The extreme mobility of droplets on non-wetting materials implies the necessity of controlling their motion, direction or speed. In this paper, we show how ridges allow us to tune drop friction. Depending on the liquid speed and viscosity, two regimes emerge: fast drops with low viscosity dynamically deform and undergo inertial friction, so that their velocity is eventually fixed by the deformations induced by the ridges; in contrast, viscous drops hardly interact with the texture, so that their velocity is classically limited by viscous dissipation, as on a flat substrate. The transition between these two regimes reveals spectacular morphological changes: drops with intermediate viscosity elongate and adopt worm-like shapes, which we qualitatively describe.

中文翻译：

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超疏水脊的摩擦特性

液滴在非润湿材料上的极端流动性意味着控制它们的运动、方向或速度的必要性。在本文中，我们展示了脊如何让我们调整液滴摩擦。根据液体速度和粘度，出现两种状态：具有低粘度的快速液滴动态变形并经历惯性摩擦，因此它们的速度最终由脊引起的变形固定；相比之下，粘性液滴几乎不与纹理相互作用，因此它们的速度通常受到粘性耗散的限制，就像在平坦的基材上一样。这两种机制之间的过渡揭示了惊人的形态变化：具有中等粘度的液滴伸长并采用蠕虫状形状，我们对其进行了定性描述。