Uncovering the mystery of the vortex dynamics in a micropolar fluid with multiple magnetic field strips: A novel case study

Abstract

From transportation to energy production, environmental protection, and medical advancements, vortices are known to influence everything. Therefore, a remarkable aspect of engineering and scientific research in these areas is the prediction, control, and optimization of such vortices. Motivated by these potential applications, we numerically study ‘how confined magnetic fields may give rise to new vortices in the micropolar flow inside a square cavity, by employing the Alternating Direction Implicit approach. Unlike most of the previous studies, we do not assume a uniform magnetic field throughout the flow domain, which is more realistic. Instead, we introduce several confined magnetic fields in the form of multiple horizontal and vertical strips. Further, we have applied the theory of micropolar fluids proposed by Eringen to model the micropolar fluid and visualize the flow patterns around the magnetic strips in the flow regime. Using our self-developed MATLAB codes, we examine how various parameters, such as the magnetic field strength, the number and position of the strips, and the micropolar parameter affect the flow and thermal properties of the micropolar fluid. The findings of this study will contribute to a better understanding of the vortex generation and heat transfer enhancement of micropolar fluids in lid-driven cavities under localized magnetic fields. The study reveals that both the Nusselt number (Nu) and skin friction (CfRe) coefficient decrease by 45% and 1% respectively with a magnetic number (Mn) for a fixed Reynolds number (Re). However, increasing the Reynolds number at a fixed magnetic number increases the Nusselt number (909%) and skin friction coefficient (7%). This means that the higher flow velocity translates into increased wall shear stress and heat transfer, which destabilizes the flow and may cause turbulence. This knowledge can be used to develop new and improved micropolar fluid-based technologies for a variety of applications, such as energy production, medical devices, and microfluidics.