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|
|Article number||Art. No. 011706|
|Number of pages||4|
|Journal||Physics of Fluids|
|Publication status||Published - Jan 2005|