Exploring the heat transfer performance and vortex-induced vibration characteristics of cylinders near a heated surface

To effectively harness vortex-induced vibration (VIV) for enhancing heat dissipation from a hot wall, this paper presents a series of studies on the VIV behavior of a cylinder near a wall and its heat transfer characteristics. The focus is on the effects of near-wall distance and the spacing ratio between cylinders in tandem on vibration response and heat transfer performance. Detailed analyses are provided for the amplitude–frequency response, lift–drag ratio, temperature distributions, averaged Nusselt number, and near-wake vortex structures. The research shows that a very narrow near-wall distance can partially suppress cylinder vibration and reduce the transport of cold fluid between the cylinder and the hot wall. Conversely, an excessively large near-wall distance diminishes the positive impact on heat transfer. For cylinders in tandem, strong interaction between the upstream and downstream cylinders at small spacing ratios leads to significant fluctuations in the averaged temperature on the wall. Specifically, the averaged temperature on the wall dropped to 326.41 K when S/D = 10.0 and U* = 6. At larger spacing ratios, the upstream cylinder exerts a shielding effect on the downstream cylinder, inhibiting its vibration and reducing its ability to enhance heat transfer through VIV. When U* ≥ 7, the averaged temperature on the wall initially decreases and then increases as the spacing ratio increases. The results indicate that cylinders in tandem with transverse free vibration achieve optimal heat transfer efficiency at H = 3.0D and S/D = 10.0.