We report herein experimental observations of the reciprocating motion of a self-propelled droplet floating on the surface of an aqueous surfactant solution and a simple reaction model capable of reproducing the observed behavior of the droplet. The reciprocating motion was observed in a quasi-one-dimensional annular channel, so the reciprocation was not caused by reflections at boundaries. To understand the reciprocation, our model assumes a reaction between the surface active substance emitted from the droplet and surfactants dissolved in the aqueous solution. This reaction invokes an inversion of the surface tension gradient and thus the droplet's reciprocation. We show that the model can reproduce experimental results semi-quantitatively using numerical simulations with realistic parameters.

中文翻译：

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自推进液滴往复运动的表面活性剂反应模型

我们在此报告了漂浮在表面活性剂水溶液表面上的自推进液滴的往复运动的实验观察结果以及能够再现观察到的液滴行为的简单反应模型。在准一维环形通道中观察到往复运动，因此往复运动不是由边界处的反射引起的。为了理解往复运动，我们的模型假设液滴释放的表面活性物质与溶解在水溶液中的表面活性剂之间发生了反应。该反应引起表面张力梯度的反转，并因此引起液滴的往复运动。我们表明该模型可以使用具有实际参数的数值模拟半定量地再现实验结果。