A droplet impinging on a liquid film finds numerous applications in diverse scientific fields. Although studies have primarily focused on spherical droplets, a droplet can present both spherical shape and non-spherical shape at the moment of impact. In the present study, the impact dynamics of a non-spherical droplet on a thin liquid film is investigated experimentally. The results show that, under the same film thickness and Weber number conditions, the splashing and deposition regimes are different for different droplet shapes such as prolate, sphere, and oblate. It is found that the splashing threshold (Ksp) is changed according to the shape of the droplet. Under the same condition when a spherical droplet is in the deposition mode, an oblate droplet is more likely to splash and form secondary droplets, while a prolate droplet is more splash-resistant even at higher Weber numbers. A modified theoretical model for crown radius evolution is developed. The predictions of theoretical model are found to agree well with the experimental results for spherical and non-spherical droplets. Moreover, at the same Weber number, a prolate droplet has a relatively higher maximum crown height than those of an oblate droplet and a spherical droplet.

中文翻译：

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非球形液滴对薄水膜的冲击动力学

撞击液膜的液滴在不同的科学领域有着广泛的应用。尽管研究主要集中在球形液滴，但液滴在撞击时可以呈现球形和非球形形状。在本研究中，通过实验研究了非球形液滴对薄液膜的冲击动力学。结果表明，在相同的膜厚和韦伯数条件下，不同液滴形状（如长条形、球形和扁圆形）的溅射和沉积状态不同。发现飞溅阈值（Ksp）根据液滴的形状而变化。在相同条件下，当球形液滴处于沉积模式时，扁圆形液滴更容易飞溅并形成二次液滴，而扁圆形液滴即使在更高的韦伯数下也更耐飞溅。开发了一种修正的冠半径演化理论模型。发现理论模型的预测与球形和非球形液滴的实验结果非常吻合。而且，在相同的韦伯数下，长圆形液滴比扁圆形液滴和球形液滴具有相对更高的最大冠高。