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Spout States in the Selective Withdrawal System

Sarah C. Case·Sidney R. Nagel
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Abstract

In selective withdrawal, fluid is withdrawn through a nozzle suspended above the flat interface separating two immiscible, density-separated fluids of viscosities $ν_{upper}$ and $ν_{lower} = λν_{upper}$. At low withdrawal rates, the interface gently deforms into a hump. At a transition withdrawal rate, a spout of the lower fluid becomes entrained with the flow of the upper one into the nozzle. When $λ= 0.005$, the spouts at the transition are very thin with features that are over an order of magnitude smaller than any observed in the humps. When $λ= 20$, there is an intricate pattern of hysteresis and a spout appears which is qualitatively different from those seen at lower $λ$. No corresponding qualitative difference is seen in the hump shapes.

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Sarah C. Case, Sidney R. Nagel. 2006-08-07. Spout States in the Selective Withdrawal System. https://arxiv.org/abs/cond-mat/0608140

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