We investigate the dynamics of spontaneous jumps of water drops from electrically charged nonwetting dielectric substrates during sudden step reductions in the gravity level. In the free-fall environment of a drop tower, the dynamics of drops subject to external electric fields are dominated by the Coulombic force instead of gravity. These forces lead to a drop bouncing behavior similar to well-known terrestrial phenomena though occurring for much larger drops (∼0.5 ml). We provide a one-dimensional model for the phenomenon, its scaling, and asymptotic estimates for drop time-of-flight in two regimes: at short-times close to the substrate when drop inertia balances the Coulombic force due to net free charge and image charges in the dielectric substrate, and at long-times far from the substrate when drop inertia balances free charge Coulombic force and drag. In both regimes, the dimensionless electrostatic Euler number $\mathbb{E}\mathrm{u}$, which is a ratio of inertia to electrostatic force, appears as a key parameter.

中文翻译：

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低重力下的电滴弹跳

我们研究了重力级突然降低过程中带电的非润湿介电基片水滴自发跳跃的动力学。在吊塔的自由下落环境中，受外部电场作用的液滴动力学主要由库仑力而不是重力支配。这些力导致液滴弹跳的行为类似于众所周知的地球现象，尽管发生的液滴更大（约0.5 ml）。我们提供了一种现象的一维模型，其缩放比例以及两种状态下飞行时间的渐近估计：在短时间接近底物的情况下，由于自由净电荷和图像导致惯性平衡库仑力电介质基板中的电荷 当掉落惯性平衡自由电荷库仑力和阻力时，长时间远离基材。在两种情况下，无因次静电欧拉数$\mathbb{Ë}\mathrm{ü}$惯性与静电力之比作为关键参数出现。