Eduction of large-scale organized structures in a turbulent plane wake

Large-scale organized structures in the turbulent plane wake of a circular cylinder are investigated in air. Particular emphasis is placed on examining alternative general schemes for educing coherent structures in natural or unexcited turbulent shear flows, especially in their fully developed states. From successive accepted structure signatures the instants of occurrence of structure centres (i. e. smoothed vorticity peaks) are identified. Unsmoothed signals are then time-aligned with respect to these instants and ensemble averaged to educe coherent structure and incoherent turbulence characteristics. Further enhancement is achieved by iteratively improving the time-alignment. Following this optimal scheme, large-scale coherent structures have been educed in the fully turbulent wake.