Département de Mécanique, LadHyX, École Polytechnique–CNRS, 91128 Palaiseau, France
Revised 14 August 2001; revised and accepted 4 February 2002

The effect of increasing length on the stability of a hanging fluid-conveying pipe is investigated. Experiments show that
there exists a critical length above which the flow velocity necessary to cause flutter becomes independent of the pipe length.
The fluid-structure interaction is thus modelled by following the work of Bourrières and of Païdoussis. Computations using
a standard Galerkin method confirm this evolution. A short pipe model is then considered, where gravity plays a negligible
role. Transition between this short length model and the asymptotic situation is found to occur where a local stability criterion
is satisfied at the upstream end of the pipe. For longer pipes, a model is proposed where the zone of stable waves is totally
disregarded. Comparison of these models with experiments and computations show a good agreement over all ranges of mass
ratios between the flowing fluid and the pipe.

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