标题： 液态蘑菇的流体动力学 显示英文标题

标题： The fluid dynamics of liquid mushrooms

摘要： 当液滴撞击深液体池的表面时，如果具有足够的撞击能量，在空腔形成事件后可能会形成垂直射流。根据相关的时标和瑞利-普拉托不稳定性的影响，这种射流可能继续上升，或者通过颈部形成卫星液滴。这些结构与第二个入射液滴碰撞，该液滴从与第一个液滴相同的分配尖端喷出，可能会根据撞击条件形成各种层状图案，从而产生液态蘑菇或伞状结构。在这项研究中，我们首次对这类液态蘑菇的流体力学进行实验，并研究液滴撞击高度、表面张力和粘度对这类层状结构动力学的影响。我们进一步探讨了入射液滴撞击方向的作用，即是否是正面对撞或偏心碰撞上升射流或卫星液滴。我们讨论了层状结构直径的时空演化及其对表面张力、粘度和液滴撞击高度的敏感性。我们提出了一种基于能量的理论模型，用于预测层状结构的最大扩展直径，该模型在我们的实验中给出了准确的预测。我们的发现可能有助于深入了解自然界中经常观察到的流体动力学现象，也可能在某些特定应用中具有重要意义。 显示英文摘要

摘要： Droplets that impact the surface of a deep liquid pool may form a vertical jet after the cavity formation event, provided they have sufficient impact energy. Depending on the associated time scales and the effect of the Rayleigh Plateau instability, this jet may either continue to rise, or may form satellite droplets via necking. Collision of these structures with a second incoming droplet, ejected from the same dispensing tip as the first droplet, may result in the formation of various lamellar patterns, depending on the impact conditions, giving rise to liquid mushroom and or umbrella structures. In this research, we experiment for the first time with hydrodynamics of such liquid mushrooms, and study the effect of droplet impact height, surface tension, and viscosity on the dynamics of such lamellar formations. We further explore the role of the orientation of incoming droplet impact, ie whether head on or offset collision with the rising jet or satellite droplet. We discuss the spatiotemporal evolution of the lamella diameters, and its susceptibility to surface tension, viscosity, and droplet impact height. We put forward a theoretical model based on energetics, to predict the maximum spread diameter of the lamellae, which yields accurate predictions with respect to our experiments. Our findings may help to provide important insights towards a fluid dynamic phenomenon observed often in nature and may be important in niche utilities as well.