We study the motion of a drop of oil inside a capillary tube induced by a gradient of surfactant concentration. We first show that the wetting condition selects whether the drop moves towards or away from the surfactant. We then focus on the non-wetting case, for which the drop eventually escapes from the tube, and explore the different dynamics of propulsion. On a long time scale, we observe two regimes: either the drop reaches a constant velocity, or it moves intermittently, by successive jumps and stops. As a paradoxical consequence, viscous drops can be as mobile or even faster than inviscid ones. © 2011 The Royal Society of Chemistry.
CITATION STYLE
Piroird, K., Clanet, C., & Quéré, D. (2011). Detergency in a tube. Soft Matter, 7(16), 7498–7503. https://doi.org/10.1039/c1sm05282a
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