An experimental study of organized motions in the turbulent plane mixing layer

Large-scale coherent structures in a large, single-stream plane mixing layer of air have been investigated experimentally. The unforced, initially fully turbulent mixing layer rolls up into organized structures whose average passage frequency f//m at any downstream distance x from the lip depends on x. These structures are detected for the entire length of the measurement. The coherent-structure properties are educed in the developing and self-preserving regions of the mixing layer using an optimized conditional-sampling method, triggered on the peaks of a local reference signal obtained from the high-speed edge of the layer. Additional study results are discussed.