Numerical analysis of flow-induced vibrations and heat transfer in a triangular arrangement of circular cylinders

This numerical study explores the flow characteristics and heat transfer performance of three isothermal circular cylinders arranged in a triangular configuration at angles of attack of 45° and 60°. The impact of one-degree-of-freedom (1DOF) flow-induced vibrations (FIV) in the cross-flow direction on forced convective heat transfer is analyzed using ANSYS FLUENT, considering reduced velocities from 4 to 8 at a constant Reynolds number of 100. Comparative simulations are conducted for both stationary and vibrating cylinders. Results indicate that, when stationary, the cylinders at a 45° angle exhibit lower heat transfer rates compared to those at 60°, with a 2.66% reduction in overall heat transfer. The study also examines the nuanced effects of 1DOF FIV in the cross-flow direction on heat transfer: while the upstream cylinder generally experiences increased heat transfer during vibrations, the downstream cylinders often show reduced rates. Specifically, at a 45° angle, the most significant reduction in heat transfer from downstream cylinders, nearly 9.99%, occurs at reduced velocities of 5 and 6. For the stationary tube bundle at 45°, the average Nusselt number is 11.77, but it decreases by approximately 5.21% at a reduced velocity of 5 under vibration. Conversely, at a 60° angle, the average Nusselt number generally increases at higher reduced velocities, except at Ur = 4, where it drops by 2.89% from the stationary state. These findings highlight the complex interplay between 1DOF vibration and heat transfer in triangular cylinder arrangements.