Analysis of Natural Convection Under the Effect of Nanoparticles Brownian Motion and a Periodic Magnetic Field Utilizing CuO–Water Nanofluid

In this article, our study aims to enhance the understanding of two-dimensional flow control by modifying specific geometric parameters and applying an external non-uniform magnetic field to the flow. The objective is to explore the influence of these modifications on flow characteristics and analyze how these adjustments can be used to impact the overall thermal behavior of the system. The studied cavity is square-shaped and filled with a nanofluid composed of CuO dispersed in water. A semi-circular cooler is positioned along the left side wall. The phenomenon of Brownian motion in nanoparticles is included in the models describing thermal conductivity and dynamic viscosity. The lattice Boltzmann method (LBM) is utilized to derive the nonlinear dimensionless governing equations. The influence of pertinent parameters such as the Rayleigh number, Hartmann number, Periodic magnetic field and nanoparticle volume concentration on the flow and heat transfer characteristics has been examined. In this investigation, it is noted that incorporating the influence of Brownian motion of nanoparticles enhances heat transfer by more than 6%. Conversely, the presence of a magnetic field introduces a contrasting effect, manifesting in a tendency to decelerate the flow dynamics. Furthermore, the numerical results indicate an increase in the average Nusselt number with a rise of the Reynolds number and the period of the periodic magnetic field. Additionally, the findings suggest that a greater average heat transport rate is observed for the non-uniform magnetic effect when λ = 0.75, considering the impact of Brownian motion, and that the average Nusselt number for this case increased by 23.59% compared to the case where the applied magnetic field is uniform.