Karman-type Vortices in the Wake of a Rotating Circular Cylinder

Flows past a rotating circular cylinder was investigated by using the dye injection method, and a computer simulation using the Vortex-in-Cell method was carried out. Results obtained by the two methods showed a good agreements. We found out that the Strouhal number increases and the width of the wake decreases as the spin parameter, which is the ratio of the peripheral speed of the cylinder to the uniform-flow velocity, increases. It is also shown that the predominant frequency of the wake, which corresponds to the frequency forming the Karman-type vortices, depends strongly on the Reynolds number.