Time-resolved stereoscopic particle image velocimetry is used to investigate the structure of the very-large-scale motions (VLSMs) in fully developed turbulent pipe flow. The motions are visualized using snapshot proper orthogonal decomposition. It is shown that the structures can be reconstructed using a small number of the most energetic modes. The results strongly suggest a possible connection between the origin of the VLSM and linear stability analysis. The structures are seen to be highly three-dimensional, meandering azimuthally and radially. At this Reynolds number (ReD=12 500), they occasionally extend from the near-wall region to the wake region of the pipe.
All Science Journal Classification (ASJC) codes
- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Fluid Flow and Transfer Processes