Three-dimensional vortical structure was investigated behind a sphere through circular multiple probe measurement. In the range of Re{sub}d≈800～7000, the low mode St number was kept constant around St{sub}L≈0.2 while the high mode St number increased discontinuously with Red. The fact means that an integral number of the small-scale high mode vortices make one large-scale low mode structure. The high mode vortex has a hairpin-shaped sculpture and the low mode structure possesses either a helical or a staggered arrangement. The high mode vortices included in the low mode structure of helical arrangement circulate on the multiple probe surface once every period of the low mode rotation, whereas the rotational direction changes at random. In the low mode structure of the staggered arrangement, a pair of the hairpin vortices alternately appears on the opposite side of the multiple probe every half period of the low mode.
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