The circular cylinder in simple shear at moderate Reynolds numbers: An experimental study

The flow around a neutrally buoyant circular cylinder in simple shear was studied using particle-image velocimetry. Steady experimental results are presented for both torque-free and fixed cylinders at shear-based Reynolds numbers between 8 and 25 at two different flow confinement values. These data, which are to our knowledge the first experimental results for this Reynolds number range, show that the normalized rotation rate decays much more slowly with Reynolds number than previous theoretical predictions for unconfined flow, with the rate of decay decreasing as confinement increases. A new simple model is proposed to explain these effects. Given physical and technological limitations upon steady and unconfined flow experiments and simulations, the effect of confinement on a cylinder in simple shear merits further study.