Hydromagnetic thermosolutal transient forced convection of radiative ternary hybrid ferrofluid with Casson fluid in a channel with a cavity and cylindrical obstacle

This study investigates a non-Newtonian ternary hybrid ferrofluid's forced convection and magnetohydrodynamic flow within a two-dimensional channel featuring a cavity and a cylindrical obstruction. The working fluid is modeled using the Casson rheological framework and consists of water as the base fluid with suspended copper (Cu), magnetite (Fe3O4), and silica (SiO2) nanoparticles. A uniform inclined magnetic field of strength B0 is applied at an angle ψ, influencing flow stability and convective transport. The primary objective is to analyze the coupled effects of non-Newtonian behavior, ternary ferrofluid composition, and magnetic field interactions on heat and mass transfer. The dimensionless governing equations, including the Casson-modified incompressible Navier–Stokes, energy, and species transport equations, are solved numerically using the Galerkin-based finite element method. This approach is chosen for its robustness in handling complex geometries and boundary conditions. Key findings indicate that increasing the Hartmann number (Ha) suppresses vortex structures, leading to a reduction of 45.7% and 58.4% in the average Nusselt (Nuavg) and Sherwood (Shavg) numbers, respectively, at ψ=0°. Conversely, at ψ=90°, the drag coefficient (CD) increases by 47.3%, while the pressure difference (ΔP) rises by 88.8%, highlighting stronger magnetic damping effects. The Casson parameter (γ) significantly enhances mass transfer, with Shavg increasing by 174% as the Lewis number (Le) rises, while heat transfer remains largely unaffected. Additionally, the ternary hybrid nanofluid improves Nuavg by 2.01% and reduces CD by 12.96%, though Shavg shows a slight decrease.