Abstract
A wake behind a circular cylinder at Reynolds number 850-1700 was visualized by the smoke-wire method. The observations of the flow together with the results of quantitative measurements, such as various velocity correlation coefficients, illustrated the formation process of spoon-shaped large eddies in the region 90≤x/d≤230 attained through the deformation and rearrangement of the regular Kármán vortices. A spoon vortex was likely to pair with the counterpart on the opposite side of the wake. The large scale bulges of the turbulent and non-turbulent interface of the wake were shown to correspond to these spoon vortices.
These results indicate that some of coherent structures are organized by rearrangement and deformation of initially regular vortex in the turbulent flow.
