Thermal performance and entropy minimization of magnetohydrodynamic flow in a triangular domain with a rotating solid cylinder

Conjugate magnetohydrodynamic (MHD) mixed convection heat transfer in an isosceles triangular fluid domain with a heat-conducting spinning internal cylinder has been numerically examined in this study. The enclosure is filled with air, and the solid cylinder is made of low-carbon steel. A steady magnetic field is imposed in the domain, resulting in a magnetohydrodynamic effect on the system. The cylinder is placed at the center of the domain and spins in a clockwise or counterclockwise direction, inducing aiding or opposing forced flow within the system. The top surface of the domain is at an elevated temperature, while the right-tilted sidewall is at a reduced temperature, thereby enforcing a natural convection current. This conjugate thermal problem is mathematically modeled using the Navier-Stokes and energy equations, along with appropriate boundary and solid-fluid interface conditions. The numerical solutions are obtained by implementing the Galerkin finite element method. The present model is also validated before carrying out the parametric simulation for this study. The results are enumerated for the broad range of governing parameters, such as Reynolds number (31.62 ≤ Re ≤ 316.23), Richardson number (0.1 ≤ Ri ≤ 10), Grashof number (10 3 ≤ Gr ≤ 10 5 ), and Hartmann number (0 ≤ Ha ≤ 20) in terms of qualitative and quantitative evaluation of flow and thermal characteristics. The analysis reveals that introducing the MHD effect reduces heat transfer by approximately 5.3% for both clockwise and counterclockwise rotations of the cylinder. It increases the average fluid temperature for clockwise rotation by up to 4.9% and decreases it for counterclockwise rotation by approximately 2%. However, the MHD effect reduces entropy generation as flow intensity increases, thereby reducing the irreversibility caused by fluid friction. Additionally, the clockwise rotation of the cylinder exhibits better heat transfer.