Numerical investigation of turbulent convection inside a square cavity under oblique magnetic field

Abstract

This study examines turbulent natural convection in a differentially heated cavity containing a Cu-water nanofluid under an oblique magnetic field. The novelty lies in investigating the effects of turbulence, magnetic-field inclination and nanoparticle concentration over a wide range of governing parameters. The standard “k-ε” turbulence model was implemented and the problem was solved using the finite element method. Key parameters include Rayleigh number (Ra = 107–109), Hartmann number (Ha = 0–6400), magnetic field inclination angle (γ = 0−90°) and nanoparticle volume fraction (φ = 2–6%). Results demonstrate that heat transfer intensifies with increasing Rayleigh number, with the Nusselt number rising by 97.5% from Ra = 107 to 109 but reducing by 57.2% at Ha = 6400. An inclination angle of γ = 60° was found to optimize heat transfer, resulting in an 11% increase in the Nusselt number compared to γ = 0° at Ha = 6400. Furthermore, increasing the nanoparticle concentration improved the thermal performance, with the Nusselt number increasing by 25.1% as φ rose from 0.02 to 0.06. Overall, these findings indicate that heat transfer can be effectively controlled by precisely adjusting the external magnetic field and nanoparticle loading.