Abstract Drop impact on small cylindrical targets has been experimentally studied. Special attention has been drawn to the effect of the different target-to-drop diameters ratio on the evolution of the drop spreading after colliding with the surface. Three distinct regions have been identified as related to the ratio of the target-to-drop diameters ( β t ≡ D t / D 0 ), and the maximum spreading to drop diameters β max ≡ D ma / D 0 . The particular response of each type group was analyzed to define the specific spreading characteristics. The small target is an obstacle on the drop way, yet it does not stop its vertical velocity completely, as for the larger surfaces. A drop that impacts a small target continues to flow, not only radially but with some vertical velocity, in accordance with an appropriate energy balance. The analysis yielded expressions for the maximal spread of each impact type. Type-A was observed for ( 1 β t ⩽ β max ) and demonstrated mainly a radial spread, type-B ( 1 / 2 β t ⩽ 1 ) with two directional spread; radial and vertical, and type-C for ( β t ⩽ 1 / 2 ) a very small obstacle which barely affects the drop flow. The present analysis yielded expressions for the maximal spread of each impact type.

中文翻译：

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对具有不同目标与落差直径比的小目标的落差冲击

摘要 对小圆柱目标的落下冲击进行了实验研究。已经特别注意不同的目标与液滴直径比对液滴与表面碰撞后扩散演变的影响。已确定三个不同的区域与目标与液滴直径的比值 (βt ≡ D t / D 0 ) 以及与液滴直径的最大扩散 β max ≡ D ma / D 0 之比相关。分析每个类型组的特定响应以定义特定的传播特性。小目标是下降路径上的障碍，但它并没有完全停止其垂直速度，对于较大的表面。根据适当的能量平衡，撞击小目标的水滴继续流动，不仅是径向的，而且还有一定的垂直速度。分析产生了每种影响类型的最大传播的表达式。A 型被观察到 ( 1 β t ⩽ β max ) 并主要表现出径向传播，B 型 ( 1 / 2 β t ⩽ 1 ) 具有两个方向性传播；径向和垂直，类型 C 用于 ( β t ⩽ 1 / 2 ) 一个非常小的障碍物，几乎不影响液滴流动。目前的分析产生了每种影响类型的最大传播的表达式。