Three-Dimensional Numerical Simulations of Flow Past a Rotating Circular Cylinder at a Reynolds Number of 500

Flow around a rotating circular cylinder at a Reynolds number of 500 is investigated numerically. The aim of this study is to investigate the effect of high rotation rate on the wake flow past a circular cylinder. Simulations are performed at a constant Reynolds number of 500 and a wide range of rotation rates from 1.6 to 6. Rotation rate is the ratio of the rotational speed of the cylinder surface to the incoming fluid velocity. It is found that increasing the rotation rate beyond a critical value results in transition to a secondary instability regime where the oscillation of the lift force on the cylinder increases drastically. There is significant increase in the three-dimensionality of the flow inside the secondary instability regime. The flow pattern in the secondary instability regime is characterized by ring-type vortices wrapping around the cylinder. The oscillation of the force coefficient in the secondary instability regime is very irregular.