Faraday instability in a surface-frozen liquid.
Faraday surface instability measurements of the critical acceleration, a(c), and wave number, k(c), for standing surface waves on a tetracosanol (C24H50) melt exhibit abrupt changes at T(s)=54 degrees C, approximately 4 degrees C above the bulk freezing temperature. The measured variations of a(c) and k(c) vs temperature and driving frequency are accounted for quantitatively by a hydrodynamic model, revealing a change from a free-slip surface flow, generic for a free liquid surface (T>T(s)), to a surface-pinned, no-slip flow, characteristic of a flow near a wetted solid wall (T<T(s)). The change at T(s) is traced to the onset of surface freezing, where the steep velocity gradient in the surface-pinned flow significantly increases the viscous dissipation near the surface.
Huber
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Technische Physik, Universität des Saarlandes, 66041 Saarbrücken, Germany. p.huber@physik.uni-saarland.de
Soprunyuk
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VP
Embs
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JP
Wagner
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Deutsch
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Kumar
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