Shapes of hanging viscous filamentsM. Le Merrer, J. Seiwert, D. Quéré and C. Clanet
Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS, ESPCI - 75005 Paris, France, EU and Ladhyx, UMR 7646 du CNRS, École Polytechnique - 91128 Palaiseau Cedex, France, EU
received 31 July 2008; accepted in final form 4 November 2008; published December 2008
published online 16 December 2008
We discuss the evolution of the shape of viscous filaments (such as honey threads) placed horizontally in the gravitational field. When attaching both ends of the filament to solid walls, the center of the filament falls down. Hence, a catenary forms and extends as a function of time, owing to gravity. However, it was noted by Koulakis et al. that a second shape roughly consisting of three perpendicular pieces (evoking a flying trapeze) is sometimes observed. We try here to understand the origin of this U-shape. We show in particular that its origin is independent of the liquid viscosity, and fixed only by the geometric characteristics (length and radius) of the (initial) filament.
68.03.Cd - Surface tension and related phenomena.
68.03.Kn - Dynamics (capillary waves).
67.25.dg - Transport, hydrodynamics, and superflow.
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