Study on the influence of the rotational degree of freedom on the heat transfer of single-y vibrating blunt bodies

Active rotation is commonly employed in traditional enhanced heat dissipation applications. However, passive rotation, which operates without external energy input, leverages environmental energy more effectively, showing great potential for enhanced heat transfer applications. This study explores the impact of passive rotation on the heat transfer characteristics of single-degree-of-freedom transverse vibrations in circular cylinders and square prisms. Numerical simulations were performed under the conditions of Re = 100, m* = 2, ζ = 0, and Pr = 0.7. The results show that the rotational degree of freedom has minimal influence on the heat transfer of circular cylinders, with only a 1.11 % increase in Nusselt number. In contrast, it significantly enhances heat transfer in square prisms, leading to a 14.21 % increase. Further analysis reveals that the rotational degree of freedom transitions the vibration mode from pure vortex-induced vibration (VIV) to a combination of VIV and galloping, which is the primary mechanism behind the heat transfer enhancement. Flow field analysis indicates that this transition strengthens vortex intensity and disturbs the thermal boundary layer, providing a microscopic explanation for the observed heat transfer improvements. The introduction of rotational freedom in such systems offers a novel and effective approach to enhance heat transfer performance.