal boundary layers, leading to improved heat transfer rates. An increase in the magnetic number (δ) from 0.0–1.0 leads to a reduction in the average Nusselt number for both mono- and hybrid nanofluids. Originality/value This work presents a novel integrated analysis of radiative heat transfer, magneto-viscous effects and geometric flow modulation within a wavy enclosure. The combined consideration of these factors offers new insights into the design of magnetically controlled thermal management systems, with practical relevance to advanced energy storage devices, battery cooling and high-temperature renewable energy applications.