Abstract
In the previous paper the authors have reported that the two-dimensional Kármán vortices behind a circular cylinder are deformed, until they form chains of spoon-shaped vortex couples whose spanwise scale is about 8d, which is a new type of coherent structure. In this report experimental evidence of this structure is presented. Formation process of the structure and the turbulence in it were investigated for the wake behind a circular cylinder with Re=2100 and 4200 by means of the flow visualization technique, simultaneous hot wire measurements, spanwise correlation measurements, construction of instantaneous velocity field by the conditional sampling method, etc.
