Mechanisms of Enhanced Heat Transfer for Oscillating Circular Cylinders

Experiments were conducted to determine the relationship between wake structure and heat transfer for an oscillating circular cylinder in cross-flow. An internally heated cylinder was suspended in a water tunnel and oscillated transverse to the freestream. The cylinder’s heat transfer coefficient was measured over a wide range of oscillation amplitudes and frequencies. By comparing these results to the known wake mode regions in the amplitude-frequency plane, relationships between wake mode and heat transfer were identified. Representative cases were investigated further by using digital particle image thermometry/velocimetry (DPIT/V) to simultaneously measure the temperature and velocity fields in the near-wake. This revealed more detail about the mechanisms of heat transfer enhancement. The dynamics of the vortex formation process, including the trajectories of the vortices during roll-up, are the primary cause of the heat transfer enhancement.