Natural Convective Heat Transfer inside a Square Cavity Filled with Hybrid Nanofluid under the influence of Oblique Variable Magnetic Field with Statistical Analysis

Abstract

The optimization and sensitivity analysis of the unsteady natural convective heat transfer flow of Cu-Al₂O₃/H₂O hybrid nanofluid in a square cavity under the influence of an oblique variable magnetic field are investigated numerically and statistically in this work. Brownian motion is taken into account in the hybrid nanofluid thermal conductivity model. The dimensionless governing equations with a sinusoidal boundary condition applied to the left heated wall have been solved using the Galerkin-based finite element method. A substantial degree of agreement is found after a comparison with earlier published findings. Results pertaining to average Nu and isotherms are presented. Tabular and graphical forms are used to present the Nu_ave. The study analyzes the sensitivity of parameters including λ, d_p and the hybrid nanoparticle volume percentage using response surface methods. The process can be optimized and the best conditions for achieving the highest heat transfer rate can be found by using response surface policy. The magnetic field and its alignment have a major impact on the hybrid nanofluid's flow pattern. The findings show that when the hybrid nanoparticle volume percentage, Ra and magnetic field inclination angle increase, the average Nu increases significantly. On the other hand, the diameter of the nanoparticles and the Hartmann number have opposing effects. The average Nu increases by 48.55% for Ra = 10⁴ with  and by 18.53% for the other case when Brownian motion is taken into account.

Jagannath University Journal of Science, Volume 12, Number 1, Jun. 2025, pp. 65−86