Flow-induced vibration and heat transfer characteristics of three elliptical cylinders arranged in an isosceles triangle

This study investigates the flow-induced vibration (FIV) and heat transfer behavior of three heated cylinders arranged in an isosceles triangle configuration at a Reynolds number of 100. A dynamic model for the FIV of two-dimensional, elastically supported cylinders was developed using computational fluid dynamics simulations and overset mesh technology. The effects of aspect ratio (AR) and angle of attack (alpha) were examined by varying alpha from 30 degrees to 90 degrees and AR from 0.75 to 2.0, with AR = 1.0 corresponding to a circular cross section. To study FIV, the two-degree-of-freedom motion of the cylinders was analyzed across a range of reduced velocities (Ur = 2-12). The results indicate that as alpha increases, the impact of the upstream cylinder's wake on the downstream cylinders gradually weakens, resulting in lower vibration amplitudes and higher heat transfer rates for the downstream cylinders. Notably, when alpha reaches 90 degrees, the streamwise amplitude becomes almost negligible. At alpha = 30 degrees and 45 degrees, the average Nusselt number of the downstream cylinder is generally lower than that of the upstream cylinder. However, when alpha reaches 60 degrees, the average Nusselt number of the downstream cylinders becomes noticeably higher than that of the upstream cylinder. As the aspect ratio increases, the lock-in region of the cylinders shifts from being concentrated at Ur = 6 and 8 to Ur = 4 and 6, indicating that the increase in aspect ratio raises the vortex shedding frequency.