Flow separation on the cylinder surface causes significant pressure gradient and result in the formation of vortices, Karman vortex street in the wake of cylinder. The flow pattern of vortex shedding depends on the Rey-nolds number and it also causes fluctuation in drag and lift coefficients. Eventually, it gives rise to turbulent mixing in the wake region of the cylinder and thus vortex-induced-vibrations (VIV) are generated. These VIVs (generated when forcing frequency approaches natural shedding frequency) are very dangerous and they might even damage the cylindrical structures. Therefore, it is important to check wake flow structure in the downstream of cylinder. There are different active and passive control techniques to control the wake flow structure. One of the most used active flow control technique is to apply rotatory oscillation to the cylinder. A review is done therefore to analyze various experimental and numerical investigations performed on flow past a rotationally oscillating cylinder. Effect of rotation amplitude, forcing ratio, channel inlet spacing is reviewed. It is found out that it is very much possible to have substantial control over wake of the cylinder by forcing of rotatory oscillating motion to the cylinder. This mo-tion increases the vorticity of shear layer behind the cylinder and affects the instability of shear layer to a great ex-tent. This controlling method is found to be more effective at high Reynolds number. In other words, the impact of forcing is strongly dependent on the Reynolds number. After a careful review, it is suggested to assess the effect of rotational oscillation on wake structures of cylinder of different shapes like square, elliptical etc. in the flow.
Volume 11 | 01-Special Issue
Pages: 1315-1322