Eduction of coherent structures in the turbulent plane wake

A new technique is developed for the eduction of large-scale coherent structures in fully-turbulent shear flows without any auxiliary reference signal. The eduction scheme is based on the recognition of large-scale vorticity, i.e. the key coherent structure property itself. With this method, coherent structures are educed in the nearly self-preserving region of the turbulent wake of a circular cylinder at a Reynolds number of 13,000. Topological features of the coherent structure and the associated incoherent turbulence characteristics demonstrate the significant role of vortex stretching at the 'saddle' in entrainment, mixing and turbulence production.