Magnetohydrodynamics forced convective flow of micropolar ferrofluid over double stationary cylinders inside a vented chamber

Abstract

This work delivers a comprehensive study on the magnetohydrodynamics (MHD) forced convective circulation of micropolar ferrofluid over two static cylinders placed within a vented cavity. The cavity has an inlet port at the left bottom and an exit port at the right top. The bottom wall has a constant heat flux source, whereas the other two walls (except the cold right wall) and the cylinder’s surfaces are adiabatic. A constant magnetic field is induced horizontally at the right wall. This study seeks to optimize heat transfer by arranging the cylinders in various configurations under the given conditions, and it also contributes to optimizing heat transfer in various engineering and industrial applications, particularly in systems where fluid flow and magnetic fields influence thermal performance. The leading equations for MHD forced convection heat transport in the cavity are solved using the finite element method. Micropolar Fe₃O₄-water ferrofluid acts as the working fluid to capture additional fluid behavior at small scales, including micro-rotation and viscous impacts on the heat transport process. The system’s thermal effectiveness can be assessed by the average Nusselt number on the heated wall, mean ferrofluid temperature, pressure coefficient, and performance evaluation criterion. Those performance parameters are computed for three configurations of the cylinder-pair with the selected ranges of Reynolds number (1 ≤ Re ≤ 10³), Hartman number (1 ≤ Ha ≤ 31.623), and material parameter (0 ≤ K ≤ 2) to understand the thermo-hydraulic characteristics. Upon extensive analysis, it is evident that the performance evaluation criterion varies significantly depending on the cylinder configurations. Heat transport in a cavity without a cylinder is less than in one with a cylinder pair at lower Reynolds numbers. The optimal horizontal position of the cylinder pair is three-fourths of the length of the cavity. The influence of the magnetic field on the average Nusselt number remains minimal across all Reynolds number ranges. Although the micropolar parameter has little effect at these lower Reynolds numbers, a rise in K leads to a decline in heat transport efficiency and an increase in pressure losses, adversely impacting thermal and hydraulic performance.