### Abstract

In the outer region of fully developed turbulent pipe flow very large-scale motions reach wavelengths more than 8R-16R long (where R is the pipe radius), and large-scale motions with wavelengths of 2R-3R occur throughout the layer. The very-large-scale motions are energetic, typically containing half of the turbulent kinetic energy of the streamwise component, and they are unexpectedly active, typically containing more than half of the Reynolds shear stress. The spectra of the y-derivatives of the Reynolds shear stress show that the very-large-scale motions contribute about the same amount to the net Reynolds shear force, d - u′v′/dy, as the combination of all smaller motions, including the large-scale motions and the main turbulent motions. The main turbulent motions, defined as the motions small enough to be in a statistical equilibrium (and hence smaller than the large-scale motions) contribute relatively little to the Reynolds shear stress, but they constitute over half of the net Reynolds shear force.

Original language | English (US) |
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Pages (from-to) | 521-542 |

Number of pages | 22 |

Journal | journal of fluid mechanics |

Volume | 554 |

DOIs | |

State | Published - May 1 2006 |

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### ASJC Scopus subject areas

- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering

### Cite this

*journal of fluid mechanics*,

*554*, 521-542. https://doi.org/10.1017/S0022112006008871