## Abstract

An upper bound lambda(max) on the friction factor lambda is found for transitional pipe flow up to Reynolds numbers of Re=4000. This bound corresponds to the laminar Hagen-Poiseuille value until the energy stability point of Re=81.52 (where lambda(max)=0.7851) after which it decreases monotonically to approach a viscosity-independent asymptote of 0.27+/-0.01 as Re-->infinity. Comparison is made with the friction factors associated with recently discovered, finite-amplitude traveling waves in rotating and nonrotating pipe flow as well as experimental data. (C) 2005 American Institute of Physics.

Translated title of the contribution | A friction factor bound for transitional pipe flow |
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Original language | English |

Article number | Art. No. 011706 |

Pages (from-to) | 011706 |

Number of pages | 4 |

Journal | Physics of Fluids |

Volume | 17 (1) |

Publication status | Published - Jan 2005 |