Spontaneous generation of spiral waves by a hydrodynamic instabilityM. Habibi1, 2, P. C. F. Møller1, N. M. Ribe3 and D. Bonn1, 4
1 Laboratoire de Physique Statistique, UMR 8550 CNRS, École Normale Supérieure - 24, rue Lhomond, 75231 Paris Cedex 05, France
2 Institute for Advanced Studies in Basic Sciences (IASBS) - Zanjan 45195-1159, Iran
3 Institut de Physique du Globe de Paris and Université de Paris-7, CNRS, Tour 14 - 2, place Jussieu, 75005 Paris, France
4 Van der Waals-Zeeman Institute, University of Amsterdam - Valckenierstraat 65, 1018 XE Amsterdam, The Netherlands
received 25 April 2007; accepted in final form 4 December 2007; published February 2008
published online 3 January 2008
The coiling of a thin filament of viscous fluid falling onto a surface is a common and easily reproducible hydrodynamic instability. Here we report for the first time that this instability can generate regular spiral patterns, in which air bubbles are trapped in the coil and then advected horizontally by the fluid spreading on the surface. We present a simple model that explains how these beautiful patterns are formed, and how the number of spiral branches and their curvature depends on the coiling frequency, the frequency of rotation of the coiling center, the total flow rate, and the thickness of the spreading fluid film.
83.60.Wc - Flow instabilities.
47.54.-r - Pattern selection; pattern formation.
47.35.-i - Hydrodynamic waves.
© EPLA 2008