An experimental study is made on the processes of heat transfer from the surface of a
forced oscillating cylinder in a crossflow. A range of oscillation amplitude (A/D
=0.1,0.2), forced oscillation frequency (0<St_c<1), and Reynolds number (Re=550,
1100, 3500) is covered in water (Pr=6). Besides the increase at the natural vortex
shedding frequency, large increases in the heat transfer are found at certain superharmonics.
By using Digital Particle Image Velocimetry/Thermometry (DPIV/T), the increase
in the heat transfer rate is found to correlate inversely with the distance at which
vortices roll-up behind the cylinder, i.e., the distance decreases when the heat transfer
increases. The cause of the increase is found to be the removal of the stagnant and low
heat convecting fluid at the base of the cylinder during the roll-up of the vortices
