Synergistic effects of magnetic fields and Y-obstacles on a nanofluid-based split lid-driven thermal system

• A Y-shaped obstacle in a nanofluid-filled cavity enhances heat transfer substantially. • An optimal magnetic field angle of 75° maximizes overall heat transfer. • Entropy generation analysis reveals system irreversibilities. • Higher reynolds numbers improve fluid mixing and heat transfer. • Complex interplay between forced convection, buoyancy, and MHD effects. This study investigates the complex hydrothermal behavior in a novel split-driven square cavity filled with CuO-water nanofluid and featuring a Y-shaped obstacle. The research explores the interplay among mixed convection, magnetohydrodynamics (MHD), and geometric factors in a previously unexamined configuration. The upper wall is split into two isothermally heated, translating sections, while the bottom wall and Y-shaped obstacle provide cooling boundaries. Using finite element analysis, we examine the effects of Reynolds number (Re = 10–200), Rayleigh number (Ra = 10 3 –10 6 ), Hartmann number (Ha = 0–70), and magnetic field inclination ( λ = 0–150°) on flow patterns, heat transfer, and entropy generation. Energy flux vectors are utilized to analyze thermal energy transport dynamics. Key findings are as follows. (1) Increasing Re enhances fluid mixing, resulting in up to a 65 % increase in the average Nusselt number (Nu). (2) Nu peaks at Ra ≈ 10 5 , then slightly decreases due to complex force interactions. (3) Increasing Ha suppresses convection, reducing Nu by up to 30 %. (4) Optimal heat transfer occurs at λ ≈ 75° (5) The Y-shaped obstacle enhances heat transfer by up to 30 %. These results provide insights for optimizing thermal management in applications requiring precise temperature control, potentially improving energy efficiency in advanced heat transfer systems.