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The fall of a viscous thread onto a moving surface: a ‘fluid-mechanical sewing machine’

Published online by Cambridge University Press:  15 November 2006

S. CHIU-WEBSTER
Affiliation:
Institute of Theoretical Geophysics, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK
J. R. LISTER
Affiliation:
Institute of Theoretical Geophysics, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, UK

Abstract

A viscous thread falling onto a steadily moving horizontal belt shows a surprisingly complex range of behaviour in experiments. Low belt speeds produce coiling, as might be expected from the behaviour of a thread falling onto a stationary surface. High belt speeds produce a steady thread, whose shape is predicted well by theory developed to describe a stretching viscous catenary with surface tension and inertia. Intermediate belt speeds show several novel modes of oscillation, which lay down a wide variety of patterns on the belt. The patterns include meanders, side kicks, slanted loops, braiding, figures-of-eight, Ws, and also period-doubled versions of figures-of-eight, meanders and coiling. The experimental boundary between steady and unsteady behaviour occurs at a slightly lower belt speed than the loss of the steady solution for a stretching catenary.

Type
Papers
Copyright
© 2006 Cambridge University Press

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