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Dombroski, Daniel E��¹��;��Crimaldi, John P��²

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Fine-scale aspects of stirring and mixing are examined in turbulent boundary layer flow using a three-dimensional planar laser induced fluorescence (3-D PLIF) system. Rhodamine 6G is released from a near momentumless source, flush with the bed of a laboratory flume. The flow rate and plume dynamics are comparable to what might be found in natural stream environments. Images of the turbulent flow are obtained using a high-speed digital camera. Individual frames, or “slices,” are reconstructed using 3D rendering software to produce volumetric flow information in an x-y-z coordinate system. The dynamics of scalar structure are demonstrated with movies of the three-dimensional evolution. Examination of instantaneous snapshots reveals the coherence of structures in three dimensions. Relationships between time-averaged scalar statistics and the instantaneous scalar field are explored.