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On large-amplitude pulsating fountains

Published online by Cambridge University Press:  10 July 1998

CHRISTOPHE CLANET
Affiliation:
Department of Applied Mechanics and Engineering Sciences, University of California San Diego, La Jolla, CA 92093–0411, USA Present address: Institut de Recherche sur les Phénomènes Hors Equilibre, Université de Provence, centre de St. Jérôme, service 252, Marseille Cedex 20, France.

Abstract

We study the behaviour of an upward vertical water jet of density, ρ, and surface tension, σ, injected through a tube of diameter, D, with a momentum-averaged velocity, V. These fountains are shown to exhibit large-amplitude oscillations in the range 0.1[les ]D/a[les ]1.6, and 20[les ]V2/(gD)[les ]400, where g is the acceleration due to gravity and a is the capillary length, a≡(2σ/(ρg))1/2. The characteristic frequency of the oscillations, f, and their limits of existence are studied experimentally. A model is developed, leading to the expression for the frequency:

formula here

This expression is shown to be in good agreement with existing data and with new measurements, conducted over a wide range of Bond (BoD/a) and Froude (FrV2/gD) numbers. The stability of the model is considered and the limits of the oscillatory regime are related to the hydrodynamic properties of the flow.

Type
Research Article
Copyright
© 1998 Cambridge University Press

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