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

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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 (α) were examined by varying α from 30° to 90° 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 α 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 α reaches 90°, the streamwise amplitude becomes almost negligible. At α = 30° and 45°, the average Nusselt number of the downstream cylinder is generally lower than that of the upstream cylinder. However, when α reaches 60°, 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.