Abstract
The characteristics of a velocity fluctuation in the wake of an axisymmetric body were measured from a rotating frame of reference. The results were compared with those in a two-dimensional flow. The following was made clear. In the rotating flow field, the mixing and diffusion of the wake are promoted by both the oncoming flow which is sheared in the spanwise direction and the intense radial outward flow in the dead flow region of the wake. Therefore the dead flow region becomes narrower and the wake width increases more quickly than in the two-dimensional flow. Vortex shedding is less regular and the circulation of the vortex is weakened. The amplitude of velocity fluctuation is smaller and its maximum position, representing vortex shedding, is closer to the body than that in the two-dimensional case. The velocity fluctuation shows a cellular structure in the spanwise direction, the scale of which is about one characteristic length of the body. This mechanism is related to the radial flow in the wake.
