Hydrodynamic and thermal behavior of tandem, staggered, and side-by-side dual cylinders

This study investigates the impact of arrangement of two cylinders on their flow-induced vibrations (FIV) and heat transfer behavior at a Reynolds number of 100. Both cylinders were allowed to vibrate in two degrees of freedom (2DOF), encompassing streamwise and transverse directions. The arrangement of identical circular cylinders was varied across tandem (α = 0°), staggered (α = 30°, 45°, 60°), and side-by-side (α = 90°) configurations, at a constant center-to-center distance of 6D. The cylinders were heated at a fixed temperature to observe the forced convection heat transfer behavior under the influence of 2DOF FIV. To observe the FIV, the reduced velocity was varied from Ur = 0 (stationary cylinders) to 14. Results unveiled cylinder response sensitivity, encompassing vibration and heat transfer, with respect to reduced velocities and arrangements. Tandem arrangement exhibited the greatest vibrations for both cylinders. While lower drag was experienced in tandem for cylinder 2 (C-2), it escalated in staggered positioning. Both cylinders experienced lock-in between Ur = 6 and 8 for all arrangements, involving significant transverse vibration amplitudes. Maximum streamwise vibration reached 6.07% of the maximum transverse vibration for C-2 and 2.34% for C-1. Distinct slender “figure-8” and “oval-shaped” cylinder trajectories emerged, accompanied by diverse vorticity patterns in cylinder wakes across arrangements. For α = 60°, C-2 experienced 75.3% lower transverse vibration and 9.4% higher average Nusselt number compared to tandem setup. Overall, a pronounced correlation emerged between cylinder hydrodynamic behavior and heat transfer characteristics, evident through cylinder vibration, vortex shedding, average Nusselt number, and temperature distribution results.